Graded oxidation state calcium phosphate graphene oxide modulates the mechanical and biological behavior of bone matrices

Calcium phosphate graphene (CaPG) is a promising reinforcement for polymeric bone matrices, yet the impact of graphene oxide (GO) oxidation on CaPG chemistry and matrix performance remains unclear. Our previous work demonstrated that 5 wt% CaPG provides optimal mechanical and biological performance of poly (lactic-co-glycolic acid) (PLGA) matrix. The present study isolates GO oxidation as the sole variable while maintaining a fixed 5 wt% CaPG loading. CaPG was synthesized under three oxidation conditions: Low Phosphate-High Oxygen at 50 °C, High Phosphate-High Oxygen at 100 °C, and High Phosphate-Low Oxygen at 156 °C and incorporated into the PLGA microspheres. Our results have shown that oxidation state regulates oxygen functional group density, calcium phosphate incorporation, hydrophilicity, and hydration behavior, which collectively modulate mechanical properties and osteogenic activity of the matrix. These findings demonstrate that oxidation can serve as a key tunable factor that generates distinct physicochemical and biological profiles, establishing oxidation programming as a practical approach for creating adaptable CaPG-reinforced PLGA matrices for diverse bone regeneration needs.