Effect of chemical and biological cross-linkers on mechanical and functional properties of shark catfish skin collagen films

The extracted shark catfish (Pangasius pangasius) skin collagen was characterized as type-I and contained three distinct chains (α, β and γ). The denaturation temperature (Td) of shark catfish collagen (37.8 °C) was comparable to mammalian collagen. Shark catfish skin collagen films were formed using different cross-linking agents such as sorbitol, glycerol, glutaraldehyde (GTA), Hexamethylene diisocyanate (HMDC), transglutaminase (TG) and k-carageenan (kCGN). Their mechanical and functional properties were studied. Tensile strength (TS) and stiffness were high in collagen-transglutaminase (collagen-TG) films (6.40 and 325 MPa, respectively), whereas elongation and swelling rate were high in collagen-sorbitol films (18.0% and 9.60%, respectively). Water solubility was high in simple collagen films (67.0%), and low in collagen-glutaraldehyde films (6.40%). FTIR spectra showed that the interaction of collagen with different cross-linking agents influenced the amide peaks absorption patterns. Collagen films made with TG had smooth and compact surfaces, while those with kCGN had rough surface in SEM analysis. In vitro biodegradation showed that all the collagen films were degraded rapidly within 4 days, except the collagen-TG films that degraded on day 6. Accordingly, collagen-TG films with high strength, solubility and stability were the best among those studied. Further work is needed to determine potential food and biomedical applications of these films.