Extraction, structural characterization and biofunctional evaluation of novel chitosan derived from freshwater...

Chitosan is a known biopolymer for biomedical applications, but its reliance on classical crustacean sources can lead to sustainability and variability problems. This is the first study to extract chitosan from a freshwater cyclopoid copepod (Thermocyclops decipiens) and characterise it in detail with respect to its physicochemical and biological properties. Chitosan was extracted from T. decipiens, and FTIR confirmed a degree of deacetylation (DA) of 78.7%. Structural characterization indicated that the functional groups were regular, and subsequent X-ray diffraction (XRD) analysis supported a semi-crystalline structure with lower crystallinity and higher solubility. The elemental composition obtained from the EDAX analysis, which included carbon (46·92%) and oxygen (47·56%) with residual elements, was correlated to the porous structure detected by SEM. Thermogravimetric analysis (TGA) revealed several degradation phases with large-scale decomposition from 250 to 350 °C, indicating that the scaffolds displayed high thermal stability. Biological evaluations demonstrated high cytocompatibility of the materials (≥99% cell viability). Highly effective healing was observed at 48 h due to the material, with 22.31% closure and significant upregulation of genes involved in angiogenesis, such as VEGF (21-fold), modest activation of PI3K signaling (1.38-fold), and no significant change in HIF expression, suggesting that this healing is mediated via angiogenesis. Activity was dose dependent with greatest inhibition zones measuring 12·2 mm (E. coli) and 7·9 mm (E. faecalis). Hemocompatibility studies also indicated degree of hemolysis, ranging from 1.10-12.19%. These findings establish T. decipiens as a novel, environmentally friendly source of chitosan that has sustainability and biocompatibility in the biomedical regenerative space.