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Symposium : R

Nano-engineered bioactive interfaces

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08:30Electrochemically Deposited Chitosan/Silver Nanocomposite film on Biomedical NiTi Alloy for Antibacterial Applications
Authors : Penghui Li1, Xuming Zhang1, Ruizhen Xu1, Wenhao Wang1, 2, Kelvin W.K. Yeung2, Paul K. Chu1
Affiliations : 1Department of Physics & Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China; 2Division of Spine Surgery, Department of Orthopaedics and Traumatology, The University of Hong Kong, Pokfulam, Hong Kong, China
Resume : Biomedical NiTi-based shape memory alloys suffer from post-surgery bacterial infection issues and it is of great importance to prevent bacteria adhesion and growth on the implants by using the proper surface modification techniques. In this study, a chitosan/silver nanocomposite film is deposited on NiTi alloy by an electrochemical method to enhance the antibacterial characteristics. The chemical structure and morphology of the films are systematically investigated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM). The presence of silver nanoparticles is confirmed by energy dispersive X-ray analysis (EDS) and X-ray diffraction (XRD). The antibacterial properties of the chitosan/silver composite films are assessed and there are significant effects against the model bacterial Escherichia coli (E. coli). Therefore, the present study suggests that the antibacterial film is promising in orthopedics, dentistry, and other biomedical devices.
R.X 1
08:50Nano Composite DLC Coating for Antimicrobial Medical Applications
Authors : Jan Heeg1, Christoph Mewes1, Antje Schütz1, Torsten Barfels1 and Marion Wienecke1, Andreas Podbielski2, Kathleen Arndt2, Henrike Rebl2 and Barbara Nebe2,
Affiliations : 1: Hochschule Wismar; 2: Universität Rostock
Resume : Surface design for medical application by nano engineering of DLC intends basic properties like biocompatibility, advanced functionality such as antibacterial or antiadhesive behavior depending on application and reliable modification, particularly permanent film adhesion and flexibility for shape changing implants. In our work we modified DLC films by nano engineering, especially by gradient and intermediate layers with nanoscaled thickness or filled with metal clusters. DLC (a-C:H) based nano composite films were deposited at relevant metallic test substrates (TiAlV/316L). The films were produced by PECVD using low pressure capacitively coupled acetylene plasma with a negative self bias tension applied to the substrate. HDMSO evaporation was used for Si deposition as adhering film component. The films were proved to show good adherence and excellent flexibility. Moreover Cu enriched a-C:H films were deposited at TiAlV substrates using a newly developed PECVD/RF-sputtering hybrid process. Biofilm formation by Staphylococcus epidermidis RP62A on specimen surface and potential antibacterial activity is monitored by viable counts over 10 days culture periods. Both planktonic and biofilm-associated bacteria are assessed. Immediately prior to counting, biofilm bacteria are mobilized by sonication. Concerning microbial colonization, so far no differences between pure DLC-layers and untreated titan surfaces could be detected. Our experiments revealed that human osteoblasts adhere and spread well on pure DLC films. In contrast, the Cu-doped DLC layer inhibited osteoblast vitality but also the microbial colonization.
R.X 2
09:10Surface characterization of micro patterned surfaces for optimization of patterned bacterial adhesion.
Authors : Nina B. Arnfinnsdottir, H. Ian Muri, Bjørn T. Stokke, Marit Sletmoen
Affiliations : Biophysics and Medical Technology, Dept of Physics, The Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
Resume : Control of bacterial adhesion in predesigned patterns supports determination of molecular parameters of individual cells in populations of bacteria in an efficient manner, while strictly controlling the environment of the bacteria. In the present project we explore application of soft lithography for preparation of patterned supports designed for monitoring of bacterial populations at the individual bacterial level. We use micro contact printing to pattern surfaces with arrays of “islands” of bacterial adhering chemicals surrounded by chemicals that resist bacterial adhesion in order to produce single bacterial arrays. These surfaces are intended to be used as a tool to study the heterogeneity of gene expression in the attached bacteria. We have produced patterned surfaces with features down to 4 µm, which is sufficiently small for capturing single bacteria. The preparation of these surfaces has been optimized with respect to process variables like stamp manufacturing, stamping pressure and duration, and selection of chemicals. The presence of the patterned areas has been confirmed using fluorescence techniques, and high resolution surface topography of the patterned areas has been obtained using Atomic Force Microscopy (AFM). This has confirmed 2D patterned surfaces of squared arrayed islands of bacterial adhering chemicals surrounded by a uniform layer of bacterial repellant. These initial results will be complemented by additional surface characterization tools to provide information on nanomechanical properties, friction and nature of interaction forces, as well as direct determination of bacterial adhesion.
R.X 3
09:25Zirconium Nitride/Silver Nanocomposite Coatings to Combat External Fixation Pin Infection
Authors : David Wickens, Glen West, Peter Kelly, Joanna Verran, Kathryn Whitehead
Affiliations : School of Healthcare Sciences, Manchester Metropolitan University; School of Engineering, Manchester Metropolitan University; School of Engineering, Manchester Metropolitan University; School of Healthcare Sciences , Manchester Metropolitan University; School of Healthcare Sciences, Manchester Metropolitan University
Resume : External bone fixation is a frequently applied medical procedure for rehabilitating severe fractures. The pins used require strict cleaning regimes at the entry site. However, the pin sites are still putative ports for conceivable pathogenic microbial infection. The study aim was to potentially combat and reduce pin tract infections (PTI) using zirconium nitride/silver coatings; investigate the coating characteristics, determine the antimicrobial properties against Staphylococcus aureus and Staphylococcus epidermidis using LiveDead™ and CTC staining, and demonstrate the coatings biocompatibility against human cells (U-937 monocyte inflammatory cell line). Zirconium Nitride (ZrN) is a hard wearing compound possessing corrosion resistance, thus giving it biomaterial potential. Combining with silver gives the coating potential for a multifunctional surface with antimicrobial characteristics. Magnetron sputtering was used to reactively co-sputter zirconium and silver, to produce nanocomposite thin films with a range of silver concentrations. Addition of silver to the coatings increased antimicrobial efficacy towards the Staphylococci. No antimicrobial leaching of silver was observed from any of the surfaces, however S. aureus was retained in higher numbers than S. epidermidis. The bacteria were reduced by 1-log when added to the U-937 cells. These coatings have demonstrated potential to be used on external fixation pins to reduce PTI’s.
R.X 4
09:40Antimicrobial designing alginate composite materials
Authors : Ioannis Liakos, Elisa Mele, Loris Rizzello, Ilker S. Bayer, David J. Scurr, Pier Paolo Pompa, Roberto Cingolani, Athanassia Athanassiou
Affiliations : (Ioannis Liakos, Elisa Mele, Loris Rizzello, Ilker S. Bayer, Pier Paolo Pompa) Center for Biomolecular Nanotechnologies, Istituto Italiano di Tecnologia @UniLe, via Barsanti, 73010 Arnesano, Lecce, Italy. (David J. Scurr) University of Nottingham, School of Pharmacy, Biophysics and Surface Analysis, Boots Science Building, University Park, Nottingham, NG7 2RD, UK. (Roberto Cingolani, Athanassia Athanassiou) Istituto Italiano di Tecnologia (IIT), via Morego 30, 16163 Genova, Italy.
Resume : Sodium and calcium alginates are natural polysaccharides derived from sea algae and were used as matrices for the encapsulation of active ingredients. Povidone Iodine (hydrophilic) and Essential Oils (hydrophobic) were employed as substances that possess antimicrobial properties and they were incorporated well into the alginate polymers. The materials formed were in the shape of films, spherical beads, fibers and electrospun nanofibers (600 nm diameter). Techniques such as Optical, Atomic Force and Scanning Electron Microscopy, Time-of-Flight Secondary Ion Mass Spectroscopy and Fourier Transform Infrared were used to analyse the topographical features of the composites. Drug delivery techniques were employed to study the kinetics of the release of the antimicrobial substances from the matrices that were depended both in the ingredient hydrophilicity and of the matrix chemistry. The antimicrobial activity of the materials was tested against Escherichia Coli bacteria and Candida Albicans fungus, where the exact effective concentration barrier for their antiseptic activity was determined. The results showed that povidone iodine and cinnamon, menthol and lemongrass essential oils encapsulated into alginates had highly antimicrobial properties.
R.X 5
10:30Shaping the biological identity of implant materials: A topographical approach
Authors : Davide Franco, Livia Banninger, Christoph Starck, Volkmar Falk, Dimos Poulikakos, Aldo Ferrari
Affiliations : Laboratory of Thermodynamics in Emerging Technologies, Institute of Energy Technology Department of Mechanical and Process Engineering, ETH Zurich, Sonneggstrasse 3, CH-8092 Zurich, Switzerland University of Zurich, Department of Cardiovascular Surgery Raemistrasse 100 Zurich CH-8091 Switzerland
Resume : Engineering life-long, functional implants that require little or no maintenance will pave the way to the next generation of biomedical devices. The development of an optimal synthetic scaffold, bearing the ideal combination of physical, chemical and biological stimuli, is now conceivable and at the verge of implementation. In this frame, a promising approach to enhance the performance of implant materials is the modification of their surface with nano- and micro-scale topographies with the goal of improving integration within the target tissue. The surface geometry has a dramatic effect on the morphology and function of cells interacting with a substrate. Therefore, topographical modifications can be exploited either to passively reduce inflammatory body responses, or to actively induce the population of the grafted material by host cells and thus the generation or re-generation of a functional tissue. Here, we report on the combined effect of topography and Wall Shear Stress (WSS) on the endothelialization of target substrates. Potential applications to reduce the thrombogenic effect of synthetic materials interacting with the human vasculature are discussed.
R.XI 1
11:00Peptide Nanotubes: From Self-Assembly Towards Applications
Authors : I. W. Hamley, V. Castelletto
Affiliations : Dept of Chemistry, University of Reading, Whiteknights, Reading RG6 6AD, U.K.
