Characterization of biochemical and optical properties of Nile tilapia (Oreochromis niloticus) corneal collagen

Background Collagen extracted from fish body parts is a promising biological material. It has an important role in many pharmaceutical, medical applications and tissue engineering such as corneal regeneration and stromal replacement. The present work investigates a new trend to extract collagen from the fish cornea, as a prospected substituent of human corneal collagen by characterizing some biochemical and optical properties of the fish corneal collagen. Results Examination of the corneal tissue of Nile tilapia; Oreochromis niloticus was conducted using electron microscopy, Fourier transform infrared (FTIR) spectroscopy, UV-visible spectrophotometry, optical properties, and thermal properties. The fish were divided into 10 groups each of which consisted of 5 fish. 2 groups of fish were examined for each technique. Results indicated that the corneal layers of O. niloticus are thin at the center and thicker at the periphery with the stroma consisting of a triple helical structure collagen type I. The fish cornea showed very weak transmission at the UV regions (190 nm) and maximum transmission at the visible regions. The values of transmission (T), reflected light (R) and scattered light (S) were 2.685 mw, 100 x 10(-3) mw at 45(degrees)and 40 x 10(-3) mw, respectively. Consequently, the percentage of absorbed light is 21.76%. The denaturation temperature of the fish corneal stroma is 22.27 C-degrees. Conclusions The method for obtaining fish collagen affects the specific properties of collagen and consequently its further uses as a potential biomedical substituent for mammalian collagen. Specification of the fish species and tissue type is crucial in identifying the quality as well as the physical and functional properties of the extracted collagen.