Electropolymerized InZnSe@PtAg quantum dots@molecularly imprinted polymer on screen-printed carbon electrodes for the ultrasensitive detection of NS1 dengue virus protein with smartphone-based sensing in saliva

• Highly conductive InZnSe@PtAg QDs were synthesized. • InZnSe@PtAg QDs@MIP was formed via electropolymerization using CV. • Dengue virus (DENV) was detected on SPCE rapidly, ultrasensitively and selectively. • The InZnSe@PtAg QDs@MIP detected DENV in saliva using a smartphone electrochemical device. According to the World Health Organization (WHO), an estimated 100–400 million cases of dengue virus (DENV) infections are recorded annually with half of the global population being at risk of infection. Currently, there is no known treatment for DENV; however, early, rapid and accurate (sensitive and selective) detection can help to alleviate fatality rates. This work reports on the novel development of a point-of-care electrochemical biosensor for DENV using nanostructured InZnSe@PtAg quantum dots (QDs)-molecularly imprinted polymer (MIP) with smartphone-based detection functionality. Highly conductive InZnSe@PtAg QDs were newly synthesized in the presence of metal precursors, organic surfactants and ligands and surface capped with glutathione (GSH) using a ligand exchange reaction. PtAg was used as an electroactive shell layer on the InZnSe QDs core surface to increase the QDs conductivity. The GSH-InZnSe@PtAg QDs were drop-casted onto screen-printed carbon electrodes (SPCEs) and electropolymerized using cyclic voltammetry (CV) in the presence of o-phenylenediamine and the template DENV. The robust electropolymerization process allowed the overcoating of the MIP layer on the QDs/SPCE, where specific DENV size and shape cavities were created. Under optimal experimental conditions, DENV was rapidly, selectively and ultra-sensitively detected. Using differential pulse voltammetry (DPV), quantitative rebinding of DENV on the MIP@QDs/SPCE surface led to a steady decrease of the anodic peak current and a limit of detection of 1.36 pg/mL was obtained for DENV detection. Using a hand-held smartphone-based potentiostat, DENV was successfully detected in human saliva with satisfactory analytic recoveries.