Resume : We have discovered ultrathin peptide nanotubes formed by several surfactant-like peptides. In several cases, evidence of the mechanism of formation of the nanotubes by wrapping of helical ribbons is directly obtained from cryogenic-TEM. Peptide (Ala)6(Arg) forms 3 nm thick sheets at low concentration, these wrap into helical ribbons and nanotubes at high concentration. The arginine functionality on the tube walls may lead to useful applications. Lipopeptide C16-KKFFVLK shows a remarkable thermoreversible transition between helical nanoribbons/nanotubes and twisted tapes. This could form the basis of a delivery system based on release of encapsulated cargo, or of a bioactive actuator material.
R.XI 2
11:15Nanofibrous scaffolds for Cartilage Regeneration: Scaffold Parameters at Nanoscale that affect Cell Function
Authors : P. Kavatzikidou1, Th. Kotziapashi1, V. Karagkiozaki1, P. Karagiannidis1, D. Georgiou1, N. Kalfagiannis2, E. Pavlidou3, S. Logothetidis1
Affiliations : 1 Dept of Physics, Laboratory for Thin Films – Nanosystems and Nanometrology, Aristotle University of Thessaloniki, GR-54124, Thessaloniki, Greece 2 Texas A&M University at Qatar, 23874, Doha, Qatar 3 Dept of Physics, Aristotle University of Thessaloniki, GR-54124, Greece
Resume : Cartilage regeneration is a complex process that requires a tissue engineering strategy at nanoscale. In an attempt to replicate the natural cartilage related environment, polymeric nanofibrous scaffolds were developed and their effect on fibroblasts and chondrocytes adhesion and growth was investigated. The correlation between the development parameters and the physical and biological properties of these nanoscaffolds was performed. The biodegradable polymeric nanofibrous (chitosan, gelatin and polycaprolactone) scaffolds were developed by the Electrospray Deposition method. MTT assay, a known cytotoxicity assay, was used to determine their cytocompatibility behaviour in direct contact with cell lines under static conditions, while SEM and fluorescence microscopy were applied to observe the proliferated cells on the nanoscaffolds. The wetting behavior, morphology and mechanical properties of the nanoscaffolds were assessed by Contact Angle and Atomic Force Microscopy, respectively, while the optical properties by Spectroscopic Ellipsometry. Different concentrations of the polymeric scaffolds produced variable nanofibrous structures with different fibres diameters that affected cell proliferation. The surface roughness of the nanoscaffolds influenced the cell proliferation. The physical properties of the nanoscaffolds accompanied the above findings. Acknowledgment: The authors would like to thank the NATIONAL ACTION:«COOPERATION 2009» Program – NanoArthroChondros.
R.XI 3
11:30Controlling collective cell behavior with topography
Authors : Ventre M., Iannone M., Natale C.F., Netti P.A.
Affiliations : Department of Materials and Production Engineering University of Naples Federico II; Center for Advanced Biomaterials for Health Care@CRIB Istituto Italiano di Tecnologia
Resume : Topographic signals deeply affect cell adhesion, polarization and migration. While various types of topographies, as gratings, pits and pillars, have been widely studied at single cell level, only few works have been reported on multicellular assemblies. In the context of submicrometric signals, cells may interact with each other and this prompts questions on the influence of topographies on multicellular assemblies. In this work, the effects of submicrometric gratings on adhesion and migration of mesenchymal cell is shown. Particular emphasis is given on the long scale order of multicellular assemblies in terms of ECM and cell orientation. Confocal imaging and time lapse videos were carried out at different time points. Cells seeded on patterned substrates, perceived the topographical signal and acquired an elongated shape perfectly parallel to the substrate grooves. In addition, these cells moved in the same direction of the topographic pattern. Focal adhesions were visualized in proximity of cell edges, and they displayed strong coalignment with the grooves. Conversely, cells seeded on flat surface did not show a visible and ordered orientation but maintained random shape and movement. Moreover SHG analysis underlined the spatial organization of the neosythesized collagen fibers. These results might be particularly relevant in the case of tissue engineering which aims at regenerating tissues with predetermined microstructural features from high densities cell cultures
R.XI 4
14:00Biomaterials for Regenerative Engineering
Authors : Garcia AJ
Affiliations : Georgia Institute of Technology
Resume : Cell adhesion to extracellular matrices plays central roles in the formation, maintenance and repair of numerous tissues. Moreover, cell adhesion to adsorbed proteins or adhesive sequences engineered on surfaces is important to biomaterials, tissue engineering, and biotechnological applications. Cell adhesion to extracellular matrix proteins is primarily mediated by the integrin family of adhesion receptors. We have established biomolecular strategies for the engineering of bioartificial materials to direct integrin binding specificity and signaling. These materials regulate cell adhesion and signaling to direct in vitro cell function (adhesion, proliferation, and differentiation) and in vivo healing responses for tissue repair and integration. Notably, these surface engineering strategies focus on modifying clinically relevant materials and are translatable to existing biomedical devices. In one application, we have engineered polymeric brush coatings on titanium that present controlled densities of engineered ligands that enhance implant osseointegration and bone repair. In another application, we have synthesized synthetic hydrogels presenting defined densities of adhesive ligands, vasculogenic growth factors, and protease degradable sequences that direct in vivo vascular growth and therapeutic vascularization. These approaches provide a basis for the rational design of robust bioinstructive materials that tailor adhesive interactions and elicit specific cellular responses for the development of 3D hybrid scaffolds for enhanced tissue reconstruction, "smart" biomaterials, and cell growth supports.
R.X12 1
14:30Synthesis and characterization of biodegradable cellulose based foams
Authors : Christian Demitri, Antonella Giuri and Alessandro Sannino
Affiliations : University of Salento, Department of Engineering for Innovation, 73100 - Lecce
Resume : Foam is a two-phase system characterized by a dispersion of a gas bubble phase in a continuous liquid or a solid phase. Cellular solids are quite diffuse in nature, e.g. cork, sponge, coral, wood, pumice stone. Many foods have a cellular structure: bread has cells created by the fermentation of yeast; meringue is foam of egg whites with sugar. The approach was to study the polymerization initiated by a thermo-initiator activated by microwaves. In this work a mixture of a sodium salt of carboxymethylcellulose (CMCNa) and PEG700 was used for the preparation of a microporous structure by using the combination of two different procedures. First a physical foaming was induced by using Pluronic as blowing agent, and followed by a chemical stabilization. The second step was carried out by means of a Azobis(2-methylpropionamidine)dihydrochloride as thermoinitiator. This reaction was activated by eating the sample using a microwave generator. The influence of different CMCNa and PEG ratios on the final properties of the foams was finally investigated. The viscosity, water absorption capacity, elastic modulus and porous structure were evaluated for each sample. The foam including the 20% of PEG in the mixture, demonstrated higher viscosity and stability before the thermo-polymerization. In addition, increased water absorption capacity, mechanical resistance, and a more uniform micro-porous structure were obtained for this sample. In particular, the foam including the 3% of CMCNa shows a hierarchical structure with open pores of different sizes. This morphology seems to increase the mechanical properties of the foams.
R.X12 2
14:45Towards hybrid PLA-organic bioactive glass fibers inducing vascularized bone regeneration
Authors : Nadege Sachot, Oscar Castano, Elisabeth Engel, Malgorzata Lewandowska, Josep Anton Planell
Affiliations : Institute for Bioengineering of Catalonia (IBEC), Barcelona, Spain; CIBER en Bioingenería, Biomateriales y Nanomedicina (CIBER-BBN), Spain; Technical University of Catalonia (UPC), Barcelona, Spain; Warsaw University of Technology (WUT), Warsaw, Poland
Resume : To date, hybrid materials appear to be one of the most promising candidates for the development of novel scaffolds for bone regeneration due to their good bioactivity and mechanical properties. However, they often lack of ability to induce vascularization, a crucial process in the formation of a viable and fully functional new tissue. The aim of this study is the design of a hybrid scaffold that mimics the fibrous structure of the extracellular matrix of natural bone and that not only possess good ostointegrative properties but that is also able to induce angiogenesis. Based on the sol-gel method, non-woven and aligned polylactic acid-Ti,Ca,P,Na organic glass fibers were successfully produced by electrospinning. Physico-chemical characterization has shown that compared to pure polymeric scaffolds, the obtained fibers exhibit excellent hydrophilic properties, enhanced mechanical features, good mineralization potential and a stable glass composition ratio when degrading in SBF. In vitro assays also revealed that mesenchymal stem cells greatly attach, spread and proliferate on the material. According to our previous studies, the glass developped by our group acts as an ion release agent that allows the triggering of specific cellular responses such as osteogenesis and vascularization. Additionally to its structure, this novel scaffold represents therefore a significant improvement toward the realization of functional cell-instructive materials.
R.X12 3
15:00Fabrication, characterization and porosity analysis of a scaffold based on a standing fibrin
Authors : M. Barbalinardo, F. Valle, B. Chelli, E. Bystrenova, E. Zanotto, G.Pellegrini and F. Biscarini
Affiliations : Consiglio Nazionale delle Ricerche (Istituto per lo Studio dei Materiali Nanostrutturati) (CNR-ISMN), via Gobetti 101, 40129 Bologna, Italy; University of Bologna “Alma Mater Studiorum”, via Zamboni 33, 40126, Bologna, Italy; Nano4bio S.R.L., viale G. Fanin 48, 40127, Bologna, Italy;Center for Regenerative Medicine “Stefano Ferrari”, University of Modena and Reggio Emilia, Modena, Italy.
