Antibacterial molybdenum disulfide with silver phosphate coating on titanium fixator in rabbit models of rib fracture infection

In rib fractures, infection of the fracture ends can affect the use of the implant, causing surgical failures. Molybdenum disulfide with silver phosphate [MoS2(S)-Ag3PO4] coating for titanium plates has bactericidal effects in vitro. This study aimed to determine the most optimal MoS2(S)-Ag3PO4 coating for fracture healing in a novel rabbit rib fracture infection (RFI) model. This study hypothesizes that MoS2(S)-Ag3PO4 coated titanium implants will reduce bacterial infection and inflammation, while promoting osteogenesis and fracture healing in a rabbit RFI model. Twenty rabbits were used to create the RFI model using 0, 1×105, 1×106, and 1×107 colony-forming units (CFU)/mL of Staphylococcus aureus culture. Twelve rabbits were used to test titanium (Ti) vs. titanium MoS2(S)-Ag3PO4-coated (Ti-MoS2-Ag3PO4) (with 808-nm near-infrared light irradiation) fixators on rib fractures with S. aureus. Tissues were examined using hematoxylin-eosin (HE) and safranin-O staining. Western blotting was performed for interleukin (IL)-6 and tumor necrosis factor (TNF)-α. MoS2(S)-Ag3PO4 safety was assessed using hemolysis, blood assays, and major organ histology. Antibacterial efficacy was tested using Gram staining and bacterial cultures. In the negative control (NC) group, the incision healed well, but the 1×105, 1×106, and 1×107 CFU/mL groups showed pus coating and abscesses. IL-6 and TNF-α expression in the infected groups was significantly higher than in the NC group (all P<0.01). Safranin-O staining showed reduced osteogenesis in the infected groups vs. the NC group (all P<0.01). Ti, Ti-MoS2, and Ti-MoS2-Ag3PO4 were biocompatible according to the hemolysis and biochemistry assays and major organ histology. Dense bacterial accumulation was seen in the Ti group, while the Ti-MoS2-Ag3PO4 group showed sparse bacterial colonies, achieving a 99.43% antibacterial rate. An RFI model was successfully constructed in rabbits. MoS2-Ag3PO4-coated titanium implants appear to be biocompatible and able to manage infection in a rabbit model of RFI.