Biosynthesis of Zr-doped WO3 nanoparticles: Evaluation of antibacterial, antioxidant, and enzymatic activities

Herein, biocompatible pure tungsten oxide (WO3) and zirconium-doped tungsten oxide (Zr-doped WO3) nano- particles (NPs) were prepared via a green approach from moringa plants with different doping concentrations (3, 5, and 7 %). The as-synthesized materials were morphologically and optically characterized using scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), Fourier-transform infrared (FTIR), and ultraviolet-visible (UV-Vis) spectroscopy. The FTIR spectra clearly showed that two distinguishing bands at 603 and 674 cm-1 of WO3 were shifted to a higher wavenumber upon doping with zirconium. EDX analysis confirmed the successful synthesis of pure WO3 and Zr-doped WO3 by the green approach. The UV-Vis study exhibited that the bandgap of pure WO3 is blue-shifted upon Zr doping due to the Burstein-Moss effect. The XRD pattern revealed that the crystalline nature of WO3 is increased by increasing the Zr content. Further, the as- synthesized materials were evaluated for enzymatic, antibacterial, and antioxidant activities. The enzymatic results showed that 7 % of Zr-doped WO3 NPs have a higher activity for the alpha-amylase enzyme. Additionally, 7 % Zr-doped WO3 also showed better antioxidant activity, up to 85 % for free radical scavenging. The antibacterial performance of 7 % Zr-doped WO3 is higher as compared to other corresponding samples for different strains of bacteria. These results demonstrated that this facile and novel synthetic route will open a new door for designing an efficient nanomaterial for biomedical applications.