Resume : Nanomedicine and tissue engineering attempt to repair or improve the biological functions of tissues that have been damaged or have ceased to perform their role through three main components: a biocompatible scaffold, cellular component and bioactive molecules. Nanotechnology, using advanced manufacturing techniques such as conventional and unconventional lithography, allows fabricating supports with geometries, sizes and displaying physical chemical properties tuneable over different lengthscales. In this work we report the fabrication of two scaffolds made of fibrin gel, standing fibrin film and standing fibrin clot, for the regeneration of tissues that can be applied to various diseases. Fibrin gel films are used to observe the growth of cells on random networks. Films of different thickness have been fabricated with special attention to the realization of a micro-frame that allows a simple manipulation of the structure. Such a standing fibrin scaffold prevents the artefacts arising from the interaction of the films with other surfaces. The fibrin gel clots have then been stretched to observe if the cells growth and migration is influenced by the orientation of the fibers. The ultrastructure characterization of the network is crucial for evaluating its morphology, porosity and biological efficacy, thus we characterized the fibrin films by scanning electron microscopy and atomic force microscopy. Power spectrum analyses of the images have been performed to provide the characteristic lengths of the fibrin network. These scaffolds can also be bi-functionalized to allow the co-culture of different cell types on the two sides thus promoting the reconstruction of complex tissues and processed to fabricate a tubular scaffold.
R.X12 4
15:15Cell viability and proliferation on 3D collagen gel scaffolds using conductive-polymer nanofibers
Authors : Sirinrath Sirivisoot (1), and Benjamin S Harrison (2)
Affiliations : (1) Biological Engineering, Faculty of Engineering, King Mongkut’s University of Technology Thonburi, Bangkok 10140, Thailand (2) Wake Forest Institute for Regenerative Medicine, Wake Forest University School of Medicine, Winston-Salem, NC 27157, USA
Resume : Nerve injuries are among the primary causes of human disability. The key component of neural communication in the body is the action potential generated at the synapse. Electrical stimulation has been used to promote neurite outgrowth and thereby enhance nerve regeneration in culture. The incorporation of conductive polymer into scaffolds would allow for localized and external control of electrical stimuli directly to the nerve cells. One current approach is the fabrication of synthetic extracellular matrix analogues using conductive polymers that can support three-dimensional (3D) cell culture and are suitable for nerve implantation. In the present study, the structure and electrical stimulation effects with conductive-collagen gels as 3D scaffolds were investigated. The scaffolds were collagen gels mixed with either as-synthesized polyaniline or poly(3,4-ethylenedioxythiophene) nanofibers, and nerve cells (PC-12). Cell proliferation assay and confocal microscope imaging showed the scaffold’s biocompatible potential. The results of electrical conductivity suggested that using conductive polymers could allow a control of electrical signals within a conductive-gel scaffold system. Using a conductive-gel scaffold may allow directed nerve growth and differentiation to form functional nerve tissue.
R.X12 5
15:30Realization of 3D ‘living’ tissue as in vitro platform for understanding of biological phenomena
Authors : F. Urciuolo, G. Imparato, C. Casale, P.A. Netti
Affiliations : Center for Advanced Biomaterials for Health Care@CRIB, Istituto Italiano di Tecnologia Largo Barsanti e Matteucci, 53 80125 Naples - Italy
Resume : The fabrication of living tissue equivalents, enabling in vitro studies of relevant biological phenomena, represents now day the new frontier in biomedical engineering. To this end, we realized a tissue equivalent made up by endogenous biological components preserving both natural extracellular matrix (ECM) architecture and Cell-ECM cross talking. This goal has been reached by means of a two-step bottom-up tissue engineering process composed by the realization of functional micrometric tissue precursors (μTP) of connective origin and their assembling up to millimitetric scale generating a 3D Human Dermis Equivalent (HDE). Histological analysis and Second Harmonic Generation imaging showed that both μTPs and HDE were composed by endogenous collagen fibers. To test ability of HDE in mimicking natural biological phenomena, its responsiveness in terms of ECM remodeling to an external induced damage (photo-aging and wound), was assessed. Moreover, the realized HDE was able to sustain the growth of an epithelial layer paving the way towards the realization of a full human skin equivalent model. By exploiting the “living” features of the realized HDE it could be possible to perform studies to figure out phenomena involved in pathologic events and to study the efficacy of therapeutic agents. In this fashion the proposed 3D model represents a biological platform that could bridge the gap between standard 2D cell-based assays and the in vivo environment.
R.X12 6
15:45An innovative approach for the design of biomimetic scaffolds for myocardial regeneration
Authors : V. Chiono 1, S. Sartori 1, A. Silvestri 1, M. Boffito 1, A.M. Di Rienzo 1, P. Mozetic 2, A. Rainer 2, S. Giannitelli 2, D. Nurzynska 3, F. Di Meglio 3, C. Castaldo 3, E. Bernard i4, G. Ciardelli 1
Affiliations : 1Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Corso Duca degli Abruzzi 24, Turin, Italy 2 Laboratory of Tissue Engineering, University Campus Bio-Medico di Roma, Via Alvaro del Portillo 21, Rome, Italy. 3 Department of Public Health, University of Naples “Federico II”, Via Pansini 5, Naples, Italy 4National Institute of Metrological Research (INRIM), Strada delle Cacce 91, Turin, Italy
Resume : The recent trend of Tissue Engineering (TE) is the use of degradable biomimetic tissue-specific materials, providing appropriate chemical and biological cues that mimic the native microenvironment. In the field of myocardial regeneration, a promising approach is to engineer scaffolds modulating cell response in a similar manner as niches found in vivo. Segmented polyurethanes are attractive for myocardial TE, being elastomeric biomaterials with tunable physicochemical properties and good biocompatibility. A biocompatible polyurethane (PU) (Mn = 22.000g/mol) was synthesised from poly-ε-caprolactone diol (PCL) (Mn= 2000 g/mol), 1,4-butanediisocyanate (BDI) and lysine ethyl ester (Lys). PU semicrystalline nature was confirmed by DSC and AFM. Tensile mechanical tests showed the elastomeric properties of PU (elastic modulus: 8,8± 0,6 MPa; elongation at break: 691,3± 38,0 %). Melt-extrusion rapid prototyping technique was applied to prepare 3D scaffolds with a 0/90° lay-down pattern. Human pathological cardiac fibroblasts (isolated from fragments of explanted hearts with ischemic cardiomyopathy) were cultured on scaffolds for 8 weeks to allow the cells to deposit extracellular matrix (biomatrix, BM) on the scaffold. Subsequently, BM-coated PU scaffolds were decellularised and seeded with cardiac progenitor cells (CPCs) showing a higher ability to support CPC adhesion, proliferation, migration and maturation, as compared to uncoated PU scaffolds.
R.X12 7
16:30Poster session 2
Authors : Barbara Palazzo, Francesca Gervaso, Francesca Scalera, Anna Gallo, Antonella Casillo, Alessandro Sannino, Luigi Ambrosio, Corrado Piconi
Affiliations : Department of Engineering for Innovation, University of Salento, Via Monteroni, Campus Ecotekne, 73100 Lecce (Italy) 2GHIMAS S.p.A.,MeLab, Cittadella della Ricerca, SS7 per Mesagne, Km 7+ 300, 72100,Brindisi, Italy 3CNR-IMCB, Piazzale Tecchio, 80, 80125, Napoli, Italy
Resume : To control the interplay between materials and cells, creating an environment able to promote functional tissues regeneration, is the goal of tissue engineering. To this aim, scaffolds can be engineered to provide biological function and actively induce tissue regeneration, not only to act as a bare physical support. Considering the above and following a biomimetic approach, a nano-Hydroxyapatite/chitosan (nHAp/Ch) scaffold as a potential osteoinductive biomaterial was developed. A freeze-drying technique combined with a novel “in situ” crystal growth method, able to nucleate “bone-like” HAp nanocrystals on polymer pores surface was developed. The biomaterials showed a highly porous and interconnected structure. The XRD patterns and calculated domain sizes of the nHAp crystals nucleated on chitosan structure are very similar to the deproteinated bone apatite ones. The nHAp/Ch equilibrium modulus from unconfined compression test in PBS was significantly higher than pure chitosan one. Osteoblasts exhibited superior initial cell attachment, spreading and proliferation on the nano-composite scaffold compared to pure chitosan scaffolds. The enhanced in vitro performance induced by nHA coating was demonstrated by good proliferation and osteogenic differentiation of mesenchimal cells. The observations related to well-developed structure morphology, physicochemical properties and high cytocompatibility suggest that nHAp/Ch scaffolds are potential candidate materials for bone regeneration.
RP.2 1
16:30A novel collagen/hydroxyapatite biphasic substitute for osteochondral repair: scaffold design and its in vivo performance in a swine model
Authors : Gervaso F., Scalera F. , Sannino A. , Deponti D. , Sosio C. , Di Giancamillo A. , Peretti G.
Affiliations : 1 Department of Engineering for Innovation, University of Salento, Via Monteroni, Campus Ecotekne, 73100 Lecce (Italy) 2 IRCCS Istituto Ortopedico Galeazzi, Milan, Italy 3 Department of Biomedical Sciences for Health, University of Milan, Italy
Resume : A novel three-dimensional biphasic substitute made of collagen scaffold located superiorly, partially penetrating into a hydroxyapatite sponge was developed for osteochondral lesion repair in a swine model. The collagen scaffold was fabricated by a freeze-dying technique, the hydroxyapatite (HA) scaffold by a polymeric sponge replica method using a reactive sub-micron powder synthesized in our laboratory by hydroxide precipitation sol-gel route. To get a partial but strong collagen/hydroxyapatite interconnection a novel multi-step procedure was assessed. Substitutes with suitable dimensions for in vivo test were fabricated and successfully implanted in osteochondral lesions of swine knees. Six osteochondral lesions were created in each trochlea of six pigs. Two scaffolds with autologous chondrocytes and two unseeded scaffolds were implanted, while two lesions were left untreated. After three months, the composites were removed and the degree of maturation of the repaired tissue was evaluated. The results showed that the novel osteochondral scaffold is easy to handle for surgical implant and stable in the site of implant; at the end of experimental time, all implants were well integrated to the surrounding tissue. At early experimental time the histological quality of the repaired tissue produced in the group implanted with the osteochondral scaffold seems to be higher than the control group.
