N,N-dicarboxymethyl Perylene-diimide modified CeCoO3: Enhanced peroxidase activity, synergetic catalytic mechanism and glutathione colorimetric sensing

N,N-dicarboxymethyl Perylene-diimide (PDI) modified CeCoO3 nanocomposites were prepared by a two-step method. After modification with PDI molecules, the obtained PDI-CeCoO3 nanocomposites were demonstrated to possess the heightened peroxidase-like activity, compared with that of pure CeCoO3 nanoparticles. In the presence of H2O2, the heightened peroxidase-like behaviors of PDI-CeCoO3 were evaluated by the oxidation of the colorless substrate 3,3,5,5-tetramethylbenzidine (TMB) into blue oxTMB, which was detected visually only in 4 min. Importantly, a systematic study of catalytic activity of PDI-CeCoO3 by different means, including fluorescent probe, electrochemical data, diffuse reflection spectra together with free radical scavenger is executed, verifying that the catalytic activity were from O2− and electron holes (h+). And, the transfer of photogenerated carriers in the PDI-CeCoO3 was the Z-scheme heterojuntion mechanism. Furthermore, the peroxidase-like activity of PDI-CeCoO3 was significantly inhibited by Glutathione (GSH), resulting in fading of blue oxTMB. Based on this, a colorimetric assay for GSH biosensing has been developed. And, the liner range for GSH detection is from 1 to 10 μM with a detection limit of 0.658 μM. The recovery of GSH with different concentrations from 90.0% to 105.9% and the relative standard deviation (RSD) from 1.9% to 5.1%. This colorimetric sensor can be used to detect GSH in real samples.