A Dual‐Functional Peptidyl Probe for Fluorometric and Colorimetric Detection of Hg ²⁺ and S ²⁻ in Real Food Samples and Biological Systems

ABSTRACT

As two notorious pollutants, the release of excessive mercury ions (Hg ²⁺ ) and sulfur ions (S ²⁻ ) poses serious risks to food safety and human health, so it is imperative to achieve precise detection of Hg ²⁺ and S ²⁻ . Herein, a novel bifunctional peptidyl probe NHK was synthesized with dipeptide backbone (His‐Lys‐His) and the 7‐nitro‐2,1,3‐benzoxadiazole (NBD) fluorescent group, thereby effectively enabling colorimetric and fluorescence detection of Hg ²⁺ and S ²⁻ . The detection limits for Hg ²⁺ and S ²⁻ were 8.6 and 42.1 nM, respectively. NHK exhibited low cytotoxicity and achieved the imaging of Hg ²⁺ and S ²⁻ in two biological systems. Subsequently, NHK successfully achieved quantitative analysis of Hg ²⁺ and S ²⁻ in water samples with satisfactory accuracy. NHK has been successfully applied to the visual detection of Hg ²⁺ and S ²⁻ residues on the surfaces of three food samples. Furthermore, the NHK ‐based test strips developed were highly suitable for the visual detection of Hg ²⁺ and S ²⁻ under two different lights. More importantly, we not only designed an ultrasensitive INHIBIT molecular logic gate to accelerate the integrated application of NHK technology in intelligent devices but also developed a portable sensing platform based on a smartphone color recognition application, enabling semiquantitative detection of Hg ²⁺ and S ²⁻ .