Quantification of circulating microRNAs (miRNAs) or viral RNAs is of great significance because of their broad relevance to human health. Currently, quantitative reverse transcription polymerase chain reaction (qRT-PCR), as well as microarray and gene sequencing, are considered mainstream techniques for miRNA identification and quantitation and the gold standard for SARS-CoV2 detection in the COVID-19 pandemic. However, these laboratory techniques are challenged by the low levels and wide dynamic range (from aM to nM) of miRNAs in a physiological sample, as well as the difficulty in the implementation in point-of-care settings. Here, we describe a one-step label-free electrochemical sensing technique by assembling self-folded multi-stem DNA-redox probe structure on gold microelectrodes and introducing a reductant, tris(2-carboxyethyl) phosphine hydrochloride (TCEP), in the detection buffer solution to achieve ultrasensitive detection with a detection limit of 0.1 fM that can be further improved if needed.
Keywords: Electrochemical sensor; Folding-based sensor; Gold microelectrode; Label-free sensor; MiRNA detection; Non-enzymatic amplification; One-step detection.
© 2023. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.