The Determination of Deoxyribonucleic Acids with Triadimenol Based on the Enhancement of Resonance Light Scattering

For the first time, triadimenol was used to determine nucleic acid (DNA) using the resonance light scattering (RLS) technique. The RLS of triadimenol was greatly enhanced by DNA in the range of pH 1.6 ～ 1.9. A resonance light‐scattering peak at 310nm was found, and the enhanced intensity of RLS at this wavelength was proportional to the concentration of DNA. The linear range of the calibration curve was 0 ～ 9 µg/ml with the detection limit of 24 ng ml^? 1. The mechanism studies of the system indicated that the enhanced RLS is due to the aggregation of triadimenol on DNA. The nucleic acids in synthetic samples and in rice seedling extraction were analyzed with satisfactory results. Compared with other methods, this method is convenient, rapid, inexpensive and simple.     

Detection of DNA using cationic polyhedral oligomeric silsesquioxane nanoparticles as the probe by resonance light scattering technique

A novel cationic polyhedral oligomeric silsesquioxane nanoparticle (cationic POSS) was synthesized and successfully used as a new probe for the detection of DNA by resonance light scattering technique (RLS). It was found that the electrostatic interaction of cationic POSS and DNA could obviously enhance the RLS signal, the enhanced RLS intensity at 360 nm was proportional to the concentration of nucleic acids within the range of 0.35-42.82 microg ml-1 for calf thymus DNA, the determination limit (3sigma) was 0.32 ng ml-1. The results showed this method was very sensitive, convenient, rapid and reproducible.     

Development of a sensitive and rapid nucleic acid assay with tetraphenyl porphyrinatoiron chloride by a resonance light scattering technique.

Based on the interaction between nucleic acids and tetraphenyl porphyrinatoiron chloride (FeTPPCl), a novel method for the determination of nucleic acids at the nanogram level has been developed. Under the optimum conditions, the weak resonance light scattering (RLS) intensity of FeTPPCl was greatly enhanced by nucleic acids and the enhanced RLS intensity was proportional to the concentration of nucleic acids in the range 0.02-2.8 microg/mL for calf thymus DNA, 0.05-3.3 microg/mL for fish sperm DNA and 0.07-4.5 microg/mL for yeast RNA. The detection limits (3sigma) were 2.9 ng/mL for calf thymus DNA, 3.9 ng/mL for fish sperm DNA and 5.2 ng/mL for yeast RNA. Almost no interference could be observed from proteins, nucleosides and most of the metal ions. The proposed method showed good reliability, sensitivity, rapidity and reproducibility when applied to the determination of nucleic acids in synthetic and biochemical samples. The time savings make this method suitable for large routine analyses.     

基于[Ru(phen)2(bpip)] 2+-DNA相互作用的共振光散射增强建立纳克级DNA的测定方法

通过研究钌多吡啶类配合物［Ru(phen)2(bpip)］2+与DNA相互作用的共振光散射等光谱,我们发现［Ru(phen)2(bpip)］²⁺与DNA相互作用的方式包括插入作用和静电作用模式.同时基于［Ru(phen)2(bpip)］²⁺ DNA体系增强的共振光散射现象,建立了一种简单、快速的测定纳克级核酸的新方法.实验结果表明体系在373 nm处共振光散射强度的增强与DNA的浓度呈线性关系.线性范围为0.025～1.250 mg/L,线性公式为△I_RLS=283.14C+2.26 (mg/L),相关系数为0.9983,DNA的检出限为5.7 ng/mL. 应用到实际样品的分析中,结果令人满意.     

Study of the interaction of hexa-amine cobalt (III) ion with DNA by a resonance light scattering technique and its analytical application.

