Electroactive Manganese Oxide–Reduced Graphene Oxide Interfaced Electrochemical Detection of Urea

Abstract

Urea, being a nitrogen fertilizer, is crucial for plant growth but when excessively provided (above biuret 2% levels specified by the World Health Organization), plant characteristics are deeply affected. A real-time sensor to check the presence of excess urea in plants is therefore necessary. Towards this goal, a manganese oxide–reduced graphene oxide composite was synthesized by modified Hummer’s method and precipitation techniques, which was subsequently used as a nano-interface to immobilize urease enzyme for specific detection of urea. The synthesized nanocomposite helped in shuttling of electrons between the redox species and in enhanced electron transfer rate due to their high surface area, vindicated by their structural and morphological characterization using X-ray diffractometer (XRD), scanning electron microscope (SEM), and X-ray photoelectron spectrometer (XPS), and electrochemical characterization using cyclic voltammetry and amperometry, respectively. The fabricated biosensor for urea exhibited a linear range of 5–100 μM with a sensitivity of 9.7 × 10−3 μA μM−1, limit of detection of 14.693 μM, and a response time of 118 s.