An enzyme-free hydrogen peroxide sensor for evaluation of probiotic potential of Enterococcus faecium

Abstract A novel strategy to realize a non-enzymatic hydrogen peroxide (H 2 O 2 ) sensor based on reduced graphene oxide dispersed in ionic liquid for monitoring the exogenous production of H 2 O 2 by Enterococcus faecium is presented in this work. The electrodes functionalization steps were studied by electrochemical impedance spectroscopy and cyclic voltammetry. FT-IR spectroscopy and scanning electron microscopy were used to characterize the electrode materials. The amperometric measurements on reduced graphene oxide-ionic liquid modified screen-printed electrode showed that the modified electrodes can be used to detect H 2 O 2 with a high sensitivity of 1,484 ± 25 μA mM −1  cm -2 and a low detection limit of 0.1 μM (for a signal-to-noise ratio of 3). In addition, the electrodes exhibited an excellent reproducibility and long-term stability as well as negligible interference from ascorbic acid, citric acid, urea and creatinine. The sensor was successful in monitoring the H 2 O 2 production from Enterococcus faecium 2980 clinical strain cultivated in anaerobic and aerobic conditions. The good correlation of the proposed sensor with spectrometric method indicates its very good potential in clinical and biochemical applications.