2023 年 131 巻 8 号 p. 398-428
Three decades of research in the last century developed silicon nitride (Si3N4) as one of the strongest and toughest ceramic material for structural applications; but in this century, we newly discovered its gifted surface biochemistry. In an aqueous environment, Si3N4 undergoes surface hydrolysis with the slow but continuous elution of both silicon and nitrogen. A unique environment is created, which greatly enhances healing of soft and osseous tissues, inhibits bacterial biofilm formation, and eradicates viruses. The discovery of Si3N4’s biochemistry opens new paths in a wide array of different disciplines inside and outside of the physical body, including orthopedics, dentistry, virology, agronomy, and environmental remediation. In the biomedical field, it paves the way for a new generation of monolithic, composite, or coated implants for bone healing, including spinal arthrodesis, joint arthroplasty, craniomaxillofacial and dental devices. This review describes Si3N4’s surface chemistry in an aqueous environment in comparison with oxide ceramics. It discusses the pH-dependent elution kinetics of ammonia and ammonium as the main phenomenon behind its unparalleled behavior and demonstrates its friendly nature to mammalian cells while concurrently lysing invasive pathogens. Finally, a wider perspective is offered for future applications of Si3N4 in disease diagnosis and therapies, personal healthcare, agriculture, food and water safety, and environmental protection.
