High-Efficiency Detection for Silver Ions Based on Fluorescence Enhancement of Peptide-Gold Nanoparticles

Silver ion (Ag+) is a highly toxic metal ion, and its monitoring in water or food resources has become extraordinarily necessary within the scope of human health. In the light of the fact of Ag+-induced folding structure of specific peptides, an unlabeled and high-selectivity Ag+ assay is presented by means of intrinsic fluorescence of peptides. Under the quenching effect of gold nanoparticles (AuNPs), characteristic fluorescence of peptides could be considerably reduced by rapid modification. Along with the Ag+ adding, the fluorescence signals of peptide-AuNPs are largely enhanced by the behavior between peptides and Ag+. This is basically involving the formation of 4-coordinated complexes, generating the changes of peptides in structure and fluorescence properties. Under this circumstance, the adverse influence of plenty of interfering ions is suppressed, including the toxic Hg2+, Pb2+. The results highlight that Ag+ ions could be selectively recognized as low as 2.4 nmol/L with a linear range of 5 to 800 nmol/L. In comparison with other programs, the given approach declares simplicity, sensitivity, and superior selectivity. Furthermore, the biosensor excels in the practical application in water samples (e.g., lake, tap and drinking water) owing to its non-interference and on-site rapid determination.