A simple and sensitive assay of nucleic acids based on the enhanced resonance light scattering of zwitterionics

A new assay of nucleic acids at nanogram level was established based on the enhanced resonance light scattering (RLS) signals of two zwitterionics cocamidopropyl hydroxysultaine (HSB) and lauryl betaine (BS-12). Under optimum conditions, the weak RLS signal of HSB is enhanced by nucleic acids, and the enhanced RLS intensity is proportional to the concentration of nucleic acids in the range of 0.02–7.3 mg l⁻¹ for calf thymus DNA and 0.01–8.6 mg l⁻¹ for fish sperm DNA. The detection limits were 1.5 ng ml⁻¹ for calf thymus DNA and 1.9 ng ml⁻¹ for fish sperm DNA. Plasmid DNA extracted from K-12-HB101 colt was determined with satisfactory results.     

Determination of dextrin based on its self-aggregation by resonance light scattering technique

A novel free-probe assay of dextrin was established based on the resonance light scattering (RLS) enhancement in aqueous solution due to the self-aggregation of dextrin. The RLS intensity was well proportional to the concentration of dextrin over the wide range 0.2-14 μg mL⁻¹ and a detection limit 0.02 μg mL⁻¹ was obtained in the optimum conditions. The effect factors such as pH, buffer medium, holding time, ionic strength and temperature were studied in detail. Little or no interference was presented in the detection when adding coexisting substances including various metal ions and some saccharine in the solution. The assay proposed owns the advantages of easy operation, rapidity, sensitivity and practicability. Three synthetic samples and three kinds of medicine samples were analyzed with satisfactory results.     

Rapid and sensitive determination of proteins by enhanced resonance light scattering spectroscopy of sodium lauroyl glutamate

A rapid and sensitive method for the determination of proteins is proposed based on the measurements of the enhanced resonance light scattering (RLS) spectroscopy of sodium lauroyl glutamate (SLG). Under the optimum conditions, the interaction between SLG and proteins occurred rapidly, resulting in greatly enhanced RLS intensity with the maximum peak located at 394 nm. It was found that the enhanced RLS intensities were in proportion to the concentrations of proteins in the range of 0.01-3.1 μg ml⁻¹ depending on the kind of proteins. The detection limits were below 6 ng ml⁻¹. Compared with some other methods for the determination of proteins, this method shows high sensitivity, low detection limit and simplicity. This is an inexpensive, simple and fast one-step procedure which requires only measuring the RLS intensities. Human serum samples were determined with satisfactory results.     

Use of Gemini surfactant in a one-step ellagic acid assay by resonance light scattering technique

Ellagic acid (EA) reacted with Gemini zwitterionic surfactant, phosphodiesters quaternary ammonium salt (PQAS), and formed fine particles which produced strong enhancement in intensity of resonance light scattering (RLS). The effects of several factors on the RLS signal, such as pH, ionic strength, PQAS concentration and so on, were optimized. The relationship between enhanced RLS intensity and EA concentration was constructed. A novel and rapid method for the determination of EA was built. The linear range of this method was 0.016-4.0 μg mL⁻¹ and the detection limit was 13.9 ng mL⁻¹. Under the optimum conditions, the proposed method was applied to determine EA in body fluids with the results of quantitative recoveries between 98.4-101.4% in human serum samples and 99.1-102% in human urine samples. This method characterized by low limit detection is very sensitive and the cost is low, and constitutes a fast one-step procedure which requires only measuring the RLS intensities. The mechanism of the reaction was also studied. This investigation could contribute to the research on the delivery and release of bioactive molecules by Gemini surfactants.     

On the factors affecting the enhanced resonance light scattering signals of the interactions between proteins and multiply negatively charged chromophores using water blue as an example

Electrostatic interactions of proteins, including bovine serum albumin (BSA), human serum albumin (HSA), γ-globulin (γ-IgG), α-chymotrypsin (Chy), lysozyme (Lys) and cellulase (Cel), with multiply negatively charged chromophores were investigated based on the measurements of the enhanced resonance light scattering (RLS) signals. Using triply negatively charged water blue (WB) as an example, the factors were discussed that affect the enhanced resonance light scattering signals of the interactions between proteins and the negatively charged chromophores. It was found that the enhanced RLS signals with the maximum light scattering peak at 346.0 nm in these interacting systems are strongly dependent on the isoelectric points of proteins and show adverse linear relationships with increasing ionic strength depending on the positive charges of the inorganic metal ions used to control the ionic strength of the medium, sufficiently disclosing that the electrostatic attraction performs an important role in the combination of proteins with WB. Linear responses were discovered between the enhanced RLS signals and the protein molecular weights (M_w), displaying the dimensions of scattered particles formed by proteins and WB make a key contribution to the RLS enhancements. An empirical equation is proposed which possibly displays the factors affecting the enhanced RLS signals of the interactions between proteins with negatively charged chromophores.     