RP.2 2
16:30A novel pyrofluidic platform for 2D-3D electrohydrodynamic manipulation of liquid at nanoscale
Authors : S.Coppola1,2, V. Vespini1, O. Gennari1, M. Paturzo1, L.Miccio1,F. Merola1,S. Grilli1 and P. Ferraro1
Affiliations : 1-INO CNR Istituto Nazionale di Ottica, Unit of Napoli,Via campi Flegrei 34, 80078 Pozzuoli (NA),Italy 2-Department of Chemical Materials and Production Engineering. University of Naples Federico II, Piazzale Tecchio 80, (Naples), Italy
Resume : Through the years in many biological and biotechnological applications much research activity has been directed towards the development of miniaturized instrumentations with the aim at fabricating highly integrated and automated ‘lab-on-a-chip’ systems based on microfluidics. Recently a novel concept was developed, where the actuation of liquids in contact with a polar dielectric crystal was achieved through an electrode-less configuration. In particular, the method made use of the pyroelectric effect induced onto Lithium Niobate (LN) crystals. This new method represents a new pyro-platform to manipulate droplets and transport micro object. This new technology could be applied to different kind of materials: from liquid to high viscous materials, such as biopolymer. At the same time the manipulation of micro-sized objects in lab-on-a-chip and microfluidic environment is essential for numerous kinds of experiments and procedure. Combining the properties of our platform we would be able to control and manipulate dielectric micro-targets by a touch-less approach. This approach enables, at same time, the handling of liquid or even dry nanoparticles and their delivery on the targets of interest, proposing a sort of microrobot for the manipulation of solid as well as liquid matter. Moreover this platform could be used for controlling the instabilities and self-assembling of polymeric liquids for fabricating single or arrays of complex 3D microstructures usable as biosensors.
RP.2 3
16:30Antibacterial calcium phosphate-based coatings containing silver for medical implants
Authors : A.A. Ivanova1, M.A. Surmeneva1, I.Y. Grubova1, A.A. Sharonova1, V.F. Pichugin1, M.V. Chaikina2, O. Prymak3, M. Epple3, R.A. Surmenev1
Affiliations : 1Department of Theoretical and Experimental Physics, Centre of Technology, Tomsk Polytechnic University, 634050 Tomsk, Russia; 2Institute of Solid State Chemistry and Mechanochemistry, Siberian Branch of Russian Academy of Sciences, 630128 Novosibirsk, Russia; 3Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, 45117 Essen, Germany.Academy of Sciences, 630128 Novosibirsk, Russia; Inorganic Chemistry and Center for Nanointegration Duisburg-Essen (CeNIDE), University of Duisburg-Essen, 45117 Essen, Germany
Resume : Surface modification is an important and predominant way to obtain biofunction in metals for biomedical application. In this study, the biocompatible antibacterial coatings on the basis of Ag-doped hydroxyapatite (Ag-HA) prepared by rf- magnetron sputtering were examined. Plates of Ti and silicon were used as substrates. The target for sputtering was sintered from a synthetic stoichiometric hydroxyapatite powder, Ca(10-x)Agx(РО4)6(ОН)(2-x), x=0.3. The influence of the processing parameters on the biocomposite surface properties, microstructure and coating’s composition was carried out by SEM, EDX, XRD, IR spectroscopy and spectroscopic ellipsometry. The investigation results revealed that coatings are nanostructured, homogeneous, dense, and pore-free. The chemical composition of the sputter-deposited coating was identical to the target. However, an increase in the negative electrical bias on the substrate led to a decrease of the coating thickness. In addition, the average size of the grains decreased from 55±15 nm (grounded substrate) up to 30±10 nm when an electrical bias of -100 V was applied. Thus, the experimental data revealed that rf-magnetron sputtering is an effective method to modify the surface of metallic implants. The variation of the process conditions allows us to deposit Ag-HA coatings with the tailored properties. Acknowledgments: the authors are thankful to Prof. M. Epple for the assistance with Ag-HA coatings characterization.
RP.2 4
Authors : R. Cristescu1, G. Dorcioman1, G. Socol1, I.N. Mihailescu1, D. Mihaiescu2, A. Grumezescu2, M. Enculescu3, C. Chifiriuc4, R. D. Boehm5, R. J. Narayan5, and D. B. Chrisey6
Affiliations : 1National Institute for Lasers, Plasma & Radiation Physics, Lasers Department, P.O.Box MG-36, Bucharest-Magurele, Romania 2Faculty of Applied Chemistry and Materials Science, “Politehnica” University of Bucharest, 1–7 Polizu Street, 011061 Bucharest, Romania 3National Institute of Materials Physics, P.O. Box MG-7, Bucharest-Magurele, Romania 4Faculty of Biology, University of Bucharest, Microbiology Immunology Department, 77206-Bucharest, Romania 5Biomedical Engineering, University of North Carolina, Chapel Hill, NC, USA 6Department of Physics and Engineering Physics, Tulane University, New Orleans, LA, USA
Resume : We report on the deposition of novel meso-phenyl unsymmetrical substituted porphyrin, 5-(4-carboxyphenyl)-10,15,20-triphenylporphyrin (CPTPP) thin films by matrix assisted pulsed laser evaporation (MAPLE) onto silicon substrates with screen-printed transparent conducting oxide electrodes, aiming to design a fluorecent-chemosensor for biogene amines. The biogene amines are directly related to the meat freshness and this kind of sensors target a rapid detection via a combined fluorescence-electrochemical detection. FTIR spectroscopy and Raman spectrometry have confirmed that the chemical structure of MAPLE-deposited thin films was preserved for fluences within the range 200-400 mJ/cm2. AFM examination has shown that the thin films had a uniform and continuous morphology for 300 mJ/cm2 laser fluence. Cyclic voltammograms on screen printed electrodes have demonstrated that CPTPP is appropriate as a single mediator for various biogene amines (histamine, cadaverine, putresceine) with high yield in fluorescence and electrochemical signal. We have shown that MAPLE deposition of CPTPP thin films can replicate both the bulk structure and serve as a soft technique in deposition of porphyrin thin films and patterns.
RP.2 5
16:30Biocompatible magnetic PLGA-PVA thin film fabricated by MAPLE for the design of new surfaces resistant to microbial colonization
Authors : Alexandru Mihai Grumezescu1, Gabriel Socol, Valentina Grumezescu1,2, Emanuel Axente2, Marcela Socol3, Anton Ficai1, Ecaterina Andronescu1, Cristina Daniela Ghitulica1, Ion Mihailescu2, Coralia Bleotu4, Carmen Mariana Chifiriuc5
Affiliations : 1University Politehnica of Bucharest, Faculty of Applied Chemistry and Materials Science, Department of Science and Engineering of Oxidic Materials and Nanomaterials, Polizu Street no 1-7, 011061 Bucharest, Romania; 2National Institute for Lasers, Plasma & Radiation Physics, Lasers Department, P.O.Box MG-36, Bucharest-Magurele, Romania; 3National Institute for Materials Physics, Magurele, Ilfov, Romania; 4Stefan S Nicolau Institute of Virology, Bucharest, Romania; 5Faculty of Biology, University of Bucharest, Microbiology Immunology Department, Aleea Portocalilor 1-3, Sector 5, 77206-Bucharest, Romania
Resume : Novel improved materials and surfaces exhibiting limiting conditions for microbial biofilm development are urgently required in the medical environment. The results of this study show the benefit of using usnic acid, an anti-biofilm natural compound, combined with a 5 nm core/shell nanosystem, entrapped into the PLGA-PVA microspheres, fabricated by MAPLE, for obtaining functionalized surfaces with improved anti-adherence and anti-biofilm properties. The fabricated thin films were characterized by Transmision Electron Microscopy, X-Ray Diffraction, Scanning Electron Microscopy, Differential Thermal Analysis-Thermogravimetric Analysis and InfraRed Microscopy. For the quantitative measurement of the biofilms formed on the obtained surfaces, a culture-based method for viable cell counts was used. Also, interaction with eukaryotic cells was evaluated to prove the biocompatibility of the fabricated thin films. The optimized surfaces proved to be more resistant to staphylococcal colonization and biofilm formation. Degradation testes of magnetic PLGA-PVA thin films were performed in stimulated body fluid (SBF) solution at 37 °C in a dynamic regime using a bioreactor which simulates the flow of blood in our vessels. The use of MAPLE could represent a very useful tool in obtaining functionalized surfaces for the prevention of microbial contamination in different natural, industrial and medical environments.
RP.2 6
16:30Bioinspired nano-shuttles to overcome blood brain barrier.
Authors : Daniela Guarnieri, Annarita Falanga, Ornella Muscetti, Rossella Tarallo, Sabato Fusco, Massimiliano Galdiero, Stefania Galdiero, Paolo Netti
Affiliations : Center for Advanced Biomaterials for Health Care@CRIB, Istituto Italiano di Tecnologia, and Interdisciplinary Research Centre on Biomaterials (CRIB), Napoli, Italy; Department of Biological Sciences, Division of Biostructures and Centro Interuniversitario di Ricerca sui Peptidi Bioattivi - University of Naples “Federico II”, Napoli, Italy; Department of Experimental Medicine - II University of Naples, Napoli, Italy
Resume : Viruses are formidable micro-machines able to overcome potent physiological barrier and to penetrate deep inside our tissues. By following a bioinspired approach, a novel class of nanoparticles able to cross the vascular brain endothelium membrane have been obtained by decorating their surface with the membranotropic gH625 peptide sequence, derived from the glycoprotein gH of Herpes simplex type 1 virus (HSV) envelope. The HSV gH-derived-peptide was covalently bonded with polystyrene nanoparticles and investigated for the ability to translocate through the BBB in an in vitro model. The functionalized nanoparticles were thoroughly characterized using a variety of complementary techniques to gain a better understanding of their properties. gH625-NPs translocated efficiently across cell membranes and cell internalization does not seem to exclusively involve classical endocytic mechanisms. In fact, conjugation with the gH625 facilitated the delivery of nanoparticles across the BBB, leading to significant higher cell uptake and crossing. This study demonstrates that, by NP surface decoration, it is possible to dictate NP fate. This promising strategy paves the way for designing delivery systems to improve administration of therapeutical compounds to the brain.
