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A novel citrate gel method was used to synthesize Zinc substituted Cobalt ferrite nanoparticles with chemical formula Coi_ x Zn x Fe204 where x=0, 0.2, 0.4, 0.6, 0.8 and 1). X-ray diffractions studies conformed the spinel formation of nano-ferrite structure and the particle size in the range of 17-24nm. TEM studies confirm the particles size of the nano-ferrites in nanorange. Electron diffraction patter of Coo.4Zno.6Fe204 sample indicating small Particle size of nano crystalline sample. The broad rings suggest a small particle size. The starting materials used in the preparation of cobalt-zinc nano particles are Cobalt nitrate, Zinc nitrate, Ferric nitrate and citric acid having molar ratio of 1:3 were dissolved in de-ionized water. Citric acid acts as chelating agent and helps in the homogenous distribution of metal ions. The p H of the solution is adjusted to 7 by using ammonia solution.

The cobalt‐zinc ferrite (CZF) nanomaterials were prepared by citrate‐gel method, and further calcined at 600°C. The single‐phase cubic spinel structure of CZF was confirmed using the X‐ray diffraction pattern. The average crystallite size was found to be in the range of 22‐29 nm. The surface morphology was examined using the scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The average particle size of Co0.6Zn0.4Fe2O4 was determined to be 19 nm using TEM study which is supporting the average crystallite size measured from the X‐ray diffraction studies. The Fourier‐transform infrared spectra revealed the two strong absorption bands in the series of ferrites between 4500 and 500 cm−1 and these are responsible for the characteristic of spinel ferrites. The presence of elements Cu, Zn, and Co of CZF was confirmed by the elemental spectral signals of energy dispersive spectroscopy. At room temperature, the magnetic measurements of pure ZnFe2O4 and Co0.6Zn0.4Fe2O4 were evaluated based on hysteresis curves (M‐H curves). The results expressed that the addition of nonmagnetic Zn2+ ions increases the magnetic behavior in the mixed CZF samples. The antimicrobial activity of the ZnFe2O4 and Co0.6Zn0.4Fe2O4 nanoferrites was tested against harmful microbes.

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Raju et al.: Antimicrobial Activity of Ledebouria hydrabadensis mediated Ag and Au nanoparticlesThe paper reports the comparative study, synthesis and evaluation of antimicrobial activity of silver (Ag) and gold (Au) nanoparticles. These are phytofabricated from root bulb extract of medicinal plant Ledebouria hyderabadensis using various methods such as stirring, sonication and autoclave. Synthesized Ag and Au nanoparticles characterized by multiple instrumental techniques such as the UV-Visible spectroscopy, the maximum absorption peak noted at 436 nm and 556 nm indicate the formation of metallic colloidal Ag and Au nanoparticles respectively. The Fourier transform infrared spectroscopy of Ag and Au nanoparticles indicates the phytochemicals proteins, alcohols and phenols present in the Ledebouria hyderabadensis rhizome extract involving in the reduction and stabilization by capping around the Ag and Au nanoparticles. The average particle size found to be below 50 nm in all the cases except Ag nanoparticles synthesized by the stirring method. The transmission electron microscopy images clearly indicating the nano-sized monoclinic, polyclinic, anisotropic, polydistributed, spherical shaped particles. These Ag and Au nanoparticles exhibited profound antimicrobial activity against harmful tested phytopathogenic fungi Sclerotium rolfsii, Rhizoctonia solani and human pathogenic fungi Aspergillus flavus as well as against human harmful bacteria Escherichia coli, Bacillus subtilis used in this experimentt.