Since initial discovery two decades ago, MicroRNAs (miRNAs) have been found to regulate approximately 30% of the human genome. However, detection of miRNAs with high sensitivity and sequence specificity remains challenging. Here, we show a concept, exchange-induced remnant magnetization (EXIRM), for detection of label-free miRNAs with single-base specificity. A magnetically labeled RNA with single-base mismatch is first hybridized to the surface. Then the perfectly complementary target miRNA is incubated and replaces the mismatching strand. The exchange reaction will produce a decrease in the magnetic signal, which is measured by an atomic magnetometer. The detection limit of the current work is in zeptomole regime. Using two miRNAs with only one base difference in sequences, we show that EXIRM has single-base specificity in multiplexed miRNAs analysis. In addition, the detection range is well beyond five orders of magnitude. With future development in sensitivity and arrayed detection, EXIRM will be capable of precise miRNA profiling.

Ultrasensitive and sequence-specific detection of microRNAs based on exchange-induced remnant magnetization

245th National Meeting (2013)

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