RP.2 7
16:30Biopolymer thin films with compositional gradient synthesized by Combinatorial Matrix-Assisted Pulsed Laser Evaporation
Authors : E. Axente1,*, F. Sima1,*, L. E. Sima2, U. Tuyel3, M. S. Eroglu4,5, N. Serban1, C. Ristoscu1, S. M. Petrescu2, E. Toksoy Oner3, and I. N. Mihailescu1
Affiliations : 1Lasers Department, National Institute for Lasers, Plasma and Radiation Physics, 409 Atomistilor Street, Magurele, Ilfov RO-77125, Romania; 2Department of Molecular Cell Biology, Institute of Biochemistry, Romanian Academy, 296 Splaiul Independentei, 060031, Bucharest 17, Romania; 3Department of Bioengineering, Marmara University, Goztepe, 34722 Istanbul, Turkey; 4Department of Chemical Engineering, Marmara University, Goztepe, 34722 Istanbul, Turkey; 5TUBITAK-UME, Chemistry Group Laboratories, 41471 Gebze, Kocaeli, Turkey
Resume : Combinatorial organic chemistry is a field which revolutionized the drug industry by the capacity to combine different innovative materials and biological entities. Here we introduce a new combinatorial approach for the fabrication of mixed organic thin films. Nanostructures with compositional gradient could be obtained under control by the simultaneous laser irradiation and vaporization of two targets. The synchronized matrix-assisted pulsed laser evaporation of levan and oxidized levan cryogenic targets was chosen for testing the transfer and assembling of a two-compound biopolymer thin film. The goal was to rapidly generate a compositional library of the two polymers with specific properties, in a single-step process, in order to select an optimum dosage with emphasis on medical application. The gradient of film composition and structure was demonstrated by infrared spectroscopy and fluorescence studies while in vitro cell culture assays evidenced characteristic responses of cells to specific surface regions. The new combinatorial method is able to rapidly generate discrete areas of new organic thin film compositions with optimized properties than starting materials.
RP.2 8
16:30Bottom-up strategy to build up 3D Dermis equivalent in vitro by tuning microscaffold degradation rate
Authors : G.Imparato, F. Urciuolo, C. Casale, P.A. Netti
Affiliations : Center for Advanced Biomaterials for Health Care@CRIB, Istituto Italiano di Tecnologia, Largo Barsanti e Matteucci n, 53 80125 Napoli, Italy.
Resume : One of the most challenging issues of in vitro tissue engineering is the implementation of strategies to successfully culture large and viable constructs in vitro, mimicking the natural tissue organization. In the present study we succeeded in realizing 3D viable dermis equivalent tissue, by means of a previously established bottom-up method and proved that the final properties, in terms of collagen assembly and organization of the 3D tissue, are strictly related to micro-scaffold degradation rate. To reach this aim gelatin porous microcarriers were chemically crosslinked with tunable degradation profile obtaining microscaffolds characterized by different stiffness and metalloproteinase’s-dependent degradation rate. Time and space evolution of de novo synthesized collagen within the 3D growing tissue was monitored by means of histological analyses, second harmonic generation imaging and ultra-structure analyses. Results showed that endogenous extra cellular matrix (ECM) was present in the 3D tissues equivalent realized. Interestingly its time evolution, organization and collagen assembly kinetics strongly depended upon the microscaffold’s crosslinking extent. The increase of the crosslinking extent sped up collagen assembly kinetic obtaining stiffer ECM able to balance both scaffold’s mass loss and cell traction. This study paves the way for the fabrication of 3D tissue made up of endogenous ECM with desired final features by controlling initial microscaffolds’ properties.
RP.2 9
16:30Chemical Vapor Deposition of Glycidyl Methacrylate Copolymers Containing Tertiary Amine Functionality For Low Temperature (bio)-Chemical Functionalization
Authors : Fatma Sarıipek, Ezgi Yenice, Emrah Demir, Mustafa Karaman
Affiliations : Department of Chemical Engineering, Selcuk University, 42031, Konya, Turkey
Resume : Polyglicydil methacrylate (PGMA) is a desirable coating for various applications because of its pendant epoxy group which can be converted into different functionalities. Ring opening reactions of epoxides usually occur with nucleophilic attack, which requires acidic or basic conditions at elevated temperatures. Tertiary amines are also efficient catalysts for the nucleophilic ring opening reactions of epoxides in water. In this sudy, it was aimed to prepare poly(glicidyl methacrylate-co-diethyl amino ethyl methacrylate) nanocoatings on different substrates by initiated chemical vapor deposition (iCVD) method. iCVD is a dry alternative to produce polymer thin films with well controlled chemistry and morphology. Usage of tert buty peroxide as an initiator allowed high deposition rates at low filament temperatures. FTIR and XPS analyses both proved the formation of chemically well-defined copolymer films. As prepared films were treated with aniline at room temperature and it was observed that, complete conversion of epoxide occurred within 3 hours. The high reaction rate at room temperature was attributed to the high retention of tertiary amine functionality in the as-deposited film. Being a low temperature and solvent free process, iCVD deposited P(GMA-co-DEAEMA) thin films can be utilized in surface modifications of high performance membranes. Also incorporation of tertiary amine functionality into PGMA enhances the potential of this material to be used for the immobilization of (bio)molecules.
RP.2 10
16:30Collagen Scaffolds Incorporating Select Therapeutic Agents in the Injured Rat Spinal Cord
Authors : Rahmat Cholas, Ph.D., Hu-Ping Hsu, M.D., and Myron Spector, Ph.D.
Affiliations : 1) Department of Engineering for Innovation, University of Salento, Lecce, Italy. 2) Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA. 3) Tissue Engineering Laboratories, Veterans Affairs Boston Healthcare System, Boston, Massachusetts, USA. 4) Department of Orthopedic Surgery, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Resume : A multifaceted therapeutic approach involving biomaterial scaffolds, neurotrophic factors, exogenous cells, and antagonists to axon growth inhibitors may ultimately prove necessary for the treatment of defects resulting from spinal cord injury (SCI). The objective of this study was to begin to lay the groundwork for such strategies by implanting type I collagen scaffolds alone and incorporating individually a soluble Nogo receptor, chondroitinase ABC (ChABC), and mesenchymal stem cells (MSCs) into a standardized 3-mm-long hemiresection defect in the rat spinal cord. Statistically significant improvement in hindlimb motor function between the first and fourth weeks post-SCI was recorded for the scaffold-alone group and for the ChABC and MSC groups, but not the control group. Four weeks post-SCI, the scaffolds appeared intact with open pores, which were infiltrated with host cells. Of note is that in some cases, a few growth-associated protein 43 (GAP-43)-positive axons were seen reaching the center of the scaffold in the scaffold-alone and ChABC groups, but not in control animals. Angiogenic cells were prevalent in the scaffolds; however, the number of both macrophages and angiogenic cells in the scaffolds was significantly less than in the control lesion at 4 weeks. The results lay the foundation for future dose–response studies and to further investigate a range of therapeutic agents to enhance the regenerative response in SCI.
RP.2 11
Affiliations : 1 Laboratory of chemistry and environmental chemistry L.C.C.E - University of Batna- Algeria 2 Laboratory of Physical chemistry L.P.C. - University of Skikda- Algeria 3 Institute of Hygiene and Industrial Safety - University of Batna- Algeria
Resume : We have found only that the polymers with aliphatic and halogened structure resist, within acceptable limit, to the ozone and the following order by sensibility were established. SBS < S but Hydro .S < EPDM << PVC < PVDF. As far as the copolymer ethylene-chlorotriflurethylene (E.Co.CTFE) is concerned we can find its reactivity around that of polyethylene P.E and poly (vinyl chloride) P.V.C but its classification remains difficult to establish since this polymer cannot undergo dosage in contrast with P.E and P.V.C. We notice that PVDF is a polymer that resist to ozone and can be activated only after extended exposure time to this gas, subsequently we have investigated in details chemical modification that happen to this polymer after ozonisation and we have tried to prepare grafted copolymers. Unfortunately very few studies have been dedicated to the action of ozone on this type of compound in comparison to the cases widely treated of polyethylene, polypropylene or even more poly (vinyl chloride). Although a lot of work has been carried out, experimental data is scattered and unreliable, since we are very much concerned with the comparison of the resistance to ozone of various hydrocarbonated and fluorine polymers, under identical and precise conditions and therefore establish a sensibility scale for them. Key words: Synthesis- Ozonisation- Peroxide – EPDM - P.E - E co C.T.F.E.
RP.2 12
16:30Development of electrical conducting scaffolds for tissue engineering
Authors : V. Karagkiozaki1, E. Georgaraki1, P. G. Karagiannidis1, P. Kavatzikidou1, M. Gioti1, D. Georgiou1, S. Logothetidis1
Affiliations : 1. Department of Physics, Lab for “Thin Films-Nanosystems & Nanometrology”, Aristotle University of Thessaloniki, Greece
Resume : Tissue engineering is a multidisciplinary field, targeting to develop tissue substitutes that will stimulate the cells to interact with their environment delivering through their cellular membrane ions or organic macromolecules vital for their proper function. Electrospinning deposition generates porous mats with high porosity and high surface area. The main target of this study is to develop, characterize and compare conductive Poly (3, 4-ethylenedioxythiophene) (PEDOT) based scaffolds to promote cell proliferation, especially for tissue engineering in bioelectronics field. To that direction, redox process of diverse PEDOT formulations was examined altering cell-substrate interactions, and hence manipulating cell growth. Specifically, two types of PEDOT doped with different ratio of polystyrene sulfonate (PSS) were used, so as to synthesize polymeric coatings by the spin coating process on glass substrate. Polyvinyl alcohol (PVA) fibers generated by an electrospinning system were also spin coated by conductive polymer PEDOT providing a 3D scaffold enabling the cell line L929 to proliferate. Fibers of blend PEDOT: PSS: PVA were also prepared in order to provide a scaffold for cell seeding. The determination of cell toxicity and proliferation of the above matrices for different time periods was determined by the MTT cell proliferation/cytotoxicity assay. Fibroblasts were observed by scanning electron microscopy and fluorescence microscopy after proper fixation and surface nanotopography of PEDOT samples (either coatings or fibers) were evaluated by Atomic Force Microscopy. The engineered conducting scaffolds were found cytocompatible with tissue engineering activities, being an index of their suitability for applications in regenerative medicine.
