Label-free microRNA detection based on exchange-induced remnant magnetization

We report a technique that is based on exchange-induced remnant magnetization for microRNA (miRNA) detection. In sequence-specific exchange reactions between label-free miRNA and magnetically labelled RNA with one mismatched base, the decrease in magnetization quantitatively represents the target miRNA. The detection limit reaches the zeptomole regime, with no amplification or washing procedures. Therefore, our technique will be suitable for precise miRNA profiling to aid in early diagnosis of cancers.