Solid-Liquid Dual-Signal Spatial Isolation in High-Spin Iron/Triethanolamine Comodified Silica for...

Co-occurrence of antibiotics and related metabolites in food chains aggravates toxic effects and the risk of drug resistance, highly requiring the development of an efficient yet convenient approach to achieve their synchronous detection in mixed systems. To meet this demand, here we design a high-spin iron/triethanolamine comodified silica-based nanoprobe featuring the solid-liquid dual-signal spatial isolation characteristic, to enable the one-pot, cross-interference-free, simultaneous colorimetric identification of chlortetracycline (CTC) and d-penicillamine (d-PA). In the probe, high-spin iron (hsFe*) serves dual roles as the coordination and redox centers toward analytes, and triethanolamine acts as both a silica structure modulator and a Fe species transformer. The CTC molecule with a high electron density easily chelates with hsFe* in the nanoprobe, forming a brown coating on the latter's surface to generate the solid-phase signal, while d-penicillamine is first dehydrogenated by hsFe* to form a disulfide-bond-containing intermediate, which then coordinates with the probe via ligand-metal charge transfer and finally forms a purple-red complex desorbed into the aqueous phase. With the unusual dual-signal spatial isolation strategy, synchronous sensing of CTC and d-PA in one pot was realized, with no cross-interference behavior between the two analytes and maintaining excellent resistance against other substances. Thanks to the merits including free from enzymes/chromogenic reagents/initiators, good resistance to dissolved O2, and compatibility within wide pH and temperature ranges, our probe was demonstrated to exhibit robust analytical performance in complex food matrices. Our study not only provides a facile and practical method to track the copollution status of CTC and d-PA leveraging solid-liquid logic-gate signals but also verifies the feasibility of producing mutually independent responses in the same pot to more than one analyte, offering new insights into constructing multiresponse platforms for multiplexed detection.