Methods and systems for identifying a protein within a sample are provided herein. A panel of antibodies are acquired, none of which are specific for a single protein or family of proteins. Additionally, the binding properties of the antibodies in the panel are determined. Further, the protein is iteratively exposed to a panel of antibodies. Additionally, a set of antibodies which bind the protein are determined. The identity of the protein is determined using one or more deconvolution methods based on the known binding properties of the antibodies to match the set of antibodies to a sequence of a protein.

Provided herein, in some aspects, are methods of imaging molecules without a microscope or other specialized equipment, referred to herein as “microscope-free imaging (MFI).” Herein, “molecular instruments” (e.g., DNA-based and protein-based molecules) are used, instead of microscopes, in a “bottom-up” approach for inspecting molecular targets.

Provided herein are assays that provide digital measurement methods to detect proteins and other biomolecules, e.g., at low- to mid-attomolar concentrations.

Provided herein are compositions and methods to identify a binding element (e.g., peptide, peptoid, or protein) that can be bound by an immunoreceptor (e.g., antibody). The binding element can be provided in a target binding unit comprising two binding elements separated by a spacer such that the two binding elements simultaneously bind to a single molecule comprising an antigen binding domain of an antibody. The present disclosure provides various methods to construct the spacer. The identified binding elements can be further used to manufacture an array which can be used to profile antibodies obtained from a blood sample.

The invention provides barcode libraries and methods of making and using them including obtaining a plurality of nucleic acid constructs in which each construct comprises a unique N-mer and a functional N-mer and segregating the constructs into a fluid compartments such that each compartment contains one or more copies of a unique construct. The invention further provides methods for digital PCR and for use of barcode libraries in digital PCR.

The invention relates to methods, compositions, kits, and assay systems for assay signal amplification. Also provided herein is a signal amplification reagent, wherein the signal amplification reagent is an antibody or antigen-binding fragment thereof.

The present invention is directed to improved methods for conducting immunoassays. The methods are designed to amplify signals in immunoassays and anchor immunoassay complexes employed therein.

The present invention provides assays and assay systems for use in spatially encoded biological assays. The invention provides an assay system comprising an assay capable of high levels of multiplexing where reagents are provided to a biological sample in defined spatial patterns; instrumentation capable of controlled delivery of reagents according to the spatial patterns; and a decoding scheme providing a readout that is digital in nature.

Methods of analyzing nucleic acids of a cell are provided.

The invention(s) cover a composition, where units of the composition are configured to interact with each other (e.g., as neighbors) in order enable decoding of positions of captured target material relative to neighboring units of the composition. In embodiments, the composition includes: a body; and a set of molecules coupled to the body, the set of molecules comprising a first subset and a second subset, wherein the first subset is structured for target analyte capture, and wherein the second subset is structured for interactions with one or more neighboring objects. The invention(s) also cover systems incorporating one or more units of the composition and methods implementing units of the composition.