Colorimetric detection of thiocyanate based on inhibiting the catalytic activity of cystine-capped core-shell Au@Pt nanocatalysts

Publication date: 1 December 2017
Source:Talanta, Volume 175
Author(s): Chi-Fang Peng, Na Pan, Qian Zhi-Juan, Xin-Lin Wei, Guang Shao
In this work, core-shell Au@Pt nanocatalysts (Au@Pt NCs) with ultrathin Pt shell were synthesized and demonstrated high peroxidase-like activity. Thiocyanate ions (SCN^-) were found to effectively inhibit the peroxidase-like activity of Au@Pt NCs, and the mechanism was discussed by the characterization of TEM, DLS, EPR and XPS, etc. The inhibition of the catalytic activity of Au@Pt NCs by SCN^- was mainly due to the decreased ability of the Au@Pt NCs for capturing ^•OH radicals and the increased ratio of Pt²⁺ to Pt° on the surface of the Au@Pt NCs. A sensitive colorimetric detection of thiocyanate (SCN^-) was developed, based on the activity inhibition of Au@Pt NCs by SCN^-. Interestingly, cystine modification of Au@Pt NCs was found to significantly improve the selectivity of SCN^- recognition. After optimization, a colorimetric assay for SCN^- was established with a detection limit of 5.0nM and a broad linear calibration over the range of 20nM to 40µM. This assay has the advantages of highly sensitive, selective and low-cost. Moreover, this assay demonstrated highly potential application in the quantitative determination of SCN^- in water and raw milk samples.

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