Jin-Hua Xue

Resonance light scattering determination of uranyl based on labeled DNAzyme-gold nanoparticle system.

A resonance light scattering (RLS) method has been developed using a uranyl (UO2(2+)) specific DNAzyme and gold nanoparticles (AuNPs). In this strategy, the cleavage of the substrate strand (SDNA) of DNAzyme results in releasing a shorter duplex in the presence of UO2(2+), leading to the aggregation of AuNPs and the increase of RLS intensity. The response signals linearly correlated with the concentration of UO2(2+) over the range of 1.36×10(-8)-1.50×10(-7) mol L(-1). The limit of detection (LOD) is 4.09×10(-9) mol L(-1). The method has excellent selectivity and higher sensitivity. It could provide a promising potential for the detection of metal ions, and be benefit to extend the application of RLS method.

Synchronous fluorescence determination of urinary 1-hydroxypyrene, β-naphthol and 9-hydroxyphenanthrene based on the sensitizing effect of β-cyclodextrin

A novel method for the simultaneous determination of 1-hydroxypyrene (1-OHP), beta-naphthol (beta-NAP) and 9-hydroxyphenanthrene (9-OHPe) in human urine has been established by using synchronous fluorescence spectrometry. It was based on the fact that synchronous fluorescence spectrometry can resolve the broad-band overlapping of conventional fluorescence spectra, which arise from their similar molecular structures. Only one single scan is needed for quantitative determination of three compounds simultaneously when Deltalambda=15nm is chosen. The signals detected at these three wavelengths, 369.6, 330.0 and 358.0nm, vary linearly when the concentration of 1-OHP, beta-NAP and 9-OHPe is in the range of 2.16x10(-8)-1.50x10(-5)molL(-1), 1.20x10(-7)-1.10x10(-5)molL(-1) and 1.07x10(-7)-3.50x10(-5)molL(-1), respectively. The correlation coefficients for the standard calibration graphs were 0.994, 0.999 and 0.997 (n=7) for 1-OHP, beta-NAP and 9-OHPe, respectively. The limits of detection (LOD) for 1-OHP, beta-NAP and 9-OHPe were 6.47x10(-9)molL(-1), 3.60x10(-8)molL(-1) and 3.02x10(-8)molL(-1)with relative standard deviations (R.S.D.) of 4.70-6.40%, 2.80-4.20%, 3.10-4.90% (n=6), respectively. The method described here had been applied to determine traces of 1-OHP, beta-NAP and 9-OHPe in human urine, and the obtained results were in good agreement with those obtained by the HPLC method. In addition, the interaction modes between beta-cyclodextrin (beta-CD) and 1-OHP, beta-NAP or 9-OHPe, as well as the mechanism of the fluorescence enhancement were also discussed.

Rapid simultaneous analysis of 1-hydroxypyrene, 2-hydroxyfluorene, 9-hydroxyphenanthrene, 1- and 2-naphthol in urine by first derivative synchronous fluorescence spectrometry using Tween-20 as a sensitizer.

A novel method of first derivative synchronous fluorescence was developed for the rapid simultaneous analysis of trace 1-hydroxypyrene (1-OHP), 1-naphthol (1-NAP), 2-naphthol (2-NAP), 9-hydroxyphenanthrene (9-OHPe) and 2-hydroxyfluorene (2-OHFlu) in human urine. Only one single scan was needed for quantitative determination of five compounds simultaneously when Deltalambda=10 nm was chosen. In the optimal experimental conditions, there was a linear relationship between the fluorescence intensity and the concentration of 1-OHP, 1-NAP, 2-NAP, 9-OHPe and 2-OHFlu in the range of 1.75 x 10(-9) to 4.50 x 10(-6) mol L(-1), 3.64 x 10(-8) to 2.20 x 10(-4) mol L(-1), 8.18 x 10(-9) to 1.20 x 10(-4) mol L(-1), 3.26 x 10(-9) to 8.50 x 10(-5) mol L(-1) and 4.88 x 10(-9) to 5.50 x 10(-6) mol L(-1), respectively. The limits of detection (LOD) were found to be 5.25 x 10(-10) mol L(-1) for 1-OHP, 1.10 x 10(-8) mol L(-1) for 1-NAP, 2.46 x 10(-9) mol L(-1) for 2-NAP, 9.77 x 10(-10) mol L(-1) for 9-OHPe and 1.46 x 10(-9) mol L(-1) for 2-OHFlu. The proposed method is reliable, selective and sensitive, and has been used successfully in the determination of traces of 1-OHP, 1-NAP, 2-NAP, 9-OHPe and 2-OHFlu in human urine samples, whose results were in good agreement with those gained by the HPLC method.

