PhD Thesis Defence: Mr. Anindo Roy (04/12/23)

Thesis title:

Bioinspiration for battling bacteria: Nature inspired high aspect ratio nanostructures for new age antibacterial surfaces

Faculty advisor(s):

Prof. Kaushik Chatterjee


04th December, 2023 (Monday), 10:30 AM (India Standard Time)


KI Vasu Auditorium, Dept of Materials Engineering


Deaths due to bacterial infections are rising across the globe and conventional biochemical approaches of treating them using antibiotics are at the risk of becoming obscure due to emergence of drug-resistant strains. Alternative approaches based on biophysical antibacterial mechanisms can be the dark horse in the fight against antimicrobial resistance, however, successful translation and commercially viable widespread adoption is dependent on clear understanding of the key bactericidal mechanisms and development of cheap, scalable nanofabrication strategies. To this end, in this work, high aspect ratio nanostructures are fabricated on titanium using dry etching in plasma and it is demonstrated that the nanostructure formation takes place due to micro-masking of the titanium surface with chemical species generated during the etch process. Furthermore, etching recipes are developed for titanium and poly (ethylene terephthalate) based on studies of the effects of several process parameters in dry etching, which are used to fabricate nanostructures with extremely high aspect ratios to study their bactericidal efficacy. It is shown that an increase in aspect ratio affects the nanomechanical properties of the structures and leads to formation of superstructures which can affect their bactericidal efficacy. Moreover, external capillary forces are shown to be capable of enhancing the killing efficiency by exerting a downward force on the bacterial cells. Finally, metal oxide nanotubes generated by electrochemical anodization are demonstrated to be equally effective as nanopillars in eliminating bacteria, but with the additional benefit of scalability, low cost, and the ability to generate such topographies on complex, 3D geometries. The work to be presented is of critical importance in developing an understanding of how bacteria interact with high aspect ratio nanostructures and will find applications in development of next generation implant and touch surfaces.