Abstract
Graphene quantum dots (GQDs) were used for surface modification of a screen-printed paper electrode (SPPE) for the development of a mobile phone-integrated immunosensor for the detection of scrub typhus. GQDs were synthesized from a 1.8% starch solution via a hydrothermal method and characterized by ultraviolet–visible (UV–Vis) spectroscopy, fluorescence, Fourier transform infrared spectroscopy and dynamic light scattering. Furthermore, anti-56 kDa type specific antigen (TSA) antibodies were used for immobilization on the GQD-modified SPPE working electrode using EDC/NHS (N-ethyl-N′-(3-(dimethylamino)propyl)carbodiimide/N-hydroxysuccinimide) (1:1) chemistry. The TSA antigen was used at different concentrations to interact with specific antibodies, and the response was recorded via cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy using potassium ferricyanide K4[Fe(CN)6]− as a redox indicator. The developed immunosensor showed an excellent sensitivity of 17.40 µA cm−2 ng−1 and a limit of detection of 0.399 ng µL−1. The developed immunohybrid sensor is a novel mobile phone-integrated, highly specific and stable platform for Orientia tsutsugamushi.
Published Version
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