Novel Hg2+-Selective Signaling Probe Based on Resorufin Thionocarbonate and its μPAD Application

摘要

In this study, a novel resorufin thionocarbonate-based Hg²⁺-selective signaling probe (>RT) for microfluidic paper-based analytical device (μPAD) applications is reported. The designed probe, >RT, was readily synthesized by the one-step reaction of resorufin with phenyl thionochloroformate. The >RT probe displayed a prominent color change from yellow to pink and a marked turn-on fluorescence signaling behavior exclusively toward the Hg²⁺ ion. The signaling of >RT was due to Hg²⁺-induced hydrolysis of the phenyl thionocarbonate moiety to form the parent resorufin dye, which restored its spectroscopic properties. In addition, >RT exhibited the Hg²⁺-selective signaling behavior without interference by coexisting environmentally relevant metal ions. The detection limit for Hg²⁺ in simulated wastewater samples was estimated to be 5.8 × 10⁻⁸ M. In particular, an >RT-equipped μPAD prepared using a wax printing technique enabled simple and convenient determination of Hg²⁺ ions in simulated wastewater samples, with a detection limit of 5.9 × 10⁻⁶ M.