The effect of hexa-amine cobalt cations on the DNA condensation in aqueous solution was investigated by resonance light scattering (RLS). When the relative concentration of hexa-amine cobalt (III) cations to DNA is in the appropriate range, the cations will induce DNA condensation and aggregation, which results in a strong RLS spectrum characterized by a peak at 290.0 nm. The RLS technique is a powerful tool for monitoring DNA condensation and, under optimal conditions, the enhanced RLS intensity at 290.0 nm was proportional to the concentration of DNA in the range 0.01-6.0 microg/mL. Based on this, a sensitive and convenient analysis method for the microdetermination of DNA was established. The detection limit (3 s) of calf thymus DNA by the proposed method is 1.9 ng/mL and few substances interfere in the DNA determination.     

Study on the Interaction Between Nucleic Acids and Imidacloprid and Its Application

The determination of imidacloprid with DNA via a resonance light scattering (RLS) technique was developed. The RLS of DNA was remarkably quenched after adding imidacloprid in aqueous medium of pH 2.10. An RLS peak at 311 nm was found, and the quenched intensity of RLS at this wavelength was proportional to the concentration of imidacloprid. The linear range of the calibration curve was approximately 0.02–2 μg/mL with the detection limit (S/N = 3) of 0.02 ng/mL. The imidacloprid in river water, cucumbers, and apple samples was determined. The recovery rates were in the range of 91.9% to 95.20%, 97.2% to 111.3%, and 94.5% to 114.8%, respectively. The mechanism of the reaction between imidacloprid and DNA is also discussed.     

Investigation on the analytical application of cationic Gemini surfactant 12‐4‐12 and its interaction with DNA

The quantitative determination of nucleic acids is of great importance in fundamental research and clinical diagnosis. In this work, the interaction between DNA and cationic Gemini surfactant 12‐4‐12, which changes the conformation of DNA, was investigated by UV‐vis absorption, FT‐IR spectra and steady‐state fluorescence techniques. A hydrophobic pyrene probe was used to investigate the microenvironment change and calculate the critical micelle concentration (CMC) of Gemini surfactant 12‐4‐12 (0.69 mmol/L), which is close to the value obtained from the conductivity method (0.79 mmol/L). A new detection assay for DNA is proposed with Gemini surfactant 12‐4‐12, using the resonance light‐scattering (RLS) technique. The formation of DNA–12‐4‐12 complex resulted in enhanced RLS signals at 368 nm, which is proportional to DNA concentration in the range 0.304–5.32 mg/L, with a detection limit of 35 µg/L. Most coexisting substances do not interfere in the detection and four synthetic samples were analyzed satisfactorily. Copyright © 2011 John Wiley & Sons, Ltd.     

A spectroscopic and thermodynamic study of porphyrin/DNA supramolecular assemblies.

Assemblies of trans-bis(N-methylpyridinium-4-yl)diphenylporphine ions on the surface of calf thymus DNA have been studied using several spectroscopic techniques: absorbance, circular dichroism, and resonance light scattering. The aggregation equilibrium can be treated as a two-state system-monomer and assembly-each bound to the nucleic acid template. The aggregate absorption spectrum in the Soret region is resolved into two bands of Lorentzian line shape, while the DNA-bound monomer spectrum in this region is composed of two Gaussian bands. The Beer-Lambert law is obeyed by both porphyrin forms. The assembly is also characterized by an extremely large, bisignate induced circular dichroism (CD) profile and by enhanced resonance light scattering (RLS). Both the CD and RLS intensities depend linearly on aggregate concentration. The RLS result is consistent with a model for the aggregates as being either of a characteristic size or of a fixed distribution of sizes, independent of total porphyrin concentration or ionic strength. Above threshold values of concentration and ionic strength, the mass action expression for the equilibrium has a particularly simple form: K' = cac-1; where cac is defined as the "critical assembly concentration."offe dependence of the cac upon temperature and ionic strength (NaCl) has been investigated at a fixed DNA concentration. The value of the cac scales as the inverse square of the sodium chloride concentration and, from temperature dependence studies, the aggregation process is shown to be exothermic.     

