Nano-technology to detect BRCA mutations
Several genetic mutations have been associated with increased risk of development of breast cancer. The most common among these mutations that increases the risk of breast cancer are called BRCA1 and BRCA2. Together BRCA1 and BRCA2 contribute to about 2.5 to 5 percent of all breast cancer in women. Identification of these two genes has markedly improved our understanding of breast cancer genetics.
OPTONANOGEN, is a prototype of the system that is currently being developed by the IST project and this will initially be used to detect mutations of the BRCA1 gene. When the work is complete the final system could be used to detect virtually any genetic anomaly as well as proteins linked to viruses, chemical contamination in food or water pollution.
"There are a broad variety of applications for this system, although the main market is in biomedicine," explains OPTONANOGEN coordinator Laura Lechuga at the National Microelectronics Centre (CNM) in Spain. "Though commercial biosensing systems exist they are larger and designed to be used in laboratories. We are the first to develop a fully integrated system on a small scale in this field."
When completed the final device will be roughly the size of a human hand, allowing it to be used in doctors' surgeries to determine the genetic predisposition of a patient to certain diseases in a matter of minutes. Currently it takes hours or even days to complete the test and is very expensive. Because of the difficulty in performing the mutation analysis, currently the genetic analysis of BRCA1 and BRCA2 are carried out only used to test high risk groups such as women with a family history of breast cancer.
To detect genetic mutations the OPTONANOGEN system uses an array of 20 microcantilevers coated in nucleic acid that react when they come into contact with a DNA sample displaying the genetic anomaly. The sample is injected into the device via a microfluidic header and the deflection of the cantilevers - by as little as 0.1 to 0.5 nanometres - is picked up by a photodetector array based on the reflection of light off the cantilevers from Vertical Cavity Surface Emission Lasers (VCSELs).
"We've patented both the microcantilever set up and the optical detection system and we are due to take out a third patent on the microfluidic header, which is unique in that it uses individual inlet and outlet paths for each cantilever rather than one for the whole array, something that has never been achieved before," Lechuga says.
The cantilever array and microfluidic header are due to be low-cost components that would be disposable if used for medical analysis but which could be cleansed and reused for other applications.
After evaluation trials later this year, a commercial variant of the system is likely to be produced within one or two years by Sensia, a 15-month-old spin-off company from the CNM.
Adjuvant: Adjuvant is a term for describing a form of treatment in which the idea is to prevent the recurrence of cancer. For example breast cancer patients who had surgery for the tumor may be offered adjuvant chemotherapy and adjuvant radiation therapy, even though there is no evidence of breast in that patient. Adjuvant therapy is aimed at decreasing the risk of cancer recurrence. See breast cancer treatment page
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