Synthesis of CeO2-NPs by chemical and biological methods and their photocatalytic, antibacterial and in vitro antioxidant activity

In the present study, biosynthesized CeO2-NPs using Solanum nigrum leaf extract were compared with chemically synthesized one. The synthesized CeO2-NPs were characterized by UV-Vis, XRD, DLS, ZP, HR-TEM, FT-IR and PL techniques. UV-visible spectrum showed absorption peak in the range of 326-355 nm. DLS studies exposed that the average size of CeO2-NPs was around 45 nm and the obtained zeta potential value of - 25.83 mV for CeO2-NPs indicated moderate stability of biosynthesized nanoparticles. HR-TEM images revealed the spherical morphology of the biosynthesized CeO2-NPs with the size of 20 nm and selected area diffraction pattern revealed the polycrystalline nature of CeO2-NPs, which was consistent with the XRD result. FT-IR analysis also confirmed the presence of metal oxide. The synthesized CeO2-NPs exhibited potential photocatalytic activity towards the degradation of methylene blue dye upon exposure to sunlight irradiation. The degradation efficiencies of Chem and biosynthesized CeO2-NPs towards methylene blue dye were 78.14 and 94.58%, respectively. In addition, antibacterial and antioxidant activity of synthesized CeO2-NPs is evaluated. The biosynthesized CeO2-NPs possess highest antibacterial activity against Gram-negative Escherichia coli (22 +/- 0.3 mm) and Gram-positive Bacillus subtilis (21 +/- 0.4 mm) at 100 mu l. The biosynthesized CeO2-NPs exhibited greater inhibition on DPPH radical IC50 mu g/ml value which was 139 +/- 45, while it was 131 +/- 21 for hydroxyl radical. The present work demonstrated an eco-friendly preparation of CeO2-NPs with good photocatalytic, antibacterial and antioxidant properties.