Ultrasensitive Immunosensor Based on Langmuir-Blodgett Deposited Ordered Graphene Assemblies for Dengue Detection

In this manuscript partially reduced graphene oxide (RGO) nanosheet-based electrodes have been utilized for quantification of the NS1 protein and subsequently for dengue detection. NS1 is the biomarker found circulating in the body of dengue-infected persons on or after first day of the appearance of disease symptoms. Graphene oxide (GO) has been synthesized using a modified Hummer's method, and its ordered nanostructured films have been electrophoretically deposited on indium tin oxide (ITO)-coated glass substrates using Langmuir-Blodgett (LB) deposition. Deposited LB films of GO have been reduced with hydrazine vapors to obtain RGO-coated ITO electrodes. NS1 antibodies have been grafted onto the ordered thin films using covalent linking, and the bioelectrodes have been utilized for the specific detection of NS1 antigen. The electrochemical performance of the fabricated bioelectrodes for NS1 antigen detection has been explored in standard and spiked sera samples. The limit of detection for the standard samples and spiked serum samples is found to be 0.069 ng mL^-1 and 0.081 ng mL^-1, respectively, with a sensitivity of 8.41 and 36.75 Ω per ng mL, respectively, in the detection range of 10¹ to 10⁷ ng mL^-1.