Rapid and facile colorimetric biosensing of dengue NS1 antigen using gold nanoparticles: potential for point-of-care...

Dengue fever is one of the major global health concerns with increasing incidence and mortality. Early and accurate detection is essential to prevent severe outcomes, especially in resource-limited facilities. Here, we report a rapid, low-cost colorimetric biosensor based on gold nanoparticles (AuNPs) synthesized using ortho-hydroxybenzoic acid, yielding a red wine-coloured solution with a surface plasmon resonance peak at 524 nm. Surface modification with N-[(3-dimethylamino)propyl]-N'-ethylcarbodiimide hydrochloride/N-hydroxysuccinimide (2 : 1 ratio) enabled efficient antibody conjugation to NS1 protein monoclonal antibodies. Colorimetric detection with the NS1 antigen provided results within 30 seconds, exhibited excellent linearity (R ² = 0.982), and demonstrated limits of detection and quantification of 49.65 ng mL^-1 and 165.48 ng mL^-1, respectively. This AuNP-based biosensor offers a fast, accurate, and user-friendly platform, potential for point-of-care dengue diagnosis, with nanoparticles remaining stable for up to 28 days.