Nanocrystalline chitin: Enhancing mechanical properties, cell growth, and hemocompatibility in alginate films

This study aims to develop alginate-based biomimetic materials with controlled physical and biological properties by incorporating chitin nanocrystals (ChNC) into their structure. The investigation explores the effects of ChNC across a wide concentration range (up to 30 wt%) on the microstructure, optical, mechanical, thermal, and surface properties, as well as the hemocompatibility and cellular response of the composite materials. Microscopic analyses revealed several stages of microstructure formation within the composites, depending on the ChNC concentration in the alginate matrix, which led to corresponding changes in their properties. Notably, the introduction of just 1 wt% ChNC resulted in a sharp increase in mechanical puncture resistance, transparency, and swelling, a decrease in water contact angle, and enhanced procoagulant properties. Further increases in nanocrystal concentration induced the formation of a secondary spatial structure composed of ChNC, producing nonlinear effects on the material's properties. Films containing 10 wt% and 30 wt% of nanocrystals exhibited improved mechanical puncture resistance and tensile strength compared to the original alginate matrix. This enhancement is attributed to the development of a reinforcing ChNC network and increased values of both the acceptor and donor components of the free surface energy. Additionally, fibroblast adhesion to the surface of highly filled films increased more than fivefold. Incubation of blood components with the composite films significantly reduced clotting times in BRT tests (up to 37-fold) and APTT tests (up to 8-fold) compared to the control.