Theoretical Analysis Concerning the Characteristics of a Dye-binding Method for Determining Serum Protein Based on Protein Error of pH Indicator: Effect of Buffer Concentration of the Color Reagent on the Color Development

Suzuki, Y.

doi:10.2116/analsci.21.83

Cited by 14 publications

(7 citation statements)

References 12 publications

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“…The colorimetric quantification of total protein content, with human serum albumin (HSA) as a representative protein, was used to demonstrate the analytical performance of an optimized µPAD design in a simple model assay. The detection relies on the pH-sensitive indicator tetrabromophenol blue (TBPB), which upon interaction with proteins at acidic pH undergoes a color change from yellow to blue [ 21 ]. A sample matrix simulating the composition of human tear fluid was selected, since it represents a type of sample typically only available at small volumes.…”

Section: Resultsmentioning

confidence: 99%

High-Resolution Microfluidic Paper-Based Analytical Devices for Sub-Microliter Sample Analysis

et al. 2016

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This work demonstrates the fabrication of microfluidic paper-based analytical devices (µPADs) suitable for the analysis of sub-microliter sample volumes. The wax-printing approach widely used for the patterning of paper substrates has been adapted to obtain high-resolution microfluidic structures patterned in filter paper. This has been achieved by replacing the hot plate heating method conventionally used to melt printed wax features into paper by simple hot lamination. This patterning technique, in combination with the consideration of device geometry and the influence of cellulose fiber direction in filter paper, led to a model µPAD design with four microfluidic channels that can be filled with as low as 0.5 µL of liquid. Finally, the application to a colorimetric model assay targeting total protein concentrations is shown. Calibration curves for human serum albumin (HSA) were recorded from sub-microliter samples (0.8 µL), with tolerance against ±0.1 µL variations in the applied liquid volume.

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Section: Resultsmentioning

confidence: 99%

High-Resolution Microfluidic Paper-Based Analytical Devices for Sub-Microliter Sample Analysis

et al. 2016

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“…In this study, an analysis of the protein error was performed in the same manner as in previous studies, [7][8][9][10][11][12] adding one more assumption that the anions derived from the inorganic salts, which are completely dissociated, also react with protein, forming an anion-protein complex, which is a colorless substance. The following chemical equilibria are assumed to exist in the test solution:…”

Section: Analysis Concerning the Dye-binding Methodsmentioning

confidence: 99%

“…6 The effect of these factors on color development can be theoretically analyzed based on the assumption that a protein error is a reaction between a positively charged protein molecule and a dissociated dye anion. [7][8][9][10][11] The change in the color development due to the concentration of the buffer solution is caused by a reaction in which the anion composing the buffer solution binds to the protein in competition with the dissociated dye anion. In serum and urine analyzed clinically, protein and various anions are known to coexist.…”

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confidence: 99%

Characteristics of a Protein Error in Determination of Serum Protein in the Presence of Inorganic Salt

Suzuki

2006

ANAL. SCI.

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The dye-binding method, which is one of the protein determination methods, is based on a protein error of a pH indicator occurring in the presence of a protein. [1][2][3][4][5] Its color development depends on the pH and the dye, as well as the buffer solution concentrations in the color reagent. 6 The effect of these factors on color development can be theoretically analyzed based on the assumption that a protein error is a reaction between a positively charged protein molecule and a dissociated dye anion. [7][8][9][10][11] The change in the color development due to the concentration of the buffer solution is caused by a reaction in which the anion composing the buffer solution binds to the protein in competition with the dissociated dye anion. In serum and urine analyzed clinically, protein and various anions are known to coexist. From this, in determining the protein by the dye-binding method the coexisting anions may affect the color development of protein. Thus, the author theoretically analyzed the chemical characteristics of the dye binding method based on the assumption that the coexisting anions also bind reversibly to the protein like the dissociated dye anion. These calculated results were then compared with the experimental results using the three sulfonphthalein pH indicators widely employed in clinical examinations and the inorganic salts chiefly including the anions of the halogen group. Experimental ReagentsAll of the reagents were obtained from Wako Pure Chemical Industries, Ltd., Osaka Japan, and were of the best quality available.Buffer solutions: those in the pH range from 1.04 to 1.94 were prepared by mixing a 0.1 mol l -1 glycine solution containing 0.1 mol l -1 NaCl and a 0.1 mol l -1 HCl solution; those in the pH range from 2.20 to 7.80 were prepared by mixing a 0.1 mol l -1 citric acid solution and a 0.2 mol l -1 Na2HPO4 solution; those in the pH range from 8.53 to 12.90 were prepared by mixing a 0.1 mol l -1 glycine solution containing 0.1 mol l -1 NaCl and a 0.1 mol l -1 NaOH solution. The pH of the solution was adjusted using a Hitachi-Horiba M8 pH meter.Dye solutions (1 mmol l -1 ): 670 mg of bromophenol blue (BPB), 700 mg of bromocresol green (BCG) and 540 mg of bromocresol purple (BCP) were dissolved separately with 10 ml of ethanol, and then diluted to 1000 ml with distilled water.Color reagent: to 10 ml of a dye solution, 40 ml of a buffer solution was added, and then diluted to 100 ml with distilled water.A protein solution (4 g l -1 ): 400 mg of human serum albumin was dissolved in 100 ml of distilled water.An inorganic salt solution (0.5 mol l -1 ): 0.05 mol of inorganic salt was dissolved in 100 ml of distilled water. ProcedureA test solution was prepared by adding 0.5 ml of an inorganic salt solution and 4.0 ml of a color reagent to 0.5 ml of a protein solution and reacted for 10 min at 25˚C. A reagent blank was prepared by adding 0.5 ml of the inorganic salt solution and 4.0 ml of the color reagent to 0.5 ml of distilled water. Their absorbances were then recorded at 600 nm...

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“…The idea of protein analysis using dry binding is desirable because it does not require expensive reagents, i.e., antibody and antigen. 30,31 Based on this principle, the negative charges of the dry molecule can be bound with positively charged basic amino acid residues of the protein by the use of electrostatic force. Also, the hydrophobic benzene rings of the dry molecule and the hydrophobic capacity of the protein affect the conjugation degree and the reduction of the π* state energy, which henceforth affects the bathochromic shift and hyperchromic effect.…”

Section: Introductionmentioning

confidence: 99%

Distance-based β-amyloid protein detection on PADs for the scanning and subsequent follow-up of Alzheimer's disease in human urine samples

Khachornsakkul

Tiangtrong

Suwannasom

et al. 2022

Analyst

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Theoretical Analysis Concerning the Characteristics of a Dye-binding Method for Determining Serum Protein Based on Protein Error of pH Indicator: Effect of Buffer Concentration of the Color Reagent on the Color Development

Cited by 14 publications

References 12 publications

High-Resolution Microfluidic Paper-Based Analytical Devices for Sub-Microliter Sample Analysis

High-Resolution Microfluidic Paper-Based Analytical Devices for Sub-Microliter Sample Analysis

Characteristics of a Protein Error in Determination of Serum Protein in the Presence of Inorganic Salt

Distance-based β-amyloid protein detection on PADs for the scanning and subsequent follow-up of Alzheimer's disease in human urine samples

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