RP.2 13
16:30Development of innovative antibacterial silver nanocoatings on catheters for haemodialysis
Authors : Federica Paladini, Mauro Pollini, Alessandro Sannino
Affiliations : University of Salento
Resume : Infections associated to vascular access are reported as the major causes of morbidity and mortality in haemodialysis therapy. The use of silver in modern medicine is growing due to its biocide activity against a broad spectrum of bacteria. In this work, antibacterial catheters for haemodialysis were obtained by the photochemical deposition of silver nanoparticles on the luminal and external surface of the device. The technology consists of the dip coating of polyurethane catheters in an alcoholic silver solution and, then, the exposure of the wet devices to a UV source in order to induce the in situ synthesis/deposition of silver particles. The process resulted in a homogeneous coating characterized by an excellent adhesion of the silver particles to the substrate, as demonstrated through SEM and TGA analyses performed even after 30 days in contact with biological fluid in flowing conditions. The impressive efficacy of the silver coating in inhibiting bacterial adhesion and biofilm formation was demonstrated on S. aureus for the whole working life of the catheters through fluorescence microscopy. The release of silver ions was determined by ICP-AES and the results were largely below the limit of toxicity reported in literature. No cytotoxic effect was demonstrated through BrdU incorporation, TUNEL assay and Actin staining in terms of viability, proliferation and morphology of a selected primary cell population.
RP.2 14
16:30Effect of BMP-2 gradients on human Mesenchymal Stem Cells (MSC) migratory behavior in 3D collagen matrices.
Authors : Iannone M., Pagano G.,Ventre M., Netti P.A.
Affiliations : Istituto Italiano di Tecnologia IIT@CRIB Center for Advanced Biomaterials for Health Care; Department of Chemical, Materials and Produduction Engineering University of Naples Federico II
Resume : The migration of cells plays a fundamental role in Tissue Engineering (TE) being the crucial event for the colonization of scaffolds. Addressing such a problem is a key step to promote scaffold tissue integration. Many approaches have been developed to promote scaffold colonization; in particular in situ TE could be a promising strategy since it envisages to potentiate the physiological tissue repair processes by recruiting the host's own cellular progenitors at the lesion site by means of a bioactive materials. In this work, we have analyzed the effects of gradients of BMP2, on the migratory behavior of MSC in 3D collagen gels. The migration analysis was carried out in a migration chamber in which cells are cultured in a three-dimensional environment that closely mimics the physiological environment of the cells. Concentration gradients of BMP were established by means of porous membranes and were calculated through numerical simulations. Relevant migration parameters as random and drift speed, persistence were evaluated using time lapse video microscopy for different concentration profiles. Our results show that BMP2 strongly affects cell motion of the hMSCs, both in terms of directional persistence and speed, suggesting an optimal range of concentration gradients for recruiting stem cells. Our observations could be of paramount importance for the design of a cell instructive material that can communicate with the cells and control and direct tissue regeneration.
RP.2 15
16:30Effect of Mineral Trioxide Aggregate on Mesenchymal Stem Cells
Authors : Di Caprio MP, Spagnuolo G, Ametrano G, Riccitiello F, Rengo S.
Affiliations : Department of Oral and Maxillo-Facial Sciences, University of Naples Federico II
Resume : Mineral Trioxide Aggregate (MTA) is a dental material used for both surgical and nonsurgical applications. Clinically MTA not only has been shown to be biocompatible to the surrounding tissues but also has demonstrated the ability to allow regeneration of hard tissues, such as bone, cementum and dentin. The aim of our study was to evaluate the surface morphology of MTA and its ability to support adhesion, proliferation and migratory ability of human bone marrow-derived mesenchymal stem cells (hMSC). ProRoot MTA (Dentsply Tulsa) and a white Portland cement were mixed and left to set 24h. MSCs were cultured on the samples and observed after 24h by confocal scanning laser microscopy (CSLM) using CellTracker reagent as marker. After 5 days, MSCs seeded on MTA in the presence and absence of osteogenic medium were observed to CLSM using the cytoskeleton marker phalloidin. Cell proliferation was evaluated by means of alamar blue assay, using cells seeded on polystyrene culture wells as controls. In order to assess the effect on migratory ability of MSCs a transwell migration assay was performed for 18 h positioning MTA and Portland cements in 6-well plates and the cells in 8 μm pore inserts. The surface topography of cements was evaluated by atomic force microscopy. After 24h, CLSM showed that MSCs seeded on MTA were attached to their substrate, even if they exhibited a worse adhesion compared to the control group. However, cell proliferation was significantly higher on MTA than on Portland cement with both culture medium . MSCs observed under CLSM after 5 days showed proliferation and spread, forming a continuous layer on the upper surface of the MTA. Cells grown on MTA were bigger with a flat and polygonal shape. Moreover, MTA was able to enhance cell migration significantly more than Portland cement. Finally, AFM images of MTA surface showed a more irregular surface compared to that of Portland Cement. The results of this study showed that MTA was able to promote MSCs adhesion, proliferation and differentiation of human mesenchymal stem cells.
RP.2 16
16:30Glucosamine grafting on poly(ε-caprolactone): a novel glycated polyester as substrate for tissue engineering.
Authors : Laura Russo,1 Antonio Gloria,2 Teresa Russo,2 Ugo D?Amora,2 Roberto De Santis,2 Luigi Ambrosio,2 Francesco Nicotra, 1 Laura Cipolla1.
Affiliations : 1*Department of Biotechnology and Biosciences, University of Milano-Bicocca, Milano, Italy 2 Institute of Composite and Biomedical Materials, National Research Council, P.le Tecchio 80, 80125 Naples, Italy
Resume : Biodegradable synthetic materials such as poly(ε-caprolactone) (PCL), has been used as scaffolds to support the regeneration of bone in tissue-engineered applications. PCL, a biodegradable aliphatic polyester, has been suggested for a wide field of applications such as drug delivery systems, tissue-engineered skin (plain film), and scaffold for supporting fibroblast and osteoblast growth. However, as any other synthetic polymer it does not present molecular motifs for cell biological recognition, and therefore it is unable to cross-talk with living cells. On the basis of these considerations, biomimetic approaches have been developed, in order to produce bioactive materials able to promote and enhance cell attachment. In the present work, we investigated the possibility of PCL bioactivation by one-step procedure of polymer aminolysis to graft bioactive molecules on the polymer surface. Small biological molecules, such as carbohydrates are usually present and involved in the mechanisms that order complex biological systems. Carbohydrate-protein interactions mediate a whole host of biological mechanisms, including those responsible for peptide conformation, enzyme activity, cell-cell recognition, cell adhesion, and cell development. Carbohydrates are involved in biological information delivery and due to their polyfunctional nature can be used for hydrophilicity and functionalisation tailoring of material surfaces, for example improving at the same time cell adhesion and bioactivity; thus, the presentation of carbohydrates in an immobilized format can be of relevant interest. PCL substrates were manufactured through melting-molding and molding -solvent casting techniques. Aminolysis on PCL substrates/scaffolds was then performed through directly functionalization with an amino sugar. The novel biofunctionalised PCL substrates were then characterised in terms of morphological, mechanical and biological properties. ACKNOWLEDGMENTS We gratefully acknowledge PRIN 2010/L9SH3K for financial support.
RP.2 17
16:30Improved performance of GOx/transparent conducting ZnO/metal doped ZnO electrode by Nafion entrapment
Authors : Fidal V T1, S. Krishnamurthy2*, E Marsili3, J. Connolly4, S. Inguva , J-P. Mosnier4, Chandra T S1
Affiliations : 1School of Biotechnology, Indian Institute of Technology Madras, Chennai, India 2Design, Development, Environment and Materials, The Open University, UK, MK7 6AA 3School of Biotechnology, Dublin City University, Dublin, Dublin 9, Ireland 4 National centre for plasma science and Technology, School of Physical Sciences, Dublin City University, Dublin, Dublin 9, Ireland
Resume : Although the glucose oxidase (GOx) immobilized ZnO electrode is one of the widely studied biosensing systems, the effect of Nafion entrapment is not well known. GOx, a flavin- dependent enzyme oxidizes glucose to gluconic acid and H2O2. FADH2 gets oxidized to FAD through intermediate formation of semiquinone. It was postulated that Nafion membrane may abstract the protons from FADH2 of reduced GOx due to its sulphonic acid functional group and thereby accelerate the process of electron transfer from FADH2 to ZnO of 5nm thin film. In the present study GOx was immobilized by drop-casting on the surface of transparent ZnO on perspex and Al(2 wt% of Al2O3) doped ZnO electrodes prepared by Pulsed Laser Deposition at room temperature. The presence of GOx on ZnO surface was confirmed by cyclic voltammetry, where a peak at 400 mV vs. Ag/AgCl was observed. With both the types of electrodes, Nafion entrapment of the enzyme after drop-casting gave higher peak currents compared to electrostatically immobilized enzyme electrodes. Detailed surface to interface characterisation were performed through HRTEM, XPS and Cylic Voltametry. These observations support our hypothesis that enzyme entrapment by Nafion membrane enhances electron transfer to the electrode by scavenging protons. This opens up interesting possibilities for testing other redox enzymes for active role of Nafion interaction with the co-enzyme component.
