and report the enhancement of permeability and ion transport characteristics of these novel membrane constructs.
1671-Pos Board B648
Impact of Pendant Functional Groups and Method of Preparation on Aggregation Behaviour of Pegylated Copolymers
Amy Won1, Frantz Le Devedec2, Christine Allen2, Christopher M. Yip1.
1
Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, ON, Canada,2Faculty of Pharmacy, University of Toronto, Toronto, ON, Canada.
Block copolymer micelle-based drug formulation has emerged as a drug delivery system for clinical development. One of the major challenges is that these block copolymer micelles often only serve to solubilize the drug but have poor stability and limited drug retention. In the current study, anionic polymerization of oxir-ane derivatives on methoxy-polyethylene glycol (mPEG) was used to obtain amphiphilic and biocompatible block copolymer micelles. Polymerization of allyl glycidyl ether (AGE) enabled functionalization with pendant alkyl chains by thiol-ene click chemistry (mPEG-b- (AGE-C6, 12, 16, or 18)n) and polymer-ization of pheyl glycidyl ether (mPEG-b-(PheGE)n). In aqueous media, these block copolymers self-assemble to form aggregates that include a mobile hydro-phobic core and a hydrophilic shell. These micelles were characterized using infrared spectroscopy, transmission electron microscopy, and atomic force mi-croscopy. All block copolymer micelles have identical fingerprint at the mPEG region at around 1100 cm-1 and distinct fingerprint for the acyl chain re-gion between 2800 and 3000 cm-1 that confirmed the chemical composition of each preparation. Depending on the core forming block and the method of prep-aration (dialysis and emulsion oil-in-water), the block copolymer micelles were found to have distinct morphologies. For instance, mPEG-b-(PheGE)n remain spherical shaped through both methods; while mPEG-b- (AGE-C6)n shaped in spheres through dialysis but short filomicelles through emulsion oil-in-water; and (mPEG-b- (AGE-C12)n) shaped as rod-like worms through dialysis but network of long worms through emulsion oil-in-water. In vitro study was also performed to demonstrate the biocompatibility of these block copolymer mi-celles supporting this series of materials exhibits great promise for future appli-cation in drug delivery.
1672-Pos Board B649
Wettability Switch of Anodic Titanium Dioxide Nanotubes with Various Diameters
Mukta Kulkarni1, Ita Junkar2, Harinarayanan Puliyalil2, Ales Iglic1.
1
Laboratory of Biophysics, Faculty of Electrical Engineering, University of Ljubljana, Slovenia, Ljubljana, Slovenia,2Jozef Stefan Institute,Ljubljana,
Slovenia, Ljubljana, Slovenia.
Surface topography and physicochemical properties such as adhesion, cohesion and wettability is presumed to alter/facilitate the protein binding, cell adhesion and proliferation, thereby reducing post-operative complications with increased lifespan of biomedical implants.1 Current study examines the ageing behaviour of titanium dioxide (TiO2) nanotubes with various diameters and
their switch in wettability by gaseous plasma treatment.
Self-organized TiO2nanotube layers were fabricated according to the
electro-chemical anodization method published earlier.2 The ethylene glycol based electrolytes were used for growing the nanostructures which contains specific amount of water and specific concentration of hydrofluoric acid. Anodization pa-rameters such as applied voltage as well as experimental time were optimized to get desired diameters (15nm, 50nm and 100nm) of TiO2nanotubes. As-anodized
surfaces are hydrophilic and tend to age with time to more hydrophobic. Water contact angle measurements were performed during seven weeks period to study ageing behaviour as well as switch in wettability after gaseous plasma treatment. All the contact angle measurements were performed with demineralized water. The contact angle was measured by fitting the water drop on the surface. Surface wettability indeed switched after plasma treatment as the surface became hydro-philic. Changes in wettability after ageing were explained by organic contami-nation from ambient atmosphere, while hydrophilic character was obtained after plasma treatment due to removal of these contaminants. Moreover storing the samples in sealed container also influenced on their ageing profile. This current work provides solution and guidelines by which switch in wetta-bility of TiO2nanotubes can be achieved and can be employed in medical
applications where hydrophilic character is desired for specific application, such as orthopedic implants.
References:
1. M. Ventre, F. Causa, P.A. Netti, J. R. Soc. Interface 9 (2012) 2017. 2. Kulkarni M.et al. Int. J. Nanomed. 10 (2015)1359.
