Ultrasensitive quantification of extracellular vesicles through dual signal amplification for the early diagnosis and prognosis of chronic obstructive pulmonary disease (COPD)Electronic supplementary information (ESI) available. See DOI: 10.1039/d1ay01294k

Accurate quantification of low-abundant EVs plays an essential role in the diagnosis and treatment of chronic obstructive pulmonary disease (COPD). Aptamers, which can specifically recognize and bind with protein molecules through transformation, make it possible to integrate DNA polymerase-based amplification strategies for protein detection. Thus, we have designed an allosteric probe and demonstrated its feasibility to convert the detection signals of EVs (extracellular vesicles) to nucleic acids through the specific recognition of target EVs. In addition, we have integrated the Nt.BstNBI and DNA polymerase based ssDNA generation process with the Exo III recycle process and greatly improved the detection sensitivity. The presence of target EVs initiates the Nt.BstNBI triggered multiple cycle amplification, enabling the achievement of high sensitivity and excellent selectivity, holding great potential in disease diagnosis and biomedical research.