Resonance light scattering method for the determination of anionic surfactant with acridine orange

The resonance Rayleigh scattering (RRS), second-order scattering (SOS) and frequency-double scattering (FDS) spectra of sodium dodecylbenzene sulfonate (SDBS) (anionic surfactant (AS)) with acridine orange (AO) system were studied. Experimental results showed that when lambda(em) = lambda(ex) = 537 nm, the RRS peak of AO was greatly enhanced with the increase of SDBS concentration at a pH range of 1.8-4.0. The linear range of the calibration curve for SDBS was 0.028-8.71 mg L(-1) with a detection limit of 8.36 microg L(-1) when the AO concentration was 2.5 x 10(-5)mol L(-1). The method has been applied to the determination of trace amount of AS in environmental water samples with satisfactory results. In addition, when lambda(em) = 321 nm and lambda(ex) = 642 nm, the intensity of FDS was proportional to the SDBS concentration ranging from 0.014 to 8.71 mg L(-1) and the correlation coefficient was 0.993 with a detection limit of 4.31 microg L(-1); when lambda(em) = 642 nm and lambda(ex) = 321 nm, the intensity of SOS was proportional to the SDBS concentration ranging from 0.050 to 8.71 mg L(-1), and the correlation coefficient was 0.993 with a detection limit of 14.9 microg L(-1).

A novel strategy for dual-channel detection of metallothioneins and mercury based on the conformational switching of functional chimera aptamer

A novel strategy for dual-channel detection of metallothioneins (MTs) and Hg(2+) has been proposed. In the absence of Hg(2+), the functional chimera aptamer (FCA) designed can form an intact G-quadruplex with flexibility, which was demonstrated to have peroxidase-like activities upon hemin binding. In the presence of Hg(2+), the formation of T-Hg(2+)-T complex results in the conformational switching of FCA, which lost the peroxidase-like activities and cannot catalyze the oxidation of ABTS by H2O2. Upon addition of MTs in this solution, MTs could interact with Hg(2+) to form a MTs-Hg(2+) complex, leading to the recovery of the G-quadruplex DNAzyme. The color and absorbance of the sensing system were also changed accordingly. In the optimizing condition, ΔA was directly proportional to the concentration ranging from 8.84 nM to 1.0 μM for Hg(2+), and 7.82 nM to 0.462 μM for MTs with the detection limits of 2.65 nM and 2.34 nM, respectively. The proposed dual-channel method avoids the label steps in common methods, and allows direct analysis of the samples without costly instruments, and is reliable, inexpensive and sensitive.

Adsorption and recovery of U(VI) from low concentration uranium solution by amidoxime modified Aspergillus niger

Amidoxime modified Aspergillus niger (AMAN) was prepared by the oximation reaction. The effects of the initial pH, contact time, initial U(VI) concentration and biosorbent dose on the adsorption of U(VI) ions from radioactive wastewater in U(VI) concentrations of less than 1 mg L−1 by AMAN and the raw Aspergillus niger (RAN) were investigated. The maximum adsorption efficiency by AMAN for the 0.5 mg L−1 U(VI) solution amounted to 98.85% under the optimum adsorption conditions, while the maximum adsorption efficiency by RAN was only 77.83%. The adsorption equilibrium data were found to be best fitted to Langmuir isotherm model, and the maximum biosorption capacity of AMAN for U(VI) was estimated to be 621 mg g−1 at 298 K. The biosorption kinetics followed the pseudo-second order model and intraparticle diffusion equation. The Gibbs free energy change (ΔG°), enthalpy change (ΔH°) and entropy change (ΔS°) showed that the adsorption process of U(VI) was spontaneous, feasible and endothermic. The SEM-EDS study indicated that much more U(VI) ions were adsorbed by AMAN than by RAN. FT-IR study showed that the –NH2 and N–OH groups of amidoxime were the dominant ones for binding UO22+ ions. Moreover, AMAN was found to have excellent selective adsorption capability of U(VI) due to amidoxime groups. The UO22+ ions adsorbed by AMAN could be desorbed using 0.1 M HCl, and the desorption efficiency reaching 87.28% at the 8th cycle of adsorption and desorption.

