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Proteinuria is a condition in which an excessive amount of protein is excreted in urine. It is, among others, an indicator of kidney disease or risk of cardiovascular disease. Rapid and reliable diagnosis and monitoring of proteinuria is of great importance for both patients and their physicians. For that reason, a paper-based sensor for proteinuria diagnosis was designed, optimized, and validated utilizing smartphone-assisted signal acquisition. In the first step, a few commonly employed protein assays were optimized and compared in terms of analytical performance on paper matrix. The tetrabromophenol blue method was selected as the one providing a sufficiently low limit of detection (39 mg·L−1) on the one hand and appropriate long-term stability (up to 3 months) on the other hand. The optimized assay was employed for protein-to-creatinine ratio (PCR) determination on a single paper-based sensor. For both analytes the linear ranges were within the clinically relevant range. The analytical usefulness of the developed sensors was demonstrated by a PCR recovery study in artificial urine. The obtained PCR recoveries were from ca. 80 to 150%.

The facile detection of phosphopeptides is important for clinical screening and phosphoproteomic research. This work develops an instrument-free, cost-effective, convenient paper-based method for quantitative analysis of phosphorylated peptides. With a novel portable device, Phos-PAD, this method can achieve selective enrichment and colorimetric detection of phosphopeptides within 15 min TiO2 nanoparticle-based chemisorption and tetrabromophenol blue-based colorimetric assay were integrated into the single paper-based analytical device. The color change can indicate the presence of phosphopeptides and the mean pixel intensity of the red channel can be used for phosphopeptide quantification. With capability of quantifying phosphopeptides in serum samples, this Phos-PAD assisted phosphopeptide assay may attract significant attention to clinical analysis of endogenous serum phosphopeptides.

Tetrabromophenol blue and Bromoxylenol blue as the sensitizers of dye-sensitized solar cells (DSSCs) are measured in experiments. In order to better understand the photoelectrical properties of the two dyes, we obtain the UV-Vis spectra, fluorescence spectra, and current-voltage characteristics. The frontier molecular orbital, energy levels, the first hyperpolarizability, the first hyperpolarizability density, and molecular electrostatic potential are calculated with density functional theory (DFT) and time-dependent DFT (TDDFT). The critical factors including the light harvesting efficiency (LHE (Tetrabromophenol blue for 0.0284 and Bromoxylenol blue for 0.0290), the driving force of electron injection (ΔGinject), x-axis direction dipole moment (μnormal), the conduction band of edge of the semiconductor (ΔECB), and the excited-state lifetime (τ)) are computed, which have a close connection to the short-circuit current density (Jsc) and open-circuit voltage (Voc). The results show that the Jsc (0.09 mA/cm2) and Voc (0.39 V) of Tetrabromophenol blue have larger values, which can be explained by a larger absolute value of ΔGinject, absolute value of μnormal, τ, and ΔECB. Therefore, Tetrabromophenol blue displays well photoelectric conversion efficiency compared with Bromoxylenol blue.

We introduce a process for the fabrication of a paper-based analytical device (PAD) for multiple colorimetric analysis via paper- cutting and inkjet-printing. To create the selective flow channels, hydrophobic barriers were formed by using hydrophobic polyvinyl chloride tape-cutting and ultraviolet-curable resin printing. Multiple paper channels were isolated by the hydrophobic barriers on a single chip. An assay model was created from bovine serum albumin (BSA) and tetrabromophenol blue (TBPB) to verify the feasibility of the fabricated PAD. A multiple colorimetric analysis was demonstrated a reaction with different BSA concentrations after the TBPB regent was elaborately deposited onto the circular test spot areas by inkjet printing.

Herein we present a diagnostic paper chip that can quantitatively detect albumin without external electronic reader and dispensing apparatus. We fabricated a diagnostic paper chip device by printing wax barrier on the paper and wicking it with citrate buffer and tetrabromophenol blue to detect albumin in sample solution. The paper chip is so simple that we dropped a sample solution at sample pad and measure the ratio of two travel distances of the sample solvent and albumin under the name of retention factor. Our result confirmed that the retention factor was constant in the samples with same concentration of albumin and useful determinant for the measurement of albumin concentration. The paper chip is affordable and equipment-free, and close to ideal point-of-care test in accordance with the assured criteria, outlined by the World Health Organization. We assume that this diagnostic paper chip will expand the concept of colorimetric determination and provide a inexpensive diagnostic method to aging society and developing country.

In a qualitative test for urine protein by a test paper based on a protein error of tetrabromophenol blue, how the color development changes was examined by experiments and calculations when a pH change in the reaction mixture occurs in immersing a test paper in a urine sample whose pH may vary approximately from as low as 4.6 to as high as 7.8. In an experiment using bromophenol blue, the color development increased due to an increase in the pH of the reaction mixture, and the relative color intensity was closely associated with the magnitude of the pH change and the concentrations of the dye, buffer and protein. That is, even if the pH change by urine samples was equal, the relative color intensity differed with the concentrations of the dye, buffer and protein. It increased with an increase in the dye and buffer concentrations, and with a decrease in the protein concentration. These experimental results coincided well with those obtained by the calculation. It is important that the detection of a urine sample with a low protein concentration is carried out by using a test paper in which the dye concentration is low in order to suppress a false-positive result.

This paper concerns the acid evaporation caused by the baking treatment of chemically amplified resists. The evaporation of photo- generated acid during the post-exposure-baking (PEB) process was measured as a spectral change of indicator film that consisted of polyvinyl alcohol (PVA) and tetrabromophenol blue sodium salt (TBPB). Using this method, it was observed that the amount of evaporated acid depended on the pre-baking and PEB conditions. A high temperature pre-baking before exposure reduced the amount of evaporated acid. By contrast, a high temperature PEB accelerated the acid evaporation, and the thickness of the insoluble layer increases with increasing PEB temperature. These results suggest that acid evaporation is concerned with the formation of the insoluble layer.