Discrimination of extracellular miRNA sources for the identification of tumor-related functions based on nanowire thermofluidics

MicroRNAs (miRNAs) are prospective biomarkers for diagnosis and prognosis due to their specific functions. Conventional methods lack the ability to discriminate two main miRNA sources—extracellular vesicle (EV) miRNAs and EV-free miRNAs (i.e., miRNAs not contained in EVs)—in one sample. Here, we demonstrate that a nanowire (NW) thermomicrofluidic device integrated with a Peltier temperature controller can capture EVs and EV-free miRNAs and then preferentially release the EV-free miRNAs by thermal energy and extract the EV miRNAs via a lysis buffer. This leads to discrimination between EV miRNAs and EV-free miRNAs from ovarian cancer serum. Statistical analysis identified a relationship between miRNA source and tumor-related functions of the miRNAs: oncogenesis miRNAs were inside the EVs, and tumor-suppressor miRNAs were outside them. We demonstrate that the NW thermomicrofluidics provides the advantages of a simple, rapid, and effective method for miRNA extraction, accompanied by information from inside or outside the EVs.