title: Single-labeled hairpin probe for highly specific and sensitive detection of lead(II) based on the fluorescence quenching of deoxyguanosine and G-quartet.
abstract: Specific and homogeneous detection of heavy metal ion is of great importance for both human health care and environmental protection. We reported a highly specific and sensitive assay for fluorescent detection of Pb(2+) based on the difference in quenching ability between deoxyguanosines and G-quartet by using carboxyfluorescein-labeled hairpin DNA (F-hpDNA) as a recognition probe. In the absence of target, the fluorescence of F-hpDNA can be quenched through photoinduced electron transfer from the dye to deoxyguanosines because the formation of hairpin brings deoxyguanosines close to the FAM. In the presence of Pb(2+), the formation of G-quadruplex DNA leads to a significant decrease in fluorescence due to the effective stack of dye on the G-quartet, which obviously intensified the quenching of fluorophore. In comparison with linear DNA probe, hairpin DNA probe greatly improved the specificity, and Pb(2+) can be highly selective detected even when coexisted with other metal ions. The quenching efficiency is linear with the concentration of lead(II) over the range of 0.5-500 nM, with a limit of detection of 0.4 nM. Conformational switch from hairpin to G-quadruplex was verified by CD measurements. Moreover, the application for detection of real samples further demonstrated its reliability. Therefore, it is a selective, simple and sensitive approach for detection of lead ion, as such, it promises to provide a solid foundation for developing universal analytical method for heavy metal ions.
authors.affiliation: Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education, School of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi'an 710062, China.
authors.forename: Wenhong
authors.initials: W
authors.lastname: Wang
authors.forename: Yan
authors.initials: Y
authors.lastname: Jin
authors.forename: Yina
authors.initials: Y
authors.lastname: Zhao
authors.forename: Xuanfeng
authors.initials: X
authors.lastname: Yue
authors.forename: Chengxiao
authors.initials: C
authors.lastname: Zhang
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D003849:Deoxyguanosine / Q000737:chemistry* / Q000235:genetics; D004784:Environmental Monitoring / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D054856:G-Quadruplexes; D055029:Inverted Repeat Sequences; D007854:Lead / Q000032:analysis*; D008832:Microchemistry / Q000295:instrumentation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000295:instrumentation*; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D014874:Water Pollutants, Chemical; D007854:Lead; D003849:Deoxyguanosine