title: Fluorescence detection of lead(II) ions through their induced catalytic activity of DNAzymes.
abstract: We have developed a fluorescence approach for the highly selective and sensitive detection of Pb(2+) ions using AGRO100, a G-quadruplex DNAzyme. The sensing strategy is based on Pb(2+) ions inducing increased DNAzyme activity of AGRO100 in the presence of hemin, which acts as a cofactor to catalyze H(2)O(2)-mediated oxidation of Amplex UltraRed (AUR). A test of eight aptamers of various sequences for the detection of Pb(2+) ions revealed that AGRO100 performed the best in terms of sensitivity. The AGRO100-AUR probe exhibited high selectivity (>100-fold) toward Pb(2+) ions over other tested metal ions. The fluorescence intensity (excitation/emission maxima, ca. 561/592 nm) of the AUR product was proportional to the concentration of Pb(2+) ions over the range 0-1000 nM, with a linear correlation (R(2) = 0.98). For 5 mM Tris-acetate (pH 7.4) solutions in the presence and absence of 100 mM NaCl, the AGRO100-AUR probe provided limits of detection (signal-to-noise ratio = 3) for Pb(2+) ions of 1.0 and 0.4 nM, respectively. We validated the practicality of the use of the AGRO100-AUR probe for the determination of the concentrations of Pb(2+) ions in soil samples. This approach allows the determination of the concentrations of Pb(2+) ions with simplicity, selectivity, and sensitivity.
authors.affiliation: Department of Chemistry, National Taiwan University, Taipei, Taiwan.
authors.forename: Chi-Lin
authors.initials: CL
authors.lastname: Li
authors.forename: Kung-Tien
authors.initials: KT
authors.lastname: Liu
authors.forename: Yang-Wei
authors.initials: YW
authors.lastname: Lin
authors.forename: Huan-Tsung
authors.initials: HT
authors.lastname: Chang
mesh_terms: D052157:Aptamers, Nucleotide / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D055162:Biocatalysis / Q000187:drug effects*; D015374:Biosensing Techniques / Q000379:methods*; D002021:Buffers; D021881:DNA, Catalytic / Q000235:genetics / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007854:Lead / Q000032:analysis* / Q000494:pharmacology*; D009838:Oligodeoxyribonucleotides / Q000235:genetics / Q000378:metabolism; D010078:Oxazines / Q000378:metabolism; D010084:Oxidation-Reduction; D012987:Soil / Q000737:chemistry; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: C513936:AGRO 100; D052157:Aptamers, Nucleotide; D002021:Buffers; D021881:DNA, Catalytic; D009838:Oligodeoxyribonucleotides; D010078:Oxazines; D012987:Soil; C470430:Amplex Red; D007854:Lead; D006861:Hydrogen Peroxide