Flash drive for HIV diagnosis
A system of rapid diagnosis of HIV infection on a USB chip has been created
Oleg Lischuk, N+1
British scientists have developed a compact device for rapid diagnosis of HIV infection, which is connected to a standard USB connector. The report on the work is published in the journal Scientific Reports (Gurrala et al., Novel pH sensing semiconductor for point-of-care detection of HIV-1 viremia).
An image from the press release of Imperial College London HIV test performed on USB stick
Timely detection of the virus content in the blood of an HIV-infected person (viremia) is of paramount importance for determining the effectiveness of antiretroviral therapy and preventing the development of HIV drug resistance. At the same time, in regions with the highest prevalence of infection, such as Black Africa, express diagnostics is often unavailable due to the complexity of the procedure and the high cost of equipment.
To simplify and reduce the cost of the test system, the staff of Imperial College London and its spin-off company DNA Electronics have developed a device based on the technology of loop isothermal amplification of nucleic acids (LAMP). This method is much more sensitive than immunochromatographic diagnostics (it is used in some experimental mobile test systems), and, unlike PCR, does not require cyclic temperature changes.
The LAMP module polymerizes DNA based on virus RNA in a patient's blood sample. During this process, protons are released that lower the pH of the solution. This change in acidity is recorded by an integrated ion-sensitive field effect transistor (ISFET). The developers created this transistor using the complementary metal oxide semiconductor (CMOS) technology, on which most modern processors and other logic chips are based. To ensure the constant temperature required for the LAMP, heaters and thermal sensors are built into the device. Information about the presence of the virus received by ISFET is transmitted via a USB port, through which the device receives electricity without needing additional power sources.
The appearance and device of the chip (figure from the article in Scientific Reports)
The operability of the device was tested on 991 plasma samples of patients with different concentrations of different HIV strains. If there were more than 1,000 copies of viral RNA in the sample, the sensitivity was 95 percent, from 50 to 1,000 copies – 88.7 percent, and less than 50 copies – 41.2 percent. The analysis took a little more than 20 minutes. Such indicators are close to those that are necessary for mobile diagnosis of infection.
Currently, the developers are engaged in improving the device, as well as its modifications for the diagnosis of other infections.
Recently, American scientists have presented a mobile platform for rapid diagnosis of infections, which is also based on LAMP technology. It is placed in a conventional thermocup, connects to a smartphone, does not need special preparation of a biological sample, a source of electricity and qualified personnel.
The LAMP method was developed by Japanese scientists in 2000.
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11.11.2016