Transforming Aquatic Waste into Healing Agent: Sustainable Extraction, Characterization and Bioactivity of Chitosan from Gibelion catla Scales

Abstract

Chitosan possesses innumerable implementations in the field of biomedical, pharmaceutical and industry. Chitin is an amino polysaccharide polymer occurring in the protective exoskeleton of fish, crustaceans, insects along with fungi, from which chitosan can be derived by deacetylation. This research aimed to extract chitosan from Gibelion catla scales and characterise it using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDX) and elemental analysis along with an investigation of antimicrobial activity, cytotoxicity and wound healing activity. The FTIR identified various functional groups associated with organic compounds such as O-H stretching at (3461 cm^–1), C=O stretching (1640 cm^–1), C-H bending (1471 cm^–1) and C-N stretching (1417 cm^–1), confirmed the presence of hydroxyl, carbonyl and amine functionalities typical of partially deacetylated chitosan. The degree of deacetylation was determined to be 60.4%, suggesting a moderate level of conversion from chitin to chitosan. X-ray diffraction (XRD) analysis revealed a semi-crystalline structure, with a prominent peak observed at 32.04º, which is indicative of the polymer’s ordered crystalline nature. Scanning electron microscopy (SEM) further supported this, showing a rough, fibrillary surface morphology with visible porosity, which is consistent with the structural features observed in chitosan-based materials. Elemental profiling demonstrated that chitosan is rich in oxygen and calcium, phosphorus and carbon, which is attributed to residual inorganic content or interactions with mineral components, while the high oxygen and carbon content aligns with the organic polymeric nature of chitosan. Chitosan induced the formation of a measurable inhibition zone against all the bacterial species (Escherichia coli, Bacillus subtilis and Staphylococcus aureus) at all the tested concentrations. MTT analysis revealed that chitosan is strongly toxic to MDA MB-231 (triple negative breast cancer) cells and non-toxic to PSVK1 (normal skin keratinocytes). The scratch wound healing assay showed significant wound closure, indicating enhanced cell migration and regenerative activity. All these findings suggest that waste scales of Gibelion catla are prominent and rich sources of chitosan and the obtained product is biodegradable, antibacterial, naturally derived polysaccharide and can be employed as anticancer agent and wound dressing material.