The Antipathogenic Properties of Silicon Nitride

Silicon nitride demonstrates exceptional biocompatibility in experimental studies. These data have supported its use in human spinal fusion implants where excellent clinical outcomes include a possible reduction in infection risk. This observation relates to an intriguing property of silicon nitride—its remarkable ability to eradicate bacteria, viruses, and fungi while being safe enough to use as an implant. As described in this chapter, several experimental investigations have shown that silicon nitride exhibits potent antibacterial activity against a variety of bacterial strains, including gram-positive and gram-negative species. This effect arises from a surface chemical reaction that releases nitrogen moieties that are converted to reactive nitrogen species that, in turn, disrupt prokaryotic cell membranes and metabolic processes, and cause cell lysis. Similar mechanisms explain the antiviral efficacy of silicon nitride against several viruses. In vitro studies have shown nearly instantaneous viral inactivation upon contact, including several variants of the SARS-CoV-2 virus. The antipathogenic effects of silicon nitride extend to fungi, such as Candida albicans, a common dental pathogen. Silicon nitride’s antifungal activity is also due to the release of reactive nitrogen species that disrupt fungal cell membranes and inhibit biofilm formation. This antifungal effect manifests itself against Plasmopara viticola, an agricultural fungus that infects grape plants. In summary, the surface chemistry that explains silicon nitride’s osteopromotive properties also contributes to its ability to resist bacteria, viruses, and fungi. Further research into this area will hopefully lead to new strategies to combat infections and surface contamination, thereby discouraging the spread of human infectious diseases.