Session: 16-01-01: Poster Session: NSF-Funded Research (Grad & Undergrad)

Paper Number: 99659

99659 - Bactericidal Effects of Nanopillars: A Molecular Dynamics Study 

Ivanova et al. were the first ones to find that cicada wings can kill bacterial cells upon contact with their nanopillar shaped features. This study also established that nanostructural surfaces can restrict the colonization of bacteria. After this finding, a race to develop chemical free nanopillar based antibacterial surfaces  started. These antibacterial nanostructural surfaces can find their applications in healthcare industry and have the potential to prevent the spread of infectious bacteria's using chemical free method. Apart from nanopillars based antibacterial surfaces many other kinds of antibacterial surfaces have also been studied which can resist the growth of bacteria. For example :- biochemical approach usually apply coatings which are toxic to the bacteria whereas biophysical approach uses surface topographies that kill the bacteria on contact with the surface. 

Findings of Ivanova et al. led to the development of titanium, silicon and polymer-based antibacterial surfaces in the recent years. Some of these antibacterial topographies can be found in the studies  of Dickson et al. Till date most of the antibacterial surfaces developed have characteristically high-aspect ratio nanopillars which on  contact with bacteria's membrane leads to its stretching and subsequent disintegration, a process also known as cell lysis.

Although different types of antibacterial surfaces have already been developed using various materials, still our knowledge on the effect of geometrical variations of these nanopillars on bactericidal activity is very limited. Studies on the influence of nanostructural topology on bactericidal efficiency have been previously conducted, but these studies have been focused on non-uniform surface geometries resulting from nanofabrication techniques that inherently contain multiple features of nanostructures. Some of the previous studies were based on experimental testing and have limitations linking  nanoscale features of antibacterial surface with its bactericidal efficiency, which further prevents the optimization of geometrical features of nanostructured surface. Molecular dynamics (MD) simulations have been adopted where experimental studies had difficulty in investigating a material behaviour due to its limitations on time and length scales. Considering relevant length scale of nanostructured surface and bacteria, MD simulations have the potential to simulate bacteria-nanopillar interaction on contact, and further investigate the potential effect of geometric parameters of nanopillars on such interactions. This may deepen our understanding about the bactericidal process of nanostructured surface. 

In this work, we have investigated the interaction of bacteria with antibacterial surfaces with highly ordered and uniformly spaced nanopillars . These surfaces have bactericidal effects on most human pathogens. In this study we have simulated a gram positive bacteria, i.e. Staphylococcus aureus as a representative of bacteria. Coarse-grained atomistic models was developed for simulating bacteria-nanopillar interaction with a single bacteria cell. The bacteria cell was simulated such that it remain suspended in water molecules. A body force was applied to the bacteria to simulate gravity and hydro-static pressure load. The effect of nanopillar diameter, height and spacing was studied on the bacteria-nanopillar interaction, the deformation of the bacteria's membrane and subsequent cell lysis. 

Presenting Author: Akash Singh University of Illinois at Urbana-Champaign

Presenting Author Biography: Akash Singh is a PhD candidate working in computational materials simulation.

Authors:

Akash Singh University of Illinois at Urbana-Champaign
Yumeng Li University of Illinois