甲醇-水、乙醇-水体系聚集态的共振散射光谱

自从Ｐａｓｔｅｒｎａｃｋ[1,2]使用普通荧光分光光度计建立共振光散射(ＲＬＳ)技术以来,人们用该技术建立了十分灵敏的蛋白质和核酸的分析方法[3,5]。同时该技术在研究化合物在溶液中的聚集态方面也有了较为广泛的应用,一般认为分子聚集体的形成是引起ＲＬＳ增强的主要原因[6]。已知甲醇、乙醇与水互溶形成均匀的溶液体系,那么在这些溶液体系中是否也存在某种形式的分子聚集体呢?为此本文研究了不同浓度的甲醇水溶液和乙醇水溶液的ＲＬＳ光谱。1　实验部分1 1　试剂和仪器甲醇(上海建鑫化工试剂厂,分析纯,含量%≥99 5);乙醇(安徽特酒总…     

Enhanced plasmon resonance light scattering signals of colloidal gold resulted from its interactions with organic small molecules using captopril as an example

Gold nanoparticles are known for their plasmon resonance absorption (PRA) depending on their size. Our this investigation shows that plasma resonance light scattering (PRLS) signals in the corresponding PRA region could be measured using a common spectrofluorometer, and be enhanced when aggregation of gold nanoparticles occurs due to their interaction with organic small molecules (OSMs). Using captopril (Cap) as an example, we investigated the interactions of gold nanoparticles with OSMs in order to propose a general method of OSMs such as typical clinic organic drugs. In aqueous medium of pH 2.09, there are about 2.2 × 10³ Cap molecules covalently binding to the surface of a 10-nm diameter gold nanoparticle through the thiol functional group of Cap, and thus forms a core-shell assembly of [(Au)₃₁₀₀₀]@[(Cap)₂₂₀₀], displaying strong enhanced PRLS signals in the PRA region of gold colloid. The PRLS intensities characterized at 553.0 nm were found to be proportional to the concentration of Cap over the range of 0.1-1.7 mg L⁻¹ with the determination limit (3σ) of 32.0 μg L⁻¹. With that, Cap in pharmaceutical preparations could be determined with the recovery of 97.0-104.5% and R.S.D. of less than 2.4%.     

A novel histidine assay using tetraphenylporphyrin manganese (III) chloride as a molecular recognition probe by resonance light scattering technique

A novel histidine-selective method has been developed for the determination of histidine in aqueous solutions by resonance light scattering (RLS) technique. At pH 8.0, the weak RLS intensity of tetraphenylporphyrin manganese (III) chloride [MnTPPCl] was greatly enhanced by the addition of histidine with the maximum peak located at 483 nm. Under the optimum conditions, it was found that the enhanced RLS intensity was in proportion to the concentration of histidine in the range 7.8 × 10⁻⁷-2.4 × 10⁻⁵ mol l⁻¹. Low detection limit of 9.2 × 10^-8 mol l⁻¹ has been achieved. The histidine concentrations in synthetic samples and real samples were determined with satisfactory results. The sensitivity and selectivity of this method are high enough to permit the determination of trace amounts of histidine without any significant interference from high levels of other components such as common anions and especially, other amino acids.     

钙试剂-蛋白质体系的共振光散射光谱研究

基于蛋白质对钙试剂共振光散射的增强作用,拟定了一种测定蛋白质的共振光散射法。在pH 4.00的水溶液中,钙试剂在595 nm处的共振光散射增强与蛋白质浓度呈线性关系。此方法对人血清白蛋白、牛血清白蛋白的检出限分别可达0.068和0.085μg/mL。同时得到钙试剂与人血清白蛋白和牛血清白蛋白的结合常数(K)以及结合位点数(n)分别为8.15×104mol/L,0.18和7.67×104mol/L,1.5。     

Human serum albumen enhanced resonance light scattering of dyes

For the first time, the relationship between the structural parameters of dye molecule and the enhanced resonance light scattering (RLS) of dye-human serum albumen (HSA) was investigated using chemometrics technique. The data set of the enhanced RLS intensity of the dye-HSA was obtained under the same experimental conditions for 22 dyes. After calculated with HyperChem software and selected by stepwise regression approach, six structural parameters for the maximum RLS wavelength were used in multivariable linear regression (MLR) (R=0.932), seven structural parameters for the corresponding enhanced RLS intensity were employed by MLR (R=0.934). According to these models, the maximum RLS wavelength and the enhanced RLS intensity are both attributed to the spatial structure and energies of dye.     

