A reliable fluorescent and colorimetric dual-readout assay for Ag+ tracing

Silver ion pollution is a great threat to global environment and public healthcare today. Thus, quick, portable and sensitive assays for Ag+ tracing are highly needed. Herein, a reliable fluorescent and colorimetric dual-channel assay has been constructed for Ag+ detection by utilizing a terbium-based fluorescent nanomaterial (named as Tb-DPA) and a Pt/Pd nanoflower (Pt/Pd NF)-triggered reaction between N-ethyl-N-(3-sulfopropyl)-3-methylaniline sodium salt (TOPS) and 4-amino-antipyrine (4-AAP). Initially, in the sensing system containing 4-AAP, TOPS, Tb-DPA and Pt/Pd NF, TOPS and 4-AAP is catalyzed by Pt/Pd NF to produce a purple compound (called as PC1), which endows a broad UV absorption that can fully cover the emission band of Tb-DPA. Thus, the system exhibits a high UV absorption (originating from PC1) and a low fluorescence intensity (originating from Tb-DPA) which has been quenched by PC1 through a filtering effect. However, when the system meets Ag+, the oxidase-like activity of Pt/Pd NF will be inhibited, leading less amount of PC1. As a result, the system exhibits a decreased UV absorption and a recovered fluorescence intensity, both of which can be used for Ag+ detection, reporting low detection limits of 3.63 nM and 1.63 nM, respectively. Specially, results from the dual-channel assay can mutually validate each other, improving the detection reliability. Moreover, this dual-mode assay shows good capability toward Ag+ detection in real samples, illustrating the potential for practical applications. (C) 2021 Published by Elsevier B.V.

Automated summary

A reliable dual-channel assay using fluorescent and colorimetric detection has been developed for the rapid detection of silver ions. The assay shows high sensitivity and portability, and demonstrates excellent detection capabilities in real samples.