Inhibition of biofilm formation on medical surfaces by novel plasma system

Bacterial infections are a global challenge all around the world which affects millions of people every year. Therefore, the utilization of alternative and effective methods to decrease bacterial adhesion on medical surfaces is an issue of highly interested. The plasma technology has been widely used, an effective and economical technique for surface modification of materials, aiming to change surface physicochemical properties and reduce biofilm formation due to a decrease of bacterial attachment. This study was aimed to investigate the anti-adhesive and anti-biofilm effects of Non-thermal Atmospheric Pressure Plasma Jet (APPJ) treatment on Stainless Steel L316 (SS) and Titanium (grade 5) (Ti) surfaces in the presence of various gases. Optical emission spectrometry was operated to identify the excited reactive species during APPJ treatment by nitrogen, oxygen and argon gases. SS and Ti surfaces were treated by the use of nitrogen, oxygen and argon APPJ system for 15 minutes, separately for each gas. Following treatment, the change of surface modifications was characterised by the attenuated total reflection fourier transform infrared, atomic force microscope, water contact angle goniometer, and scanning electron microscope. Early adhesion and biofilm formation of Pseudomonas aeruginosa PAO1 on the APPJ treated surfaces were investigated by culture plate method. APPJ treatment showed different effects on the native surface properties and also surface roughness parameters according to the presence of different gases. APPJ treated surfaces exhibited increasing hydrophilicity and significantly reducing P. aeruginosa adherence. This reduction was sufficient to decrease of biofilm formation on nitrogen and oxygen APPJ treated SS surfaces, however, biofilm formation was not significantly decreased on argon APPJ treated SS surface and also APPJ treated Ti surfaces. The present study highlights the potential benefits of APPJ treated SS and Ti surfaces with different gases. These positive effects of APPJ treatment could enhance the biological activity of medical surfaces over time.