Biosynthesis of mixed nanocrystalline Zn–Mg–Cu oxide nanocomposites and their antimicrobial behavior

Joghee Suresh, Lingaraj Ragunath and Sun Ig Hong

Abstract

In this work we synthesised ZnO, MgO, CuO and its composite mixed oxide nanoparticles via green process using medicinal plant Pisonia grandis R.Br. leaf extract. The synthesised ZnO, MgO, CuO nanoparticles were characterised by using x-ray powder diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) analyses. The mixed oxide nanocomposite materials were characterised by using UV–vis, Fourier-transform infrared spectroscopy (FTIR), Raman, XRD, SEM-EDX, elemental mapping, transmission electron microscopy (TEM), selected area electron diffraction (SAED) analyses. UV–vis studies confirm the absorption of mixed oxide nanocomposites. The presence of biomolecules and metal oxides was confirmed by FTIR. Furthermore, Gas chromatography–mass spectrometry (GC-MS) result also confirms the presence of phenolic biomolecule momeinositol. Structural analysis revealed that mixture of hexagonal ZnO, cubic MgO and monoclinic CuO particles were formed. Morphology of mixed oxide nanocomposites observed by SEM suggests that most oxides particles were flower shaped. TEM and EDS further confirm the presence of mixed oxide nanocomposites. The successful synthesis of mixed zinc, magnesium and copper oxides proves that, biosynthesis of the mixed oxide particles by a plant extract is an effective processing method. The fraction of MgO was found to be the highest because MgO is one of the most stable oxides. The fraction of various oxides may be controlled by modifying the fraction of initial Cu nitrate, Mg nitrate and Zn nitrate. The biosynthesised oxides show good antimicrobial activity under the laboratory condition.