Operando Investigation of Locally Enhanced Electric Field Treatment (LEEFT) Harnessing Lightning-Rod Effect for Rapid Bacteria Inactivation.

Ting Wang,Devin K Brown,Xing Xie

doi:10.1021/acs.nanolett.1c02240

Abstract

The growth of undesired bacteria causes numerous problems. Here, we show that locally enhanced electric field treatment (LEEFT) can cause rapid bacteria inactivation by electroporation. The bacteria inactivation is studied in situ at the single-cell level on a lab-on-a-chip that has nanowedge-decorated electrodes. Rapid bacteria inactivation occurs at the nanowedge tips where the electric field is enhanced due to the lightning-rod effect. Electroporation induced by the locally enhanced electric field is the predominant mechanism. The antimicrobial performance depends on the strength of the enhanced electric field instead of the applied voltage, and no generation of reactive oxygen species (ROS) is detected when >90% bacteria inactivation is achieved. Quick membrane pore closure under lower voltages confirms that electroporation is induced in LEEFT. This work is the first-time visualization and mechanism elucidation of LEEFT for bacteria inactivation at the single-cell level, and the findings will provide strong support for its future applications.

Highlights

Version of Record: A version of this preprint was published at Nano Letters on November 4th, 2021
Effective physical processes, such as thermo/ultraviolet radiation,[3], acoustic vibration,[5, 6] microwave,[7] and electric field treatment (EFT),[8] can be superior alternatives to chemical approaches for bacteria inactivation, many of them suffer from high capital cost or energy consumption
The EFT aims to inactivate bacteria by electroporation: when a cell is exposed to a strong electric field, an induced transmembrane voltage (TMV) will cause pore formation on the lipid bilayer membrane,[13,14,15] and when this external electric field is strong enough, the membrane damage, i.e., the pores, will become lethal to the bacterial cells.[10]

Summary

Introduction

Version of Record: A version of this preprint was published at Nano Letters on November 4th, 2021. V/2 μs/100 μs/500,000 pulses, see the waveform in Fig. S3), the bacteria at the tips of nanowedges on both positive and negative electrodes show red fluorescence of the PI stain, indicating cell membrane damage, while cells anywhere else are intact (Fig. 1d). Fluorescence indicates that the cell membrane damage takes place at the position adjacent to the nanowedge tip, where the nano-enhanced electric field has the highest strength.

Results

Conclusion