Green synthesis of metallic nanoparticles using biopolymers and plant extracts

Abstract

Over the last few decads, the metal nanoparticles (MNPs) have been extensively studied because of their attractive optical and electronic properties related to the quantum size effect in addition to their promising applications in a wide range of fields such as optics, catalysis, nanostructures fabrication, chemical/biochemical sensing, and medicine. Therefore, the synthesis of MNPs is an expanding research area. There are two main approaches for the preparation of MNPs, top-down and bottom-up techniques. The top-down methods depend mainly on the production of isolated atoms from the bulk materials using a variety of distribution techniques. Milling or attrition, repeated quenching and photolithography are some of the approaches that are usually involved in the top-down strategies. On the other hand, the bottom-up techniques start with metal salt precursor (dissolved in a solvent) that is reduced in a chemical reaction, followed by formation of the MNPs through nucleation and growth. With the bottom-up approaches, the use of capping agents is of great importance to control the particle size, shape, and stability for the resulting NPs. Depending on the type of capping agent, the bottom-up approach could be classified into either green or non-green. Green approaches use environmentally friendly agents such as sugars and plant extracts to form and stabilize MNPs. This chapter summarizes the various green approaches for synthesis of MNPs using biopolymers, and plant extracts which qualify as a green chemistry concept and also retain their biological properties. - 2018 Scrivener Publishing LLC.