A simple new method of extracting viral RNA from blood samples allows
quick, on-the-spot identification of dengue fever in patients
Dengue fever is a disease passed
to humans by mosquitoes. Millions of people every year are infected worldwide,
and around 4,000–5,000 of these cases will suffer severe complications or
death. Dengue fever most commonly affects young people between the ages of 15
and 24.
Currently, doctors identify
dengue fever by clinical observations followed by a series of laboratory tests
of blood and urine samples. These tests can take seven to ten days to complete,
and require highly skilled staff and specialist equipment. Due to the
complexity of the process, there is also a chance of cross-contamination during
the procedure.
For these reasons, researchers
are keen to develop quicker, more accurate ways of identifying viruses such as
dengue fever. Siti Mohamed Rafei and co-workers at A*STAR’s Institute of
Microelectronics, together with scientists from Veredus Laboratories in
Singapore and the National University of Singapore, have designed and built a
new self-contained microsystem1 that can ascertain the presence of dengue fever
in blood samples within 30 minutes. Crucially, the new cartridge can be
operated by non-skilled staff.
The microsystem works by
extracting viral RNA from patients’ blood samples. Using a silicon-based viral
extraction chip, and a cartridge containing reservoirs pre-filled with the
different reagents required to extract viral RNA, the microsystem is fully
self-contained.
In conventional virus detection
systems, the chance of cross contamination is high because the extraction
process requires extensive manual pipetting of reagents. In the newly designed
system, the silicon chip is embedded in a polymeric cartridge that allows the
user to preload all necessary reagents, making it fully self-contained and
disposable. This added feature is extremely useful for testing infectious
disease that might be highly virulent or contagious.
The cartridge is placed inside a
handheld computer device with a touch screen. Pressing the start button
operates a pre-determined series of plungers, which release the reagents into
the silicon chip containing the blood sample. The reagents allow for the extraction
of viral RNA and virus identification readout within 30 minutes.
The sequence of plungers and
their speed are fully computer-controlled, thus the cartridge is configurable,
user-friendly and does not require specialist knowledge to operate. In addition,
the cartridge is adaptable to multiple biochemical protocols, not just to the
viral RNA for dengue fever as described here. In future, the researchers hope
to identify many infectious diseases with this technology.
The A*STAR-affiliated researchers
contributing to this research are from the Institute of Microelectronics
References
- Zhang, L. et al. A self-contained
disposable cartridge microsystem for dengue viral ribonucleic acid
extraction.Sensors and Actuators B: Chemical 160,
1557–1564 (2011). | article
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