Completely Green Synthesis of Antimicrobial Nanocomposites Based on Hydrogels Containing Silver Nanoparticles for 3D Biofabrication of Smart Scaffolds

Lack of biomaterials feasible for three-dimensional (3D) biofabrication and the limited capability to sterilize some of these items are current gaps that need to be settled to strengthen studies in this area. Silver nanoparticles (AgNPs) are known for their enhanced antimicrobial capability against a great number of microorganisms and consequently have the potential to be applied in areas that need novel sterilization strategies. Therefore, this study aimed to produce hydrogels containing AgNPs in a completely green way with possible applications in 3D bioprinting. AgNPs were synthesized using banana peels and their physico-chemical characteristics were evaluated. Hydrogels were produced using mixtures with different proportions of carboxymethyl cellulose, gelatin, and agar, and were characterized concerning their swelling capability, consistency, and printability. Citric acid (CA) was tested as a sustainable crosslinking agent at different time intervals and concentrations. Lastly, one selected hydrogel was chosen based on performed assays and was prepared with the AgNPs for tests against Gram-negative and Gram-positive bacteria models. From the 36 initial hydrogels, 8 were chosen to be extruded manually based on swelling assay and consistency and, from those, 2 were chosen for 3D bioprinting assays. Finally, one was chosen to be prepared with AgNPs and was used for antibacterial assays. In the crosslinking assay, the best parameter was an exposure of 1 min to CA at a concentration of 5%. Hydrogel + AgNP was effective in inhibiting bacterial growth. Thus, it was produced a nanocomposite biomaterial in a completely green manner with potential applications in 3D biofabrication that presented antibacterial capability.