Stimuli-responsive SERS nanoprobes for multiplexing detection

Abstract

Surface-enhanced Raman scattering (SERS) is an ultrasensitive analytical tool for a variety of assays. However, its applications have been limited to sense molecules with high Raman cross-sections. Here we develop a new strategy for the SERS monitoring of species with low Raman cross-sections based on the stimuli-responsive Raman reporters (SRRRs). The SRRRs display tunable chemical structures and Raman fingerprints under the external stimulus, allowing the detection of their corresponding stimulus. A new SRRR, Bis [4,4′-(dithiophenyl azo)-1,3-benzenediamine] (DTPABDA), was reported to demonstrate multiple fingerprints and high reactivity with Cu2+ or HClO via an oxidant cyclization or cleavage reaction of azobenzene moiety, resulting in their concentration-dependent fingerprint change. The combination of DTPABDA with our reported SERS substrate (cabbage-like Au microparticles, or CLMP), SERS sensing of these two species with high sensitivity and selectivity were reported. This new sensing strategy may open a new avenue to break through the existing limitations of SERS sensors.