Bioconversion of Eel Skin Waste into Valuable Collagen: Isolation, Spectral Characterization, and Biocompatibility Assessment

Abstract

Abstract The current investigation was carried out to evaluate the structural and cell proliferation capability of pike conger eel collagen derived by acid and enzymatic extraction methods. The recovery yield of pepsin-soluble collagen (PSC) (40.65%) was significantly higher (p<0.05) than acid-soluble collagen (ASC) (29.9%) on a dry weight basis. In terms of molecular weight pattern, α1 and α2 bands of extracted collagen occurred to be 130KDa and 112KDa, respectively, and were confirmed to have a Type 1 structure. The presence of characteristic peaks of amide bands in Fourier transform infrared spectra (FTIR) and the d value of 12.28 Å and 11.37 Å in X-ray diffraction (XRD) revealed no significant changes in the highly ordered, intact triple helical structure of collagen through pepsin digestion. The higher thermal stability with a denaturation temperature of 33.3°C for ASC and 35.1°C for PSC was well documented in the differential scanning calorimetry (DSC) curve, which showed a substantial correlation with the findings of the imino acid content of both ASC and PSC collagen (203.5 ± 1.06 and 216.81 ± 0.32 residues/1000g respectively). In addition, the nontoxic behavior of isolated collagen samples to L929 fibroblast cell lines emphasized the possible utilization of pike conger eel skin as a safe source of thermally stable collagen.