Ratiometric G-Quadruplex Assay for Robust Lead Detection in Food Samples

Lead (Pb2+) pollution is a serious food safety issue, rapid detection of Pb2+ residual in food is vital to guarantee food quality and safety. Here we proposed ratiometric aptamer probes, allowing robust Pb2+ supervision in food samples. Pb2+ specific aptamer can bolster a transition of G-quadruplex structural response to Pb2+; this process can be monitored by N-methyl mesoporphyrin IX (NMM), which is highly specific to G-quadruplex. Particularly, the utilization of G-quadruplex specific dye and terminal-labeled fluorophore allowed to endue ratiometric signal outputs towards Pb2+, dramatically increase the robustness for lead detection. The ratiometric G-quadruplex assay allowed a facile and one-pot Pb2+ detection at room temperature using a single-stranded DNA aptamer. We demonstrated its feasibility for detecting lead pollution in fresh eggs and tap water samples. The ratiometric G-quadruplex design is expected to be used for on-site Pb2+ testing associated with food safety.