Bio-Based Silica-Reinforced Chitosan/Collagen Thermogels: Synthesis, Structure, and Rheological Behavior

Silica-reinforced chitosan/collagen hydrogels are useful for biomedical applications. In this study, thermosensitive chitosan/collagen hydrogels were prepared with different amounts of rice husk ash-derived silica (RHA-Si). Fourier-transform infrared (FTIR) spectroscopy was used to analyze the chemical structure. Results showed that adding RHA-Si did not change the main chemical groups but caused slight shifts, indicating physical interactions. Micro-Computed Tomography (Micro-CT) revealed that RHA-Si altered the shape and size of the pores in the hydrogel. The pore structure became more spherical at certain RHA-Si levels, but not consistently. Rheological tests showed that increasing RHA-Si made the hydrogel stiffer and reduced the gelation time. However, the hydrogel weakened under high strain due to broken physical bonds. Compression tests indicated that low RHA-Si (1% w/v) improved the hydrogel's strength during small deformations. In contrast, the hydrogel was less resistant to compression at higher RHA-Si levels (2-3% w/v). In summary, adding RHA-Si can improve the structure and strength of chitosan/collagen hydrogels, but excessive RHA-Si may reduce flexibility. The RHA-Si content should be adjusted to match the intended application of the hydrogel.