Digital Microfluidics-Powered Real-Time Monitoring of Isothermal DNA Amplification of Cancer Biomarker.

We introduce a digital microfluidics (DMF) platform specifically designed to perform a loop-mediated isothermal amplification (LAMP) of DNA and applied it to a real-time amplification to monitor a cancer biomarker, (associated to 40% of all human tumors), using fluorescence microscopy. We demonstrate the full manipulation of the sample and reagents on the DMF platform, resulting in the successful amplification of 90 pg of the target DNA (0.5 ng/µL) in less than one hour. Furthermore, we test the efficiency of an innovative mixing strategy in DMF by employing two mixing methodologies onto the DMF droplets-low frequency AC (alternating current) actuation as well as back-and-forth droplet motion-which allows for improved fluorescence readouts. Fluorophore bleaching effects are minimized through on-chip sample partitioning by DMF processes and sequential droplet irradiation. Finally, LAMP reactions require only 2 µL volume droplets, which represents a 10-fold volume reduction in comparison to benchtop LAMP.