Ultra-sensitive detection of molecules by capture-and-release using reducing agents followed by quantification

A system for detecting analyte molecules or particles in a fluid sample, comprising:

• a first substrate comprising a plurality of capture components able to become specifically immobilized with respect to a plurality of analyte molecules or particles in the fluid sample, such that the analyte molecules or particles associate with capture components to form a plurality of complexes;
• wherein at least a portion of at least some of the complexes is susceptible to being dissociated from the first substrate by exposure to a reducing agent, to form a plurality of dissociated species;
• a second substrate configured to receive and contain dissociated species therein or thereon;
• and
• a detector configured to detect dissociated species in or on the second substrate.

A method for determining a measure of the concentration of analyte molecules or particles in a fluid sample, comprising:

• capturing a plurality of analyte molecules or particles on a substrate;
• causing at least a portion of at least some of the plurality of molecules or particles to dissociate from the substrate by exposing the plurality of molecules or particles to a reducing agent, thereby forming a plurality of dissociated species;
• detecting at least a some of the dissociated species;
• and
• determining a measure of the concentration of the analyte molecules or particles in the fluid sample based on the detection of at least some of the plurality of dissociated species.

A method for determining a measure of the concentration of analyte molecules or particles in a fluid sample, comprising:

• capturing a plurality of analyte molecules or particles on a first substrate by immobilizing the plurality of analyte molecules or particles on the first substrate;
• exposing the first substrate to a reducing agent to cause a plurality of dissociated species to be released from the substrate;
• detecting at least some of the plurality of dissociated species, wherein the number of dissociated species detected is no greater than the number of dissociated species released from the substrate in the exposing step and is also no greater than the number of analyte molecules or particles captured on the first substrate in the capturing step;
• and
• determining a measure of the concentration of the analyte molecules or particles in the fluid sample based on the detection of dissociated species.

A method of detecting analyte molecules or particles in a fluid sample, comprising:

• exposing a substrate comprising a plurality of capture components to a sample comprising a plurality of analyte molecules or particles, so that analyte molecules or particles associate with capture components to form a plurality of complexes, each complex being immobilized with respect to the substrate and comprising at least one capture component, at least one analyte molecule or particle, and at least one disulfide linkage;
• cleaving at least some of the disulfide linkages to cause at least a portion of at least some of the plurality of complexes to dissociate from the substrate to form a plurality of dissociated species, which are not immobilized with respect to the substrate;
• and
• determining the presence of and/or a measurement of the amount or concentration of the analyte molecules or particles in the fluid sample based at least in part on detecting a least some of the dissociated species.

A method of detecting analyte molecules or particles in a fluid sample, comprising:

• exposing a substrate comprising a plurality of capture components to a sample comprising a plurality of analyte molecules or particles, so that analyte molecules or particles associate with capture components to form a plurality of complexes, each complex being immobilized with respect to the substrate and comprising at least one capture component and at least one analyte molecule or particle;
• exposing the plurality of complexes to a reducing agent to cause at least a portion of at least some of the plurality of complexes to dissociate from the substrate to form a plurality of dissociated species, which are not immobilized with respect to the substrate;
• and
• detecting at least some of the plurality of the dissociated species substantially simultaneously, wherein each of the detected dissociated species are spatially separated with respect to the other detected dissociated species during detection, such that detection is able to resolve individual dissociated species of the plurality of dissociated species