Determination of proteins at nanogram levels based on their enhancement effects of Rayleigh light scattering on dibromomethylchlorophosphonazo

A new Rayleigh light scattering (RLS) assay of protein was conducted in this paper. At the optimum pH conditions, and in the presence of Tween-20, the weak RLS of dibromomethylchlorophosphonazo (DBM-CPA) can be enhanced greatly by the addition of proteins. Based on this, the reactions of DBM-CPA and proteins were studied. A new quantitative determination method for proteins has been developed. The method is simple, practical and relatively free from interference from coexisting substances, as well as much more sensitive (the dynamic ranges of 0.065-40.05 microg ml(-1) and detection limit of 30 ng ml(-1) for bovine serum albumin (BSA)) than most of the existing assays. The determination results of human body serum samples are identical to those by the CBB method, with relative S.D. of six determination of 0.5-2.2%.     

Microdetermination of proteins with the arsenazo-DBN-Al(III) complex by Rayleigh light-scattering technique and application of the method

The determination of proteins with arsenazo-DBN and Al3+ by Rayleigh light-scattering (RLS) is described. The weak RLS of arsenazo-DBN and BSA can be enhanced greatly by addition of Al3+ in the pH range 5.3-7.0; this resulted in two enhanced RLS signals at 420-440 nm and 460-480 nm. The reaction between arsenazo-DBN, Al3+, and proteins was studied and a new method was developed for quantitative determination of proteins. This method is very sensitive (0.34-41.71 microg mL(-1) for bovine serum albumin, BSA, and 0.29-53.41 microg mL(-1) for human serum albumin, HSA), rapid (< 2 min), simple (one step), and tolerant of most interfering substances. The effects of different surfactants were also examined. When these proteins were determined in four human serum samples the maximum relative error was not more than 2% and the recovery was between 97 and 103%.     

Determination of proteins at nanogram levels with Bordeaux red based on the enhancement of resonance light scattering

A simple, sensitive and selective method was proposed for the determination of proteins by using a resonance light scattering technique. The weak resonance light scattering (RLS) of Bordeaux red (BR) can be enhanced greatly in the pH range 3.87-3.96 by the addition of micro amounts of proteins, resulting in four characteristic peaks in the wavelength range 250-600 nm. At the maximal wavelength of 363 nm, the enhanced RLS is proportional to the concentration of proteins in the range 0.12-10.8 microg ml-1 for bovine serum albumin (BSA) and 0.24-18.0 microg ml-1 for human serum albumin (HSA). The detection limits were 40.0 and 52.9 ng ml-1 for BSA and HSA, respectively. The present method has been applied to the determination of total proteins in human serum, urine and saliva samples. The obtained results are in good agreement with those obtained by the Bradford method with relative standard deviations (R.S.D.) of 0.9-2.3%.     

Determination of proteins with tetracarboxy manganese(II) phthalocyanine by resonance light scattering technique

A novel method for the determination of proteins by using tetracarboxy manganese(II) phthalocyanine (MnC4Pc) as a resonance light scattering (RLS) probe has been developed. At pH 3.0 Britton-Robinson (B-R) buffer solution, the RLS intensity of MnC4Pc at 385 nm is greatly enhanced in the presence of proteins. The effects of pH, reaction time, concentration of MnC4Pc and interfering substances on the enhanced RLS intensity are investigated, respectively. Under optimal conditions, the linear ranges of the calibration curves are 0-2.00 microg mL(-1) for bovine serum albumin (BSA) and human serum albumin (HSA), 0.0-1.75 microg mL(-1) for human-IgG and ovalbumin, with a detection limit of 16.37 ng mL(-1) BSA, 17.62 ng mL(-1) HSA, 19.41 ng mL(-1) human-IgG and 20.72 ng mL(-1) ovalbumin. The method has been applied to the determination of total proteins in human serum samples collected from a hospital and the results are in good agreement with those reported by the hospital.     

Study of the reaction of proteins with Beryllon II-AlIII by the Rayleigh light scattering technique and its application

The determination of proteins with tetrasodium 2-(3,6-disulfo-8-hydroxynaphthylazo)-1,8-dihydroxynaphthalene-3,6-disulfonate (Beryllon II) by Rayleigh light scattering (RLS) was studied. The weak RLS of the Beryllon II-bovine serum albumin (BSA) complex can be greatly enhanced by the addition of Al3+ in the pH range 5.6-7.2; there was a maximum RLS platform at 400-420 nm. Based on the reaction between Beryllon II, Al3+ and proteins, a new method for the determination of proteins was developed. This method is very sensitive [0.20-41.42 micrograms ml-1 for BSA and 0.18-48.15 micrograms ml-1 for human serum albumen (HSA)], rapid (< 2 min), simple (one step) and tolerant towards most interfering substances. The effects of different surfactants were also examined. Four samples of protein in human serum were determined; the maximum relative error was no more than 5% and the recovery was 96-105%.     

