Immunomodulatory and bone regenerative properties of copper/procyanidins-modified titanium surfaces

The inflammatory response triggered by the interaction between implants and macrophages is essential for bone regeneration around these implants. This study presents the application of dopamine hydrochloride to develop a copper and procyanidins coating on titanium surfaces to investigate its effects on bacterial inhibition, macrophage polarization, and osteogenic differentiation. The results demonstrated that this copper/procyanidins coating significantly suppressed the growth of Escherichia coli and Staphylococcus aureus. Notably, the initial release of Cu²⁺ ions promoted macrophage polarization toward a pro-inflammatory phenotype while stimulating the secretion of anti-inflammatory factors. Subsequently, the reduced Cu²⁺ release combined with procyanidins facilitated the transition from M1 to M2 macrophages-an essential process for bacterial phagocytosis and bone regeneration. Furthermore, this coating enhanced the secretion of osteogenic factors by bone marrow mesenchymal stem cells, enhancing their osteogenic differentiation and integration with bone tissue. These findings highlight the potential of copper/procyanidins coating in developing implant surfaces with immune-modulating and sustained antibacterial properties.