Sustainable hybrid nanocomposites of Au nanoparticles modified carboxylated nanographene oxide: Electrochemical characterisation and estrone detection

This study introduces novel green and biocompatible hybrid nanocomposites formed of carboxylated nanographene oxide (c-NGO) flakes, decorated with colloidal gold nanoparticles (Au NPs) to functionalise disposable screen-printed carbon electrodes (SPCEs). These c-NGO/Au NPs nanocomposites stand out from state-of-the-art counterparts with similar composition synthesised by other solution-based methods, as our synthesis approach yields water-dispersible nanocomposites with c-NGO sheets densely coated with monodisperse NPs. As a result, the nanocomposite modified electrodes exhibit superior electroactive surface area, electrocatalytic effect, electrochemical reactivity, and electron transfer rates in the electroanalysis of common redox indicators, outperforming bare SPCEs as shown by cyclic voltammetry. Furthermore, these functionalised sensors were evaluated using a competitive immunomagnetic assay to detect estrone, a crucial estrogen in clinical diagnostics, in synthetic urine. The sensor demonstrated sensitivities comparable to those registered with commercial colorimetric ELISA kit, reaching limits of detection suitable for clinical hormone analysis.