Biodegradable, Antibacterial TCP Implant Coatings with Magnesium Phosphate-Based Supraparticles

This work highlights the potential of porous, bioactive coatings to advance implant technology and address critical clinical challenges. A key issue in implant coatings is to achieve the balance between infection prevention and successful osseointegration. Although titanium implants are widely used due to their mechanical strength and biocompatibility, their bioinert nature limits integration with bone tissue. To address these issues, porous calcium phosphate (CaP) coatings have been developed to enhance cell attachment and bone growth. However, CaP, especially in the widely used form of hydroxyapatite (HAp), has a low resorption rate, which often leads to prolonged coating stability and impairs natural bone remodeling. To overcome this limitation, magnesium phosphate (MgP), an underexplored but promising biomaterial with high biocompatibility and osteogenic potential, can be introduced. Another innovative strategy is the doping of biomaterials with antibacterial ions, among which copper (Cu) has attracted particular attention. The incorporation of Cu into the coating matrix can significantly reduce the risk of post-operative infection while promoting angiogenesis, a key factor for rapid and stable implant integration. This study presents bone implant coatings composed of tricalcium phosphate (TCP) and Cu-doped MgP clustered nanoparticles (supraparticles) fabricated via high-velocity suspension flame spraying (HVSFS). This particle system addresses current challenges in bone tissue regeneration by synergistically combining the high biodegradability of MgP, the bone-mimicking properties of CaP, and the antibacterial capabilities of Cu. In addition, the HVSFS process enables the creation of thin layers with porous microstructures. Biocompatibility of the prepared coatings was assessed using MG63 osteosarcoma cells, while the antibacterial efficacy was tested against Staphylococcus aureus and Escherichia coli. The incorporation of Cu-doped MgP supraparticles (MgPCu and MgPCu HT) into TCP coatings resulted in high Cu release and pronounced antibacterial efficacy compared to the TCP reference, while the addition of Cu-doped FT supraparticles (FTCu) led to high cell proliferation.