Tracking Live‐Cell Response to Hexavalent Chromium Toxicity by using Scanning Electrochemical Microscopy

Abstract

The effects of exposure to toxic heavy metals, such as chromium, are of interest in scientific research, owing to its association with oxidative stress, cytotoxicity, and carcinogenicity. This study aims to explore the effects of Cr (VI) on live cell responses. Herein, scanning electrochemical microscopy (SECM) is employed by using depth scan imaging and feedback mode to monitor the membrane permeability of single live human bladder cancer (T24) cells following 1 h incubations with Cr (VI) stimuli. By using membrane‐permeable and impermeable redox mediators, ferrocenemethanol and ferrocenecarboxylic acid, respectively, SECM depth scans yield both electrochemical and topographic information. This provides insights into the relative changes in membrane homeostasis with increased exposure to Cr (VI). Here, SECM has shown great power in determining membrane response to Cr (VI) exposure. Dependent on the level of exposure, transition between three distinct trends was observed. At low incubation concentrations of Cr (VI), the cell membrane permeability coefficients were relatively unaffected. With moderate increases in Cr (VI) concentrations, membrane permeability coefficients of the incubated cells were observed to decrease. Finally, with the higher incubation concentrations, membrane permeability coefficients were found to increase toward values similar to control cells. The Cr (VI) toxicity was further investigated by means of a MTT cell viability study, which exhibited a similar decreasing trend to the cell membrane permeability. These findings further demonstrate the strength of SECM as a bioanalytical technique for monitoring cellular homeostasis.

New Insight into Procedure of Interface Electron Transfer through Cascade System with Enhanced Photocatalytic Activity

“…However, there are still challenges that the local PEC activity of surface of semiconductor cannot be analyzed at micrometric scales, i.e., their photocatalytic activities are investigated by a relatively “big” photoelectrode, and little is afforded as desired requirements, such as local electrochemical activity or charge transfer dynamics in single channel (i.e., binary composites) or multiple steps (i.e., ternary composites). Thus, toward monitoring the superiority of MET channel for the efficient suppression of electron–hole pairs recombination, UV–vis/scanning electrochemical microscope (SECM) is viewed as a unique and powerful technique in situ characterization of “fast” and “slow” dynamics based on a recyclable probe molecular (e.g., Fe(CN) 6 ) 3+ /Fe(CN) 6 ) 2+ , FcMeOH, and MV 2+ /MV + ) at a ultramicroelectrode (UME). In the different electron‐collecting platforms, MET process can be observed through changing in faradaic current by a feedback mode.…”

In Situ and Operando Techniques for Investigating Electron Transfer in Biological Systems

“…modified conductive colloid AFM‐SECM probes with polystyrene sulfonate and poly(3,4‐ethylenedioxythiophene) to use them for single‐cell force measurements in mouse fibroblasts and investigate single‐cell interactions under different applied electric potentials. This approach has been used as a bioanalytical technique for monitoring cellular homeostasis through the evaluation of living cell membrane permeability to a series of compounds such as toxic heavy metals [128–130] . AFM‐SECM is also useful for the study of living single‐cell microorganisms such as bacteria, providing insights into metabolic exchange between two different bacteria [131] or even furnishing information on the efficiency of charge transfer from yeast cells under anaerobic conditions [132] .…”

Development of a Temperature‐pulse Enhanced Electrochemical Glucose Biosensor and Characterization of its Stability via Scanning Electrochemical Microscopy

“…Scanning electrochemical microscopy (SECM) is a scanning probe technique frequently used for the electrochemical characterization of surfaces and interfaces. Common application fields include corrosion research [1], biological studies with cells [2], and enzymes [3], as well as material characterization [4]. Among the various measuring modes of SECM, the generation/collection (G/ C) mode suffers from limited reproducibility and contrast issues due to a growing diffusion layer at the generator electrode.…”