Synchronous Fluorescence Intensity Research Articles

Preparation of novel composite nanoclusters and their application in the ultrasensitive detection of proteins

An ultrasensitive method for detecting protein by synchronous fluorescence scan technique with a novel composite nanoclusters has been developed. The novel composite nanoclusters has been prepared by an in situ polymerization method and applied as a protein synchronous fluorescence probe. The surface of the composite nanoclusters was covered with functional groups (−COOH, −CONH−, −OH). These groups may have “synergistic effect” and play a major role in the ultrasensitive method. The nanoclusters are water-soluble, stable and biocompatible. The synchronous fluorescence intensity of the composite nanoclusters is significantly increased in the presence of trace protein at pH 1.09. Based on this, a new synchronous fluorescence scan (SFS) analysis was developed for the determination of proteins including BSA, HSA and human γ-IgG. The liner range is 0.03–2.0μgml−1 for HSA, 0.02–2.2μgml−1 for BSA and 0.02–1.5μgml−1 for human γ-IgG, respectively. Besides high sensitivity, the method is characterized by good reproducibility, excellent accuracy and few interfering substances.

Determination of proteins at nanogram levels by synchronous fluorescence scan technique with a novel composite nanoparticle as a fluorescence probe

A novel composite nanoparticle has been prepared by an in situ polymerization method and applied as a protein fluorescence probe. The nano-CdS has been prepared, then the polymerization of acrylic acid (AA) was carried out by initiator potassium persulfate (KPS) under ultrasonic irradiation. The surface of the composite nanoparticles was covered with abundant carboxylic groups (COOH). The nanoparticles are water-soluble, stable, and biocompatible. The synchronous fluorescence intensity of the composite nanoparticles is significantly increased in the presence of trace protein at pH 6.90. Based on this, a new synchronous fluorescence scan (SFS) analysis was developed for the determination of proteins including BSA, HSA, and human γ-IgG. When Δ λ=280 nm, maximum synchronous fluorescence is produced at 290 nm. Under the optimum conditions, the response is linearly proportional to the concentration of proteins. The linear range is 0.1–10 μg ml −1 for HSA, 0.09–8.0 μg ml −1 for BSA, and 0.08–15 μg ml −1 for human γ-IgG, respectively. The method has been applied to the determination of the total protein in human serum samples collected from the hospital and the results are satisfactory.

Preparation and application of cysteine-capped ZnS nanoparticles as fluorescence probe in the determination of nucleic acids

Cysteine-capped ZnS nanometer-sized fluorescent particles were produced by a colloidal aqueous synthesis. The functionalized nanoparticles are water-soluble and suitable for biological application. A synchronous fluorescence method has been developed for the rapid determination of DNA with functionalized nano-ZnS as a fluorescence probe, based on the synchronous fluorescence enhancement of cysteine-capped nano-ZnS in the presence of DNA. When Δ λ=190 nm, maximum synchronous fluorescence is produced at 267 nm at pH 5.12. Under optimum conditions, the synchronous fluorescence intensity is proportional to the concentration of nucleic acids in the range 0.1–1.2 μg ml −1 for calf thymus DNA, 0.1–0.6 μg ml −1 for fish sperm DNA. The corresponding detection limit is 32.9 ng ml −1 for calf thymus DNA and 24.6 ng ml −1 for fish sperm DNA. This method is simple, inexpensive, rapid and sensitive. The recovery and relative standard deviation are satisfactory.

Fluorescence Spectroscopic Analysis of Tars from the Pyrolysis of a Victorian Brown Coal in a Wire-Mesh Reactor

Constant-energy synchronous fluorescence spectroscopy was used to examine the aromatic structural features of the tars from the pyrolysis of Loy Yang brown coal in a wire-mesh reactor. Tars from the pyrolysis of the raw coal and its H-form and Ca-form coal samples at various heating rates, peak temperatures, and holding times at the peak temperature were analyzed. The synchronous spectra of all of the tars showed two characteristic peaks with centers at ca. 335−340 and 385−390 nm. Synchronous fluorescence intensity per unit absorbance was found to be a useful parameter to examine the changes in the intramolecular energy transfer due to the changes in tar structural features. The degree of intramolecular energy transfer is considered a measure of the relative amounts of aromatic ring systems in oligomeric structures. Increasing heating rate during pyrolysis was found to enhance the release of larger (3 or more fused rings) aromatic ring systems. The introduction of ion-exchangeable cations (e.g., Ca2+) int...

