3D microdevices that perform sample purification and multiplex qRT-PCR for early cancer detection with confirmation of specific RNAs

MicroRNA expression analysis is an important screening tool for the early detection of cancer. In this study, we developed two portable three-dimensional microdevices for multiple singleplex RNA expression analysis by microRNA purification and qRT-PCR as a prototype for point-of-care testing. These microdevices are composed of several types of modules termed ‘chemical IC chips’. We successfully reduced the heating area and fluorescence observation area, reduced the energy required for the reaction, and improved the portability of all systems in the devices. The purification microdevice could purify the microRNA from the sample using the FTA elute card system. The disposable reactor module mounted on both devices was easily fabricated by deforming a 100-μm-thick polypropylene film using an uncomplicated procedure. The qRT-PCR microdevice could perform reactions for samples of small volume. We purified microRNA from the HepG2 liver cancer cell line using the purification microdevice and confirmed the expression level of miR-224, which is a potential biomarker for liver cancer. Furthermore, we observed an increase in the fluorescence intensity when we performed qRT-PCR in the qRT-PCR microdevice. Therefore, the two developed microdevices show promise as a new portable tool for early cancer detection.