Jinghe Yang

Fluorimetric determination of ascorbic acid with o-phenylenediamine

A simple and sensitive fluorimetric method for the determination of ascorbic acid (AA) is described. The method is based on the condensation reaction between AA and o-phenylenediamine (OPDA) in the absence of the oxidant. The fluorescence intensity is measured at excitation and emission wavelengths of 360 and 430 nm, respectively. Under optimum condition, a linear relationship is obtained between the fluorescence intensity and the concentration of AA in the range of 0.05-40 mug ml(-1). The detection limit is 0.006 mug ml(-1), which is obviously lower than that of other fluorimetric methods reported.

Study of the interaction of nucleic acids with acridine red and CTMAB by a resonance light scattering technique and determination of nucleic acids at nanogram levels

In this paper, a determinating method of nucleic acids at nanogram levels by a resonance light scattering (RLS) technique with a common spectrofluorometer has been reported. The characteristics of RLS spectra of acridine red (AR) with nucleic acids, the effective factors and the optimum conditions have been studied. In the pH range 6.40‐7.10, nucleic acids and surfactant CTMAB can jointly enhance the intensity of resonance light scattering of AR and the interaction of AR with nucleic acids results in three characteristic peaks of RLS at 410, 470 and 555 nm. Mechanistic studies shows that when the molar ratio of nucleic acids to AR (m) is smaller than 5:1, the assembly of AR on the molecular surface of nucleic acids occurs and the enhancement of RLS can be observed. The binding numbers resulting from the Scatchard plot are increased in the presence of CTMAB. Whenm is higher than 5:1, AR intercalates into the base pairs of DNA. The enhanced intensity of RLS is in proportion to the concentration of nucleic acids in the range 5.010 8 to 8.010 6 gm l 1 for yeast RNA, 5.010 9 to 5.010 6 gm l 1 for fish sperm DNA and 5.0 10 8 to 1.210 6 gm l 1 for calf thymus DNA. The limits of detection are 1.28, 0.095 and 8.53 ng ml 1 , respectively. Synthetic samples were determined satisfactorily. Especially, the detection limit of fish sperm DNA has reached 10 11 gm l 1 . It shows that this method has high sensitivity.

Enhanced fluorescence of the terbium-gadolinium-nucleic acids system and the determination of nucleic acids

It is first found that the fluorescence of Tb‐nucleic acids (fish sperm DNA (fsDNA) and yeast RNA (yRNA)) can be increased by Sc 3C ,Y 3C ,L a 3C ,G d 3C and Lu 3C , among which Gd 3C and Lu 3C have the greatest enhancement. This is a new co-luminescence system. This system is studied in detail and is applied to determine nucleic acids. The experiments indicated that under the optimum conditions, a linear relationship was obtained between the fluorescence intensity ( If ) and the concentration of nucleic acids. The linear ranges are 1.0 10 8 ‐1.2 10 4 g/ml for DNA and 2.5 10 8 ‐8.5 10 4 g/ml for RNA. The detection limits (signal : noise = 3) for DNA and RNA were 4.3 10 9 and 6.4 10 9 g/ml, respectively. The mechanism of the co-luminescence effect is also discussed. ©2000 Elsevier Science B.V. All rights reserved.

Resonance light scattering technique for the determination of proteins with resorcinol yellow and OP

A new resonance light scattering (RLS) assay of proteins is presented. In the citric acid-NaOH (pH 2.35) buffer, the RLS of Resorcinol yellow (RY)-protein system can be greatly enhanced by addition of nonionic surfactant OP, owing to the interaction between OP and RY-protein. The enhanced RLS is in proportion to the concentration of proteins in the range 0.02-4.0 mug ml(-1) for both bovine serum albumin (BSA) and bovine hemoglobin (HEM), the detection limits were 10.4 ng ml(-1) (S/N=3) for BSA and 11.4 ng ml(-1) (S/N=3) for HEM. Samples were determined satisfactorily.

Granulocyte colony-stimulating factor improves alternative activation of microglia under microenvironment of spinal cord injury.

Granulocyte colony-stimulating factor (G-CSF) was investigated in the present study to examine whether it could affect the activation status of microglia under microenvironment of spinal cord injury and provide a potential therapeutic treatment for spinal cord injury. We established mouse spinal cord hemisection model and injected recombinant human G-CSF (rhG-CSF) subcutaneously. The results demonstrated that G-CSF could recruit microglia to the injury site in the first 72h after spinal cord injury. Moreover, G-CSF inhibits the expression of pro-inflammatory factors and promotes the expression of neurotrophic factors. Additionally, G-CSF also increases the expression of markers of M2 macrophage and inhibits the expression of markers of M1 macrophage in BV2 microglia in vitro model, favoring the M2 polarization of microglia under the microenvironment of spinal cord hemisection. NFκB signal pathway was involved in G-CSF-induced polarization of BV2 microglia. As a conclusion, we suggested that administration of G-CSF within the first 72h after spinal cord injury might reduce early inflammation-induced detrimental effect and promote an anti-inflammatory response that favors repair via improving alternative activation of microglia. Administration of G-CSF in the acute phase of spinal cord injury may be a promising strategy in restorative therapy after spinal cord injury.

