Parallel Evaluation of Melting Temperatures of DNAs in the Arrayed Droplets through the Fluorescence from DNA Intercalators.

Parallel evaluation of melting temperatures (Tm's) of DNA molecules in multiple floating droplets (20 μm in diameter) was demonstrated. The Tm values were evaluated from the melting curves which were observed through the fluorescence from the DNA intercalators. The Tm values measured in the droplets corresponded well to those measured in the bulk, indicating the validity of the measurement. The parallel evaluation of Tm's was realized by observing melting curves of DNAs in the different droplets at the same time using the "droplet guide", which guided and fixed the floating droplets to the designated points in the observing plane. This demonstration would pave the way for the improvement of the precision of droplet digital PCR (ddPCR), whose state-of-the-art ascribes color and intensity of fluorescence to the base sequence of DNA in the droplet.