RP.2 18
16:30In vitro characterization and mechanical properties of PVA-Ag wound dressings
Authors : Renata Nunes Oliveira, Rossana Mara da Silva Moreira Thiré, Garrett Brian McGuinness, Gloria Dulce de Almeida Soares
Affiliations : Renata Nunes Oliveira, Federal University of Rio de Janeiro - UFRJ; Rossana Mara da Silva Moreira Thiré, Federal University of Rio de Janeiro - UFRJ; Garrett Brian McGuinness, Dublin City University - DCU; Gloria Dulce de Almeida Soares, Federal University of Rio de Janeiro - UFRJ
Resume : Dressings should keep a burn site moist to improve healing. Biocompatible transparent PVA hydrogels, which swell in aqueous media, are attractive for this purpose, but infection control remains necessary. To combine the hydrogel with a bactericide agent, like silver, would benefit the healing and control infection. However, high amounts of silver could be toxic to human cells. In this work, PVA-Ag hydrogels were produced by mixing a PVA aqueous solution (10 wt%) with different amounts of AgNO3 and, after drying, submitting them to gamma radiation (15 kGy). The samples were analyzed via XRD; by swelling tests, using saline solution, PBS and PBS pH 4.0; via tensile tests with swollen samples; and by cytotoxicity tests. All samples presented the main peak of PVA, although the PVA-Ag samples presented two peaks un-related to the PVA, probably result of the interaction between silver and PVA. The samples swollen in saline and in PBS presented a similar swelling profile: The PVA swelling degree was lower than the 0.25%Ag one, which was lower than the 0.5%Ag swelling degree, indicating that silver probably interferes with the crosslinking. The samples in PBS pH 4.0 presented almost the same swelling level. There was no significant difference in the failure strengths or in the Young’s modulus results of all samples in different media. In cytotoxicity tests with mice fibroblasts, the mitochondrial activity, the cell density and the membrane integrity of the cells were not damaged.
RP.2 19
16:30Influence of a cross-linking agent in a chitosan and poly (vinyl alcohol) scaffold with potential use in tissue engineering
Authors : I. M. Garnica-Palafox 1, C. Velasquillo 2, Z. García-Carvajal 2, J. García-López 2, C. Ortega-Sánchez 2, L. Solis-Arrieta 2 G. Luna-Bárcenas 3 and F. M. Sánchez-Arévalo 1
Affiliations : 1 Instituto de Investigaciones en Materiales. Universidad Nacional Autónoma de México. Apdo. Postal 70-360, Cd. Universitaria, México, D. F. 04360; 2 Unidad de Ingeniería de Tejidos, Terapia Celular y Medicina Regenerativa Instituto Nacional de Rehabilitación, México, D.F.; 3 Polymer and Biopolymer Research Group, CINVESTAV, Querétaro, México.
Resume : The development and mechanical characterization of novel hybrid hydrogel based on chitosan (CS) and polyvinyl alcohol (PVA) and chemically crosslinked by epichlorohydrin (ECH) for use as scaffold in tissue engineering is presented. The mechanical response of hydrogels was evaluated by uniaxial tensile tests; their structural properties such as average molecular weight between crosslink points (Mcrl), mesh size (DN) and volume fraction (vs) were determined through the results obtained by tensile tests, swelling tests and the equivalent network model. The scaffolds showed Young modulus values of 11.5±2.5 MPa and 9.2±1.4 MPa for sterilized and not sterilized hydrogel respectively. The CS-PVA-ECH allowed the cell growth and extracellular matrix formation. This novel hybrid hydrogel showed adequate mechanical and structural properties for potential use in tissue engineering applications.
RP.2 20
16:30Integration of organic electronics on biodegradable scaffolds: towards implantable transducers
Authors : Alessandra Campana, Tobias Cramer, Giulia Foschi, Silvia Tortorella, Pierpaolo Greco, Beatrice Chelli, Francesco Valle,Stefano Pluchino, Elena Giusto, Matteo Donegà, Fabio Biscarini
Affiliations : A Campana, CNR, ISMN, I-40129 Bologna, Italy and Alma Mater Studiorum Univ Bologna, Dipartimento Chim G Ciamician, I-40126 Bologna, Italy; T Cramer, CNR, ISMN, I-40129 Bologna, Italy; G Foschi CNR, ISMN, I-40129 Bologna, Italy; S Tortorella, CNR, ISMN, I-40129 Bologna, Italy and Alma Mater Studiorum Univ Bologna, Dipartimento Chim G Ciamician, I-40126 Bologna, Italy; P Greco, Scriba Nanotecnologie, Bologna, Italy; B Chelli, CNR, ISMN, I-40129 Bologna, Italy; F Valle CNR, ISMN, I-40129 Bologna, Italy; S Pluchino, Univ Cambridge, Cambridge Ctr Brain Repair & Cambridge Stem Cell, Dept Clin Neurosci, Cambridge CB2 0PY, England; E Giusto, Univ Cambridge, Cambridge Ctr Brain Repair & Cambridge Stem Cell, Dept Clin Neurosci, Cambridge CB2 0PY, England; M Donegà, Univ Cambridge, Cambridge Ctr Brain Repair & Cambridge Stem Cell, Dept Clin Neurosci, Cambridge CB2 0PY, England; F Biscarini, CNR, ISMN, I-40129 Bologna, Italy
Resume : Implantable medical devices have to exhibit viscoelastic properties and surface chemistry matching those of the tissue/organ. Minimizing invasiveness and immune reaction of the living system allows the functionality of the device performance to be retained. One strategy towards this aim is to use biodegradable materials, whose degradation rate in living conditions is tailored to the duration of the device application. In this work we target new active implants aimed to monitor, stimulate, and control the regeneration of the CNS nerves in spinal cord injury. We aim to integrate in the same device transducers, inflammations sensors, drug-eluting devices and other cues for optimum interfacing with neurons. We present here electrolyte-gated organic field effect transistor (EGOFET) on a biodegradable scaffold made of poly(lactic-co-glycolic acid)(PLGA) processed into transparent films. PLGA surface is fabricated for the deposition of test structures active layers, adhesion protein patterns. The fabrication of the implantable device avoids the wet chemistry involved in standard lithographic techniques. Structural integrity of functional structures is maintained for several days when immersed in cell medium. Operations of such device in vitro and during degradation will be shown and discussed. This work was supported by the European project: FP7-NMP-2011-280772 "Implantable Organic Nano-Electronics" (I-ONE).
RP.2 21
16:30Laser-activated chitosan films doped with gold nanorods as adhesives for biomedical applications
Authors : Matteini P, Ratto F, Rossi F, de Angelis M, Cavigli L, Centi S, Dei L, Pini R
Affiliations : Institute of Applied Physics “Nello Carrara”, National Research Council, Sesto Fiorentino, Italy; Department of Clinical Physiopathology, University of Florence, Florence, Italy; Department of Chemistry and CSGI Consortium, University of Florence, Florence, Italy
Resume : Stimuli-responsive polymeric biomaterials have attracted much attention for their prospective application in several fields including biomedicine, biotechnology and biosensing. We have recently engineered an hybrid bioadhesive consisting in a chitosan film doped with gold nanorods (GNRs) that can be activated by near-infrared (NIR) laser light [1,2]. These films ( 0.8 cm diameter, 40 μm thickness) are insoluble, flexible, resistant and stable in a physiological environment. The use of GNRs provides amplified optical absorbance of the laser light due to efficient plasmon bands in the NIR window, where tissue components and chitosan are mostly transparent. Upon laser irradiation a well-localized photothermal effect can thus be produced in the film, which is in turn stimulated to produce adhesion with a proximal tissue surface (e.g. arterial wall, tendon, lens capsule). Optimal irradiation conditions were observed with laser pulses in the millisecond timescale and about 1 W power, which proved reliable and reproducible. This technology may enable a number of key applications in medicine including tissue repair, wound dressing and drug delivery. [1] Matteini P et al. Chitosan films doped with gold nanorods as laser-activatable hybrid bioadhesives. Adv Mater 22 4313 (2010) [2] Matteini P et al. Hybrid nanocomposite films for laser-activated tissue bonding. J Biophotonics 5 868 (2012)
RP.2 22
16:30nanoParticle Coatings for Cyanoacrylate-based Glue dedicated to Intraluminal Bowel Magneto-Retraction
Authors : Pascal André,1 Ipek Birced,1 Zhigang Wang,2 Andrew Brown,2 Stuart I. Brown,2 Gordon J. Florence,3 Alfred Cuschieri2
Affiliations : 1 School of Physics and Astronomy (SUPA), University of St Andrews (St Andrews, UK) 2 Institute for Medical Science and Technology, University of Dundee (Dundee, UK) 3 School of Chemistry (EaStChem), Biomedical Sciences Research Complex, University of St Andrews (St Andrews, UK)
Resume : Reducing tissue trauma is needed for surgery applications when physical retraction is completed with graspers. In this medical field, small magnets have been used for magnetic tissue retraction, however magnetic particles offers further advantages which we currently explore. In this presentation, we will describe a novel method of magnetisation of bowel segments by intraluminal injection of magnetic glue. Following materials’ characterisation studies, micro-particles of stainless steel and iron oxide nanoparticles could be mixed with medical grade cyanoacrylate glues to design an injectable magnetic media suitable for surgery applications. During intra-luminal injection of the magnetic glue using ex-vivo porcine colonic segments, a magnetic probe placed at the injected site ensured that the particles dispersed in the glue as it polymerized to form an intra-luminal mucosally-adherent coagulum. This report will show how the magnetized porcine colonic segments can be retracted by magnetic probes placed external to the bowel wall. A tensiometer was used to record the retraction force and distance. The results of this study indicate that the formation of an intra-luminal coagulum produces sufficient magnetic retraction for bowel retraction. This ex-vivo study requires confirmation by in-vivo animal studies before clinical translation to Minimal Access Surgery.
RP.2 23
16:30Supramolecular systems for the electrochemically controlled release of cells.
Authors : J. Brinkmann, P. Neirynck, A. Qi, J. de Boer, L. Brunsveld, P. Jonkheijm
Affiliations : Molecular Nanofabrication Group, MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands & Tissue Regeneration, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands; Laboratory of Chemical Biology, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands; Molecular Nanofabrication Group, MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands & Tissue Regeneration; Tissue Regeneration, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, Enschede, The Netherlands; Laboratory of Chemical Biology, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands; Molecular Nanofabrication Group, MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands.
