Methods, compositions, and kits for assay signal amplification

A method of detecting an analyte of interest in a sample, comprising:

• (I):
• a. contacting a first complex that comprises (A) a first detectable label, wherein the first detectable label is an electrochemiluminescent (ECL) label, and (B) the analyte of interest, with a signal amplification reagent that specifically binds to the first detectable label, wherein the signal amplification reagent comprises a nucleic acid probe, thereby forming a second complex comprising the first complex and the signal amplification reagent;
• b. extending the nucleic acid probe to form an extended sequence;
• and
• c. measuring the amount of extended sequence, thereby detecting the analyte of interest;
• or
• (II):
• d. forming a first complex on a surface comprising the analyte of interest, a capture reagent that specifically binds to the analyte, wherein the capture reagent is immobilized on the surface or wherein the capture reagent is capable of being immobilized to the surface;
• and a detection reagent that specifically binds to the analyte and that comprises a first nucleic acid probe;
• e. extending the first nucleic acid probe to form a first extended sequence comprising a first anchoring region, wherein the first anchoring region binds a first anchoring reagent that is immobilized on the surface;
• f. binding the first extended sequence to a first labeled probe comprising a first detectable label, wherein the first detectable label is an electrochemiluminescent (ECL) label;
• g. contacting the first labeled probe bound to the first extended sequence with a signal amplification reagent that specifically binds to the first detectable label, wherein the signal amplification reagent comprises a second nucleic acid probe, thereby forming a second complex comprising the signal amplification reagent and the first labeled probe;
• h. extending the second nucleic acid probe to form a second extended sequence comprising a second anchoring region, wherein the second anchoring region binds a second anchoring reagent that is immobilized on the surface;
• and;
• i. measuring the amount of (I) the second extended sequence or (II) the first extended sequence and the second extended sequence bound to the surface, thereby detecting the analyte of interest.