On the deposition of dual-functional antimicrobial coatings with an aerosol-assisted atmospheric pressure plasma

Preventing bacterial adhesion and biofilm formation on material surfaces is crucial for medical applications [1, 2]. Antimicrobial coatings have become a significant strategy to combat bacterial pathogens by providing antimicrobial properties with antibacterial or antifouling strategies on the surface, without affecting the bulk properties of materials [3]. Dual-functional antimicrobial coatings can be deposited using aerosol-assisted atmospheric pressure radio-frequency (RF) plasma. These coatings integrate antibacterial and antifouling composite coatings. The bottom layer comprises plasma polymerized hexamethyldisilazane (HMDSN) and AgNO
3
, which embeds Ag as the biocidal agent. The top layer is plasma polymerized perfluorodecyl acrylate (PFDA) coating, which is superhydrophobic and can repel bacteria. When aerosols are introduced, spherical particles are found in the coating. The core of spherical particles embeds Ag, and a polymeric silicone-like matrix serves as the shell. The size of spherical particles from HMDSN/ AgNO
3
deposition ranges from hundreds of nanometers to several micrometers. As the concentration of AgNO
3
increases, more particles with larger sizes are formed, coupled with an increase in surface roughness. This results in a high amount of silver being embedded in the coating to enhance antibacterial efficiency. Nanospheres in the PFDA coatings are connected to form a porous structure, which can be beneficial for releasing $\mathrm{Ag}^{+}$ for antibacterial purposes. The coating with a nano-structured PFDA layer on top has excellent repellence of bovine serum albumin (BSA) proteins, showing potential in antifouling applications and confirming the possibility of advanced coating deposition by means of aerosol-assisted atmospheric pressure RF plasma.