Determination of nucleic acids based on the quenching effect on resonance light scattering of the Y(III)-1,6-bi(1'-phenyl-3'-methyl-5'-pyrazolone-4'-)hexane-dione system.

Nucleic acids can quench resonance light scattering (RLS) intensity of the Y(III)-1,6-bi(1'-phenyl-3'-methyl-5'-pyrazolone-4'-)hexane-dione(BPMPHD) complex in the pH range 5.0-5.8. Under optimal conditions, there are linear relationships between the quenching of RLS and the concentration of nucleic acids in the range 6.3 x 10(-8)-2.1 x 10(-5) g/mL for fish sperm DNA (fsDNA), 1.2 x 10(-8)-5.0 x 10(-5) g/mL for calf thymus DNA (ctDNA) and 6.0 x 10(-8)-2.0 x 10(-5) g/mL for yeast RNA (yRNA). The detection limits (3 s) of fsDNA, ctDNA and yRNA are 0.7 ng/mL, 3.8 ng/mL and 4.2 ng/mL, respectively.     

Determination of nanograms of proteins based on decreased resonance light scattering of zwitterionic gemini surfactant

A new high-sensitivity detection of protein assay at the nanogram level is proposed based on the decreased resonance light scattering (RLS) signals of zwitterionic gemini surfactant (phosphodiesters quaternary ammonium salt [PQAS]). It was found that PQAS self-assembled into nanometer-scale PQAS aggregates, which induced intense RLS signal in Britton-Robinson (BR) buffer solution (pH 10.5). Under the optimum conditions, the RLS intensity quenching extent of PQAS aggregation was in proportion to the concentration of proteins in the range of 0.0012-1.08 μg/ml for bovine serum albumin, 0.0015-0.95 μg/ml for human serum albumin, and 0.0025-1.3 μg/ml for γ-globulin. The detection limits were 0.8, 1.2, and 2.0 ng/ml, respectively. The proposed method was successfully applied to determine total protein in human serum samples, and the results were identical to those obtained by the Bradford assay. The mechanism of interaction between PQAS and protein was studied using RLS, fluorescence, and time-resolved fluorescence, which indicated that the new complex formed between them, disaggregating self-aggregation of PQAS, resulted in the dominated quenching of RLS signal of the assay system.     

Flow-injection resonance light scattering detection of proteins at the nanogram level.

A resonance light scattering (RLS) detection method for protein was developed, using a flow-injection system based on the enhancement of RLS signals from Biebrich scarlet (BS) by protein. The enhanced RLS intensities at 286.0 nm, in acidic aqueous medium, were proportional to the protein concentration over the range 0.005-18 microg/mL and 0.008-16 microg/mL for human serum albumin (HSA) and bovine serum albumin (BSA), respectively, with corresponding limits of detection (3sigma) of 5.00 ng/mL for HSA, and 7.80 ng/mL for BSA. The method was successfully applied to the quantification of total proteins in human serum samples.     

Determination of proteins with fullerol by a resonance light scattering technique

Fullerol has been synthesized through the reaction of fullerene C60 with NaOH in aqueous solution by means of ultrasonic agitation and characterized by infrared and 1H-nuclear magnetic resonance spectroscopy. The fullerol obtained shows good solubility and excellent stability in water. A weak resonance light scattering (RLS) spectrum of fullerol was observed in aqueous solution. However, the intensity of the RLS signal could be enhanced in the presence of proteins, including bovine serum albumin (BSA), human serum albumin (HSA), pepsin (Pep), and lysozyme (Lys). Based on the enhancement of the RLS, a sensitive method for the determination of proteins has been established. The quantitative conditions were considered with regard to the effects of the pH, the ion strength, and the concentration of the fullerol. Under the optimum conditions, the intensity of the RLS was proportional to the concentration of proteins with the limits of detection of 9.7, 10.9, 57.4, and 8.5 ng mL(-1) for BSA, HSA, Pep, and Lys, respectively. Almost no interference can be observed from some amino acids, nucleic acids, and most of the metal ions. The model samples and human serum samples were determined satisfactorily with the proposed method.     

