Plasmonic Nanoparticles and Their Conjugates: Preparation, Optical Properties and Antimicrobial Activity

Abstract

To manipulate the size of noble metal particles on a nanometer scale are priority subjects in the field of nanotechnology. So far various approaches have been developed to synthesize noble metal nanoparticles in controlled sizes and dimensions. Among them the colloidal systems become broadly used. These systems can be made up of several very different reactants and solvents: a continuous medium water or alkane, surfactant and precursor(s). In some systems the formation of (sub) nanoparticles is based on the supersaturation of solution by reactants. The existence of the microenvironments gives them a particular ability to modulate the chemical reactivity of the reactants due to their compartmentalization in different microenvironments. The size and shape of noble metal nanoparticles follow the feed composition of reactants in the precursor solution, the reaction conditions and concentration and type of reactants. Surface modification and functionalization is expected to increase the stability of nanoparticles and organize them to the assembly of higher order array conjugates. Various soft and hard templates can be applied to produce noble metal nanoparticles in different shaped nanoreactors. Monodisperse gold nano crystals can grow inside soft templates and the cavities of hard templates by the reduction of metal ions trapped in the cavities. The interesting optical properties of noble metal nanoparticles and their (bio)conjugates results from the strong absorption in the visible spectrum region, so called the surface plasmon absorption. Some noble metal nanoparticles have been studied for their antimicrobial potential and have proven to be antibacterial and antiviral agents.