DNA-Assembled Size-Permeable Microcapsule Bioreactor Enables Direct and Rapid Sensing of Trace Circulating MicroRNA Biomarkers in Undiluted Cancer Patient Serum

Sensitive and direct detection of circulating microRNAs (miRNAs) in undiluted human serums can significantly facilitate the diagnosis of different diseases in the early stages; however, the achievement of such a goal is highly challenged by the extremely complex sample matrix nature of serums. Here, we show that sensitive and rapid detection of the circulating let-7a miRNA biomarker in undiluted cancer patient serums can be realized by a new size-permeable microcapsule bioreactor. The Cas13a/crRNA-dsDNA@polyethylene glycol core/shell biomicrocapsules are synthesized by simple encapsulation and etching steps. Such biomicrocapsules exhibit high stability, enhanced protein antifouling capability, and size-selective permeability that only allows short miRNA sequences to enter the core cavities, thereby enabling highly sensitive and direct detection of let-7a miRNA in undiluted serums down to 0.21 pM within 20 min via signal amplification by Cas13a/crRNA and near-infrared (NIR) fluorescence signals. The biomicrocapsule also allows unambiguous discrimination of the clear cell renal cell carcinoma patients from the healthy groups via direct detection of let-7a miRNA in the serum samples, thereby highlighting its robust clinical potential for early disease diagnoses.