Diagnosing dengue infections is a difficult task for the symptoms are nonspecific and current laboratory techniques are expensive, time-consuming and require highly skilled personnel. As such, innovative new methods of detecting the disease must be devised. One potential new method utilises long-range surface plasmon waveguides to detect the presence of dengue NS1 antigen in an infected patient. Biosensor based on this method is compact, cost-effective, label-free and capable of giving rapid readings in real-time. With careful design considerations and proper fabrication, the devices’ ability to give accurate readings will be improved.
Dengue is a tropical mosquito-borne disease affecting over half of the world’s population, with about 390 million cases annually.
Despite this, diagnosing the disease is a difficult process as the symptoms are nonspecific and current laboratory techniques are expensive, time-consuming and require highly skilled personnel.
Because of this, extensive research had been conducted over the years to find a more rapid and efficient means of detecting or diagnosing dengue infections. Unfortunately, however, none of the studies have fulfilled the requirements of an “ideal” dengue diagnostic test which should be sensitive regardless of the stage of infection.
Recent studies do suggest that the combined detection of dengue non-structural 1 (NS1) antigen and dengue-specific antibodies can improve diagnostic sensitivity. Detecting dengue NS1 is, however, much more difficult than detecting dengue-specific antibodies due to the NS1’s smaller molecular weight and its lower concentration in blood.
Dr. Wong Wei Ru of the University of Malaya studied the potential of using straight long-range surface plasmon polariton (LRSPP) waveguides – magnetic polarized optical surface waves that propagate along a thin symmetric metal slab or stripe over an applicable length (centimetres) – to detect purified dengue NS1 antigen in patient’s blood plasma, creating the first biosensor to utilize this method.
“My research focuses on the development of a rapid dengue detection technology to expedite the detection of the dengue infection in blood” Dr. Wong says with regard to her research. “Currently, my group is in the process of making both the sensor chips and the assessment modules to be very low cost and user-friendly with the support of a pre-commercialization fund by Newton-Ungku Omar Fund worth close to RM 2mil.”
The study used five clinical plasma samples for the test and compared the LRSPP method with the performance of three-commercially available anti-NS1 monoclonal antibodies to detect dengue NS1 antigen.
LRSPP’s primary advantage over other detection methods is its ease of excitation, enabling the creation of compact and miniaturized biosensors.
Based on the experiment’s findings, although the positive-to-negative ratio of results obtained using long-range surface plasmon polariton waveguides is not as high as those measured using other detection methods, the biosensor was nonetheless able to identify the presence of the dengue NS1 antigen in clinical plasma samples with high reliability and real time.
Dr. Wong says of the findings,” The results obtained are comparable to, or of greater quality, than those collected by conventional IgM antibody capture enzyme linked immunosorbent assay (MAC-ELISA) which provides label-free and real-time dengue detection in blood samples.”
The LRSPP biosensor provides a compact, cost-effective, label-free and real-time alternative to the current methods of detecting and diagnosing dengue. However, careful design considerations and better fabrication are required in order to improve the accuracy of the biosensor’s results.
Reference
Wong, W.R., Sekaran, S.D., Adikan, F.R.M., Berini, P. (2016) Detection of dengue NS1 antigen using long-range surface plasmon waveguides. Biosensors and Bioelectronics, 78 (2016), 132-139. https://doi.org/10.1016/j.bios.2015.11.030