Electropolymerized methylene blue on graphene oxide framework for the direct voltammetric detection of gallic acid

Abstract

Electropolymerized materials are cost efficient, sensitive and durable for sensor applications. Herein, the cationic dye, methylene blue, electropolymerized on graphene oxide framework using cyclic voltammetry and processed for voltammetric sensor platform. The surface chemistry, topology and wettability of the prepared electrode material was comprehensively studied with Raman spectroscopy, field-emission scanning electron/atomic force microscopes and contact angle measurement. The electrochemical quartz crystal microbalance analysis was done to quantify the mass adsorbed on the graphene oxide framework. Cyclic voltammetric study of the prepared methylene blue-graphene oxide framework electrode exhibits a reversible redox behavior at the electrode-electrolyte interface, following surface confined process with a coefficient determination of 0.99. Electrochemical sensing ability of the prepared electrode material was tested against the clinically important phytomedicine, gallic acid. Linear sweep voltammetric analysis enabled that methylene blue-graphene oxide framework is highly sensitive and selective toward electrooxidation of gallic acid, exerting a detection limit of 49.2 μM in the studied experimental concentration range from 50 μM to 1 mM. Real sample validation with commercial herbal tablet extracts of Euphorbia prostrata containing spiked gallic acid suggest that the prepared sensor platform could be a potential analytical probe for herbaceutical testing.