A flow injection sampling resonance light scattering system for total protein determination in human serum

A novel flow injection method with resonance light scattering detection was developed for the determination of total protein concentrations. This method is based on the enhancement of RLS signals from Methyl Blue (MB) by protein. The enhanced RLS intensities at 333 nm, in a pH 4.1 acidic aqueous solution, were proportional to the protein concentration over the range 2.0-37.3 and 1.0-36.0 microg ml-1 for human serum albumin (HSA) and bovine serum albumin (BSA), respectively. The corresponding limits of detection (3sigma) of 45 ng ml-1 for HSA and 80 ng ml-1 for BSA were attained. The method was successfully applied to the quantification of total proteins in human serum samples, the maximum relative error is less than 1% and the recovery is between 98% and 102%. The sample throughput was 60 h-1.     

Quantitative determination of proteins at nanogram levels by the resonance light-scattering technique with macromolecules nanoparticles of PS-AA

The polystyrene-acrylic acid (PS-AA) nanoparticles have been prepared by ultrasonic polymerization, characterized by FT-IR and TEM. It is the first report on the determination of proteins with macromolecules nanoparticles of PS-AA by resonance light-scattering (RLS). At pH 6.9, the RLS of macromolecules nanoparticles of PS-AA can be enhanced by proteins. Based on this, a novel quantitative assay of proteins at the nanogram levels has been proposed. At pH 6.9, the RLS signals of PS-AA were greatly enhanced by proteins in the region of 250-700 nm characterized by the peak at 342 nm. Under optimal conditions, the linear ranges of the calibration curves were 0.02-11.0 microgml-1, 0.04-10.0 microgml-1 and 0.03-10.0 microgml-1 for gamma-globulin (gamma-IgG), bovine serum albumin (BSA) and human serum albumin (HSA), respectively. The detection limits were 16.0 ngml-1, 19.0 ngml-1, and 15.0 ngml-1 for gamma-IgG, BSA and HSA, respectively. The method has been applied to the analysis of total proteins in human serum samples collected from the hospital and the results were in good agreement with those reported by the hospital, which indicates that the method presented here is not only sensitive, simple, but also reliable and suitable for practical application.     

Determination of proteins by flow injection analysis coupled with the Rayleigh light scattering technique

A novel flow injection analysis (FIA) method with Rayleigh light scattering (RLS) detection was developed for the determination of protein concentrations. This method is based on the weak intensity of RLS of p-nitrohenzene-azo-3,6 disulfo-1-amino-8-naphthol-7-azo-benzene disodium salt (Amide Black-10B) which can be enhanced by addition of protein in weakly acidic solution. It has proved that the application of this method to quantify the proteins by using human serum albumin was available in real samples. In addition, this method is very sensitive (the determination limits are 0.11 μg/mL for human serum albumen (HSA) and 0.85 μg/mL for bovine serum albumen, BSA), simple, rapid and tolerance of most interfering substances. The FIA-RLS method was more stabile than the general RLS method and the average R.S.D. value of FIA-RLS less than general RLS. The effects of different interfering substances will be also examined. The amount of proteins in human serum sample was determined and the maximum relative error was no more than 3.00% as well as the recovery was between 94.9 and 105.9%.     

Determination of proteins at nanogram levels by a resonance light-scattering technique with tetra-substituted sulphonated aluminum phthalocyanine

This is the first report on the determination of proteins with tetra-substituted sulphonated aluminum phthalocyanine (AlS₄Pc) by resonance light-scattering (RLS). At pH 3.0, the weak RLS of AlS₄Pc can be enhanced by the addition of proteins. Based on this, a novel quantitative method has been developed for the determination of proteins in aqueous solutions. Under optimal conditions, the linear ranges of the calibration curves were 0.050–2.0 μg ml⁻¹ for both human serum albumin (HSA) and human r-IgG. The detection limits were 12.7 ng ml⁻¹ for HSA and 16.1 ng ml⁻¹ for human r-IgG. The method has been applied to the analysis of total protein in human serum samples collected from the hospital and the results were in good agreement with those reported by the hospital, which indicates that the method presented here is not only sensitive, simple, but also reliable and suitable for practical applications.     

