The PhD meeting of this month will take place on December 10th. Reema will give a talk about:
Activation of biocompatible polysaccharides for making biomimetic surface coatings with recombinant growth factors for regeneration of bone and ligaments
time: 4 pm
place: SR 1.03 Von-Seckendorff-Platz 1
This research project shall study the effect of different cross-linking degree of semisynthetic polysaccharides during multilayer formation on mechanical properties and controlled release of growth factors to control differentiation of mesenchymal stem cells towards fibrocartilage and bone in a spatially controlled manner. Therefore, many tasks have to be performed; starting with synthesis of libraries of polysaccharides having different degrees of functionalization, formation of multilayers from functionalized libraries of polysaccharides resulting in different crosslinking degree. Changes of mechanical properties of substrata and release of growth factors was studied to relate these parameters to cell differentiation. So far, a library of functionalized hyaluronic acid (HA), chondroitin sulfate (CS) and low molecular weight chitosan (LMW Chi) was generated by thiolation with various degrees of functionalization (10_ 25_ 50_ 100%) to enable covalent bonding by disulfide or thioether bond formation. The second approach of cross-linking was achieved by oxidation of polysaccharides to establish imine bond formation with pendant amino groups of chitosan or collagens. Thiolated polysaccharides were characterized qualitatively via 1H-NMR and quantitatively using Ellman’s assay. The oxidized heparin and chondroitin sulfate were also synthesized and aldehyde contents characterized by Schiff’s test. Multilayers were formed first from oxidized polysaccharides as polyanions and compared to native. Wettability of these multilayers was studied using water contact angle (WCA) measurements, multilayer formation via surface plasmon resonance (SPR), thickness of multilayers via ellipsometry and roughness via atomic force microscopy (AFM). Further, biological studies were carried out on these multilayers in which growth factor release studies, adhesion and differentiation of C2C12 cells were studied.