Ultrasound-assisted rapid biological synthesis and characterization of silver nanoparticles using pomelo peel waste

The synthesis of metallic nanoparticles is an active area of academic and, more importantly, "application research" in nanotechnology. A variety of chemical and physical procedures could be used for synthesis of metallic nanoparticles. However, these methods are fraught with many problems including use of toxic solvents, generation of hazardous by-products, and high energy consumption. Accordingly, there is an essential need to develop environmentally benign procedures for synthesis of metallic nanoparticles. A promising approach to achieve this objective is to exploit the array of biological resources in nature. Indeed, over the past several years, plants, algae, fungi, bacteria, and viruses have been used for production of low-cost, energy-efficient, and nontoxic metallic nanoparticles. In this review, we provide an overview of various reports of synthesis of metallic nanoparticles by biological means. This review provides an overview of various methods of synthesis of metallic nanoparticles by biological means. Many chemical and physical procedures used for synthesis of metallic nanoparticles are fraught with major problems: toxic solvents, hazardous by-products, high energy consumption. Over the past several years, plants, algae, fungi, bacteria, and viruses have been used for production of low-cost, energy-efficient, and nontoxic metallic nanoparticles. Copyright 2010 Elsevier Inc. All rights reserved.

Development of reliable and eco-friendly process for synthesis of metallic nanoparticles is an important step in the filed of application of nanotechnology. One of the options to achieve this objective is to use natural processes such as use of biological systems. In this work we have investigated extracellular biosynthesis of silver nanoparticles using Aspergillus fumigatus. The synthesis process was quite fast and silver nanoparticles were formed within minutes of silver ion coming in contact with the cell filtrate. UV-visible spectrum of the aqueous medium containing silver ion showed a peak at 420 nm corresponding to the plasmon absorbance of silver nanoparticles. Transmission electron microscopy (TEM) micrograph showed formation of well-dispersed silver nanoparticles in the range of 5-25 nm. X-ray diffraction (XRD)-spectrum of the silver nanoparticles exhibited 2theta values corresponding to the silver nanocrystal. The process of reduction being extracellular and fast may lead to the development of an easy bioprocess for synthesis of silver nanoparticles.