Rhamnolipid biosurfactant adsorption on a plasma-treated polypropylene surface to induce antimicrobial and antiadhesive properties

A glycolipid type of biosurfactant (rhamnolipid), which is obtained from Pseudomonas aeruginosa MA01, was adsorbed on a polypropylene film to produce an antimicrobial and antiadhesive polymeric surface for the first time. The polypropylene film was modified using oxygen and air plasma. The effects of the plasma operating conditions, including the plasma power and the time of plasma exposure, were studied. The characteristics and hydrophobicity of the polypropylene surface were evaluated by several techniques including ATR-FTIR, XPS, SEM and AFM as well as measuring water contact angles (WCA). The results confirmed the successful attachment of rhamnolipid on plasma-treated surfaces, however in different degrees based on the plasma conditions. The antibacterial and antiadhesive performance of the rhamnolipid-adsorbed-films was investigated against pathogenic bacteria, and the results showed considerable activity of the surface to reduce the number of bacteria on the treated polymeric film. The optimum plasma conditions, in which the best antimicrobial and antiadhesive surface was obtained, were revealed as a power of 50 W and an exposure time of 6 min with air as the plasma gas.