Enzymes and nanoparticles: Modulation of enzymatic activity via nanoparticles.

Enzymes are biocatalysts that speed up the reactions taking place inside the cell. They are widely used in industries, scientific research and clinical diagnostics. Enzymes are specific for their substrates. They increase the rate of reaction by lowering the activation energy required to convert the substrates into the products. The catalysis by an enzyme is influenced by the nature of medium, substrate, enzyme concentration, temperature, pH, and the presence of activators and inhibitors. Nanoparticles are solid dispersion particulates of size range 10-1000 nm. They cause enhancement of particle mobility, diffusion, thermal stability, storage capacity, greater surface area and also modulate catalytic activity of the attached enzymes. Enzymes can be immobilized on nanoparticles by simple adsorption or via chemical linkages. Immobilization is a commercially applicable and a convenient method because it usually results in enhanced thermal and pH stabilities of the enzyme, lower cost of production, reusability with easy handling and separation. Primary objective of writing this review is to give an overview of the various aspects of enzymology, enzyme catalysis, enzyme immobilization and modulation of enzyme activity with special emphasis on modulation through different types of nanoparticles including their synthesis, characterization and applications.