A paper origami-based micro-total electrochemical immunoassay (μTEI) for the detection of total malachite green in aquatic products

Malachite green (MG) and its metabolite leucomalachite green (LMG) are aquaculture-banned drugs whose rapid detections are required yet hindered by the use of expensive instruments as well as the tedious pretreatment procedures for aquatic samples. An integrated workflow for total MG (MG and LMG) analysis in aquatic samples is reported combining a deep eutectic solvent (DES) as the extractant and a paper origami-based micro-total electrochemical immunoassay (mu TEI). DES solution (mixture of glycine betaine and ethylene glycol) enables the extraction of MG and LMG with high efficiency from tissue samples and allows grease for separation. The mu TEI is compartmentalized simply by manual-folding to implement multiple analytical steps in a programmable manner, including impurity removal, LMG oxidation, MG enrichment, and electrochemical analysis. The entire workflow can be accomplished in 1.0 h, showing a wide linear range of 0.5-100 ppb, a low limit of detection of 0.07 ppb, and a high recovery rate of 78.9-97.6%. The mu TEI offers a solution for the rapid accurate monitoring of total MG in aquatic samples and is potentially available for the analysis of other contaminants with proper modifications.

Automated summary

In this study, an integrated workflow combining deep eutectic solvent extraction and paper origami-based micro-total electrochemical immunoassay was developed for the analysis of total malachite green in aquatic samples. The method offers a rapid and accurate solution for the monitoring of malachite green in aquatic samples.