Nanostructured Coatings with Advanced Antimicrobial Properties

Abstract

Antimicrobial surface coatings are important for the prevention of bacteria growth, having extensive applications in areas such as food packaging and medical applications. In this study ionomer Nafion (N) was used, in conjunction with synthetic polymer (QPDMAEA-PLMA Diblock (M) and Polyvinylpyrrodidone (P)) and naturally occurring biocides (Lysozyme (L) and Chitosan (C)), to synthesise antimicrobial surface coatings. This was achieved through a layer-by-layer assembly method, using a Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D). Nafion (negatively charged) was deposited in alternating layers with the positively charged materials, this allowed electrostatic bonds to form between each of the layers, allowing for a durable and stable coating. Electrostatic forces and hydrogen bonding were observed through FT-IR analysis showing the interactions between the positive and negatively charged layers. The coatings were tested for antimicrobial effectiveness, with all coatings showing antimicrobial properties and (N/L/N/C)x2 and (N/Lx6) showing more than 99.9% reduction in bacteria.
Atomic Force Microscopy (AFM) was used to analyse the coatings (N/L/N/C)x2, (N/L)x6 and (N/C)x6, these all showed high levels of surface roughness. Contact Angle measurements was used to analyse the coatings hydrophobicity. Coatings (N/L)x6, (N/C)x6, (N/L/N/C)x2, (N/P)x3, and (N/P/N/L)x1 all showed wettability values between 75⁰-45⁰. UV-Vis spectroscopy was used to test the coatings transparency with (N/L)x6, (N/C)x6 and (N/L/N/C)x2 showing transparency.