Silicon Nitride Coatings on Titanium for Cardiovascular Applications: Interface Engineering, Hemocompatibility, and...

Titanium and its alloys are widely used in cardiovascular devices because of their favorable mechanical properties, corrosion resistance, and biocompatibility. Nevertheless, their surfaces do not fully prevent nonspecific protein adsorption, platelet activation, thrombosis, bacterial colonization, or long-term degradation under physiological conditions. Silicon-nitride-based (SiN_x) coatings represent a promising strategy for addressing these limitations by combining chemical stability, mechanical durability, hemocompatibility, and antibacterial activity. This review critically examines silicon-nitride-based (SiN_x) coatings on titanium for cardiovascular applications, focusing on deposition technologies, interfacial phenomena, surface characteristics, and biological performance. Particular attention is given to physical vapor deposition parameters, coating adhesion, residual stresses, interfacial reactions, corrosion resistance, and mechanical stability. Relationships between surface chemistry, wettability, protein adsorption, platelet response, hemolysis, and cellular behavior are discussed, alongside the effects of static and dynamic testing conditions. SiN_x is also compared with Au, TiN, TiO₂, ZrN, and silicon carbide-based coatings. Despite encouraging in vitro results, clinical translation remains limited by insufficient standardization, scarce long-term and flow-dependent data, and an incomplete understanding of degradation mechanisms. Future studies should integrate interface engineering with microfluidic models, standardized hemocompatibility testing, artificial intelligence-assisted optimization of process-structure-property-biological response relationships, and regulatory considerations to support the safe clinical translation of SiN_x-coated cardiovascular devices.