Portable graphene oxide modified immunosensor for the detection of Vitamin D3

Abstract

The prompt asserts that identifying low levels of vitamin D (hypovitaminosis D) in pregnant women and infants at an early stage is crucial due to the irreversible clinical consequences that can result. The measurement of 25-hydroxy Vitamin D3 levels can serve as a valuable indicator of the risk of developing Vitamin D deficiency. Graphene, a two-dimensional material composed of sp2 hybridized carbon atoms, is highly regarded due to its exceptional thermal, electronic, optical and mechanical properties, as well as its single-atom thickness and large surface area. In this investigation, graphene oxide (GO) were incorporated into paper electrodes, creating a cost-effective material that served as a matrix for developing an immunosensor. Using modified Hummer’s method, graphene oxide was synthesized and subsequently drop-cast onto the surface of a screen-printed paper electrode (SPPE), resulting in enhanced electrochemical signal. Thereafter, SPPE was modified with graphene oxide (GO) and further functionalized with 25-hydroxy Vitamin D3 monoclonal antibody using cross-linking chemistry of EDC:NHS. To characterize the synthesized GO, various analytical techniques were employed, including UV–Vis, FT-IR, Particle Size Analyser, Raman analysis, FE-SEM, TEM and XRD analyses. The stratified modification of the electrode surface was monitored through FT-IR and EIS techniques. Finally, the sensor response was measured after hybridization with different antigen concentrations by CV and DPV analyses. For electrochemical measurements, “K3[Fe (CN)6]3-/4- (5 mM in PBS buffer, pH 7.2)” was utilized as a redox indicator. The developed smart phone android based immunosensor showed a sensitivity of 2036.12µA/mm2/fg and LOD 5.96 fg/µL for electrochemical detection of vitamin D3.