1673-Pos Board B650
A Minimalistic in Vitro 3D Model to Study F98 Rat Brain Tumor Growth Emilie Gontran, Marjorie Juchaux, Christophe Deroulers,
Mathilde Badoual, Olivier Seksek.
Universite´ Paris-Saclay, IMNC - CNRS 8165, Orsay cedex, France. Classical in vitro methods for studying cell behavior, mainly 2D cell cultures on Petri dishes, suffer from many biases (simple dimensionality, absence of biochemical gradients, rigidity/). On the other hand, in vivo studies involve very complex systems and do not allow separating the role of each component. Alternative strategies inspired from in vivo tissue’s architecture and composi-tion, have been under development for years, in order to mimic extracellular 3D matrix (ECM). Among them, synthetic hydrogels are good in vitro minimalistic models, allowing fine tuning of their composition as well as their structural and functional features.
In this context, we manufactured an original PEG-based hydrogel grafted with poly-L-lysine moieties in order to: i) validate this substrate as an artificial 3D ECM; ii) follow the growth (proliferation, migration) of a population of the F98 rat glioma cell line in this minimalistic tissue-like structure.
First, we studied the hydrogel physical properties when varying the size and concentration of PEG and poly-L-lysine, using rheology and FRAP. In partic-ular, we explored a range of rigidities, including that of brain ECM (1kPa), and diffusivities following different polymer mesh size. In a second step, we exam-ined how the gel properties and its composition (PEG and poly-L-lysine) influ-ence the organization and growth rate of the cell population.
In our 3D substrate, cells have rounded shape different from 2D form. They organize as aggregates for which growth rate and shape varies as a function of hydrogel composition: the higher is the density of PEG and poly-L-lysine, the smaller is the size of the aggregates.
Finally, our data clearly give an insight on how spatial constraints in the 3D hydrogel architecture limit tumor’s progression into the polymer network. Cor-relation with in vivo characteristics would be further investigated.
1674-Pos Board B651
Caf1 ofYersinia pestis Forms Complex Highly Stable Protein Polymers and Hydrogel Scaffolds
Helen Waller1, Yakup Ulusu2, Jeremy H. Lakey1.
1ICAMB, Newcastle University, Newcastle upon Tyne, United Kingdom, 2
Department of Bioengineering, Karamanoglu Mehmetbey University, Karaman, Turkey.
Caf1 is a polymeric protein from the plague bacteriumY. pestis which is secreted via the chaperone-usher pathway and protects the pathogen from macrophages of the host’s immune system by forming a protective layer around the cell. The 15.5kDa monomer has beta structure and resembles the extracellular matrix pro-tein fibronectin. The polymer is expressed recombinantly inEscherichia coli, secreted by the bacteria forming a flocculent layer above the cell pellet that can be harvested and the polymer extracted in large quantities. An NHS-PEG crosslinker was used to form a stable hydrogel which has potential for develop-ment in 3D-tissue culture and regenerative medicine applications due to its low cost, high stability and biodegradable nature. We have selectively reversed the natural non-stick behaviour of the WT polymer by introducing an integrin bind-ing sequence, RGDS, into loop5 and can promote fibroblast adhesion and growth. Here we describe the high stability of the WT protein which confirms its potential as a medical polymer. The polymer is stable on SDS-PAGE gels and this analysis revealed it’s resistance to a range of proteases. Circular dichro-ism spectroscopy and differential scanning calorimetry revealed it is extremely thermostable from pH2.0 to 11.0 with maximum stability at pH6 of>90C. It is also stable at high ionic strength and in a range of detergents. Several cell binding motifs have been introduced into the polymer; bone morphogenic protein and collagen motifs (for promoting bone cell adhesion) and laminin motifs (for ker-atinocyte applications such as wound healing). Degradation sites such as matrix metalloproteinase and thrombin cleavage motifs can be located in regions which promote efficient breakdown of the hydrogel. Co-polymers have been produced by expressing selectively designed monomers off separate plasmids, giving almost limitless possibilities for hydrogel design.
1675-Pos Board B652
Adsorption of DNA and Reca to Conjugates of Single-Walled Carbon Nanotubes and Poly(N-isopropylacrylamide) Molecules
Katsuki Izumi1, Yoshikazu Kumashiro2, Kazuo Umemura1.
1
Tokyo University of Science, Tokyo, Japan,2Tokyo Women’s Medical University, Tokyo, Japan.
Poly(N-isopropylacrylamide) (PNIPAAm) is one of the temperature responsive polymers, having the lower critical solution temperature. Cell sheet engineering