Quantitative determination of proteins at nanogram levels by the resonance light-scattering technique with composite nanoparticles of CdS/PAA

This paper describes the development of composite nanoparticles. A novel composite nanoparticle has been prepared by an in situ polymerization method. 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. Reaction of the composite nanoparticles with proteins results in an enhanced resonance light scattering (RLS) at 380 nm. Based on this, a new resonance light-scattering (RLS) method was developed for the determination of proteins including BSA, HSA and human gamma-IgG. Under the optimum conditions, the enhanced RLS intensity is linearly proportional to the concentration of proteins. The liner range is 0.1-15 microgmL(-1) for HSA, 0.2-20 microgmL(-1) for BSA and 0.1-50.0 microgmL(-1) for human gamma-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 in good agreement with those reported by the hospital. This method proved to be very sensitive, rapid, simple and tolerant of most interfering substances.     

Determination of protein by its enhancement effect on the Rayleigh light scattering of carboxyarsenazo

This is the first report on the determination of proteins based on the interaction with carboxyarsenazo (CAA) by Rayleigh light scattering (RLS). At pH 4, the weak RLS of CAA can be enhanced greatly by the addition of proteins, resulting in three characteristic peaks. Based on this, the interactions of CAA with nine kinds of proteins were studied and a new quantitative determination method for proteins has been developed. This method is very sensitive (0.10-15.3 mug ml(-1) for bovine serum albumin (BSA)), rapid (<2 min), simple (one step), tolerant of most interfering substances, and gives a close value to that of the Coomassie brilliant blue (CBB) method in the determination of proteins in human serum. Thus, the CAA assay can be useful for routine analytical purposes and may overcome some of the limitations of other currently employed methods. Mechanism studies show that the three RLS peaks correspond to the absorption valleys of the CAA-protein complex.     

A highly sensitive and rapid assay for protein determination in human urine and penicillin using a Rayleigh light-scattering technique with benzeneazo-8-acetylamino-1-naphthol-3,6-disulfonic acid sodium salt.

A simple and sensitive method was conducted for the determination of trace amounts of proteins with benzeneazo-8-acetylamino-1-naphthol-3,6-disulfonic acid sodium salt (azophloxine, AP) using a Rayleigh light-scattering (RLS) technique. At pH 2.60 and in the presence of an emulsifier OP microemulsion, the RLS of AP can be greatly enhanced by proteins, owing to the interaction between AP and protein. The enhanced intensity is proportional to the concentration of proteins. Four proteins, including bovine serum albumin (BSA), human serum albumin (HSA), lysozyme (Lys) and gamma globulin (gamma-G) have been tested. For example, the linear range of BSA was 0 - 0.06 microg mL(-1) with detection limits of 2.38 ng mL(-1). The method was applied to the analysis of protein in human urine and penicillin samples with satisfactory results. The relative standard deviation was in all instances less than 4.0%, and the recovery was in the range of 97.5 - 104%.     

A rapid and sensitive method for the determination of trace proteins based on the interaction between proteins and Ponceau 4R

The interactions between proteins and Ponceau 4R (PR) in aqueous solution have been studied by the techniques of resonance light scattering (RLS) spectroscopy, the absorption spectroscopy, zeta potential assay and circular dichroism (CD) spectrum. The dry PR can assemble on the surface of protein via electrostatic and hydrophobic forces to produce an associated compound of protein-PR, this compound can enhance the RLS of protein. Based on this fact, a simple, rapid, and sensitive method has been developed for the determination of proteins at nanogram level by RLS technique with a common spectrofluorimeter. Under optimum conditions, the linear range is 0.10-39.2 μg mL⁻¹ for the determination of both bovine serum albumin (BSA) and human serum albumin (HSA). The detection limits (S/N = 3) are 6.96 ng mL⁻¹ for BSA and 5.71 ng mL⁻¹ for HSA, respectively. There is almost no interference from amino acids, most of the metal ions, and other coexistent substances. The method has been satisfactorily applied to the direct determination of the total protein in human serum.     

A highly sensitive assay for protein with dibromochloro-arsenazo-Al(3+) using resonance light scattering technique and its application

A simple, sensitive and selective method has been developed for the determination of protein using resonance light scattering (RLS) technique. The method is based on the interaction of protein and arsenazo-DBC-Al(3+) in the pH range of 5.0-7.0, which causes a substantial enhancement of the resonance scattering signal of arsenazo-DBC-Al(3+) in the wavelength range of 300-550 nm with the maximum RLS platform at 405-420 nm. With this method, 2.50-50.00 mug ml(-1) of bovine serum albumin (BSA) and 2.50-60.00 mug ml(-1) of human serum albumin (HSA) can be determined, and the detection limits, calculated three times the standard deviation (S.D.) of six blank measurements, for BSA and HSA were 123.4 and 89.6 ng ml(-1), respectively. Moreover, the method is free from interference from many amino acids and metal ions. The method, with high sensitivity, selectivity and reproducibility, was satisfactorily applied to the determination of total protein in human serum samples. Mechanism studies indicated that arsenazo-DBC-Al(3+) could bind to BSA depending mainly on electrostatic forces, which results in enhanced RLS in the arsenazo-DBC-Al(3+)-protein system.     

