DNAzyme-Functionalized R-Phycoerythrin as a Cost-Effective and Environment-Friendly Fluorescent Biosensor for Aqueous Pb(2+) Detection

The sensitive detection of Pb(2+) is of significant importance for food safety, environmental monitoring, and human health care. To this end, a novel fluorescent biosensor, DNAzyme-functionalized R-phycoerythrin (DNAzyme-R-PE), was presented for Pb(2+) analysis. The biosensor was prepared via the immobilization of Iowa Black(®) FQ-modified DNAzyme–substrate complex onto the surface of SPDP-functionalized R-PE. The biosensor produced a minimal fluorescence signal in the absence of Pb(2+). However, Pb(2+) recognition can induce the cleavage of substrate, resulting in a fluorescence restoration of R-PE. The fluorescence changes were used to measure sensitively Pb(2+) and the limit of detection was 0.16 nM with a linear range from 0.5–75 nM. Furthermore, the proposed biosensor showed excellent selectivity towards Pb(2+) even in the presence of other metal ions interferences and was demonstrated to successfully determine Pb(2+) in spiked lake water samples.