Gel-based colorimetric sensors with gold nanoparticles (AuNPs) are designed as a simple kit for rapid and accurate detection of the NS1 antigen. AuNPs are synthesized by mixing HAuCl₄ and α-Cyclodextrin (α-CDs) in an optimized 1:1 (v/v) ratio, followed by surface modification using 11,1-Mercaptoundecanoic Acid (MUA), 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC), and N-hydroxysuccinimide (NHS). The modified AuNPs-EDC/NHS were formed into gel-AuNPs and produced a redwood colour. The resulting gel-AuNPs are intended for detecting the NS1 antigen, resulting in a colour change from redwood to pink, which can be analyzed visually and digitally. The visual colour change is more distinct, and the intensity of the colour increases with higher concentrations of NS1 antigen (75–250 ng mL-1) in the gel-AuNPs, and takes 10 minutes (rapid test). The gel-AuNPs sensor exhibits linear regression with R² = 0.9939 with a limit of detection (LoD) of 12.8 ng mL-1 and a limit of quantification (LoQ) of 42.8 ng mL-1. Selectivity analysis of gel-AuNPs with cholesterol, uric acid, and glucose showed no detection response, showed good selectivity for NS1 antigen. The NS1 antigen detection test in human serum revealed specific changes in the measurement signal, enabling the gel-AuNPs sensor to be applied to blood samples for dengue disease testing
Andreani et al. (2025) studied this question.