Siloxane-Reinforced GelMA/Methacrylated Chitosan Hydrogels for DLP Printing

Photocrosslinked gelatin methacryloyl/methacrylated chitosan (GelMA/CSMA) hydrogels are attractive for biomedical applications but are limited by insufficient mechanical strength. Here, γ-methacryloxypropyltrimethoxysilane (MPTS) was prehydrolyzed and condensed to generate siloxane species retaining polymerizable methacrylate groups, which were subsequently incorporated into the GelMA/CSMA network as a reinforcing phase. The effects of MPTS precursor concentration (2-5% w/v) and prehydrolysis time (12-48 h) on the morphology, viscoelasticity, compressive behavior, cytocompatibility, and DLP printability of the resulting GCM hydrogels were systematically investigated. FTIR confirmed methoxy-group consumption while retaining C=C functionality. SEM showed that increasing MPTS precursor concentration increased the apparent abundance of granular features, whereas prolonged prehydrolysis produced larger structures. XRD indicated a predominantly amorphous MPTS-derived phase. GCM-48 h-5% achieved a storage modulus of 23.5 kPa, compressive modulus of 0.682 MPa, and maximum compressive stress of 1.081 MPa, corresponding to 7.4-, 16.9-, and 4.0-fold increases over the GelMA/CSMA control, respectively. The hydrogels exhibited favorable L929 cytocompatibility and retained DLP printability under 405 nm irradiation. These findings demonstrate that regulating MPTS precursor concentration and prehydrolysis time provides a simple route to mechanically reinforce DLP-printable GelMA/CSMA hydrogels without directly incorporating preformed silica particles.