Peptide and/or protein quantitation methods, kits, and compositions, particularly useful for mass spectrometry, are provided herein based on a bathocuproine-based composition complex such as bathocuproinedisulfonic acid disodium salt hydrate complex. The methods are one-step rapid absorbance methods using small sample volumes. They produce a robust signal with high signal to background ratio and accurately quantitate even complex peptide mixtures with low variability and high sensitivity.

Provided herein is the use of measurements of cell-free DNA, protein, and/or metabolite found in biofluid (e.g., urine) for identifying and treating organ injury. Provided herein are methods and compositions for monitoring, detecting, quantifying, and treating kidney injury in subjects suffering from or suspected of having an altered renal status by measuring amounts of cfDNA and one or more other markers, such as inflammation markers, apoptosis markers, protein, and DNA methylation.

Amyloids have been known to arise from many different proteins and polypeptides. These polypeptide chains generally form β-sheet structures that aggregate into long fibers; however, identical polypeptides can fold into multiple distinct amyloid conformations. The diversity of the conformations may have led to different forms of the prion diseases. In particular, large populations of small globular amyloid oligomers (gOs) and curvilinear fibrils (CFs) precede the formation of late-stage rigid fibrils (RFs), and have been implicated in amyloid toxicity. As disclosed herein, triarylmethane f dye crystal violet is a highly selective indicator of gOs and CFs. Therefore, disclosed herein are compositions, kits, and methods for detecting amyloids in a tissue, either in vitro or in vivo.

Methods and systems for identifying capsid viral proteins in a sample containing viral vectors are provided, including determining the ratio of the capsid viral proteins of adeno-associated virus. The methods and systems comprise denaturing the capsid viral proteins in the sample, labeling the denatured capsid viral proteins with a lysine-conjugation dye, generating a separation profile of the denatured/labeled capsid viral proteins using microchip capillary electrophoresis, quantifying levels of the capsid viral proteins based on the separation profile, determining a quantification ratio of the capsid viral proteins based on the separation profile, and normalizing the quantification ratio based on lysine contents of the capsid viral proteins.

Some embodiments described herein relate to systems and methods operable to combine immunoassay and Total Protein techniques in a single sample run. Some embodiments described herein allow for multiple sequential immunoassays to be performed in the same microfluidic device. Some embodiments described herein relate to stripping reagents operable to remove primary antibodies associated with immunoassays. Such stripping reagents can allow for additional immunoassays and/or Total Protein assays to be performed on the same sample.

Some embodiments described herein relate to systems and methods operable to combine immunoassay and Total Protein techniques in a single sample run. Some embodiments described herein allow for multiple sequential immunoassays to be performed in the same microfluidic device. Some embodiments described herein relate to stripping reagents operable to remove primary antibodies associated with immunoassays. Such stripping reagents can allow for additional immunoassays and/or Total Protein assays to be performed on the same sample.

Some embodiments described herein relate to systems and methods operable to combine immunoassay and Total Protein techniques in a single sample run. Some embodiments described herein allow for multiple sequential immunoassays to be performed in the same microfluidic device. Some embodiments described herein relate to stripping reagents operable to remove primary antibodies associated with immunoassays. Such stripping reagents can allow for additional immunoassays and/or Total Protein assays to be performed on the same sample.

Some embodiments described herein relate to systems and methods operable to combine immunoassay and Total Protein techniques in a single sample run. Some embodiments described herein allow for multiple sequential immunoassays to be performed in the same microfluidic device. Some embodiments described herein relate to stripping reagents operable to remove primary antibodies associated with immunoassays. Such stripping reagents can allow for additional immunoassays and/or Total Protein assays to be performed on the same sample.

Described herein is a method for mixing unequal amounts of two reagents to produce a detectable reaction in a microfluidic chip. In one example, there is a fluorescent microfluidic urinary albumin chip (UAL-Chip) that exploits the nonimmunological fluorescent assay. In this chip, we constructed a passive and continuous mixing module, in which the loading process requires only an inexpensive dropper, and the signal is stable over time, as discussed below. We applied a pressure-balancing strategy based on the immiscible oil coverage which highly improves the precision in controlling the mixing ratio of sample and dye. The UAL-Chip has achieved an estimated limit of detection (LOD) of 8.4 μg/ml using albumin standards, which is below the 30 μg albumin per ml urine level considered to be indicative of kidney damage.

The present invention relates to the detection and quantitative measurement of proteins with the Coomassie Brilliant Blue Assay with improved sensitivity and maintaining high linearity over a broad measuring range. In particular the present invention relates to a method of detecting a protein in a protein-containing sample, comprising providing a sample comprising a protein, a reagent comprising Coomassie Brilliant Blue, combining the sample and the reagent and determining of the absorption to determine the amount of protein in the sample, wherein the pH-value of the reagent is between pH-value 0.85 and pH-value 1.1, and the ratio of the absorption value at a first wavelength of between about 580 to 620 nm to the one at a second wavelength of between about 520 to 370 nm is used in the spectral photometric determination of the amount of protein.