Label-Free Detection of Single Living Bacteria via Electrochemical Collision Event

Abstract

We detected single living bacterial cells on ultramicroelectrode (UME) using a single-particle collision method and optical microscopic methods. The number of collision events involving the bacterial cells indicated in current-time (i-t) curves corresponds to the number of bacterial cells (i.e., Escherichia coli) on the UME surface, as observed visually. Simulations were performed to determine the theoretical current response (75 pA) and frequency (0.47 pM−1 s−1) of single Escherichia coli collisions. The experimental current response (83 pA) and frequency (0.26 pM−1 s−1) were on the same order of magnitude as the theoretical values. This single-particle collision approach facilitates detecting living bacteria and determining their concentration in solution and could be widely applied to studying other bacteria and biomolecules.

Lipid Membrane Permeability of Synthetic Redox DMPC Liposomes Investigated by Single Electrochemical Collisions

“…Electrochemical discrete collisions at an ultramicroelectrode (UME) is a useful technique to detect one at a time single biological entities such as cells, [1][2][3] bacteria, [4][5][6][7] macromolecules, 8 viruses, [9][10][11] and synthetic or biological vesicles. [12][13][14][15] Especially, electrochemical detection of single liposome collisions by recording electron transfer from the UME to an encapsulated redox species is fully appropriate for studying their membrane permeability.…”

Recent Progress on the Electrochemical Biosensing of Escherichia coli O157:H7: Material and Methods Overview

“…The detection of the nanoimpact is performed using the change in diffusion current. Lee et al [90] has reported a fast electrochemical label-free approach through current blockages caused by collision events for E. coli single cell detection on an ultramicroelectrode. The ferrocyanide-ferricyanide redox couple was used in this study.…”

“…The ferrocyanide-ferricyanide redox couple was used in this study. This methodology has the capability to be used to study other pathogenic bacteria and different target molecules [90]. The problem with the surface blockage detection strategy is the lack of selectivity between various bacterial species and dead and alive cells.…”

Advanced Nanoscale Approaches to Single-(Bio)entity Sensing and Imaging

“…A second work from the same authors proposed an improved strategy where the signal was enzymatically amplified through the detection of the specific collision of a single virus on a Pt electrode with the aid of a glucose oxidase (GOx)-functionalised specific antibody [265]. Similar approaches were employed using the blocking of the electrode surface to detect other electrochemically inactive single (bio)entities such as bacteria [266,267], proteins and DNA [240].…”