Preparation of palladium/carbon dot composites as efficient peroxidase mimics for H₂O₂ and glucose assay

In this study, palladium/carbon dot composites (Pd-CDs) were fabricated via a facial hydrothermal route using ethanediamine and palladium chloride dihydrate as precursors. The obtained Pd-CDs showed an excellent intrinsic peroxidase-like activity, which could catalyze the oxidization of 3,3'5,5'-tetramethylbenzidine with the assistance of hydrogen peroxide (H₂O₂) and thus resulted in color change, accompanied by an absorption peak which appeared at 652 nm. Such response is H₂O₂ concentration-dependent and allows for the assay of H₂O₂ in the range of 0.1 to 30 μM with a limit of detection of 0.03 μM. Simultaneously, by combination of enzymatic oxidation of glucose with glucose oxidase and Pd-CD catalytic reaction, a colorimetric sensing platform was also constructed for glucose detection with high selectivity and sensitivity (limit of detection as low as 0.2 μM). Additionally, the proposed method exhibited capability for determination of glucose in real samples (fruit juice) with satisfactory recovery (98.5-103%), indicating potential application prospects in biochemical analysis.