Dual-signal amplification strategy based on BiBDC-AuNPs nanozyme and RecJf Exo for colorimetric-electrochemical dual-mode detection of Pb2+ in rice

Lead ion (Pb 2+ ) contamination poses severe threats to food safety and human health, demanding rapid, sensitive, and reliable on-site analytical detection techniques. Herein, a colorimetric-electrochemical dual-mode aptasensor was developed for the ultrasensitive detection of Pb 2+ in rice, utilizing a dual-signal amplification strategy integrating bismuth terephthalate material (BiBDC)-AuNPs nanozyme and RecJf exonuclease (RecJf Exo)-assisted target recycling. BiBDC uniformly disperses and immobilizes AuNPs, significantly enhancing their peroxidase-like catalytic activity for robust signal output. Meanwhile, RecJf Exo specifically hydrolyzes Pb 2+ -bound aptamer strands to achieve cyclic release and reuse of target Pb 2+ , effectively amplifying the response signal. Under optimal conditions, the dual-mode aptasensor exhibited low detection limits of 4.52 pg/mL (colorimetric) and 0.035 pg/mL (electrochemical). The developed sensor demonstrated excellent specificity, reproducibility, stability, and satisfactory recoveries (93.54–102%) in real rice samples. This dual-signal amplification strategy provides a reliable platform for highly sensitive and accurate detection of Pb 2+ in food matrices, showing great potential for food safety monitoring.