Yu et al., J Biosens Bioelectron 2012, 3:5
Biosensors & Bioelectronics
Nucleic-Acid Based Lateral Flow Strip Biosensor via Competitive Binding for Possible Dengue Detection
Henson L. Lee Yu1, Christine Marie Montesa2, Nina Rosario L. Rojas1 and Erwin P. Enriquez1* 1
Department of Chemistry, Ateneo de Manila University, Quezon City, Philippines JEOL Asia Ltd., Corporation Place, Singapore
A low-cost, simple, rapid and selective nucleic-acid based lateral flow strip biosensor (LFSB) for possible dengue viral RNA detection is described in this study. The detection is based on competitive binding, where gold nanoparticles (AuNPs), with average size of ~10 nm confirmed using UV-Vis, TEM and AFM images, are used as visualizing agents. These are bioconjugated with DNA which competitively binds with its complementary strand either in the sample or in the test line of the LFSB. The detection scheme reduces the number of probes which effectively lowers the cost for the design of the test strip. The whole test took less than five minutes to complete and a red line signifies a negative result, while the absence of the line signifies a positive result. Quantification of the intensity of the red band reveals proportionality of the color to the amount of DNA present in the sample. The visual limit of detection of the LFSB is 10-7 M. It demonstrates selectivity in a blood matrix and selectivity over a synthetic Influenza. This study brings us closer to an amplification-free, point-of-care method for dengue detection.
Keywords: Lateral flow strip biosensor; Dengue detection; Gold nanoparticles; Competitive binding assay
A lateral flow strip biosensor (LFSB) is a type of sensor in which the elements are arranged in a strip of membrane and a test sample is allowed to elute through the membrane. The interpretation of the results will vary depending on the signal transduction mechanism. LFSB’s are gaining more attention as a detection platform because they are easy-to-use, rapid, and amenable to point-of-care testing. This allows for a test that requires minimal technical expertise to interpret the results .
LFSB may be used to detect various targets including nucleic acids [2,3], proteins , bacteria [5,6] and small organic compounds [7,8], among others. Most common forms of LFSB use gold nanoparticles conjugated to the antibody of the analyte to be studied, and a secondary antibody immobilized into the test strip to give a characteristic red band if the analyte is detected. Gold nanoparticles are often used because of the ease of modification and bioconjugation to different biomolecules, and its high extinction coefficient . Depending on the antibody attached to the gold nanoparticles, the LFSB format has been used in several applications including bacterial and viral infections such as Citrus tristeza virus in plants, leptospirosis, rotavirus, hepatitis B and C virus. .
For this study, nucleic acids are used as a target and dengue is chosen to be the initial application because there has been no reported nucleic-acid based lateral flow strip biosensor for dengue, and dengue fever is rampant in the Philippines. The World Health Organization (WHO) has estimated that some 50-100 million are affected by this disease in a year and 20,000 died from the disease in its report in 2004. Dengue is one of the most widely spread mosquito-borne disease. Early diagnosis of the disease is one of the key ways to address this concern; however, this remains a challenge because of the similar symptoms at the onset of the disease. Thus, there is a need for a simple, rapid, and low cost detection for dengue. Also, for viral infections, the virus RNA appears at the onset of the disease, and this is important for early detection. Previous studies on the detection of dengue include detection via electrochemiluminescence , RNA...
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