Droplet digital PCR enabled by microfluidic impact printing for absolute gene quantification.

Digital PCR enabled high-sensitivity and quantitative measurements of rare biological variants. A new digital droplet-enabled PCR technology was introduced in this paper, which partitioned genetic targets into a planar nanoliter droplet array by using a microfluidic impact printer (MIP) with a disposable microfluidic chip. The accuracy of this MIP-enabled PCR technology was verified by detecting a series of concentration gradients of GAPDH gene across spanning four orders of magnitude (from 0.464 copies/μL to 464 copies/μL). Furthermore, this technology was applied to detect the expressions of p53 gene in colon cancer tissues and adjacent nontumorous tissues, from which the copies of the nucleic acids could be absolute-quantitatively determined. The outcomes were consistent with the results of using the conventional real-time PCR, demonstrating a great potential of the MIP-enabled digital PCR in detecting gene expression in clinical samples.