Property modellingDevelopment of a method for measuring and modeling the NH2 content and crosslinking density of chitosan/gelatin/nanohydroxyapatite based microspheres

Nanocomposites based chitosan/gelatin/hydroxyapatite are widely used in biomedical application. However, to maintain their mechanical stability in aqueous media, they need to be crosslinked. NH2 content and crosslinking density of such composites has great impacts on their performances. In this study, a method is developed using combination of TNBS method, DD measurements and law of mixtures in composites to measure NH2 content of EDC crosslinked chitosan/gelatin/nanohydroxyapatite microspheres. Crosslinking density and NH2 content of nanocomposite microspheres were modeled using Surface Response Method. Microspheres were characterized using SEM, TEM, XRD and FTIR. Effects of EDC concentration, nanohydroxyapatite/biopolymer and chitosan/biopolymer weight ratio on crosslinking density and NH2 content of nanocomposite microspheres, swelling ratio and cell viability were investigated. Data showed by controlling nHA/BP ratio, concentration of EDC, chitosan/biopolymer ratio, microspheres with different ranges of crosslinking density and NH2 content can be fabricated. Results of cell proliferation studies implied superior biocompatibility of these microspheres.