Silicon role on genipin-mediated crosslinking and in vitro apatite deposition over collagen hydrogels

Abstract

The field of biomaterials is in constant improvement. The biocompatibility with the surrounding tissues is essential for their clinical use. Collagen has been used in many different tissue applications due to its high biocompatibility. Several crosslinking reagents for collagen, among them genipin, has been proved to influence the physicochemical properties of the scaffold. Genipin has the benefit of having lower cytotoxicity, in comparison to other crosslinking reagents. The aim of this work was to evaluate the effect of silicon on crosslinked collagen hydrogels and to evaluate its effect on apatite deposition in vitro. Genipin crosslinking was analyzed in presence of sodium silicate, through color assessment of hydrogels. Subsequently, collagen hydrogels were incubated in simulated body fluid (SBF) for three weeks; then samples were lyophilized and analyzed. Scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and rehydration experiments were carried out. Qualitatively, a synergistic effect was observed in collagen crosslinking when sodium silicate and genipin were combined. Therefore it’s presumed that silicon is stimulating the crosslinking process of collagen molecules at the structural level. Microscopy results show mineral deposition on the surface of the samples with sodium silicate and/or genipin treatment that had been immersed in SBF. Through EDX analysis, calcium and phosphate presence was confirmed; although Ca/P ratio was significantly different from the desirable physiologic value of 1.67 of HAP.