ABSTRACT
The authors describe a fluorometric assay for the determination of Hg(II). A naphthalimide derivative is used as a label for a thymine (T) rich ssDNA, and graphene oxide magnetized with Fe3O4 nanoparticles acts as a quencher and preconcentrators. In the absence of Hg(II), the labeled ssDNA does not separate from the magnetized graphene oxide. As a result, fluorescence is fully quenched. In the presence of Hg(II), a T-Hg(II)-T link is formed dues to the highly affinity between T and Hg(II). Hence, fluorescence is restored. The assay has a linear response in the 1.0 to 10.0 nM Hg(II) concentration range, and a 0.65 nM detection limit. The method is selective and sensitive. It was applied to the analysis of spiked environmental water samples, and data agreed well with those obtained by atomic fluorescence spectrometry. Graphical abstract Strategy of a fluorescent probe for detecting Hg(II). The method has a 0.65 nM detection limit and is selective. MGO: magnetized graphene oxide, AHN: a fluorescent derivative of naphthalimide.
Subject(s)
Biosensing Techniques/methods , DNA, Single-Stranded/chemistry , Graphite/chemistry , Mercury/analysis , Mercury/chemistry , Oxides/chemistry , Thymine/chemistry , Fluorescent Dyes/chemistry , Limit of Detection , Linear Models , Magnets/chemistry , Models, Molecular , Naphthalimides/chemistry , Nucleic Acid ConformationABSTRACT
Bisphenol A (BPA) is commonly considered to cause a health hazard to wildlife and humans, acting as an exogenous estrogen. Herein, a magnetic separate "turn-on" fluorescent method for the detection of BPA was proposed based on fluorescence resonance energy transfer (FRET) between fluorescein-labeled BPA aptamer and magnetic oxidation graphene (MGO). At different concentrations of BPA, the fluorescence intensity of the sensing system was varied. The detection limit of 0.071ng/mL was obtained with the linear range of 0.2-10ng/mL. The biosensor exhibited excellent anti-interference ability and selectivity in actual water samples.
Subject(s)
Aptamers, Nucleotide/chemistry , Benzhydryl Compounds/analysis , Biosensing Techniques/methods , Fluorescence , Graphite/chemistry , Magnetics , Phenols/analysis , Water Pollutants, Chemical/analysis , Benzhydryl Compounds/chemistry , Fluorescence Resonance Energy Transfer , Limit of Detection , Oxidation-Reduction , Phenols/chemistry , Water Pollutants, Chemical/chemistryABSTRACT
This paper describes a label-free 17E DNAzyme-based time-gated fluorescence sensor for Pb2+ detection by unmodified gold nanoparticles (GNPs) and a terbium ternary complex. The fluorophore that used in this paper is a terbium ternary complex. Its signal can be measured in a time-gated manner which could eliminate most of the unspecific fluorescent background. It is well known that unfolded single-stranded DNA (ssDNA) could be adsorbed on GNPs while double-stranded DNA could not. The cleavage of the substrate by the 17E DNAzyme in the presence of Pb2+ causes the release of ssDNA from the 17E-17S duplex to be absorbed onto GNPs, preventing the aggregation of GNPs and then leading to a fluorescence decrease of terbium ternary complex. By means of this method, the authors have successfully detected Pb2+ over a range of 10 nM to 2500 nM with a detection limit of 1.7 nM. The sensor also exhibited good selectivity. The sensor provided a simple, cost-effective, rapid and sensitive measurement tool for Pb2+ detection.
