Nanostructured Bubbles-Enhanced Fluorescence for Ultrasensitive Portable MicroRNA Detection

The unmet on-site clinical diagnostics are increasingly demanding portable bioassays, but compromised by sensitivity and throughput. Herein, a nanostructured bubbles-enhanced fluorescence (nBEF) assay is reported by interfacing with smartphone imaging system to enable portable, ultrasensitive, and specific miRNA detection in parallel. In nBEF, the high-curvature bubbles allow physically enhancing optical propagation, chemically enhancing fluorescence, assembling more DNA probes, undergoing faster self-suspension and more efficient self-aggregation fluorescence enhancement relative to their smooth counterparts. By coupling with bubble-driven signal amplification by a plug-and-play DNA concatemer, and with a smartphone imaging system, this nBEF assay achieves a portable and ultrasensitive fluorescent assay of miRNA at the femtomolar level with one-base resolution in a single test, and is capable of monitoring drug-induced miRNA dynamic expression and accurate cancer diagnosis (AUC = 1) through profiling 40 plasma samples after RNA extraction. This assay further integrates an R-value analysis in RGB module with the smartphone to realize automated, on-site miRNA readout. Such a high-performance nBEF assay provides a low-cost, portable, and highly sensitive tool to enable accurate clinical diagnosis.