An electrochemical sensor based on hydrangea like AuPt NPs@ZnNi-MOF combined with hyperbranched HCR signal amplification strategy for Cd2+ detection

Cadmium ions (Cd 2+ ) as a class of widespread pollutants, can cause Irreversible damage to population health and habitat quality with small amounts of Cd 2+ . an electrochemical sensor for Cd 2+ detection was developed based on AuPt NPs@ZnNi-MOF bimetallic nanocomposites combined with hyperbranched hybridization chain reaction (HCR) signal amplification strategies. The sensor employed AuPt NPs@ZnNi-MOF as the electrode modification material, which promoted the electron transport on the electrode surface and significantly increased the current signal by 49.16 %, as well as provided a large number of active sites for the sensor. 3D DNA walker was initiated in the presence of the target, generating many DNA single strands that triggered catalytic hairpin self-assembly (CHA) at the electrode. The production of intermediate strand output is induced, which leads to the construction of hyperbranched HCR. Hyperbranched HCR amplification demonstrated high efficiency, producing numerous long double-stranded chains and creating abundant embedding sites for electroactive molecules. These signal amplification strategies led to a remarkable 2.52-fold enhancement in the current signal. Under the optimal experimental conditions, the detection range of the sensor was 0.001–500 nmol/L, and the limit of detection (LOD) was 0.221 pmol/L. Furthermore, the sensor exhibits excellent specificity, reproducibility, and stability, and has been successfully applied for the detection of Cd 2+ in tap water and tea, as well as achieving satisfactory results in the analysis of quality control samples such as rice flour and pork liver powder.