Rolls and sandwiches: cages and Barrels.

Abstract

Abstract This chaper describes the synthesis of nanoparticles and the available approaches for the synthesis of nanoparticles, which include the use of chemical (the sol-gel method and gas phase synthesis), biological (microorganisms, plant extracts, enzymes and proteins), liposomes and viral capsids. Though still in its infancy, with room for significant improvements, enzymes, as natural biocatalysts, must be regarded as prime players in support of 'green' nanotechnology. Enzymes regarded as nanoreactors not only may influence a size-controlled formation of nanoparticles but also may serve both as extremely efficient stabilizing agents for various nanoparticles as well as being a reactive ingredient associated with a specific biomimetic enzyme reaction. There are many enzyme classes that have been used as biocatalytic templates in the 'green' synthesis of nanoparticles. According to CATH protein structure classification, there exist three secondary structural levels (i.e. α, β and α,β) and architectural domains such as cages, barrels, rolls and sandwiches. This review has focused on the syntheses of metal nanoparticles by means of these different protein structural architectures and has attempted to illustrate the influence that such particle-enzyme/protein bioconjugates have on enzyme activity. The mechanistic aspects and reasons behind these differences in reactivity are also presented.