Target-activated transcription for the amplified sensing of protease biomarkers

Signal amplification is an effective way to achieve sensitive analysis of biomarkers, exhibiting great promise in biomedical research and clinical diagnosis. Inspired by the transcription process, here we present a versatile strategy that enables effective amplification of proteolysis into nucleic acid signal outputs in a homogeneous system. In this strategy, a protease-activatable T7 RNA polymerase is engineered as the signal amplifier and achieves 3 orders of magnitude amplification in signal gain. The versatility of this strategy has been demonstrated by the development of sensitive and selective assays for protease biomarkers, such as matrix metalloproteinase-2 (MMP-2) and thrombin, with sub-picomole sensitivity, which is 4.3 × 10