Visual Cu2+ Detection of Gold-Nanoparticle Probes and its Employment for Cu2+ Tracing in Circuit System

Abstract

Highly sensitive, simple and reliable colorimetric probe for Cu2+-ion detection was visualized with the L-cysteine functionalized gold nanoparticle (LS-AuNP) probes. The pronounced sensing of Cu2+ with high selectivity was rapidly featured with obvious colour change that enabled to visually sense Cu2+ 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 Cu2+ 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 Cu2+ ions in a quantitative way.

Sensitivity improvement of Au-nanoparticle-based colorimetric probes via surface decoration of carbon quantum dots

“…It is found that good reliability and repeatability of CQD@AuNP 2-based colorimetric probes are validated. In addition, sensing performances were compared with other reported designs, 15,34–43 where the present work indeed demonstrated a remarkable improvement in viewing LOD criteria, covering a wide detectable range and pH environmental tolerance, as indicated in Table 1. This benefited practical employment for instant, visual and reliable Cu 2+ sensing.…”

“…Accordingly, the reduction of covalently bonded thiol groups that bridged the CQDs and AuNP cores was accompanied by the oxidation of Cu 2+ ions, which was exploited as the key for the morphological transition from aggregated state to dispersed feature, as evidenced in the literature 15 and Fig. S2(b) (ESI†).…”

“…4 by summarizing functional features, morphological evolutions and optical characteristics. The CQD@AuNP probes essentially enabled the rapid interaction with trace Cu 2+ ion analytes according to the following reaction: 15 6RS − + 2Cu 2+ → RSSR + 2 RS-Cu + -SR…”

“…For instance, the probing of the anti-aggregation Cu 2+ colorimetric tracing sensor was demonstrated with gold NPs (AuNPs) functionalized with l -cysteine. 15–18 Although macroscopic phenomena behind such detections are highly feasible for practical Cu 2+ ion examinations, improvements in environmental detection reliability and LOD (limit of detection) remain in high demand. In this work, carbon quantum dots (CQDs) 19,20 were incorporated with AuNP cores as hybrid analyte probes via heterostructure engineering.…”