An aptamer based resonance light scattering assay of prostate specific antigen

Prostate specific antigen (PSA) is a valuable tumor marker for prostate cancer screening. In this work, a novel and sensitive resonance light scattering (RLS) spectral assay of PSA was proposed based on PSA aptamer modified gold nanoparticles (AuNPs). The sulfhydryl modified single-strand aptamer could interact with AuNPs, which made the AuNPs stable in high concentration of salt. In pH 7.0 BR buffer solution, the highly selective combination of PSA and AuNPs-labeling aptamer resulted in the aggregation of AuNPs which showed high RLS intensity. Under the optimal conditions, the magnitude of enhanced RLS intensity (ΔI(RLS)) was proportional to the concentration of PSA in the range from 0.13 to 110 ng/mL, with a detection limit (LOD, 3σ) of 0.032 ng/mL. This developed RLS assay as well as a commercially available enzyme-linked immunosorbent assay (ELISA) kit was successfully applied to the detection of PSA in 15 serum samples, and an excellent correlation of the levels of PSA measured was obtained. This is the first report of the aptamer based RLS assay for PSA and it is also a significant application of instrumental analysis technique.     

Circular dichroism and the interactions of water soluble porphyrins with DNA

The size, sign, and profile of induced circular dichroism (CD) features in the Soret region are reliable indicators of the binding modes of porphyrins and metalloporphyrins to DNA. Porphyrins shown (using such CD criteria) to be intercalators in monodispersed DNA duplexes prove extremely useful for the detection and characterization of organized, condensed forms of nucleic acids (psi-condensates). In addition, certain select porphyrin derivatives can form extended assemblies on nonaggregated DNA templates. A combination of CD and resonance light scattering (RLS) measurements allows for sensitive detection and characterization of these porphyrin arrays.     

Resonance light scattering study on the interaction of benproperine phosphate with eriochrome blue black R in the presence of sodium dodecylbenzene sulphonate and its analytical application

The interaction of benproperine phosphate (BPP) with eriochrome blue black R (EBBR) in the presence of sodium dodecylbenzene sulphonate (SDBS) was studied using resonance light scattering (RLS) technology and ultraviolet‐visual (UV‐vis) spectrophotometry. Under optimum conditions, BPP reacts with EBBP and SDBS to form a three‐component complex, which results in strong RLS signal and a new RLS peak. The enhanced RLS intensities are proportional to the concentration of BPP over the range 0.6–28.0 µg/mL, with a detection limit of 0.053 µg/mL. The affecting factors as well as the influence of coexisting substances were investigated. The results indicate that this assay method could be applied to the determination of BPP in pharmaceuticals, serum and urine samples with satisfactory results. Copyright © 2008 John Wiley & Sons, Ltd.     

Detection of Vascular Endothelial Growth Factor Based on Gold Nanoparticles and Immunoreaction Using Resonance Light Scattering

In the study, a new assay of vascular endothelial growth factor (VEGF) has been developed by the use of gold nanoparticles (GNPs)–anti-VEGF conjugates. The immunoreaction between GNPs–anti-VEGF conjugates and VEGF took place in pH?7.5 PBS buffer solution after the addition of VEGF. The formation of GNPs modified VEGF immunocomplex resulted in the enhanced resonance light scattering (RLS) intensity at 388.0 nm. Under the optimal conditions, the magnitude of enhanced RLS intensity (ΔI _RLS) was proportional to the VEGF concentration in the range from 100 to 1,500 pg?mL^?1, with a detection limit of 60 pg?mL^?1. The surface plasma resonance absorption spectrum, the characteristics of RLS, the VEGF immunocomplex, and the optimum conditions of the immunoreaction have all been investigated. The VEGF concentrations of 20 serum specimens detected by the developed assay showed consistent results in comparison with those obtained by commercially available enzyme-linked immunosorbent assay kit.     