Simultaneous spectrofluorimetric determination of terbium, samarium and europium with hexafluoroacetylacetone-trioctylphosphine oxide and Triton X-100

Abstract In aqueous solution, the fluorescence intensity is a linear function of concentration in the ranges 1.0 × 10 −4 -1.0 × 1.0 −6 M Sm and 1.0 × 10 −6 -1.0 × 10 −8 M Tb and Eu. The optimum conditions are 1 × 10 −3 M hexafluoroacetylacetone, 1 × 10 −4 M trioctylphosphine oxide and 0.05% Triton X-100 at pH 3.0.

Flow injection-chemiluminescence determination of phenol using potassium permanganate and formaldehyde system.

It is found that phenol can react with potassium permanganate in the acidic medium and produce chemiluminescence, which is greatly enhanced by formaldehyde. The optimum conditions for this chemiluminescent reaction are in detail studied using a flow injection system. The experiments indicate that under optimum conditions, the chemiluminescence intensity is linearly related to the concentration of phenol in the range 5.0x10(-9) to 1.0x10(-6)gmL-1 with a detection limit (3sigma) of 3x10(-9)gmL-1. The relative standard deviation is 1.2% for 4.0x10(-7)gmL-1 phenol solution in 11 repeated measurements. This method has the advantages of simple operation, fast response and high sensitivity. The method is successfully applied to the determination of phenol in the waste water.

Determination of chromium in waste-water and cast iron samples by fluorescence quenching of rhodamine 6G.

A new simple, selective and sensitive fluorescence quenching method was developed to determine chromium with rhodamine 6G. The method is based on the oxidation of rhodamine 6G by chromium(VI) in sulfuric acid solution. The linear calibration graph was obtained in the range 8-80 ng ml(-1) chromium(VI). The detection limit is 0.8 ng ml(-1). The method was applied successfully to the determination of chromium in waste water and cast iron samples.

Interaction of cetylpyridine bromide with nucleic acids and determination of nucleic acids at nanogram levels based on the enhancement of resonance Rayleigh light scattering

Resonance Rayleigh light scattering (RRLS) spectra of cetylpyridine bromide (CPB)-nucleic acid system and their analytical application have been first studied. The effective factors and optimum conditions of the reaction have been investigated. After CPB and nucleic acid are mixed together, a new absorption peak located at 300 nm appeared, which is due to the formation of new ion associate of CPB-nucleic acid. The new associate can result in two apparent RRLS peaks at 310-400 and 460-480 nm. The RRLS peak of the corrected spectra located at 290-350 nm, which indicate that the RRLS is originated from the absorption of CPB-nucleic acid associate. The peak at 460-480 nm disappears in the corrected RRLS spectra, which indicated that this peak is originated from the strong line emission of the Xe lamp. Under the optimum conditions, the enhanced intensity of RRLS is proportional to the concentration of nucleic acid in the range of 5.0 x 10(-9)-5.0 x 10(-5) g ml(-1) for calf thymus DNA (ctDNA), 1.0 x 10(-8)-4.0 x 10(-5) g ml(-1) for fish sperm DNA (fsDNA) and 1.0 x 10(-8)-5.0 x 10(-5) g ml(-1) for yeast RNA (yRNA). The detection limits (S/N = 3) are 4.3, 8.7 and 7.4 ng ml(-1), respectively. Synthetic samples were determined satisfactorily.

Study of the interaction of nucleic acids with acridine orange-CTMAB and determination of nucleic acids at nanogram levels based on the enhancement of resonance light scattering

The resonance light scattering (RLS) of acridine orange (AO) are greatly enhanced by both nucleic acid and cetyltrimethyl ammonium bromide (CTMAB). Based on this, nucleic acids can be sensitively determined. The interaction of AO with nucleic acid in the presence of CTMAB is studied by using RLS, absorption spectroscopy, zeta potential assay, transmission electron microscope (TEM) image and molecular molding. On its surface, nucleic acid acts as the template to promote the assembly of both AO and CTMAB in close proximity, which formatted large AO-nucleic acid-CTMAB association. Therefore, RLS intensity of cationic dye is greatly enhanced.