A simple SPR absorption method for ultratrace Pb2+ based on DNAzyme-COFPd nanocatalysis of Ni-P alloy reaction

Abstract Due to the non-degradability of lead, it in food poses a huge threat to human health. Therefore, it is very important to establish a sensitive and rapid detection method for Pb2+ in food. In this paper, a new palladium-doped covalent organic framework (COFPd, TpPaPd) was prepared using CO as the reducing agent, and it was characterized in details. Experiments show that TpPaPd strongly catalyze the reduction of Ni(II) by sodium hypophosphite to form Ni-P alloys, and the system has a surface plasmon resonance (SPR) absorption peak at 395 nm. Combing the nanocatalytic reaction with the DNAzyme reaction of the aptamer (Apt)-Pb2+-hemin (HM), a new SPR spectrophotometric method was established to detect 0.001−0.1 nmol/L Pb2+ in food sample, with a detection limit of 0.0004 nmol/L.