A catalase enzyme biosensor for hydrogen peroxide at a poly(safranine T)-ternary deep eutectic solvent and carbon nanotube modified electrode

Abstract

A new electrochemical enzyme biosensor has been developed to monitor hydrogen peroxide. The sensor uses a multiwalled carbon nanotube modified glassy carbon electrode covered by a poly(safranine T) polymer film prepared by potential cycling electropolymerization in ternary deep eutectic solvent (DES), prepared from choline chloride (ChCl), ethylene glycol (EG) plus malonic acid (MA) or lactic acid (LA) with composition optimization. It is shown that this leads to greater polymer growth and improved film properties compared to binary DES; the process was monitored by an electrochemical quartz crystal microbalance. The best ternary DES composition was found to be 16 % ChCl:MA / 84 % ChCl:EG. Electrochemical characterisation was done by cyclic voltammetry and electrochemical impedance spectroscopy, and the morphology of the synthesized polymer films was examined by scanning electron microscopy. Catalase enzyme was immobilized on the modified electrode and the enzyme biosensor used for measurement of hydrogen peroxide, with a very low detection limit of 34 nM. The selectivity was found to be excellent in relation to common interferents and the biosensor showed very good recovery in peroxide measurements in commercial samples.