Understanding Governing Physical Mechanism of Bio-Inspired Nanostructured Antifouling Coating

Abstract

Abstract Nanostructured anti-fouling surface has been discovered on the wings of insects like Cicada, which have the ability to kill bacteria on contact. The discovery of such nanostructured surface on cicada wings started a race amongst researchers to find and develop anti-biotic coating for implantable devices, which can prevent the infection from harmful bacteria and simultaneously reduce the use of antibiotic chemicals. To develop and design such biomimetic bactericidal surfaces, thorough understanding of the bactericidal mechanism is critical. However, due to extremely small relevant length and time scales, it is challenging to investigate the bactericidal process in an experimental setting. Molecular Dynamics (MD) simulation provides an exceptional tool to predict structural and material behaviors at small length and time scales with good accuracy and a fraction of costs relative to experimental testing. We have developed a coarse-grained model to simulate the deformation of bacteria on nanopillared array/surfaces to investigate the governing killing mechanism of bacteria. This study has investigated the effect of nanopillars height and bending rigidity of the bacteria’s membrane on the governing killing mechanism and bactericidal efficiency. It is suggested that for bacteria with high membrane bending rigidity, nanopillar height is not an important factor and piercing of the bacteria’s membrane is the dominating bactericidal mechanism. For bacteria’s with low bending rigidity sagging of the bacteria’s cell membrane between nanopillars and resulting stretching/tearing is the major killing mechanism. Therefore, nanopillar height is an important factor for governing the bactericidal efficiency because small nanopillars allow the bacteria to sag down and reach the bottom surface for extra support without damaging. In addition, the present study implies that there exists a critical height of nanopillars for the development of efficient antifouling surfaces against bacteria with low membrane bending rigidity.