A carbon ink screen-printed immunoelectrode for Dengue virus NS1protein detection based on photosynthesized amine gold nanoparticles

Dengue virus (DENV) is a reemerging mosquito-borne disease that is endemic in more than 125 countries, affecting 200 million people per year. Screening testing has been a good attempt to minimize the impact caused by high morbity and mortality rates of DENV. In this study, a simple and disposable label-free electrochemical immunosensor based on a carbon ink graphite screen-printed electrode (SPE) one-step fabricated was developed for detection of non-structural 1 protein (NS1). The SPE surface was modified by drop casting, depositing a colloidal suspension containing amine-functionalized gold nanoparticles (AuNP-NH2). AuNPs were synthetized by a photoinduced physical method, illuminating preformed gold seeds with a light-emitting diode (LED,) at blue region, by using the polyethyleneimine (NH2) as reductor and stabilizing agent. UV-VIS spectroscopy and Transmission Electron Microscopy (TEM) were used to characterize the amine AuNPs. Electrocatalytic activity of AuNPs allowed more sensitivity for a label-free detection of NS1 by square wave voltammetry (SWV), with linear response from 0.1 to 2 µg mL-1. It was found a good linearity (coefficient of correlation of 0.995 (p<0.01) and a limit of detection of 0.03 µg mL-1 NS1 for analytical responses. AuNP-NH2 synthesis provided an easy oriented immobilization of anti-NS1 antibodies by Fc portion, resulting in a simple fabrication immunosensor with relative high performance and feasibility for early diagnostic of DENV.