Search

In this work we use a water-soluble cationic perylene derivative (compound 1) as the G-quadruplex (G4) structure fluorescence indicator to construct a fluorescent biosensor for simple, rapid and label-free detection of Pb 2+ . In the absence of Pb 2+ , strong electrostatic interactions between compound 1 and the G-rich DNA probe (PW17) induced the aggregation of compound 1 and resulted in the fluorescence quenching. In the presence of Pb 2+ , the PW17 formed Pb 2+ -stabilized G4 structure, which reduced the aggregation of compound 1 and gave rise to high fluorescence. This allowed us to use convenient “mix-and-detect” protocol for quantitative analysis of Pb 2+ . Since Pb 2+ can specially induce PW17 to form compact DNA fold, our proposed biosensor displayed high selectivity for Pb 2+ . It also exhibited a high sensitivity to Pb 2+ , with a limit of detection of 5.0 nM observed. Furthermore, the biosensor was applied for the detection of Pb 2+ in urine and paint samples, and both showed satisfactory results. [ABSTRACT FROM AUTHOR]

DNAzyme-based catalytic beacons have been widely studied for both in vivo and in vitro molecular detection. However, only a few label-free catalytic beacons with excellent analytical performance have been reported so far. In this work, by combining a catalytic DNAzyme for amplified sensing through enzymatic turnover with cleavage-induced G-quadruplex formation, a label-free DNAzyme biosensor was developed for amplified “turn-on” fluorescence detection of Pb 2+ with a detection limit of 3 nM. The method is very competitive compared to many other labeled or label-free methods with or without signal amplification. Due to the inherent specificity of the GR-5 DNAzyme, the method also exhibits excellent selectivity. This biosensor successfully detected Pb 2+ in river water samples with high sensitivity and selectivity. Such a method might provide a universal DNAzyme-based sensing platform for sensitive detection of various targets both in environmental and biomedical fields. [ABSTRACT FROM AUTHOR]