A nanozyme-catalysis-based ratiometric electrochemical sensor for general detection of Cd2+. Issue 23 (31st October 2022) - Luo, Shan
Abstract : AuPt–rGO showed good peroxidase-like activity for the oxidation of OPD to DAP (a novel internal reference) and achieved sensitive and reliable detection of Cd 2+ based on a ratiometric strategy. Abstract : A new kind of internal reference probe was developed to construct a ratiometric electrochemical sensor for accurate and sensitive Cd 2+ detection. AuPt nanoclusters (AuPt NCs) were synthesized and then evenly distributed on reduced graphene oxide (rGO) to form a nanocomposite (AuPt–rGO), which showed peroxidase-like activity and catalyzed the oxidation of o -phenylenediamine (OPD) to 2, 3-diaminophenazine (DAP) in the presence of H2 O2 . It was found that DAP was further reduced on the electrode with a constant current intensity whether Cd 2+ was added or not, which enabled it to function as an excellent internal reference probe. Thus, the ratio between the reduction currents of Cd 2+ and DAP ( i Cd 2+ / i DAP ) was proposed to monitor Cd 2+ based on the ratiometric strategy. Additionally, the high surface area and good conductivity of AuPt–rGO endowed the sensor with enhanced sensitivity. A wide linear range and a low limit of detection were measured at 5.0 × 10 −8 –1.0 × 10 −4 mol L −1 and 3.1 × 10 −8 mol L −1, respectively. Compared with the single signal sensors, this ratiometric sensor presents more accuracy and reliability in the detection of Cd 2+, facilitating the quantification of Cd 2+ concentration in different water samples with good recoveries. The novel internal reference probe proposed here shows great possibilities for accurate and sensitive Cd 2+ detection based on the ratiometric strategy.