Study of the acid-base properties of leaf litter extracts

The acid-base properties of four leaf litter extracts, LLE (eucalyptus, fern, oak and chestnut coverture), were characterized by synchronous fluorescence (SyF) spectroscopy and compared with those of two fulvic acids (FA) extracted from two different horizons (0–5 and 5–15 cm) of an oak forest soil. The characterization was based on the variation with the pH of the properties of the fluorescent structures present in the samples, which function as probes and provide a macroscopic image of their acid-base properties. These sets of SyF spectra collected as a function of the pH show fingerprinting potential. They were treated by a self-modeling curve resolution procedure, evolving factor analysis with a gradient concentration window (EFA-GCW), to reduce the raw spectral data to the number of components, their spectra, and SyF intensity profiles (pH distribution diagrams). Four acid-base systems were detected for all samples of LLE and FA with pKas ranging from 2.5 to 10.0 (pKas about 3, 5, 7 and 9, except for the fern LLE sample which showed pKas about 5, 7, 9 and 10). A similarity analysis of the spectra of the components, performed by cluster analysis, showed that the most acidic fluorescent structures of the LLE are not similar to those of the soil FA, but the less acidic are.

微分シンクロ蛍光法によるフェナントレン中の微量アントラセンの定量法

Since ordinarily available phenanthrene contains impurities such as phenanthrenequinone and fluoranthene, it is difficult to determine anthracene by spectrofluorimetry directly. Trace amounts of anthracene in phenanthrene can, however, be selectively determined by using the 4th-derivative synchronous fluorescence intensity without interference of these impurities. In 5 mL of cyclohexane, 25 mg of the sample is dissolved. The synchronous fluorescence spectrum of the solution is measured with wavelength interval (Δλ) of 24 nm in the range of 360-395 nm. Trace amounts of anthracene in phenanthrene can be determined from the 4th-derivative intensity at 376 nm, which is obtained by computation of the synchronous fluorescence spectrum. By this method, anthracene can be determined simply and rapidly. The determination limit is 0.5 ppm.

Zone-Melting Separation of Carbazole and Anthracene from Polynuclear Aromatic Compounds Using Biphenyl as a Medium, Followed by the Synchronous Fluorometric Determination

Abstract Biphenyl is favorable as a zone-melting medium for the selective separation of small amounts of carbazole and anthracene and a subsequent determination. A definite amount (20–100 mg) of an aromatic sample was mixed with 4 g of purified biphenyl. The mixture was zone-melted 20 times. The two analytes were accumulated in the beginning part of the zone-molten ingot, but many others were eliminated from the part. After being dissolved in xylene along with the biphenyl, carbazole and anthracene could be simultaneously determined up to 10 ng ml−1 by measuring the synchronous fluorescence intensities at 340 and 384 nm, respectively.

Synchronous Fluorometric Determination of Trace Amounts of Anthracene in Fluoranthene Using Dibenzofuran as a Zone-melting Medium for the Separation

Trace amounts of anthracene can be separated from fluoranthene and most of the concomitant impurities by a zone-melting technique using dibenzofuran as a zone-melting medium. Anthracene thus separated can be determined by synchronous fluorescence spectrometry without removal of dibenzofuran. The determination limit is 2ppm. After 100mg of a fluoranthene sample and 4g of purified dibenzofuran had been uniformly mixed, the mixture was charged in a glass tube with an i.d, of 4mm. The zone-pass was repeated 20 times with an upward travel at a speed of 100mm/h under constant stirring. The lower half of the zone-molten ingot was cut out exactly and dissolved in xylene. Anthracene could be determined from the synchronous fluorescence intensity at 384nm.

Simultaneous Determination of Trace Amounts of Carbazole and Anthracene in Dibenzofuran by Synchronous Fluorescence Spectrometry after Zone-melting Separation

Abstract Trace amounts of carbazole and anthracene in dibenzofuran can be simultaneously determined by measuring the synchronous fluorescence intensities at 336 and 381 nm respectively. The determination limit is 2 ppm. For the application of this method to the practical samples containing interfering impurities, a zone-melting technique was applied successfully to remove the impurities prior to the determination. The recoveries of carbazole and anthracene were 99 and 92% respectively.