Fluorescent biosensor for lead ion detection based on GR-5 DNAzyme and self-hybridization chain reaction.

BACKGROUND

Lead ion (Pb2+) is a typical heavy metal pollutant, and the water and food contaminated by lead may pose a potential threat to the environment and human health. In the natural environment, it can accumulate in soil and water, affecting the entire food chain. For human health, even if the Pb2+ content is very low, it can cause a series of adverse health effects. In order to effectively address the issue of lead pollution, it is particularly important to develop highly sensitive and selective Pb2+ detection technology.

RESULTS

In this study, we designed a single-hairpin based self-hybridization chain reaction (SHCR) system for Pb2+ detection based on GR-5 DNAzyme. Compared with the traditional hybridization chain reaction (HCR) which requires two hairpins, this strategy only needs one hairpin probe, this design not only reduces the experimental cost, but also simplifies the sequence design and experimental operation. Once Pb2+ was added in the system, GR-5 DNAzyme can be actived and then a trigger DNA was released to trigger the SHCR reaction, thereby a signal-amplified fluorescent biosensor for Pb2+ detection was developed, which exhibited a good linear range from 100 to 500 nM with a low detection limit of 24.8 nM, and has been successfully applied to the determination of Pb2+ in environmental water and Chinese Baijiu.

SIGNIFICANCE: This simple, sensitive, and selective Pb2+ detection system demonstrates significant potential for a wide range of practical applications in both environment and food monitoring. In addition to its specific application for Pb2+ detection, by introducing different DNAzymes, this SHCR system can be applied for the detection of other heavy metal ions.