Antioxidant and physicochemical study of Psidium guajava prepared zinc oxide nanoparticles

Abstract

This study reports preparation, characterization and in vitro antioxidant activities of zinc oxide (ZnO) nanoparticles (NPs), using 0.03:1 aqueous (aq) Psidium guajava leaf extract (LE) and aq ZnCl2 (as precursor), to cap in situ with LE antioxidant polyphenols (APP). The maximum UV/Vis absorbance at 345nm depicts APP capped ZnO (c-ZnO) NP formation. The (28.32 to 91.06) nm particle sizes (PS), (0.472 to 1.222) polydispersity indices (PDI) and (−15.91 to −22.54) mV ζ-potentials have revealed moderate to excellent LE APP capping stabilities. Scanning Electron Microscopy (SEM) analysis inferred a spherical morphology where 36.32° as major X-ray diffraction (XRD) peak depicted hexagonal wurtzite geometry having 33nm as crystalline size. The 3390, 1607, 1378, 898 and 470cm−1 stretching frequencies (SF) infer LE APP reducing and capping activities. The 77.80–81.35% ranged in vitro 2,2-Diphenyl-1-picrylhydrazyl (DPPH•) free radical scavenging activities (FRSA), have inferred biological efficacy of c-ZnO NPs. The FRSA for aq LE, ZnCl2 and c-ZnO NP have retrieved an inverse correlation with dispersion efficacy, ascertained through friccohesity (σ). The σ smartly infers optimization of functional factors of cohesive and frictional forces to channelize the required localized chemical activities. Boltzmann probability distribution and linear angular momentum predictions have inferred adequate intermolecular activities that support a kinetically stable distribution of c-ZnO NPs.