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June 5, 2013 by APRIL McCARTHY
Detecting Viral DNA Via Smartphones


On the spot field testing of genetic material has now become a reality with smartphones. Cornell University engineers have created a new smartphone-based system, consisting of a plug-in optical accessory and disposable chips, for in-the-field detection of viral DNA that causes a specific cancer.



The incidence of Kaposi's sarcoma (KS), a type of cancer linked to AIDS, remains prevalent in sub-Saharan Africa, where poor access to medical care and lab tests only compound the problem.

The cause of KS is the Kaposi's sarcoma-associated herpesvirus, an oncogenic herpesvirus that while routinely diagnosed in developed nations, provides challenges to developing world medical providers and point-of-care detection.

A major challenge in the diagnosis of KS is the existence of a number of other diseases with similar clinical presentation and histopathological features, requiring the detection of a biopsy sample.

"The accessory provides an ultraportable way to determine whether or not viral DNA is present in a sample," says mechanical engineer David Erickson, who developed the technique along with his graduate student, biomedical engineer Matthew Mancuso. The technique could also be adapted for use in detecting a range of other conditions, from E. coli infections to hepatitis.

The system developed here is integrated with microfluidic sample processing to create a final device capable of solving the two major challenges in point-of-care KS detection.

Mancuso will describe the work at the Conference on Lasers and Electro Optics (CLEO: 2013), taking place June 9-14 in San Jose, Calif.

"Modern biological research is also allowing an extension of laboratory devices on to small computer chips to detect biological information within DNA sequences," said biotech specialist Dr. Marek Banaszewski. "Bioinformatic algorithms within programs will aid the identification of transgenes, promoters, and other functional elements of DNA, making detection of genetically modified foods on-the-spot and real-time without transportation to a laboratory." In the not too distant future, consumers will be able to run on-the-spot tests for environmental toxins, GMOs, pesticides, food safety and more with their smartphones and other hand-held devices.

Unlike other methods that use smartphones for diagnostic testing, this new system is chemically based and does not use the phone's built-in camera. Instead, gold nanoparticles are combined (or "conjugated") with short DNA snippets that bind to Kaposi's DNA sequences, and a solution with the combined particles is added to a microfluidic chip. In the presence of viral DNA, the particles clump together, which affects the transmission of light through the solution. This causes a color change that can be measured with an optical sensor connected to a smartphone via a micro-USB port. When little or no Kaposi's virus DNA is present, the nanoparticle solution is a bright red; at higher concentrations, the solution turns a duller purple, providing a quick method to quantify the amount of Kaposi's DNA.

The main advantage of the system compared to previous Kaposi's detection methods is that users can diagnose the condition with little training. "Expert knowledge is required for almost every other means of detecting Kaposi's sarcoma," Mancuso says. "This system doesn't require that level of expertise."

Erickson and Mancuso are now collaborating with experts on Kaposi's at New York City's Weill Cornell Medical College to create a portable system for collecting, testing, and diagnosing samples that could be available for use in the developing world by next year. The team's start-up company, vitaMe Technologies, is commercializing similar smartphone diagnostic technologies for domestic use.

Detecting Kaposi's sarcoma is not the only goal, Mancuso says. "Nanoparticle assays similar to the one used in our work can target DNA from many different diseases," such as methicillin-resistant Staphylococcus aureus (MRSA), a bacterium responsible for several difficult-to-treat infections in humans, and syphilis. The smartphone reader could also work with other color-changing reactions, such as the popular enzyme-linked immunosorbent assays (ELISA), a common tool in medicine to test for HIV, hepatitis, food allergens, and E. coli. The lab also has created smartphone accessories for use with the color-changing strips in pH and urine assays. "These accessories could form the basis of a simple, at-home, personal biofluid health monitor," Mancuso says.

April McCarthy is a community journalist playing an active role reporting and analyzing world events to advance our health and eco-friendly initiatives.

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