A functional peptide-mediated colorimetric assay for mercury ion based on dual-modified gold nanoparticles

In the work, a rapid and accurate biosensor for mercury ions (Hg²⁺) was constructed, with which aggregation of dual-modified (DGPFHR- and CALNN-) gold nanoparticles (D/C-AuNPs) could be triggered by the high specificity of peptides to Hg²⁺. The given peptide DGPFHR possesses great capability of capturing Hg²⁺, accompanied by the conformational folding. Under the circumstances, D/C-AuNPs were employed as the detection probes to accomplish the quantitative analysis of Hg²⁺. This is primarily because the specific Hg²⁺-induced folding of peptides reduces the electrostatic repulsion and steric hindrance, thus accelerating the AuNPs aggregation. The principle and application potential of this proposal was proved by evidence. And the results demonstrated that Hg²⁺ ions could be selectively detected as low as 28 nM with a linear range of 100-800 nM. In consideration of superior simplicity, selectivity, accuracy and stability, the protocol was advantageous over other projects in practical measurement of various water samples.