QX200 (Bio-Rad Laboratories, Inc.) is currently the most popular digital PCR instrument. Digital PCR improves upon the sensitivity of qPCR and enables the detection of rare events such as single-nucleotide mutations in a population of wild-type sequences.
The basic principle of digital PCR is to dilute and separate the DNA molecules of a single sample into thousands of independent reaction vessels and perform conventional PCR with them. By measuring the fluorescence signal of each vessel induced by the presence of double stranded DNA and by applying a defined cut-off the positive (1) and the negative (0) ones can be counted directly. This allows among others the direct measurement of DNA copy numbers without the need of predefined standards with all their limitation as it is done in quantitative Real-Time PCR (qPCR).
In consequence, ddPCR greatly improves the discriminatory capacity of assays that may differ even just by a single nucleotide. With the QX200, the DNA molecules are packed into nanoliter-sized droplets and this allows to process several thousand independent reaction into one single tube. Up to today the scientific community has developed a constantly growing number of applications. See a selection below:
- Liquid biopsy
- Copy number variation (CNV)
- Rare sequence detection
- Single cell analysis
- Quality control in Next Generation Sequencing (NGS)
The QX200 works with both hydrolysis probes and Eva Green fluorescence detection chemistries. Up to 96 samples can be processed per run.
Find more detailed information about digital PCR and possible applications at the following websites: