Highly sensitive detection of mercury(II) based on colorimetric-SERS dual signal recognition strategy

Abstract

A novel colorimetric/surface-enhanced Raman spectroscopy (SERS) dual-signal nanozyme sensor was developed for the rapid and sensitive detection of Hg²⁺ based on peroxidase-like gold-platinum core–shell nanoflowers (Au@Pt NFs). Au@Pt NFs catalyzed the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) to its blue oxidation product, 3,3′,5,5′-tetramethylbenzidinediamine (oxTMB), which exhibits high Raman activity. However, the presence of Hg²⁺ inhibited the catalytic activity of Au@Pt NFs, leading to a gradual disappearance of the blue color of oxTMB. Consequently, both the absorbance at 650 nm and the Raman intensity at 1639 cm⁻¹ decrease with increasing Hg²⁺ concentration. The limits of detection (LODs) were 3.2 nM for colorimetric and 0.22 nM for SERS. The preparation method of Au@Pt NFs dual-signal nanozyme sensor was simple and allowed for naked-eye colorimetric detection as well as simultaneous SERS signal measurement. In addition, this nanozyme sensor demonstrates excellent selectivity and sensitivity, making it a promising probe for water quality monitoring.