Valorization of Channa striatus waste skin for developing marine collagen peptide based hydrogels for potential wound dressings

This study focuses on the extraction and characterization of a bioactive collagen peptide from waste skin of a local species of fish, the Channa striatus/snakehead/'shol' fish. The extracted peptides were characterized and optimized for the formulation of chitosan/PVA/collagen peptide (CP) hydrogel which has not been done previously. The facile extraction process involved using alkali, butanol, and protease for non-collagenous protein and fat removal, and enzymatic hydrolysis respectively. Hydrogels were formulated using a non-toxic freeze-thaw technique with multiple combinations of chitosan, PVA, and collagen peptide and characterized with SEM, FTIR, swelling ratio, gel content, porosity, evaporation rate, and antibacterial and anti-inflammatory activity. The FTIR fingerprint of the collagen peptide confirmed the presence of characteristic amide bonds. The SEM image of the collagen peptide reveals an open morphological structure suggesting that enzymatic hydrolysis could produce lower molecular weight collagen peptide. The collagen peptide retained 53.31% total protein in which essential amino acids - 27.3% glycine, 8.74% arginine, and 14.11% proline - were present. Antioxidant properties - DPPH, hydroxide, and superoxide radical scavenging activity - demonstrated a linear correlation with collagen peptide concentration. The swelling ratio, a crucial structural property for a hydrogel, was the highest (619%) for Ch/PVA₅-CP₂ (Chitosan: PVA: Collagen peptide = 1 : 5 : 2). The chitosan and collagen peptide served as key bioactives to facilitate wound healing, and PVA reinforced the bionanocomposite. The Ch/PVA₅-CP₂ hydrogel had multiple bioactive properties and antibacterial activity against Gram-positive bacteria S. aureus and Gram-negative bacteria E. coli, anti-inflammatory activity, antioxidant activity and well-balanced mechanical stability and elasticity. In a preliminary seven-day trial on mice, this formulation showed promising results in treating burn wounds compared to commercial burn ointment (silver sulfadiazine 1%), and a negative control, warranting further in vivo studies using the hydrogel.