Antimicrobial coatings and antimicrobial polymers have become popular in recent years to help reduce the spread of microorganisms at a lower financial and environmental cost than more traditional cleaning methods.
Mechanical methods of antimicrobial activity often include the use of nanospikes which disrupt bacterial membranes causing cell lysis and therefore cell death. They can also trap viruses, preventing them from spreading to other surfaces, so they can be more easily cleaned- ultimately reducing the spread of disease.
Using SEM the topography of a surface can be analysed to assess the viability of microorganisms attaching to the surface and also of bacteria forming biofilms. OCA (Optical Contact Angle) can be used to determine surface wettability, which also links directly to bacterial attachment on a surface. XPS can determine the chemistry of the outer atomic layers, critical in antimicrobial action. The uniformity of a coating can be analysed to predict how effective the overall coating will be.
Commonly used cationic antimicrobial polymers, such as chitosan, quaternary ammonium compounds or organosilanes, adsorb onto the surface membrane of microbes, disrupting the cell structure and causing cell death. Organic coatings and polymers may be analysed by XPS and FTIR to correlate a certain functional group with efficacy, or to analyse degradation of the polymer/ coating. FTIR mapping can also be used to observe inhomogeneity across a surface, where the proportion of active cell membrane disruptive functional groups should be proportional to the surface coverage chemically.
Analysis of the coating or polymer allows the material to be fabricated to the right specifications for optimal functional performance.