Antimicrobial and Superhydrophobic CuONPs/TiO Hybrid Coating on Polypropylene Substrates against Biofilm Formation.

Biofilm formation in common public places and hospitals is of great concern. Active antimicrobial coatings can prevent the formation of bacterial biofilms and the spreading of primary and secondary infections caused by contagious bacteria and viruses. In the present work, we report a simple spray coating process using copper oxide (CuO) nanoparticles (NPs) dispersed in a titanium dioxide (TiO) sol, where CuONPs act as the active antimicrobial agent and TiO as the inorganic binder. Homogeneous CuONPs/TiO coating was obtained on polypropylene substrates by spraying the CuO/TiO sol using a commercial air gun, followed by drying at 80 °C. The amount of CuONPs loading in the coating was adjusted by controlling the number of coated layers. CuONPs and CuONPs/TiO coatings were characterized by XRD, BET, X-ray fluorescence spectroscopy, AFM, and field emission scanning electron microscopy techniques. All of the coated films showed dual activity, i.e., antimicrobial and superhydrophobicity. A high bactericidal effect against both and was observed for the coated substrates. Coatings with higher CuONPs showed greater antibacterial activity, reaching value >6, and no bacterial colonies were detected after 24 h of incubation. An increasing trend of water contact angle was observed with the increasing amount of CuONP loading.