A Miniaturized Two-Electrode Detection System for Convenient and Rapid Ferricyanide-Mediated Chemical Toxicity Screening

Toxicity bioassays play a crucial role in chemical risk assessment; however, conventional methods usually require specialized equipment, and limited accessibility is a significant drawback. Here, we present a user-friendly version using a simple two-electrode ferricyanide-mediated scaling of microbial respiration for rapid, convenient, and reliable toxicity assessment. The electrochemical cell is designed for continuous pulse-amperometric analysis, eliminating the need for disassembly/assembly and enabling a straightforward protocol to obtain a comprehensive evaluation of bacterial viability across a specific toxicant gradient in a single test run. Dose-response toxicity trends were directly observable, and half-maximal inhibitory concentration (IC₅₀) values were derived for comparative analysis. For a representative set of toxic chemicals, our assay produced an IC₅₀ ranking of Ni²⁺ > Cd²⁺ > Pb²⁺ for heavy metal ions and DCP > PNP > carbaryl for organic toxicants. The IC₅₀ values correlate well, in most cases, with results from other electrochemical toxicity assays and Microtox data. Our specialized bioassay enables a simple, accessible, cost-effective, and rapid toxicity assessment, providing instant toxicity clarification and making it suitable as a first-line screening tool. Additionally, the method can potentially be included in a broader toxicity assessment battery and has feasible applicability in other fields.