Resume : Coronary artery disease is a frequent and life threatening problem. Due to their non-invasive nature, coronary artery stents are placed during balloon angioplasty to widen the area of arterial blockage. However, often restenosis or re-narrowing occurs. The importance of rapid re-endothelialization of stent surfaces to prevent such complications has become well acknowledged. In our work we develop smart biomaterials using supramolecular host-guest chemistry as a tool to create self-organizing responsive materials to guide endothelial cells. Supramolecular host-guest chemistry provides versatile and reliable systems fulfilling a number of biological requirements for peptide or protein immobilization. Interactions between these molecules are non-covalent and molecular recognition concepts are inspired by natural systems. For the supramolecular immobilization of biomolecules on surfaces two host-guest systems are currently being investigated. In the first system cell adhesive RGD peptides are coupled to ferrocene, serving as the guest complex, and forming an inclusion complex with its host, cucurbit[7]uril. In the second system an inclusion complex is formed between the host cucurbit[8]uril and two aromatic guests, the peptide WGGRGDS and the electroactive viologen. Here, an electrochemical stimulus can dissociate the complex, thus releasing the cells from substrates and allowing dynamic control over the cell-surface interaction.
RP.2 24
16:30The effect of the ytterbium doping hydroxyapatite nanoparticles on the changes density, opacity constructed implants as the way to follow their interface biotransformation process in vivo without biopsy surgery
Authors : Oleksii Dubok (1,2), Oleksandr Shynkaruk (2), Iryna Tomylko (1), Eugenia Buzaneva(1)
Affiliations : (1)Taras Shevchenko National University of Kyiv, 64/13, Volodymyrska Street, City of Kyiv, Ukraine, 01601; (2) Institute for Problems of Material Science NASU, Kryzhanivskogo str.3, 03142, Kyiv, Ukraine
Resume : The analysis for the theoretical dependence structural parameters of the hydroxyapatite nanoparticles (HAp NPs) on the composition changing due to different lanthanides doping what is aimed to nano-engineered bioactive interface has been carried out. This analysis permitted to chose the ytterbium Yb doping for HAp NPs, as optimal, to increase surface activity of constructed HAp ceramic for an implant in bone-forming cells and a density, an opacity implant which controlled with X-ray imaging method during remodeling natural bone in vivo without biopsy surgery. The developed work model predicts that the ytterbium doping for HAp NPs controls to an surface activity nanoparticles and their structure due to the Yb3+ ions distributed on the Ca2+ ions sites, size, form similar. The experiments confirmed this model. The ytterbium-doped hydroxyapatite (Yb:HAp, Ca10_xYbx(PO4)6(OH)2) with 0 < x < 0.2 nanocrystalline powders was synthesized by coprecipitation in suspensions and the tablets from the NPs , as the implants, were prepared. The structural, morphological, and textural properties from the X-ray diffraction, scanning electron microscopy, transmission electron microscopy results were determine. The FTIR, XPS measurement for the NPs composition detection carried out. The X-ray diffraction analysis revealed that Yb:HAp NPs are the crystalline constituent, indicating that Yb has been successfully inserted into the HAp lattice. The Yb 3+ doping inhibits HAp crystallization , decreased average crystallite size with the high Yb concentration and nanostructured implant surface. The X-ray images for the interfaces of the animal bone with the both implants (with the Yb doping and without) confirmed that the broad at the interface with Yb(1procent):HAp implant only is overviewed as the contrast image due to the implant opacity increased (USB Radiology System Visiodent, RSV-HD).
RP.2 25
16:30The sweet side of Hydroxyapatite
Authors : Antonella Sgambato, Laura Cipolla, Laura Russo, Davide Bini, Antonino Natalello, Monica Sandri, Francesco Nicotra
Affiliations : 1Dept. Of Biotechnology and Biosciences, University of Milano-Bicocca, della Scienza 2, 20126 Milano-Italy, Institute of Science and Technology for Ceramics, National Research Council, Faenza, Ravenna, Italy
Resume : The promising trends in biotechnology and tissue engineering are based on development of advanced materials with biomimetic features created by designing and tailoring of specific surface properties such as the enhancement of the surface affinity to selective adhesion and proliferation of different cell strains, improvement of biological response and tissue compatibility. It has been widely described the ability of bioceramics such as hydroxyapatite (HA) to form a bonding with the surrounding bone tissue. Since inorganic materials such as hydroxyapatite possess a paucity of reactive functional groups, biomolecular modification of these materials is still challenging. An efficient method for the direct and covalent decoration of granules of nanostructured apatite with a sample monosaccharide is presented. The hydroxyapatite material was directly functionalised with a short azido-containing spacer arm, to which α-propargyl glucopyranoside has been chemoselectively ligated by Huisgen-type cycloaddition. The “glycosylated” hydroxypatite was characterised by its ability to interact with glucose recognising lectins. Aknowledgments. We gratefully acknowledge MIUR, under project PRIN 2010/L9SH3K
RP.2 26
16:30Tissue engineered vascular grafts based on poly-lactic acid blends
Authors : V. Brucato*, G. Ghersi°, F. Carfì Pavia*, S.Rigogliuso°, V. La Carrubba*
Affiliations : *Università di Palermo - Dipartimento di Ingegneria Civile, Ambientale, Aerospaziale, dei Materiali (DICAM) - V.le delle Scienze - Ed. 8 - 90128 Palermo - Italy °Università di Palermo - Dipartimento di Scienze e Tecnologie Biologiche Chimiche e Farmaceutiche - V.le delle Scienze - Ed. 16 - 90128 Palermo - Italy
Resume : A great deal of research has been pursued in the last decade with the goal of developing blood vessel substitutes. Tissue engineering has emerged as a promising approach to address the shortcomings of current options. One of the major tasks in this research field is the possibility to tune the biodegradability of the implantable devices (scaffolds). After implantation, the scaffold has to be replaced by extra cellular matrix; with this respect, it is crucial that this replacement takes place with appropriate dynamics and a well-defined timescale. In this work tissue-engineered vascular graft were produced, utilizing several PLLA/PLA blends (100/0, 90/10, 75/25 wt/wt) in order to tune their biodegradability. The tubular-shape scaffolds were obtained by performing a dip-coating around a nylon fibre, followed by a diffusion induced phase separation process. A porous open structure was detected across the thickness of the walls of the scaffold. Moreover, the internal surface is homogeneous with micropores 1–2 μm large. The results have shown that it is possible to obtain the required morphology of the scaffold, in term of wall thickness, for each PLA/PLLA ratio, by varying simple experimental parameters. Moreover a decrease of crystallinity was observed, when raising the amorphous polymer content. Cell cultures were carried out into the scaffold and the non-cytotoxicity of scaffolds, adhesion and cell proliferation inside them were evaluated. The results have shown that the scaffold do not induce cell toxicity; cells are able to grow into the scaffold covering its internal surface, so they can be considered suitable for the application for the designed aimed.
RP.2 27
16:30Understanding of the infection mechanisms of silver nanoparticle-based antibacterial coatings, through the use of novel nanoengineered (gradient) substrata
Authors : Jules Valentin1, Judith Böhmler1, Shima Taheri2, Karine Anselme1, Krasimir Vasilev2, Lydie Ploux1
Affiliations : 1Institute of Materials Science of Mulhouse (IS2M), CNRS, Mulhouse, France 2Mawson Institute, University of South Australia, Adelaide, Australia
Resume : In the context of biomaterial-related bacterial infections, silver has been recognized as a promising antibacterial agent, which can be easily incorporated to coatings in various forms. Debates remain about the doses able to assure antibacterial effect and safety for eukaryotic cells. We demonstrated that a coating with both antibacterial and biocompatible properties can be achieved by careful adjustment of silver ion release through adding an adequate polymer overlayer on antibacterial coating. We fully unraveled the antibacterial action of the coatings, focusing on diverse aspects of antibacterial properties by considering effects on quantity and physiological state of planktonic and adhered bacteria, when different thickness of the overlayer were used. For the first time, it was suggested that diverse ways of action of SNPs entrapped in a polymer matrix may impact bacterial colonization: Direct toxic effect of Ag+ released from SNPs and reduction of the bacterial adhesion strength to SNPs compared to the coating. To further investigate the impact of SNPs concentration, we conducted bacterial adhesion and proliferation kinetics studies on new substrata with concentration gradients of SNPs, allowing the study of a large range of concentration on single sample. Gradients with silver but also gold NPs were considered aiming especially at distinguishing the specific, chemical, antibacterial effect of SNPs from the impact of the immobilized SNPs-related nanotopography.
RP.2 28
16:30Well controlled platforms dedicated to biointerface study allow to study bacterial ability to sense chemical heterogeneities
Authors : Judith B?hmler, Arnaud Ponche, Karine Anselme, Lydie Ploux
Affiliations : Institute of Materials Science of Mulhouse (IS2M), CNRS, Mulhouse, France
Resume : Biofilms cause dramatic problems in medical fields. Despite years of research, bacterial adhesion, first step of biofilm formation, remains poorly understood. Surely, an essential parameter for its controlling is the accessibility of material surface functional groups, strongly related to surface molecular density. Mixed model surfaces suitable for addressing this topic are rare and mostly incompletely characterized in terms of surface chemistry, layer structure and organization. We report characterization methodology, specifically developed to sufficiently analyze monolayers on silicon wafers, the comprehensive synthesis and analysis of well-organized and well-structured mixed monolayers showing various densities of NH2 backfilled with CH3 on silicon wafers, and the investigation of bacterial adhesion on such model surfaces of various chemistries at molecular scale. The results demonstrate a significant impact on bacterial adhesion (two bacterial strains) of weak differences in the surface chemistry at molecular scale. Two zones were determined, in which bacterial adhesion is not affected by the change of amine surface concentration. On the contrary, one transition zone exists in which slight change in amine concentration leads to significant increase / decrease of bacterial adhesion. This may have crucial consequences if weak surface modification of biomaterials, done for biofunction or biocompatibility enhancement, may also significantly affect the risk of infection.
RP.2 29

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