Combined gelatin-chondroitin sulfate hydrogels with graphene nanoparticles

Creating flexible, high-strength hydrogels from harmless, low-cost natural polymers is an area of intense research today due to their potential applications in the biomedical field, which demands materials with ambivalent physicochemical features. In particular, great efforts were devoted to the preparation of sustainable biohydrogels, composed of hydrophilic networks of renewable, biocompatible, biodegradable, and low-cost biopolymers. Bionanocomposites are a promising synthetic approach to combine specific multifunctional materials with targeted physicochemical properties. Novel bionanocomposite hydrogels were designed by combining both chondroitin sulfate (CS) as well as gelatin (GE) obtained from the waste generated by the fish industries to form double fibre networks with tailored properties. In addition, hybrid bionanocomposites were achieved by introducing graphene nanoparticles (xGnP) into the double fibrillar network (GE/CS) to enhance the physicochemical properties. The bionanocomposite nanostructures were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimeter (DSC) while their rheological properties and thermal stability were determined by rheological and thermogravimetric analyses (TGA), respectively. The likely interactions between CS and gelatin in the GE/CS hydrogel network were proved by ATR-FTIR spectroscopy. The incorporation of xGnP improved the mechanical properties of the GE/CS fibrillary network by an order of magnitude in the shear storage modulus. Eventually, the generated bionanocomposites hydrogels and bionanocomposite hybrid hydrogels have promising potential for applications in many biomedical fields, including drug delivery and tissue engineering by mimicking tissue extracellular matrix components such as the gelatin for collagen and the CS in the cartilage.