Resonance light scattering technique for the determination of protein with rutin and cetylpyridine bromide system

A new resonance light scattering (RLS) assay of protein is presented. In Tris-NaOH (pH = 10.93) buffer, the RLS of rutin-cetylpyridine bromide (CPB) system can be greatly enhanced by protein, including bovine serum albumin (BSA) and human serum albumin (HSA). The enhanced RLS intensities are in proportion to the concentration of proteins in the range of 5 x 10(-9) to 2.5 x 10(-6) g ml(-1) for BSA and 2.5 x 10(-8) to 3.5 x 10(-6) g ml(-1) for HSA. The detection limits (S/N = 3) are 3.0 ng ml(-1) for BSA and 10.0 ng ml(-1) for HSA. Samples are determined satisfactorily.     

Study of the interaction of proteins with curcumin and SDS and its analytical application

It is found that protein and sodium dodecyl sulphonate (SDS) can enhance resonance light scattering (RLS) of curcumin (CU). Based on this phenomenon, a new quantitative method for protein in aqueous solution has been developed. In the BR (pH 3.5) buffer, the RLS intensity of CU-SDS system is greatly enhanced by protein. The enhanced RLS is proportional to the concentration of protein in the range of 0.00020-20.0 microgml(-1) for bovine serum albumin (BSA) and 0.00040-1.0 microgml(-1) for human serum albumin (HSA) and their detection limits are 0.16 and 0.041 ngml(-1), respectively. An actual sample is satisfactorily determined. In addition, the interaction mechanism between protein and CU-SDS is also studied by using multi-techniques such as RLS, absorption spectroscopy and fluorescence, zeta potential assay measurement.     

Flow injection analysis: Rayleigh light scattering technique for total protein determination

A novel flow injection analysis (FIA) method with Rayleigh light scattering (RLS) detection was developed for the determination of total protein concentrations. This method is based on the weak intensity of RLS of bromothymol blue (BB) (3',3"-dibromothymolsulfonephthalein) which can be enhanced by the addition of protein in weakly acidic solution. A common spectrofluorimeter was used as a detector. It was proved that the application of this method to quantify the total proteins in real samples by using bovine serum albumin was possible. The RLS signal was detected at lambda(ex)= lambda(em)=572 nm. The linear range was 7.0-70.0 microg mL(-1), the detection limit was 3.75 microg mL(-1), the reproducibility was 5.5% (n=7), and the sample throughput was 26 h(-1).     

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。     

Determination of nucleic acids with a near infrared cyanine dye using resonance light scattering technique

A new method for the determination of nucleic acids has been developed based on the enhancement effect of resonance light scattering (RLS) with a cationic near infrared (NIR) cyanine dye. Under the optimal conditions, the enhanced RLS intensity at 823 nm is proportional to the concentration of nucleic acids in the range of 0-400 ng mL-1 for both calf thymus DNA (CT DNA) and fish sperm DNA (FS DNA), 0-600 ng mL-1 for snake ovum RNA (SO RNA). The detection limits are 3.5 ng mL-1, 3.4 ng mL-1 and 2.9 ng mL-1 for CT DNA, FS DNA and SO RNA, respectively. Owing to performing in near infrared region, this method not only has high sensitivity endowed by RLS technique but also avoids possible spectral interference from background. It has been applied to the determination of nucleic acids in synthetic and real samples and satisfactory results were obtained.     

Resonance Light Scattering Method for Microdetermination of Proteins Based on Aggregation of Au Nanoparticles

By using a resonance light scattering (RLS) technique, a highly sensitive method for protein determination based on the aggregation of Au nanoparticles on protein template is described. For the Au nanoparticles of 15 nm, the detection limit of bovine serum albumin was 5.0 ng/mL and the linear range was 10–300 ng/mL. The experimental results indicated that various metal ions do not interfere with this assay. The proposed RLS assay exhibited lower variation in response signals for the same weight of different proteins and showed satisfactory results when it was used for determination of proteins in human serum.