title: A label-free DNAzyme-cleaving fluorescence method for the determination of trace Pb(2+) based on catalysis of AuPd nanoalloy on the reduction of rhodamine 6G.
abstract: The substrate chain of double-stranded DNA (dsDNA) could be specifically cleaved by Pb(2+) to release single-stranded DNA (ssDNA) that adsorbs onto the AuPd nanoalloy (AuPdNP) to form a stable AuPdNP-ssDNA complex, but the dsDNA can not protect AuPdNPs in large AuPdNP aggregates (AuPdNPA) under the action of NaCl. AuPdNP-ssDNA and large AuPdNPA could be separated by centrifugation. On increasing the concentration of Pb(2+) , the amount of released ssDNA increased; AuPdNP-ssDNA increased in the centrifugation solution exhibiting a catalytic effect on the slow reaction of rhodamine 6G (Rh6G) and NaH2 PO2 , which led to fluorescence quenching at 552 nm. The decrease in fluorescence intensity (ΔF) was linear to the concentration of Pb(2+) within the range 0.33-8.00 nmol/L, with a detection limit of 0.21 nmol/L. The proposed method was applied to detect Pb(2+) in water samples, with satisfactory results.
authors.affiliation: Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection, Ministry of Education of China, Guangxi Normal University, Guilin, China.
authors.forename: Meiling
authors.initials: M
authors.lastname: Tang
authors.forename: Guiqing
authors.initials: G
authors.lastname: Wen
authors.forename: Yanghe
authors.initials: Y
authors.lastname: Luo
authors.forename: Caiyan
authors.initials: C
authors.lastname: Kang
authors.forename: Aihui
authors.initials: A
authors.lastname: Liang
authors.forename: Zhiliang
authors.initials: Z
authors.lastname: Jiang
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry; D002384:Catalysis; D004277:DNA, Single-Stranded / Q000737:chemistry; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry; D006047:Gold Alloys / Q000737:chemistry; D007854:Lead / Q000032:analysis*; D008855:Microscopy, Electron, Scanning; D049329:Nanostructures / Q000737:chemistry*; D012235:Rhodamines / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods*; D062065:Wastewater / Q000032:analysis
chemical_list: D052157:Aptamers, Nucleotide; D004277:DNA, Single-Stranded; D005456:Fluorescent Dyes; D006047:Gold Alloys; D007854:Lead; D012235:Rhodamines; D062065:Wastewater; C026188:rhodamine 6G
keywords: AuPd nanoalloy; Pb2+; fluorescence; label-free aptamer; nanocatalysis