Dual color fluorescence quantitative detection of mercury in soil with graphene oxide and dye-labeled nucleic acids

Abstract

A dual color fluorescence quantitative detection method for Hg 2+ in soil has been developed by synchronous fluorescence analysis based on graphene oxide (GO) and dye-labeled nucleic acids. In this strategy, two complementary dye-labeled single-stranded nucleic acids (ssDNAs) with thymine-thymine (T-T) mismatches and GO were employed. Two dyes 6-carboxyfluorescein (FAM) and 6-carboxy-xrhodamine (ROX) were labeled on 3 0 ends of two different ssDNAs, respectively. In the absence of Hg 2+ , dye-labeled ssDNAs were adsorbed on GO, then the fluorescence of dyes was quenched by GO and the fluorescence signals were very weak. But in the presence of Hg 2+ , two complementary ssDNAs with T-T mismatches formed double-stranded DNA (dsDNA) via the T-Hg 2+ -T coordination structure. The formation of dsDNA resulted in the release of dye-labeled ssDNA from GO, and the fluorescence of dyes was restored. The wavelength intervals between the maximum excitation and emission of FAM and ROX are very close, so the fluorescence signals of two dyes can be obtained simultaneously using synchronous fluorescence analysis. Thus, dual color fluorescence quantitative detection of Hg 2+ can be realized by simultaneously measuring the fluorescence signals of FAM and ROX, respectively. Under optimum conditions, the total fluorescence intensity of FAM and ROX exhibited a good linear dependence on the Hg 2+ concentration in the range from 8 Â 10 À10 to 8 Â 10 À8 mol L À1 . The fitted regression equation was obtained with a correlation coefficient (R 2 ) of 0.9952 and the detection limit (3s) of Hg 2+ was estimated to be 5 Â 10 À10 mol L À1 . This proposed method can use the total fluorescence intensity of FAM and ROX to realize the quantitative detection of Hg 2+ , so the detection sensitivity of the analytical method can be greatly improved.

A graphene oxide-based fluorescent platform for selective detection of amyloid-β oligomers

“…Graphene oxide (GO), a single-atom-thick and two-dimensional carbon material, has shown extraordinarily high quenching ability toward uorescently labeled (e.g., dye, quantum dots or metal nanoclusters) DNA, peptides and antibodies because of the prominent nanoscale-surface energy transfer effect from the uorophore to GO. [16][17][18][19][20][21] Thus, there has been intense interest in developing GO-based uorescent sensors for the probing of enzymatic activities, measuring the concentrations of various analytes (e.g., nucleic acids, proteins, metal ions and small molecules), and imaging of cells and animals. [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] In a typical detection format, uorescence is quenched aer the dye-labeled ssDNA or peptide probe binds to GO via electrostatic and p-p interactions.…”

Smart nano-architectures as potential sensing tools for detecting heavy metal ions in aqueous matrices

“…Similarly, Hg 2+ (Ag + , Pb 2+ ) ions sensing platforms have been constructed based on fluorescence variation because of conformation DNA development on combining with Hg 2+ (Ag + , Pb 2+ ) ions to create the T-Hg 2+ -T (C-Ag + -C, Pb 2+ -G-quadruplex) base pairs [136][137][138]. The sensing platforms for Hg 2+ and Pb 2+ ions identification have been proposed on basis of quenching nanoparticles 35 fluorescence [139,140].…”

Laser-Induced Graphene Electrochemical Sensor for Quantitative Detection of Phytotoxic Aluminum Ions (Al 3+ ) in Soils Extracts

“…Detecting metals in foods or food sources requires sensitivities in parts per billion (ppb) concentrations when trace amounts pose an immediate risk to human health [34]. This is the case of Cadmium (Cd), Mercury (Hg), Lead (Pb), and other heavy metals [35][36][37]. Human exposure to aluminum, on the other hand, is unavoidable in today's world.…”