Novel biomimetic enzyme for sensitive detection of superoxide anions

Superoxide anion (O₂^•-), one of the most active reactive oxygen species (ROS) in micro-environment of the human body, is involved in some diseases if there is excess O₂^•- associated with oxidative stress. Accurate detection of its concentration has important medical diagnostic significance. In this work, a new electrochemical sensor was designed and fabricated for sensitive detection based on Mn-superoxide dismutase (MnSOD) that decorated onto the surface of magnetic polymeric nanotubes by surface self-assembly processes. The composite nanotubes were characterized by transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR), Zeta potential analyzer, energy dispersive spectroscopy (EDS) and vibrating sample magnetometer(VSM), and the biosensor exhibited excellent analytical performance, for example, the interference could be eliminated with high selectivity, the linear range from 0.15 to 3.0μM with a detection limit of 0.0136μM (S/N=3)，Cyclic voltammogram (CV) curves of the biosensor for 30 overlapping cycles showed the biosensor had a good cycle stability. Results indicated that the magnetic polymeric nanotubes that decorated by Mn₃(PO₄)₂ nanoparticles could effectively catalyze the dismutation of O₂^•- that attributed to its high surface areas and a large number of active sites of self-assembled Mn₃(PO₄)₂ nanoparticles. This method combining nanotechnology and self-assembly technique provided a new appropriate platform to design and fabricate electrochemical sensor with high performance.