The detection of microRNAs (miRNAs) has emerged as a new era of disease diagnosis since their discovery. The small endogenous oligos of about 22 base pairs (bp) have proven to be critical biomarkers for a variety of cancers. In this study, we present an ultrasensitive, highly specific, rapid, and affordable biosensor for detection of miRNA-122a, a biomarker for hepatocellular carcinoma, using a singled-walled carbon nanotube-based field-effect transistor functionalized with the probe RNA. Upon the incubation with the miRNA- 122a, the duplex with 22 bp length was formed and resistance change was recorded. Then the Carnation Italian ringspot virus p19 protein was used to amplify the resistance change by about 2 folds since the p19 selectively binds to 21-23 bp RNA duplexes in a size-dependent and sequence-independent manner. The biosensor demonstrated a very low 0.1 aM limit of detection with a wide dynamic range up to 1 fM. The biosensor was fabricated in a paper-based microfluidic pattern that shows potential in multiplexed detections of multiple miRNAs, and the potential for simple, rapid, and affordable diagnostic screening of cancers at point of care.

Paper-based field-effect transistor biosensor for point-of-care affordable detection of microRNAs at a sub-attomolar level for cancer diagnosis

ACS Fall 2021

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