Droplet Digital PCR (ddPCR) – QX200

Description

Bio-Rad’s QX200 Droplet Digital PCR (ddPCR) System consists of two instruments, the QX200 Droplet Generator and the QX200 Droplet Reader, plus their associated software and consumables. The QX200 Droplet Generator partitions samples (20 µl into 20,000 nanoliter-sized droplets) for PCR amplification. Following amplification using a thermal cycler, droplets from each sample are analyzed individually on the QX200 Droplet Reader, where PCR-positive and PCR-negative droplets are counted to provide absolute quantification of target DNA in digital form. ddPCR measures absolute quantities by counting nucleic acid molecules encapsulated in discrete, volumetrically defined water-in-oil droplet partitions. Sample partitioning allows the sensitive, specific detection of single template molecules as well as precise quantification. It also mitigates the effects of target competition, making PCR amplification less sensitive to inhibition and greatly improving the discriminatory capacity of assays that differ by only a single nucleotide. Digital PCR offers the benefits of absolute quantification and greatly enhanced sensitivity. Therefore, its application in the following areas is growing:

• Absolute quantification — ddPCR provides a concentration of target DNA copies per input sample without the need for running standard curves, making this technique ideal for target DNA measurements.
• Genomic alterations such as gene copy number variation (CNV) —  ddPCR enables measurement of 1.2x differences in gene copy number.
• Detection of rare sequences — researchers must amplify single genes in a complex sample, such as a few tumor cells in a wild-type background. ddPCR is sensitive enough to detect rare mutations or sequences.
• Gene expression and microRNA analysis — ddPCR provides stand-alone absolute quantification of expression levels, especially low-abundance microRNAs, with sensitivity and precision
• Next-generation sequencing (NGS) — ddPCR quantifies NGS sample library preparations to increase sequencing accuracy and reduce run repeats. Validate sequencing results such as single nucleotide polymorphisms or copy number variations with absolute quantification
• Single cell analysis — the high degree (10- to 100-fold) of cell-cell variation in gene expression and genomic content among homogeneous post-mitotic, progenitor, and stem cell populations drives a need for analysis from single cells. ddPCR enables low copy number quantification