QX200 droplet digital PCR system
The Bio Rad QX200 droplet digital PCR (ddPCR) system is a next generation PCR technology that generates highly uniform water-oil emulsions, effectively partitioning a conventional 20ul PCR reaction into 20 000 compartments or sub-reactions. The workflow is designed such that each of these compartments contains, at most, only a single copy of the target DNA/RNA. Thus, each compartment acts as an individual reaction chamber and amplification occurs only in compartments where a target molecule was present. Template quantification is achieved by counting the number of positive chambers (the detection of fluorescence in compartments where amplification took place) relative to the number of negative compartments. This process allows for an absolute quantification of DNA or RNA based on poison statistics, without the need for an external standard, providing a significant improvement in the precision and sensitivity of quantification when compared to real-time PCR.
Digital PCR represents a major technological advancement for amplification based detection and quantitation of low abundance target DNA or RNA. ddPCR is a powerful tool for the detection of differentially expressed transcripts; the identification of bacterial, or host, disease causing mutations present at trace levels, as well as quantification of viral nucleic material. These applications make ddPCR applicable to a wide range of research disciplines including microbiology, genetics and cancer research, virology, as well as molecular and cell biology.
The Bio Rad QX200 system will go a long way toward maintaining the status of University of Cape Town as a leader in scientific research within Africa and the world.
Report by Dr Colin Anthony
HIV Diversity Group
Department of Medical Virology
University of Cape Town