Antibacterial superhydrophobic surfaces

Abstract

Antibacterial Superhydrophobic Surfaces

Biofilms, the sessile colonies of bacteria have a ubiquitous presence in the natural ecosystem. The shift of human life to an artificial environment has led to the creation of a microbiota inhabited by bacteria. Biofilms of virulent bacteria in these artificial environments, for instance in a hospital environment has been a major reason for the epidemic called hospital-acquired infections. In the wake of biofilms developing drug resistance, the challenge to combat these infections has shifted the scientific endeavour from conventional antibiotics to antibacterial surfaces. Further, bacteria also cause fouling in wet environments, leading to heavy waste of human resources and capital investments. Hence developing durable and functional antimicrobial surfaces to combat these infections are of utmost infections. In this research, we developed a durable lotus leaf resembling superhydrophobic surface (SHS) and studied bacterial adhesion on it at different conditions. The coating maintained superhydrophobic contact angles up to 100 cycles of abrasion. The coating resisted 99.99% of bacteria and maintained this for 4 hours exposure in bacterial suspension, making it a superior choice for coating hospital environments to prevent biofilm formation. For the first time, we demonstrated how bacteria float on the air-layer or plastron of a superhydrophobic surface and deduced the difference between cell-surface interactions on a non-coated surface vs a coated one. Hence, by throwing light into microbiota formed by these cells on abiotic surfaces, the research here significantly advances the literature on developing antibacterial coatings. We also mechanistically studied the bubble bursting effect of an SHS immersed in water for prolonged times and threw light into limited applicability of SHS for marine antifouling. After studying bacterial adhesion by taking an SHS as a model resistant surface, we improved its functionality to extend its scope to applications in wet environments. We introduced zeolite imidazolate -8 (ZIF-8) based submicron particles into the coating. An increase in contact angles owing to the additional roughness created by the ZIF-8 particles was observed. Also, the coating killed 99.9% of bacteria after 9 days of incubation in a culture, making it a superior approach to be used as a dual functional antimicrobial surface. Show more