In Vitro Comparison of Bioactive Silicon Nitride Laser Claddings on Different Substrates

The performance, durability, and bio-integration of functional biomedical coatings can be enhanced by changing or improving their substrate properties. In this study, we applied silicon nitride powder-based laser claddings to various substrates and undertook an in vitro assessment of their osteoconductive and antibacterial properties. The substrates included common arthroplasty materials: polyethylene, titanium, zirconia-toughened alumina, and zirconia. Multiple analytical techniques were used to characterize the physical and chemical structure of the claddings after deposition. Partial decomposition of the silicon nitride powders occurred during the cladding process, resulting in nitrogen loss during intermetallic formation phases under some substrate and treatment conditions. The osteoconductive capabilities of various laser-cladded substrates were evaluated in a SaOS-2 osteosarcoma cell culture by measuring the amount of bone formation on the coated surface. Antibacterial testing was performed using Gram-positive Staphylococcus epidermidis at 24 and 48 h of incubation. Silicon nitride coating enhanced both osteoconductive and antibacterial properties.