Devices and methods to perform a competitive immunoassay are disclosed. In some embodiments, the competitive immunoassay is for the detection of tacrolimus. The devices comprise a plurality of layers optionally made of cellulose-based material, wherein the plurality of layers comprises at least one read-out layer displaying a colorimetric readout of the device to indicate the result of the test to the user.

The present disclosure provides a reagent kit for detecting a sex hormone, which contains a first reagent containing a metal nanoprobe in which a sex hormone and a Raman reporter are immobilized and a second reagent containing a magnetic particle in which an antibody for detecting the sex hormone is immobilized, and a method for detecting a sex hormone using the same.

Provided herein is an antibody specifically reactive with an N-terminus neo-epitope of collagen type X alpha 1 in the amino acid sequence H.sub.2N-GIATKGLNGP, and its use in an immunoassay for evaluating a disease associated with collagen type X alpha 1, such as osteoarthritis.

This disclosure describes recombinant angiotensin-converting enzyme II (ACE2) polypeptides, fusion proteins, and compositions thereof having improved binding affinity for the SARS-CoV-2 spike protein receptor binding domain relative to wild-type ACE2. Also provided are methods of using the recombinant ACE2 polypeptides, fusion proteins, and compositions thereof for treating subjects infected with a SARS-CoV-2 virus (i.e., subjects with COVID-19), subjects having symptoms suggestive of a SARS-CoV-2 infection, and subjects exposed to or at risk of exposure to SARS-CoV-2 virus. Other virus infections may also be treated.

Disclosed is a glucose-6-phosphate dehydrogenase mutant and a use thereof in preparing a detection reagent. Compared with a wild-type glucose-6-phosphate dehydrogenase mutant, the glucose-6-phosphate dehydrogenase mutant contains a combination of the following mutations: 56C, 306C, and 454C. A detection kit prepared by using the glucose-6-phosphate dehydrogenase has strong specificity, high sensitivity, convenient operation, a short detection time, accurate quantification, and is suitable for high-throughput detection.

Protein biosensors and methods of using these sensors to detect anti-SARS-CoV-2 patient antibodies (Abs) in a solution-based, rapid, and quantitative COVID-19 serological assay are provided. In certain aspects, the sensors each comprise a first fusion protein that comprises a first SARS-CoV-2 viral protein and a first peptide fragment of a split reporter protein, and a second fusion protein that comprises a second fusion protein that comprises a second SARS-CoV-2 viral protein domain and a second peptide fragment of the split reporter protein. Only if the test sample comprise SARS-CoV- antibodies, the first and second peptide fragments associate to produce an enzymatically active reporter protein.

The present disclosure an ELISA-based assay that uses a glycosylated s1F polypeptide fragment derived from the SARS-CoV-2 spike protein (Covid-19) spike protein, the N-terminal domain of which has affinity for the tyrosine-protein kinase receptor UFO (AXL). The S1F polypeptide can be generated by expression of an encoding nucleic acid by a human cell expression system resulting in glycosylation of the expressed S1F polypeptide at least at the N343 N-glycosylation site thereof, and which surprisingly and significantly increases the affinity of the S1F for AXL, provides a significant increase in the sensitivity of the assay compared to other known assays. Further the AXL polypeptide can be glycosylated, which further increases the affinity for S1F and AXL to each other.

Systems and methods are disclosed. An example method of determining the concentration of at least one analyte in a plurality of samples by sequentially subjecting each sample to an analysis cycle includes contacting the sample or a sample-derived solution with a sensor surface supporting a species capable of specifically binding the analyte or an analyte-binding species, detecting the amount of binding to the sensor surface, and regenerating the sensor surface to prepare it for the next analytical cycle, and based on the detected binding to the sensor surface determining the concentration of analyte in each sample using virtual calibration data calculated for each analysis cycle from real calibration data obtained by contacting the solid phase with samples containing known concentrations of analyte.

An object of the present invention is to provide a kit for quantitatively determining a bile acid, in which it is possible to improve measurement accuracy by sufficiently dissociating the bile acid from a polymer component, and to rapidly carry out the quantitative determination of the bile acid with high accuracy under various environments, and a method for quantitatively determining the bile acid. According to the present invention, a kit for quantitatively determining a bile acid in a biological sample, including a compound represented by General Formula (I) defined in the present specification in a dry state; a fluorescent particle that has a first binding substance capable of binding to the bile acid; and a substrate that has a detection region having a second binding substance capable of binding to any one of the bile acid and the first binding substance, is provided.

Lateral flow assay devices, systems, and methods described herein measure concentration of a plurality of analytes of interest in a sample, and can determine the precise concentration of the plurality of analytes of interest, where one or more analytes of interest are present in the sample at high concentration and where one or more analytes of interest are present at low concentration. Precise concentration of each of the plurality of analytes can be determined when a single sample is applied to a single lateral flow assay in a single application, including when a first analyte of interest is present in the single sample at one-millionth the concentration of a second analyte of interest in the single sample.