Detection of Newcastle disease virus with quantum dots-resonance light scattering system

A sensitive QDs-based RLS assay method for the detection of Newcastle disease virus (NDV) antibody has been developed. CdTe quantum dots (QDs) were conjugated with Newcastle disease virus and used as RLS-based probes to detect NDV antibody. The electrostatic interaction between CdTe QDs and NDV resulted in enhanced resonance light scattering (RLS) signal characterized at 555 nm. Upon the addition of NDV antibody, QDs-NDV formed dispersive immunocomplex that can decrease the RLS signal. The decreased RLS intensity at 555 nm (ΔI_RLS) was linearly proportional to the concentration of NDV antibody (C_anti-NDV) in the range of 0.5-50 ng/mL, with correlation coefficient of 0.974 and detection limit of 0.1 ng/mL under the optimization conditions. The proposed method was applied to the determination of NDV antibody in spiked samples with satisfactory results.     

Determination of trace metallothioneins at nanogram levels with Eosin Y by resonance light scattering method

The interactions of metallothioneins with Eosin Y were studied by the absorption spectra and resonance light scattering (RLS) spectra methods. A direct RLS spectra method was applied for the determination of trace metallothioneins. The interaction of Eosin Y and metallothioneins enhanced the RLS intensity of system in Britton-Robinson buffer (pH 3.91), with the help of anionic surfactant (sodium dodecyl benzene sulphate). The mechanism was studied and discussed in terms of the RLS and UV-absorption spectra. Under optimal experimental conditions, at 366 nm, there was a linear relationship between the RLS intensity and the concentration of the metallothioneins in the range of 0.04–14.0 μg mL^?1, with a correlation coefficient of r = 0.9985 and detection limit of 11.9 ng mL^?1. The relative standard deviation was 3.1% (n = 11), and the average recovery was 95.2%. The method proposed was reliable, selective and sensitive in determining trace metallothioneins in human urine samples with the results in good agreement with those obtained by high-performance liquid chromatography.     

Determination of deoxyribonucleic acids by a resonance light scattering technique and its application

For the first time, acetamiprid has been used to determine nucleic acid (DNA) using the resonance light scattering (RLS). The RLS of acetamiprid was greatly enhanced by DNA in the range of pH 1.6-1.8. A RLS peak at 313 nm 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 0-11.0 microg ml(-1) with the detection limit of 20 ng ml(-1). The nucleic acids in synthetic sample and in rice seedling extraction were determined satisfactorily. The interaction mechanism of acetamiprid and DNA is discussed. Mechanism studies show that the enhanced RLS is due to the aggregation of acetamiprid in the presence of DNA.     

共振散射法测定中草药中的微量铬

研究了在H2SO4介质中,Cr(Ⅵ)与碘化物和淀粉形成离子缔合物的共振光散射增强现象,拟定了一种新的测定Cr(Ⅵ)的共振光散射方法,通过实验确定了溶液中Cr(Ⅵ)浓度与散射光强度之间的关系,在λex＝λem＝290 nm处,共振光散射最强,且共振光散射强度与Cr(Ⅵ)浓度呈线性关系,该方法简便快速,线性范围为34～400 μg/L,检出限为6.7 μg/L,可用于中草药样品中铬的测定.     

同多酸和染料探针共振光散射法测定蛋白质

在酸性条件下,铬黑T、钼酸铵与蛋白质形成聚合物,使体系的共振光散射明显增强。据此建立了利用共振光散射技术测定总蛋白含量的新方法。在最佳条件下,体系的最大散射峰位于555nm处。共振光散射增强的程度与蛋白质的浓度呈良好的线性关系。牛血清白蛋白和人血清白蛋白的线性范围分别为0.20～10.0μg/mL和0.10～8.0μg/mL,检出限为0.050μg/mL和0.039μg/mL。方法已用于人血清样品的分析,并与考马斯亮蓝的测定结果进行了比较,两者无显著性差异。     

A resonance light scattering ratiometry applied for binding study of organic small molecules with biopolymer

