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REAL
TIME PCR WITH SMART CYCLER II (Cepheid, USA)
The GeneXpert® System utilizes real-time polymerase
chain reaction (PCR) to amplify and detect target DNA.
The system is the first to fully automate and integrate
all the steps required for PCR-based DNA testing: sample
preparation, DNA amplification and detection. Designed
to simplify hands-on preparation, the system provides
PCR test results from a raw sample in 30 minutes or
less, enabling time-critical DNA tests at the point of
need. Current techniques for accomplishing this same
series of procedures require extensive labor by skilled
technicians and can take hours to several days to
deliver results. The GeneXpert module forms the core of
the Biohazard Detection System deployed nationwide by
the United States Postal Service for anthrax testing in
mail sorting facilities. An expanded menu of tests is
currently in development.
The GeneXpert System is a 1 to 4-site, random access
instrument integrating real-time amplification and
detection features seen in the SmartCycler System, but
delivering results from unprocessed samples in less than
30 minutes. The internal module is the common technology
link between the SmartCycler and GeneXpert, performing
real-time amplification and detection. The GeneXpert
automates sample preparation, integrating the complex
steps of DNA extraction in the microfluidic cartridges.
Each GeneXpert cartridge also incorporates a syringe
drive, rotary drive and a sonic horn. The sonic horn
delivers ultrasonic energy necessary to lyse the raw
specimen and release nucleic acids contained within,
while the combination of the syringe drive and rotary
drive moves liquid between cartridge chambers in order
to wash, purify and concentrate these nucleic acids.
After the automated extraction is complete, the nucleic
acid concentrate is moved into the cartridge reaction
chamber where amplification and detection takes place.
The GeneXpert software and barcode scanner easily manage
data and display results. The GeneXpert has a small
footprint and low power requirement making it suitable
for applications requiring portability.
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