Bioinspired Metal Nanoparticle: Synthesis, Properties and Application

Nanomaterials with a characteristic dimension in the range of 1-100 nanometers (nm) are at the leading edge of nanoscience and nanotechnology. In recent years nanomaterials, and specifically metal nanoparticles, have received particular interest in diverse field ranging from material science to biotechnology (Guo et al. 2005, Daniel and Astruc 2004, Huang et al. 2007). Although widespread interest in nanomaterials is recent, the concept was introduced over 40 years ago. Nanomaterials have actually been produced and used by humans for hundreds of years: for example, the beautiful ruby red colour of some glass is due to gold nanoparticles (AuNP) trapped in the glass matrix. In the decorative glaze known as luster, found on some medieval pottery, the special optical properties of the glaze arose from metallic spherical nanoparticles which were dispersed in the glaze in a random fashion. Michael Faraday in 1857 on his pioneering work “Experimental relations of gold (and other metals) to light” (Faraday, 1857) explain the properties of this glaze. Now with advances of science and technology, the morphology of this material, which contains metallic nanoparticles, has been understood. Because of extremely small size and high surface volume ratio of nanoparticles, the physicochemical properties of nanoparticles-containing materials are quite different to those of the bulk materials (El-Sayed 2001). Thus, nanomaterials have potential applications in electronics and photonics, catalysis, information storage, chemical sensing and imaging, environmental remediation, drug delivery and biological labelling (Guo et al. 2005, Daniel and Astruc 2004, Huang et al. 2007). It is well known that the optical, electronic, and catalytic properties of metal nanoparticles are greatly influenced by their size, shape, and crystal structure. For example, silver (Ag) and gold (Au) nanocrystals of different shapes possess unique optical scattering responses (Daniel and Astruc 2004, Roduner 2006). Whereas highly symmetric spherical particles exhibit a single scattering peak, anisotropic shapes such as rods, triangular prisms, and cubes exhibit multiple scattering peaks in the visible wavelengths due to highly localized charge polarizations at corners and edges (Mie 1908). Thus, synthesis of metal nanoparticles with defined morphology gained much interest. A variety of strategies have been developed for the synthesis of metal nanoparticles (MNPs) and nanomaterials. Optimizing the nanomaterial synthesis has now become a prolific area of investigation. In the first part of this chapter, we will review the synthetic methods for MNPs production, with particular regard to biosynthesis in viable organisms and protein extracts. In the second part, we will discuss the most recent finding on the biosynthetic mechanism, the properties of the nanobioconjugates, and recent applications of MNPs.