Resonance light scattering (RLS) technique is a creative application of light scattering signals detected by using a common spectrofluorometer, but it has drawbacks such as the fluctuation of signals caused by poorly quantified or variable factors. Herein we develop a RLS ratiometry to overcome the drawbacks of the technique and apply to measure the binding nature of organic small molecules (OSM) with biopolymer using the binding of cation porphyrins with heparin (HP) as an example. In near neutral solution, cationic porphyrins meso-tetrakis [(trimethylammoniumyl) phenyl] porphyrin (TAPP) and meso-tetra (4-methylpyridy) porphyrin (TMPyP-4) interact with heparin, resulting in hypochromatic effect, and enhanced RLS signals. Linear relationship could be established between the ratio of enhanced RLS signals at two wavelengths, where the maximum and minimum are available in the ratio curve of UV-vis spectrum of porphyrin to that of heparin-porphyrin complex, and the logarithm of heparin concentration, and thus a wide dynamic range detection method of biopolymers could be developed. In comparison with RLS method, this RLS ratiometric one is less affected by environmental conditions such as pH, ionic strength. The mechanism of these interactions was investigated based on the charge density distribution of the two porphyrin molecules and it could be concluded that the enhanced RLS intensity is proportionally promoted by the charge capacity of components in the complex. Additionally, the binding number and binding constant were measured scientifically by Scatchard plot.     

Determination of proteins with Alizarin Red S by Rayleigh light scattering technique

A new protein determination method by enhanced Rayleigh light scattering (RLS) technique has been developed. In acid condition (pH=3.60), RLS of 1,2-dihydroxyanthraquinone-3-sulfonate (Alizarin Red S) can be greatly enhanced by addition of proteins, resulting in two characteristic peaks, 360 and 505 nm, respectively. The new protein assay is based on the RLS enhancement and spectrum change. The optimum condition for the reaction was investigated. The linear range is 0.20-24.9 μg ml⁻¹ for BSA and 0.20-15.5 μg ml⁻¹ for HSA. The detection limits (S/N=3) are 9.59 ng ml⁻¹ for BSA and 9.51 ng ml⁻¹ for HSA. The results of determination for human serum samples were comparable to those obtained by Bradford method. The binding stoichiometry was determined.     

Determination of methylene blue by resonance light scattering method using silica nanoparticles as probe

A simple and novel method was developed to determine methylene blue(MB) by resonance light scattering(RLS) using silica nanoparticles(SiO_2NPs) as the probe.It was found that MB could enhance the RLS intensity of SiO_2NPs.Moreover,the increase in RLS intensity was linear with the concentration of MB over the range of 0.01-3.0 μg mL~(-1).The limit of detection(LOD) was as low as 4.36 ng mL~(-1)(3σ) and the relative standard deviation(RSD) was 2.4%(n=6).Under the optimum experimental conditions,this proposed method was successfully applied for the determination of MB in aquaculture samples with recoveries between 96.3% and 107%.Possible mechanisms for the RLS enhancement of SiO_2NPs in the presence of MB were also discussed.     

木质素桃红与蛋白质作用的共振光散射研究

研究了木质素桃红与蛋白质结合的共振光散射光谱. 实验结果表明, 在pH 2.56的酸性介质中, 木质素桃红与蛋白质发生静电作用产生以282.0、 346.0、 420.0 nm以及570.0 nm为特征峰的共振光散射（RLS）增强光谱. 在570.0 nm波长光激发下, 蛋白质的质量浓度与增强共振光散射强度ΔIRLS呈线性关系, 对BSA和HSA的检出限分别为39.0和22.3 ng/mL. 方法已用于尿样中总蛋白质分析.     

Ferric nanoparticle-based resonance light scattering determination of DNA at nanogram levels

A novel assay of DNA has been proposed by using ferric nanoparticles as probes coupled with resonance light scattering (RLS) detection. At pH 7.40, the RLS intensity of ferric nanoparticles can be greatly enhanced by the aggregation of positively charged ferric nanoparticles through electrostatic interaction with negatively charged DNA. The enhanced intensity of RLS at 452 nm is proportional to the concentration of DNA in the range of 0.01-0.8 μg ml⁻¹ for calf thymus and salmon sperm DNA and in the range of 0.005-0.3 μg ml⁻¹ for E. coli K12 genomic DNA. Detection limits are 3.6 ng ml⁻¹ for calf thymus DNA, 4.4 ng ml⁻¹ for salmon sperm DNA, and 1.9 ng ml⁻¹ for E. coli K12 genomic DNA, respectively. Compared with the chromophores previously used in RLS assay, the ferric nanoparticles have offered several advantages in easy preparation, good photostability and high sensitivity without being modified or functionalized.