Oxytetracycline (OTC) is one of the widely used antibiotics in veterinary practices because of its broad-spectrum antibacterial activity and low cost. However, drug abuse has triggered adverse effects on human health, which brings a growing demand for on-site diagnosis of OTC residues in animal-derived foods. In this study, we demonstrated the combined use of interdigital electrode microarray and electrochemiluminescence (ECL) imaging for parallel multiplex measurement of OTC. Well-ordered and vertically aligned mesoporous silica nanochannels modified on microarray substrate could exert a strong electrostatic attraction to the ECL luminophores and accelerate their mass transport to generate enhanced ECL signal. The performance of the integrated ECL microarray sensor was fully validated with respect to linearity (0.5 μM to 50 μM), sensitivity (limit of detection 0.26 μM), accuracy (recovery rate between 96.78% and 106.1%), low operating sample volume (480 nL), short assay time (1.5 min), and antifouling ability toward complex media. The multiplex microarray platform can serve as a simple, fast, and low-cost tool for the detection of a wide spectrum of antibiotics in the field of food safety.
Electrochemiluminescence (ECL) has emerged as a valuable tool for understanding multiphasic and compartmentalized systems, which have crucial wide-ranging applications across diverse fields. However, ECL reactions are limited to the vicinity of the electrode surface due to spatial constraints of electron transfer and the short lifetime of radical species, making ECL emission in bulk multiphasic solution challenging. To address this limitation, we propose a novel bipolar electrochemistry (BPE) approach for wireless dual-color ECL emission at the water/oil (w/o) interface. Firstly, amphiphilic glass carbon (GC) microbeads with distinct hydrophilic and hydrophobic regions are prepared by bipolar electrografting of hydrophobic trifluoromethyl diazonium salt, then the resulting Janus beads are positioned at the w/o interface. Subsequently, two model ECL systems containing luminol and H2O2 in the aqueous phase, and [Ru(bpy)3]²⁺ and benzoyl peroxide (BPO) in the organic phase, are selected based on their solubility to confine light-emitting reactions to their respective phases. Upon application of an electric field perpendicular to the interface, the Janus microbeads get polarized, triggering simultaneous oxidative blue ECL (425 nm) and reductive red ECL (620 nm) in the aqueous and organic phases, respectively. Taking advantage of ECL imaging, the potential gradient distribution on the GC microbead at the w/o interface is revealed, indicating a "pseudo-closed" bipolar system due to limited ion transfer between phases. We also investigate the effect of changing the electric field direction parallel to the interface, which alters the ECL emission area from a hemisphere to a quarter of the microbead's surface. This bipolar ECL approach at the w/o interface not only offers opportunities for imaging the aqueous phase and organic phase simultaneously, but also enables ECL imaging and light generation in the bulk solution, thus overcoming the usual spatial limitation requiring proximity to the electrode surface.
危险品化学品经营许可证（带存储）