Biowaste-derived gold nanoparticles on reduced graphene oxide: An innovative nanoplatform for the label-free immunosensing of dengue NS1

Background: Dengue virus (DENV) infection poses a considerable risk to human health, especially in tropical and subtropical regions where the probability of Aedes aegypti mosquito proliferation is high. To date, no effective vaccination or antiviral medicine has been available to combat dengue. Traditional detection methods are often complex, costly, time-consuming, and cumbersome. Therefore, there is a crucial need for an alternative detection method that allows for rapid and accurate identification of the DENV-specific non-structural protein 1 (NS1). The present study aims to develop biowaste-mediated gold nanoparticles on reduced graphene oxide (AuNPs/rGO) for the early detection of dengue NS1. Results: Herein, a label-free electrochemical immunosensing platform based on green-synthesized (using biowaste, i.e., Potato peel extract) AuNPs in combination with rGO was designed and used for early detection of DENV-NS1. These synthesized AuNPs/rGO provide an ideal environment for immobilizing dengue-specific anti-NS1 antibodies. The immunosensor's performance was assessed through electrochemical techniques such as differential pulse voltammetry (DPV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS). The immunosensor exhibited linearity with the concentrations of DENV-NS1 in 0.01–100 ng mL⁻¹, with the limit of detection (LOD) 1.43 ng mL⁻¹ and 2.40 ng mL⁻¹ in DPV and SWV analyses, respectively. Immunosensor shows remarkable stability and reproducibility, with low relative standard deviation (RSD) values of 3.35 % and 1.43 % for DPV and 1.21 % and 0.90 % SWV, respectively. The immunosensor exhibited selectivity for DENV-NS1 against other interfering species commonly found in blood serum (bovine serum albumin (BSA), glucose, and cysteine) with minimal non-specific binding of 9.09 %, 7.04 %, and 5.64 %, respectively, in DPV analysis. In SWV analysis, the non-specific binding was 7.31 %, 6.18 %, and 5.08 %, respectively. This indicates that immunosensors can offer reliable and accurate outcomes when assessing DENV-NS1 in blood serum samples. Significance and novelty: This immunosensing platform can be used to circumvent complex sample pretreatment processes and enable early and rapid detection of DENV-NS1. Hence, this method offers a rapid, selective, sensitive, and cost-effective alternative to conventional methods, eliminating the need for toxic chemical reagents.