Novel coating containing molybdenum oxide nanoparticles to reduce Staphylococcus aureus contamination on inanimate surfaces

We previously synthetized molybdenum oxide (MoO 3 ) nanoparticles (NP) and showed their antibacterial activity against a representative collection of the most relevant bacterial species responsible for hospital-acquired infections, including Staphylococcus aureus . The aim of the present study was to prepare and characterize a novel coating with these MoO 3 NP, confirm its mechanical stability, and investigate its biocidal effect to reduce S . aureus contamination on inanimate surfaces. In addition, the novel MoO 3 NP coating was compared to a silver (Ag) NP coating synthetized by the same procedure. The MoO 3 and Ag NP coatings were characterized in terms of their chemical structure by FT-IR, surface morphology by scanning electron microscopy, and mechanical properties by tensile and adhesion tests. The antimicrobial activity of the coatings was tested by following the loss of viability of S . aureus after 6h, 24h, 48h, and 72h exposure. MoO 3 and Ag coatings exhibited surfaces of comparable morphologies and both presented elastomeric properties (tensile strength of ~420 kPa, Young’s modulus of ~48 kPa, and maximum elongation of ~12%), and excellent (classification of 5B) adhesion to glass, steel and polystyrene surfaces. The two coatings exhibited a good antibacterial activity (R) against S . aureus over time (R MoO3 = 0.2–0.81; R Ag = 0.61–2.37), although the effect of the Ag NP coating was more pronounced, especially at 72h (R MoO3 = 0.81 vs R Ag = 2.37). Noteworthy, contrary to the Ag NP coating, the MoO 3 NP coating was colourless and transparent, avoiding undesired unaesthetic effects. The synthetized coating with NP of MoO 3 , which has low toxicity to humans, capability of biodegradation, and rapid excretion, can be applied onto most standard materials and therefore is a promising tool to reduce S . aureus contamination on usual inanimate surfaces found in healthcare and community environments.