Novel Colorimetric Sensor Based on Peroxidase-Like Activity of Chitosan-Stabilized Au/Pt Nanoclusters for Trace Lead Publisher



Dehghani Z¹ ; Hosseini M^{1, 2} ; Mohammadnejad J³ ; Ganjali MR^{3, 4}
Source: Analytical Methods Published:2019

Abstract

In this study we propose a new colorimetric sensor for trace lead ions in milk samples. Au/Pt nanoclusters were synthesized using chitosan as the stabilizer at room temperature. Chitosan-protected Au/Pt nanoclusters exhibit strong peroxidase-like activity, and could catalyze the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) in the vicinity of hydrogen peroxide (H 2 O 2 ) and create a visual blue color. The detection mechanism is based on the Pb 2+ ions-induced aggregation of chitosan-Au/Pt NCs that causes changes in size and impairs the enzymatic performance of Au/Pt NCs. Experiments indicated that a step-by-step increase in concentration of Pb 2+ ions gradually decreased peroxidase activity and this reduction was linear. Based on the declared procedure, a colorimetric detection for Pb 2+ was obtained with a detection limit (LOD) of 16 nM and a linear range from 25 nM to 1 μM. The method was considerably selective toward Pb 2+ over other metal ions. Low price and simplicity support the application of sensing Pb 2+ in milk samples. © 2019 The Royal Society of Chemistry.