POINT OF CARE
The so-called VIRASENS project was undertaken to pioneer the combination of electronics and biotechnology as part of the development of a prototype PoC diagnostic biosensor device for respiratory virus detection.
protein technology to create a device that gives highly specific responses when coming into contact with samples containing markers of the diseases concerned. SAW chips have been in commercial use for over 40 years and are widely used in the telecoms industry and in base stations where they act as bandpass filters. Now, for the first time, the combination of novel antibodies, nanoparticles and multiplexing methods enables SAW technology to be used to its full potential with biological samples. When samples, from serum, urine, saliva or blood are applied to the biochip (held in a disposable cartridge), the presence of a disease antigen causes a shift in the phase angle of the surface acoustic wave passing across the chip surface and this is translated into an electronic signal. The signal can be detected and converted into a ‘yes’ or ‘no’ signal for the presence of a disease. The new chips are designed and manufactured to allow operation in liquids with high sensivity to perform as an immunoassay device that detects the mass and viscosity changes of a biological molecule on the surface of the SAW sensor devices. This also enables the system to provide an accurate measure of the target biomarker present as well as a simple ‘yes’ or ‘no’ result. The sensor area is modified with
capture antibodies that are specific to each target marker and are held in the correct orientation to react with disease antigens. When the target marker in solution binds to the immobilised capture antibody, the binding causes a shift in the phase angle of the surface acoustic wave passing across the chip surface, producing an electronic signal. Different capture coatings can be tested immediately on a working prototype measurement unit so that robust assays can be developed. In this way, disposable SAW sensors can be inserted into an electric reader to detect multiple antigen-antibody reactions via changes in the phase/amplitude of the input/output signals. This will allow medical staff to perform rapid near-patient testing without the need for complex or cumbersome equipment. Importantly, the diagnostic device can be used at a patient’s bed side or other
PoC location, such as a GP surgery, health centre or pharmacy, with the results being available immediately and without samples being sent for laboratory analysis. This capability also enables the device to be used in the patient’s home. As well as results from the biosensor device being displayed on a
complementary App enabled, hand-held reading device, such as a mobile phone, the data can also be wirelessly transmitted to a central resource for remote connectivity to healthcare networks, records and facilities. This capability also makes the technology ideal for remote disease monitoring, with many applications for rural use or situations where clinical readings are needed without patient transfer.
PoC diagnosis of viruses 54 THE CLINICAL SERVICES JOURNAL
PoC diagnosis of respiratory viruses As part of the initial research into the development of accurate, rapid and low-cost, PoC testing for respiratory viruses, OJ Bio led a project in which a new SAW biosensor was developed and then tested in collaboration with what was then the Health Protection Agency (HPA) in Newcastle (now Public Health England). The so-called VIRASENS project was undertaken to pioneer the combination of electronics and biotechnology as part of the development of a prototype PoC diagnostic biosensor device for respiratory virus detection. Initial work was undertaken at the
APRIL 2015
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