The present invention relates to the field of biochips, and provides a chip surface linker and a preparation method and a use therefor. The chip surface linker is obtained by means of applying a direct current voltage to an aromatic amine bonding molecule in the presence of an acid and a nitrite to cause a reaction with a chip surface to form a bonding molecular group connected the chip surface, and then using a functional molecular for reaction and modification to add a functional molecular group containing a hydroxyl group and an ester group. The chip surface linker obtained in the present invention is able to bond more stably with a chip surface, being stable in hot water and basic conditions, and features relatively good electrical conductivity, stability during energization, and resistance to organic solvents required for nucleic acid synthesis, and is thus very advantageous for subsequent nucleic acid synthesis and other uses.

Methods of detecting SARS-CoV-2 antibodies with improved specificity are described. The methods can include contacting a sample potentially containing SARS-CoV-2 antibodies with a reagent to remove non-anti-SARS-CoV-2 antibodies, such as a reagent comprising an epitope from a nucleocapsid protein or spike protein of a common coronavirus. The methods can include contacting the sample with a mutant SARS-CoV-2 nucleocapsid protein or spike protein comprising a reduced number of common coronavirus epitopes. The methods can involve comparing results from an immunoassay performed with a SARS-CoV-2 protein to results obtained from immunoassays performed with analogous protein from one or more common coronaviruses.

Methods, compositions and apparatus useful for individually manipulating and individually detecting analytes such as proteins. Analytes can be attached to particles to facilitate individual manipulation or detection of the particle-attached analytes. The particle-attached analytes can be composed of a single analyte attached to a single particle, such that no more than one analyte is attached per particle and no more than one particle is attached per analyte.

A microfluidic device system includes a channel having an entrance and an exit, a height at the entrance being greater than a height at the exit. The height of the channel may decrease continuously from the height at the entrance to the height at the exit. Cells or particles or beads traveling through the channel become trapped based on their size and/or deformability. A visual sensor captures images of the trapped cells or particles or beads, and image software analyzes the captured images to provide size and/or deformability and/or fluorescence information. A method of fabricating such a microfluidic device includes introducing a glass wafer to an etching solution at a specific rate such that a first end of the glass wafer is etched longer than other portions of the glass wafer.

The present invention relates to a method for determining an analyte in a sample suspected to comprise said analyte, comprising a) contacting with said sample at least a first and a second capture compound for said analyte, wherein said first and second capture compounds are nonidentical capture compounds, and wherein said capture compounds compete in binding to said analyte; b) contacting said capture compounds contacted with said sample with a specifier, wherein said specifier competes in binding to said capture compounds with said analyte; c) determining the amount of complexes comprising said specifier and a capture compound; and d) determining said analyte in a sample based on the result of step c). The present invention further relates to a method for improving the specificity of an indirect immunoassay for determining an analyte, comprising replacing at least 10% of a capture compound by a non-identical capture compound; wherein the capture compound replaced competes in binding to said analyte with the capture compound introduced. The present invention further relates to kits, devices, and uses related to the aforementioned methods.

Provided herein are immunofluorescence assays that do not use an intensely colored lipophilic dye, and that result in a significant reduction of fluorescence due to aldehyde fixation, collagen, elastin, and/or red blood cells. In certain embodiments of the present invention, a two-step treatment of the tissue is contemplated that leads to the incorporation of reduced heteropoly acids or salts thereof (e.g., phosphomolybdate species) in the tissue. This reagent binds tightly to hydrophilic regions of the tissue and effectively quenches the fluorescence in those regions. In doing so, the overall signal-to-noise ratio for the immunofluorescence assay is increased.

Provided are a kit for measuring a titer of a human antibody, a humanized antibody, or a human Fc-fusion protein in human plasma or serum, and a method for measuring a titer of a human Fc-containing protein in human plasma or serum using the same, and more specifically, a kit for measuring a titer of human Fc-containing protein in human plasma or serum, the kit including a diluent for sample, a diluent for conjugate, and a cleansing solution and being used in analysis through an indirect enzyme-linked immunosorbent assay (indirect ELISA), and a method for measuring a titer of human Fc-containing protein in human plasma or serum using the same.

The present invention relates to the use of a composition comprising (a) at least three different amino acids, (b) at least two different amino acids and a saponin or (c) at least one dipeptide or tripeptide for stabilizing biomolecules immobilized on a solid carrier. The invention furthermore relates to a method for producing stabilized biomolecules, comprising embedding the biomolecules in the composition according to the invention and a method of producing a solid carrier having biomolecules attached thereto. The invention furthermore relates to a solid carrier producible or produced by the method of the invention and a method of diagnosing a disease using the carrier of the invention.

An assay device includes: a liquid sample zone; a reagent zone downstream and in fluid communication with the sample zone that includes a reagent cell having a line of symmetry in the direction of fluid flow; a reagent material in the reagent cell, wherein the reagent material includes a first reagent material located at the axis of symmetry and is left-right symmetric, and a second and third reagent material having a substantially identical shape and volume and located in mirror locations from the line of symmetry; a detection zone in fluid communication with the reagent zone; and a wicking zone in fluid communication with the detection zone having a capacity to receive liquid sample flowing from the detection zone. The sample addition zone, the detection zone and the wicking zone define a fluid flow path.

The present invention provides methods, devices, compositions (e.g., capture complexes), and kits useful for enhancing the detection of antibodies in a test sample. The methods, devices, and compositions utilize detectable Fc-binding molecules such as Protein A, Protein G, and/or an Fc-specific antibody to amplify the signal of a detected antibody in immunoassays, such as lateral flow assays.