Anamperometric superoxide anion radicalbiosensor based on SOD/PtPd-PDARGO modified electrode

In the present work, a high-performance enzyme-based electrochemical sensor for the detection of superoxide anion radical (O 2 ●− ) is reported. Firstly, we employed a facile approach to synthesize PtPd nanoparticles (PtPd NPs) on chemically reduced graphene oxide (RGO) coated with polydopamine (PDA). The prepared PtPd-PDARGO composite was well characterized by transmission electron microscopy , scanning electron microscopy, Fourier transform infrared spectra , X-ray diffraction, X-ray photoelectron spectroscopy and electrochemical methods. Then the assembled composite was used as a desired electrochemcial interface for superoxide dismutase (SOD) immobilization. Owing to the PDA layer as well as the synergistic effect of PtPd NPs, the fabricated SOD/PtPd-PDARGO sensor exhibited an outstanding sensitivity of 909.7   μA   mM −1   cm −2 upon O 2 ●− in a linear range from 0.016   mM to 0.24   mM ( R 2 =0.992), with a low detection limit of 2   μM (S/N=3) and excellent selectivity, good reproducibility as well as favorable long-term stability.