Methods and systems for quantitative fluorescence-based detection of molecules and proteins

A kit and method for detection of a target in a sample. An assay mixture provided in the kit and used in the method includes a first probe with a first antibody recognizing a first epitope of the target and conjugated to an RNA oligonucleotide; a second probe with a second antibody recognizing a second epitope of the target and conjugated to a DNA oligonucleotide; a reverse primer with a first region complimentary to the RNA oligonucleotide and a second region complimentary to the DNA oligonucleotide; and a reverse transcriptase that creates a DNA transcription product from the RNA oligonucleotide using the reverse primer only if the RNA oligonucleotide and the DNA oligonucleotide are in close proximity. If the target is present in the sample, the reverse primer binds the RNA oligonucleotide and the DNA oligonucleotide to bring the RNA oligonucleotide and the DNA oligonucleotide in close proximity.