Cold-Spray Deposition of Antibacterial Molybdenum Coatings on Poly(dimethylsiloxane)

Despite their widespread utilization in biomedical applications, these synthetic materials can be susceptible to microbial contamination, potentially compromising their functionality and increasing the risk of infection in patients. In this study, molybdenum (Mo), an essential metal in biological systems, was investigated as a Mo-based cold-sprayed coating on poly(dimethylsiloxane) (PDMS) for its potential use as biocompatible and antimicrobial surfaces for biomedical applications. Various cold-spray parameters were employed in the fabrication of Mo-embedded PDMS surfaces to alter the surface structure of the substrate, Mo loading density, and embedding layer thickness. Specifically, relatively low nozzle scanning speeds were used to develop high-density Mo-embedded PDMS surfaces. A comprehensive analysis was conducted to investigate how cold-spray processing parameters affect the surface topography, wettability, and chemical properties. The ability of the Mo-embedded PDMS to inhibit the colonization of Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa bacterial species was demonstrated by both live/dead staining and disk diffusion methods. Surfaces with higher Mo loading densities significantly reduced the level of bacterial attachment and enhanced the bactericidal activity upon contact. Also, the level of Mo ion release over a 14-day period was measured and correlated to the properties of the substrate surface. Furthermore, attachment, viability, and proliferation of osteoblast-like MG63 cells were assessed to investigate the effect of Mo ion release on the biocompatibility of fabricated coatings. A notable decrease in cell viability and delayed growth of MG63 cells became evident after 7 days of incubation with the highly Mo-loaded samples. While this study enhanced our understanding regarding the engineering of composite materials for combatting microbial infections, the findings also suggest that the release of Mo ions may detrimentally affect osteoblast survival, potentially compromising the long-term functionality of orthopedic implants produced using this technique.