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Kanpur- In the year 2018, Techsolver Communications & Innovative Platforms Pvt. Ltd. was founded by Prof. Shantanu Bhattacharya with a mandate of developing a connection between technology and communications domain to harvest the innovation ecosystem of the country. Prof. Shantanu Bhattacharya and his team will be productizing and scaling up innovative solutions that would be related to domains of healthcare, energy, environment, knowledge dissemination through animations and comics, cognitive initiatives, and some other industrial challenges.
Currently, the team is developing a low-cost solution for ultrasensitive detection of dengue NS1 by designing an optimized paper-based lateral flow assay. The developed assay brings together various innovative modules to observe extremely sensitive and specific detection of dengue NS1 antigen. The developed assay allows for rapid (10 min) and sensitive detection of dengue NS1 with a detection limit of 4.9 ng/mL, 11- fold improvement over the previously reported values. The clinical application of the developed assay has been demonstrated by testing it for dengue virus spiked in human serum. The reported lateral flow immunoassay shows significant promise for early and rapid detection of several target diseases.
Dengue virus, a Flaviviridae family member, has emerged as a major worldwide health concern, making its early diagnosis imperative. Presently, laboratory-based reverse-transcription polymerase chain reaction (RT-PCR) and antigen capture-enzyme linked immunosorbent assay are used for diagnosis of dengue. These techniques are highly accurate but are expensive, have a slow turnaround time, and require a sophisticated process.
In recent years, several biosensors have been developed for rapid detection of NS1, such as enzyme immunoassay, long-range surface plasmon waveguides, electrochemical lateral flow immunosensors, and colorimetric sensors. Among these, colorimetric sensors exhibit significant advantages such as simplicity, real-time naked eye detection, and no external power requirement. This has led to the development of lateral flow immunoassays based on colorimetric detection schemes, as an alternative to the conventional laboratory-based assays. These lateral flow devices have been widely employed as point-of-care screening tools for rapid detection of dengue. They are made of cellulose-based paper utilizing either chromatographic paper or nitrocellulose (NC) membrane.
Colloidal metal nanoparticles such as gold (Au) and silver (Ag) are exploited as detection labels owing to their monodispersive size, ease of functionalization with antibodies/antigens, high stability, and tunable optical properties. The easy use and low cost of these lateral flow assays make them particularly attractive for rapid and sensitive diagnostics. While the current lateral flow-based colorimetric biosensors are robust and inexpensive, various limitations such as poor sensitivity, specificity, and high limit-of-detection (LOD) are associated with these devices. One of the major reasons for the high LODs is the tendency for destabilized self-aggregation of plasmonic metal nanoparticles. As a consequence of this aggregation, the number of active binding sites for antibody immobilization decreases, leading to low sensitivity. In order to prevent this, metal nanoparticles have been anchored on specific supports.
In this work, Prof. Shantanu Bhattacharya and his team developed a simple, highly sensitive, and low-cost lateral flow immunoassay for early detection of dengue NS1 in human serum. They demonstrate for the first time introduction of a tapered NC membrane, simultaneously leveraging on the benefits of Au-rGO as a detection label. Gold nanoparticles anchored on rGO sheets have been utilized for labeling, enabling the device to exhibit high sensitivity levels. The high surface-to-volume ratio offered by the rGO sheets inhibits gold nanoparticle aggregation, increasing the number of active binding sites for immobilization of the anti-dengue antibodies.
Further, an interesting architectural approach was employed wherein a modified tapered NC membrane was used. The modification led to an increase in the concentration gradient of the antigen bound nanoparticles at the test line, thus increasing the color intensity at the test line. This substantial signal enhancement translated into achieving an extremely low detection limit of 4.9 ng/mL. The taper angle of the NC membrane has been optimized to achieve this high level of analytical sensitivity. Together, an assay exploiting the superior physical and chemical properties of Au-rGO nanocomposite along with architectural modifications yields an 11-fold increase in the device sensitivity as compared to the conventional lateral flow assays. They believe that the proposed assay can establish a significant advancement in the area of point-of-care disease diagnostics enabling sensitive and accurate detection.
Hence the reported device can be observed as an ultrasensitive detection means for the specific detection of dengue NS1 and is extremely helpful in early detection in primary dengue patients as well in case of secondary patients where sensitivity requirement is very high due to low level of an antigen in the blood.
To know more contact, Prof. Shantanu Bhattacharya, at [email protected].
