Biomarkers from liquid biopsies (in body fluids such as blood, urine, etc.) are to-go strategies in current diagnostics and development of precision medicine as they enable a rapid, non-invasive diagnosis of disease and monitoring of treatment. The development of a novel and powerful detection assay based on exponential DNA amplification and Förster resonance energy transfer with reduced background signal is required. This will form the basis for a novel diagnostic tool with the potential for creating significant breakthroughs in the multiplexed, selective, and sensitive detection of cancer protein biomarkers from liquid biopsies. The original concept combines an exponential and low-temperature isothermal signal amplification technology with highly sensitive spectrally resolved and time-gated Förster resonance energy transfer. This approach includes optimization and modification of microplate assay that may allow ultrasensitive high-throughput multiplex screening of proteins (antibodies, antigens).