Fig. 1

NOS-like activity of CeO₂NPs. (A) Chemical equation to show nitric oxide production by CeO₂NPs simulating NOS to catalyze L-Arg. (B) NO generation process is detected by Griess Reagents, all tests were performed in 0.01 M PBS buffer, where (i) is L-Arg alone, (ii) is Griess Reagents plus CeO₂NPs, (iii) is Griess Reagents plus CeO₂NPs and L-Arg, while (iv) shows the dynamic change process in (ii) and (iii) within 1 h. (C) NO generation process is detected by DAF-FM-DA, a fluorescent probe of NO, where (i) (ii) (iii) (iv) are similar to that in (C), but the excitation wavelength is set at 495 nm and emission wavelength of 515 nm is counted in (iv). In above tests, concentration of L-Arg is fixed at 0.29 mg/mL, the concentration of CeO₂NPs is fixed at 1mM (Ce element)