A series of degradable polyurethane-based light-curable elastic hydrogels were synthesized from polycaprolactone diol, polyethylene glycol (PEG), lysine diisocyanate (LDI), and 2-hydroxyethyl methacrylate (HEMA) through UV light initiated polymerization reaction. LDI was used as hard segment and polycaprolactone (PCL) and/or PEG were used as soft segments. By changing the PCL to PEG ratio during the prepolymer synthesis, polyurethanes with different soft segmental structures, hydrophilicity, and cytophilicity were obtained after light-initiated polymerization. The chemical structures of the synthesized polymers were characterized using differential scanning calorimetry and Fourier transform infrared spectroscopy. Physical properties such as swelling, mechanical properties, and in vitro degradation were evaluated. Materials containing a higher ratio of PEG exhibit higher water absorbance, higher degradation rate in vitro, and lower mechanical strength in the hydrated state. Mouse embryonal carcinoma-derived clonal chondrocytes were used as a model cell type to study the cytocompatibility of the synthesized polymers. Chondrocyte attachment, proliferation rates, and morphologies varied with changes in the PCL/PEG ratio. With a higher PEG ratio, lower cell attachment and proliferation were observed. To improve the cell attachment and proliferation on high PEG content hydrogels, bioactive molecules, such as peptides and proteins, were conjugated or immobilized in the gel matrix during the light-curing process. In this study, a short peptide, Arg-Gly-Asp-Ser, was used as a model biomolecule and incorporated into the gels during the light-curing process and improved cell growth was observed. In summary, the use of PCL/PEG at different ratios, as well as the introduction of HEMA into polyurethane, allows the synthesis of a series of biocompatible elastic hydrogels with tunable physical and cytophilic properties through light-initiated polymerization. This series of materials also allows for controlling cell attachment and growth by incorporating bioactive molecules during the light-curing process.
In order to improve the guidance potential of a nerve entubulation bridging device, highly aligned textures were formed on the inner surface of semipermeable hollow fiber membranes (HFMs) during the wet phase inversion process. By precisely controlling the fabrication parameters, such as polymer solution flow rate, coagulant solution flow rate, and the air-gap distance, also called drop height, different-sized aligned grooves can be fabricated on the inner surface of HFMs. Preliminary studies using in vitro dorsal root ganglion (DRG) regeneration assay showed that both the alignment and outgrowth rate of regenerating axons increased significantly on HFMs with aligned textures compared to those on HFMs with a smooth inner surface. Studies in progress are evaluating axonal outgrowth and regeneration using in vivo sciatic-nerve and spinal-cord-injury models.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.