Ingenious aspartic acid-functionalized gold nanoparticles by one-pot protocol for the sensitive detection of chromium (III) ions

In this work, we report an effective one-pot strategy for synthesizing aspartic acid-functionalized gold nanoparticles (Asp-AuNPs) and constructing chromium (III) ion (Cr3+) colorimetric sensing system. Aspartic acid, acting as a reductant and stabilizer, was used directly to synthesize functionalized AuNPs without additional surface modification procedure. The Asp-AuNPs possesses the same good stability and optical properties as citrate-stabilized AuNPs, which become a new option for preparing AuNPs. More importantly, aspartic acid exhibits superior performance than citrate and other succinic acid derivatives because of its Cr3+ identifying property. The Asp-AuNPs was used for the sensitive and selective detection of Cr3+ based on the aggregation-induced color change of AuNPs from wine red to blue-gray. Under optimal conditions, the absorbance ratios (A660 nm/A520 nm) show good linearity with Cr3+ concentrations with a limit of detection of 0.6 nM. Furthermore, the proposed method was applied for the analysis of Cr3+ in environmental water samples successfully with a reliable recovery of 95.4%-105.1%. Besides, the scanometric analysis model based on three primary colors change was established to deal with the requirement for the rapid quantitative determination of Cr3+ in environmental emergencies.