Nanostructured antimicrobial ZnO surfaces coated with an imidazolium-based ionic liquid

Abstract

The global COVID-19 pandemic and widespread concerns about antimicrobial resistance (AMR) have intensified research efforts towards the development of innovative methods and technologies to suppress the spread of infectious pathogens facilitated by high touch surfaces. Thus, surfaces and coatings capable of inhibiting bacterial growth and preventing biofilm formation are being comprehensively explored in healthcare sectors to mitigate the spread of infectious pathogens. With the emergence of resistant strains of bacteria, due to over usage of conventional antibiotics, it becomes essential to develop a new class of materials with higher antibacterial efficiency. In the present study, the various morphologies of zinc oxide (ZnO) nanostructures have been exploited as efficient antimicrobial surfaces. This work aims to enhance the bactericidal properties of ZnO nanostructured surfaces by tuning their wettability and surface chemistry. Silicon substrates decorated with ZnO structures such as flowers, needles, and fibers are characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). These surfaces are further spin-coated with an ionic liquid 1-decyl-3-methylimidazolium tetrafluoroborate (DMIM-BF4), which causes a drastic impairment of bacterial cell viability on the surfaces. This bactericidal activity has been compared with that of a well-known low surface energy material 1H,1H,2H,2H-perfluorooctyl-trichloroethoxysilane (FOTES) by performing spot assay and colony-forming unit (CFU) analysis. The ionic liquids, commonly known as green solvents, are found to be emerging coating materials to develop advanced antimicrobial surfaces.