Colorimetric detection of metallothioneins using a thymine-rich oligonucleotide-Hg complex and gold nanoparticles

A simple and sensitive method for label-free, colorimetric detection of metallothioneins (MTs) has been developed by using a thymine (T)-rich oligonucleotide (TRO)-Hg-AuNP system. In this colorimetric strategy, the thiol groups of MTs could interact with mercury from the T-Hg(2+)-T complex to release TRO, resulting in a color change of the system. The response signals linearly correlated with the concentration of MTs over the range of 2.56 × 10(-8) to 3.08 × 10(-7) mol L(-1), and the limit of detection was 7.67 × 10(-9) mol L(-1). The relative standard deviation and the recovery were 2.3-4.8% (n = 11) and 94.2-103.9%, respectively. The proposed method avoids the label and derivatization steps in common methods, allows direct analysis of the samples by the naked eye without costly instruments, and is reliable, inexpensive, and sensitive.

An enzyme-free strategy for ultrasensitive detection of adenosine using a multipurpose aptamer probe and malachite green

We report on an enzyme-free and label-free strategy for the ultrasensitive determination of adenosine. A novel multipurpose adenosine aptamer (MAAP) is designed, which serves as an effective target recognition probe and a capture probe for malachite green. In the presence of adenosine, the conformation of the MAAP is converted from a hairpin structure to a G-quadruplex. Upon addition of malachite green into this solution, a noticeable enhancement of resonance light scattering was observed. The signal response is directly proportional to the concentration of adenosine ranging from 75 pM to 2.2 nM with a detection limit of 23 pM, which was 100-10,000 folds lower than those obtained by previous reported methods. Moreover, this strategy has been applied successfully for detecting adenosine in human urine and blood samples, further proving its reliability. The mechanism of adenosine inducing MAAP to form a G-quadruplex was demonstrated by a series of control experiments. Such a MAAP probe can also be used to other strategies such as fluorescence or spectrophotometric ones. We suppose that this strategy can be expanded to develop a universal analytical platform for various target molecules in the biomedical field and clinical diagnosis.

Determination of trace formaldehyde in blood plasma by resonance fluorescence technology.

A novel method for the determination of trace formaldehyde in blood plasma has been established by using resonance fluorimetry technique. It was based on the fact that oxidation of pyronine Y by potassium bromate was catalyzed by formaldehyde in sulfuric acid. When the wavelength interval was at Δλ=0 nm, it was found that the decreased intensity (ΔF) of resonance fluorescence at 574.6 nm was proportional to the concentration of formaldehyde in the range of 1.27×10(-2) to 2.28 μg mL(-1). The limit of detection and the average recovery for formaldehyde were 3.80 ng mL(-1) and 101.6% (n=6), respectively. The present method had been applied to the determination of trace formaldehyde in blood plasma, and the obtained results were in good agreement with those obtained by the resonance light scattering method.

Resonance light scattering determination of metallothioneins using levofloxacin-palladium complex as a light scattering probe.

A novel method of resonance light scattering (RLS) was developed for the analysis of trace metallothioneins (MTs) in human urine. In a CH(3)COOH-CH(3)COONa buffer solution of pH 4.5, the formation of a complex between levofloxacin (LEV)-Pd and MTs led to enhance the RLS intensity of the system, and the enhanced RLS intensity at 468 nm was proportional to the concentration of MTs in the range of 0.059-22.4 μg mL(-1). The linear regression equation was ΔI=127.5 ρ (μg mL(-1))-88.02 with a correlation coefficient of 0.9992, and the detection limit of 17.8 ng mL(-1). The relative standard deviation and the average recovery were 3.8-5.4% (n=11) and 92.15%, respectively. The proposed method is convenient, reliable and sensitive, and has been used successfully for the determination of trace MTs in human urine samples.