Visual Cu(2+) Detection of Gold-Nanoparticle Probes and its Employment for Cu(2+) Tracing in Circuit System

Highly sensitive, simple and reliable colorimetric probe for Cu(2+)-ion detection was visualized with the L-cysteine functionalized gold nanoparticle (LS-AuNP) probes. The pronounced sensing of Cu(2+) with high selectivity was rapidly featured with obvious colour change that enabled to visually sense Cu(2+) ions by naked eyes. By employing systemic investigations on crystallinities, elemental compositions, microstructures, surface features, light absorbance, zeta potentials and chemical states of LS-AuNP probes, the oxidation-triggered aggregation effect of LS-AuNP probes was envisioned. The results indicated that the mediation of Cu(2+) oxidation coordinately caused the formation of disulfide cystine, rendering the removal of thiol group at AuNPs surfaces. These features reflected the visual colour change for the employment of tracing Cu(2+) ions in a quantitative way. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s11671-022-03742-z.