Summary: | The sensitive detection of Pb<sup>2+</sup> 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<sup>2+</sup> analysis. The biosensor was prepared via the immobilization of Iowa Black<sup>®</sup> 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<sup>2+</sup>. However, Pb<sup>2+</sup> recognition can induce the cleavage of substrate, resulting in a fluorescence restoration of R-PE. The fluorescence changes were used to measure sensitively Pb<sup>2+</sup> 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<sup>2+</sup> even in the presence of other metal ions interferences and was demonstrated to successfully determine Pb<sup>2+</sup> in spiked lake water samples.
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