Antimicrobial resistance (AMR) is the result of the continuous rampant overuse of antibiotics. It is now accepted as a global health concern by the World Health Organization and countries of all income levels. Mechanobactericidal nanostructures, first discovered on the wings of insects like cicadas and dragonflies, are a promising new avenue in nano-microbiology that presents an alternative to traditional biochemical approaches and possesses enormous potential to tackle the growing menace of AMR. We develop nanofabrication protocols that allow us to generate dense arrays of nanostructures with tunable aspect ratios on a clinically relevant biomaterial, titanium, using maskless reactive ion etching. We demonstrate that precise control of several process parameters can produce a library of nanostructures such as nanopillars, nanowires, and interconnected networks of nanoridges. We then investigate the bactericidal efficacy and mechanism of these surfaces as a function of the aspect ratio for both Gram-positive and Gram-negative species using a standardized protocol for testing bacterial cell viability on nanostructured surfaces and demonstrate the crucial importance of nanomechanical properties of the nanostructures and the bacterial strain (Gram-positive or Gram-negative) towards determining the mechanobactericidal efficacy. We further verify our conclusions using finite element modeling of the mechanical behavior of the nanostructures and correlate these properties with the bacterial cell behavior on such surfaces. Finally, we explore the cytocompatibility, cytoskeletal arrangement, and morphology of MC3T3 cells on these surfaces in a quest to identify bactericidal yet non-cytotoxic surfaces. The insights obtained from our studies have important implications for the fabrication of a wide range of nanostructures on titanium and towards understanding the behavior of bacteria on nanostructured surfaces.

Fabrication of nanostructures with tunable aspect ratios for mechanobactericidal activity and cytocompatibility

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.