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Crystallized and spherical-shaped Au and Au-Ag alloy nanoparticles have been synthesized and stabilized using a fungus, F. semitectum in an aqueous system. Aqueous solutions of chloroaurate ions for Au and chloroaurate and Ag + ions (1 : 1 ratio) for Au-Ag alloy were treated with an extracellular filtrate of F. semitectum biomass for the formation of Au nanoparticles (AuNP) and Au-Ag alloy nanoparticles (Au-AgNP). Analysis of the feasibility of the biosynthesized nanoparticles and core-shell alloy nanoparticles from fungal strains is particularly significant. The resultant colloidal suspensions are highly stable for many weeks. The obtained Au and Au-Ag alloy nanoparticles were characterized by the surface plasmon resonance (SPR) peaks using a UV-vis spectrophotometer, and the structure, morphology and size were determined by Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), and transmission electron microscopy (TEM). Possible optoelectronics and medical applications of these nanoparticles are envisaged.

This is an extended work on the biosynthesis of noble metal nanoparticles using dried clove buds. Here microwave assistance is taken not only for accelerating the reaction rate but also for denaturing the proteins and other enzymes, which will prevent obtaining desired functionalized nanoparticles. FTIR studies infer that nanoparticles thus obtained are found adsorbed with water soluble organic moieties, mostly flavonoids. The bathochromic shift from 320 nm in ultra-violet range indicates the involvement of water soluble bio-moieties of the clove in the formation of AgNP . X-ray diffraction (XRD) spectrum confirmed that the AgNP are crystalline in nature. The surface morphology is studied using FESEM, TEM and AFM techniques infer that the AgNP are well dispersed, roughly spherical in shape and are in the range of 30–60 nm. The AgNP with the organic moiety will have synergic antimicrobial action.

Nanocrystals of maghemite (-Fe 2 O 3 ) have been prepared at the interface of organic-aqueous layer by the reaction of ferric acetylacetonate in toluene with sodium hydroxide in aqueous solution. The nanocrystals of -Fe 2 O 3 formed at the interface of the organic-aqueous layer have been con¯rmed by X-ray di®raction (XRD) pattern. The sample has been characterized morphologically by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM) techniques. Magnetic hysteresis loop and zero-¯eld cooling measurements exhibited superparamagnetism behavior for -Fe 2 O 3 nanocrystals.