Nucleic Acid Recovery from Droplets

The droplets (in ddPCR) being water-in-oil emulsions means that they can disrupted and the encapsulated nucleic acid sequences recovered (for example after the PCR step). A quick and efficient way to recover partitioned and amplified nucleic acids is through the use of the liquid nitrogen method, described by Dutra et al., 2020. This method has introduced a simple, non-toxic, and cost-effective protocol utilizing liquid nitrogen to recover DNA from ddPCR emulsions in three simple steps:

1. Rapid Freezing: The ddPCR emulsion is rapidly (~1 min.) frozen using liquid nitrogen.
2. Thawing: The frozen emulsion is then thawed at room temperature, leading to the coalescence of the droplets.
3. DNA Recovery: Post-thawing, the DNA (upper aqueous phase) is recovered from the now-coalesced emulsion.

This method avoids the use of toxic solvents, such as chloroform, and is environmentally friendly. It also preserves the integrity of the DNA, making it suitable for downstream applications such as sequencing or further amplification.