Hidrogéis de colágeno, ácido hialurônico e sulfato de condroitina a partir de resíduos de tilápia do Nilo (Oreochromis niloticus): uma valorização da indústria do pescado

Abstract

Brazil is among the main countries that stand out in the fishing industry, including Nile tilapia (Oreochromis niloticus). Consequently, it is one of the largest generators of waste (~70%), which ends up generating environmental impacts. The by-products of fish processing, Nile tilapia waste in particular, are a promising source of biomolecules with wide applicability, being, therefore, a potential attraction in the generation of products with high added value. Aiming at this, the present work aimed, initially, to obtain and characterize hyaluronic acid (HA) (present in the vitreous humor) from by-products of the eyeball of Nile tilapia (O. niloticus), since this biopolymer has wide applications in the cosmetic, pharmaceutical and medical industries. Afterwards, HA extracted (HAE) was used together with collagen (from the skin) and chondroitin sulfate (from the spine), also from tilapia residues, obtained from partner projects, with the objective of producing and characterizing hydrogels cross-linked with N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide/N-hydroxysuccini mide (EDC/NHS). Therefore, first, the HAE was characterized in terms of structural chemical, thermal, morphological and cytotoxic analyses. The yield obtained in the enzymatic extraction process was 0.054 mg of AH/g of vitreous. The compositions of C, H, N, S and O for HAE were 38.44, 6.08, 2.23, 3.67 and 0%, respectively. The electrophoresis, FTIR, NMR and HPLC assays allowed the identification of the molecule of interest. The biomaterial extracted is of low molecular mass (� തതതത ௪ ത= 37 KDa), with thermal stability superior to commercial HA from Streptococcus equi, in addition to having a partially crystalline character and having a porous structure. The cytocompatibility assay demonstrates that HAE, in addition to not being cytotoxic, also stimulates cell proliferation. The hydrogels were characterized by the analysis of FTIR, TGA, DSC, crosslinking degree (TNBS assay), X-ray diffraction, SEM, cytotoxicity in fibroblast cells (L929) and keratinocytes (HaCat). Analyzes of crosslinking degree, FTIR, TGA, DSC and XRD confirmed the formation of crosslinked structures in hydrogels produced with EDC/NHS. The SEM analysis allowed us to identify the presence of pore regions with adequate diameters to be used as biocuratives. The cytotoxicity assay of the hydrogels in fibroblast cell lines (L929) and keratinocytes (HaCat) reveals a high potential in the application of biomaterials produced as biocuratives. Therefore, both the HAE and the hydrogelsproduced from crosslinking this waste source with EDC/NHS constitute new biotechnological alternatives with adequate quality for broad biomedical applications.