Hydrogel is composed of three-dimensional polymer network retaining a large amount of water and has been utilized in a wide applications such as food, pharmaceutics, drug delivery system, and tissue engineering. Schizophyllan (SPG) is a water soluble beta-glucan with beta-1,6 branching obtained from fungus, <i>Schizophyllum commune</i> and has excellent biocompatibility as well as immunomodulatory function. However, hydrogel fabrication and its biomedical application using SPG has been relatively less studied for low processibility of SPG. In this study, we synthesized SPG-derivatives (i.e., SPG-carboxylic acid (SPG-COOH), SPG-thiol (SPG-SH), SPG-norbornene (SPG-NB)) for thiol-norbornene photo-crosslinked hydrogel fabrication. For synthesis, intact SPG was treated with ultrasonication to obtain low molecular weight SPG (ultrasonicated SPG). Then, SPG-COOH was synthesized by carboxymethylation with ultrasonicated SPG. Both SPG-SH and SPG-NB were synthesized by EDC (1-Ethyl -3-(3-dimethylaminopropyl)) chemistry with cysteamine and norborneneamine, respectively. Synthesis of SPG derivatives were confirmed by FTIR and <sup>13</sup>C-NMR analyses. Two types of SPG-based hydrogels (SPG-NB/DTT and PEG/SPG-SH) were fabricated based on thiol-ene click-reaction under flood of ultra violet (UV) light. The hydrogel formation was confirmed by in-situ rheometry, resulting in rapid gelation (&lt; 5 s). The hydrogel properties (i.e., shear modulus, swelling ratio, gel fraction) were also characterized. As a result, SPG hydrogel showed variable shear modulus (0.5-10 kPa) and swelling ratios (20-40) with controlling SPG contents and crosslinker concentrations in precursor solutions. PEG/SPG hybrid hydrogel showed increased shear modulus and decreased swelling ratio as SPG contents increased. In degradation test, the degradation rate of PEG/SPG hybrid hydrogels slowed down as SPG contents increased. Bundle-shaped physical crosslinked SPG was found in hybrid hydrogel via SEM images and Congo red assay. These embedded SPG fibrils could enhance the mechanical properties and decrease the degradation rate of hydrogel. Taken together, photo-crosslinked SPG hydrogel and PEG/SPG hybrid hydrogel can be utilized as a promising biomedical materials.

Fabrication and characterization of thiol-norbornene schizophyllan hydrogels

253rd National Meeting (2017)

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