Fabrication of flexible Au microsensors by a simple stamping method for the point-of-care direct detection of trace leucomalachite green

Abstract

Leucomalachite green (LMG) is the metabolic product of malachite green, which is a common aquaculture antimicrobial known for its high toxicity and long persistence. To date, few reports on the direct detection of LMG using electrochemical point-of-care (POC) sensors have been published. In the present work, flexible gold (Au) microsensors were fabricated from nanometer-thin Au leaves for the first time on different substrates, such as polyethylene terephthalate, thermoplastic polyurethane, silicone, polyvinyl chloride wristbands, and nitrile gloves, through simple hot stamping. The entire fabrication process did not involve toxic solvents and complex equipment, and the material cost was only $0.1 per microsensor. The morphology, electrochemical properties, and sensing performance of the microsensors were characterized by scanning electron microscopy, cyclic voltammetry, and differential pulse voltammetry. Benefiting from the excellent catalytic activity and conductivity of Au, the microsensors exhibited outstanding direct sensing capability for LMG with a detection limit of 6.3 nM. Moreover, the microsensors demonstrated excellent recovery rates in real sample analysis, validating their practicality. The technology reported in this work provides a pioneering and effective solution for the sensitive and convenient POC direct detection of LMG and further allows for the fabrication of Au microsensors on different flexible and conformal substrates, offering sensitive solutions for POC detection in environmental, food safety, and healthcare applications.