Binding of the Mn(III) complex of meso-tetrakis (4-N-methyl-pyridiniumyl) porphyrin to DNA. Effect of ionic strength

Interactions of the water-soluble Mn(III) complex of meso-tetrakis (4-N-methyl-pyridiniumyl) porphyrin (Mn(III)TMPyP) with DNA in aqueous solutions at low (0.01 M) and high (0.2 M) ionic strengths have been studied by optical absorption, resonance light scattering (RLS) and 1H NMR spectroscopies. Optical absorption and RLS measurements have demonstrated that in DNA solutions at low ionic strength the Mn(III)TMPyP form aggregates, which are decomposed at DNA excess. At high ionic strength the aggregation was not observed. We explain this effect by assuming that upon increase in ionic strength, Mn(III) TMPyP dislocates from the DNA sites, which produces better conditions for the porphyrin aggregation, to sites where the aggregation is hindered. The 1H NMR data demonstrated that the aggregation observed at low ionic strength reduces the paramagnetism of Mn(III)TMPyP. This phenomenon was not observed at the high ionic strength in the absence of aggregation.     

Resonance light scattering study on the interaction between quinidine sulfate and congo red and its analytical application

The interaction between quinidine sulfate (QDS) and congo red (CR) was studied using resonance light scattering (RLS) technique, ultraviolet–visual spectrophotometry and fluorimetry. In weak acidic medium, QDS reacts with CR to form a supermolecular complex which results in the enhanced RLS intensity. Some important interacting parameters, such as the solution acidity and CR concentration, salt effect and addition order of the reagents, were investigated and optimized. Under the optimum conditions, it was found that the enhanced RLS intensity was in proportion to the concentration of QDS in the range 0.2–8.4 µg mL^?1. The corresponding detection limit was 12.0 ng mL^?1. The results showed that this new method enabled simple, sensitive and rapid determination of QDS and was used for the determination of QDS in urine and simulated huamn serum samples. Copyright © 2009 John Wiley & Sons, Ltd.     

Fluorescence resonance energy transfer studies of U-shaped DNA molecules

Fluorescence resonance energy transfer studies allow to determine global shape properties of nucleic acids and nucleoprotein complexes. In many DNA-protein complexes, the DNA is more or less bent and the degree of bending can be obtained by FRET. For example, the DNA in complex with the integration host factor (IHF) is kinked by approximately 160 degrees building a U-shaped structure. The two DNA helix ends come close to one another in space in a distance range easily measurable by FRET. The global DNA structure of this complex can be mimicked by introducing two regions with unpaired bases ('bulges') into the DNA each producing a sharp kink of approximately 80 degrees. These U-shaped DNA constructs were used to measure the electrostatic interaction of the two nearly parallel negatively charged DNA helix arms. The electrostatic repulsion between the helix arms, and as a consequence their distance, decreases with growing salt concentration of mono- or divalent cations. This experimental approach also allows the sensitive study of the local structure of DNA sequences positioned between the two bulges.     

Selective determination of cysteine by resonance light scattering technique based on self-assembly of gold nanoparticles

The interaction between cysteine and gold nanoparticles was studied. Through the covalent combination with the -SH group and the electrostatic binding with the -NH3+ group of cysteine, gold nanoparticles can self-assemble to form a network structure, which results in greatly enhanced resonance light scattering (RLS). The experimental results demonstrate that the RLS technique offers a sensitive tool for investigations of self-assembly of nanoparticles. On the other hand, the RLS method can be applied to selectively determine cysteine with high sensitivity and simple operation. The linear range of determination of cysteine is from 0.01 to 0.25 microg/mL with the detection limit of 2.0 ng/mL (16.5 nM, 3sigma). None of the amino acids found in proteins interferes with the determination.