A single gold nanoprobe for colorimetric detection of silver(i) ions with dark-field microscopy

Abstract

Highly sensitive colorimetric detection of silver(I) ions (Ag⁺) at the single-particle level was developed based on the color of a gold nanoparticle (AuNP) assembly captured by dark-field microscopy (DFM) imaging. Formation of C–Ag⁺–C bonding between cytosines was utilized to induce interparticle coupling of AuNPs modified with single-strand DNA, resulting in a color change as the signal transduction to quantify Ag⁺ under DFM imaging. This method allowed visual quantitation of Ag⁺ in the range of 0.05 nM–250.00 nM and a detection limit of 28.8 pM was achieved. Furthermore, we demonstrated its applicability for the colorimetric detection of Ag⁺ in a small quantity of real samples, showing the good potential of this developed method for environmental monitoring and drug quality control.