Nanostructured materials enzymes

Self-assembly processes in nature are sometimes catalyzed by enzymes. Zeolites are, in many ways, the inorganic counterparts of enzymes, with their ability to selectively bind other substances and perform catalysis. Can templates or catalysts be effective in increasing rates and reducing defects in a wide range of nanostructured materials ... 

Enzyme Stabilization in Nanostructured Materials, for Use in Organophosphorus Nerve Agent Detoxification and Prophylaxis... 

Keywords Enzymes Nanostructured materials Organophosphorus Detoxification... 

In recent times the incorporation of enzymes into nanostructured materials is commonly referred to as nanobiocatalysis. Nanobiocatalysis has emerged as a rapidly growing research and development area. Lately, nanobiocatalytic approaches have evolved beyond simple enzyme immobilization strategies to include also topics like artificial enzymes and cells, nanofabrication, and nanopatterning [18]. A recent bibliometric analysis [19] of nanobiocatalysis publications shows a strong increase within the last decade (Fig. 14.1). The analysis has been compiled from... 

In this section, the potential application for amyloid fibrils and other selfassembling fibrous protein structures are outlined. These include potential uses in electronics and photonics presented in Section 4.1, uses as platforms for the immobilization of enzymes and biosensors presented in Section 4.2, and uses as biocompatible materials presented in Section 4.3. Each of these applications makes use of the ability of polypeptides to self-assemble and form nanostructured materials, a process that can occur under aqueous conditions. These applications also seek to exploit the favorable properties of fibrils such as strength and durability, the ability to arrange ligands on a nanoscale, and their potential biocompatibility arising from the natural materials used for assembly. 

In this chapter we will focus on the most recent developments in the use of nanostructured materials such as nanoclays, carbon nanotubes and magnetic nanoparticles for enzyme immobilization and stabilization, together with their potential applications in various fields, such as development of biosensors and biofuel cells, biocatalytic processes, enzyme purification/separation, intracellular protein transportation etc. 

The non-specific adsorption of proteins on carbon nanotubes is an interesting phenomenon but represents a relatively less controllable mode of protein-CNT interaction. Moreover, in non-covalent immobilization process, the immobilized protein is in equilibrium between the surface of the carbon nanotubes and the solution and can therefore be gradually detached from the nano-material surface, a phenomenon called protein leakage [127]. To prevent the leaching of enzymes, covalent bonds have been used to attach the enzyme molecules to the nanostructured materials, which lead to more robust and predictable conjugation. Experimental evidences prove that proteins can be immobilized either in their hollow cavity or on the surface of carbon nanotubes [130]. 

New advances in enzyme inhibition biosensors apply nanostructured materials and nanocomposites to obtain increased sensitivity and also use transgenic enzyme systems [77,78]. 

Nanostructured materials obtained by sol-gel encapsulation of biomolecules are a novel class of biomaterials. The biological macromolecules, confined within the nanometer-size pores of the matrix, show both similarities to and differences from solution characteristics. The effects of nanoconfinement on the structural and reactivity patterns of the proteins and enzymes are discussed. The applications of these nanostructured biomaterials in the area of molecular biorecognition, detection, and biosensing are also presented. 

The paper is organized in three parts. First, the effects of nanoconfinement on the structure of the sol-gel trapped biomolecule are discussed. Second, from the results on apparent reactivity of these biomaterials, the effects of the matrix on the reactivity of trapped enzyme are elucidated. Finally, the interaction of the confined biomolecules with exogenous ligands/substrates and the applications of these materials in the area of molecular biorecognition are discussed. The reaction chemistries of biologically active molecules in die nanostructured materials have been crucial in establishing the role of the matrix upon the structure and reactivity of the confined proteins. 

Once the proteins are confmed within the porous structure of the sol-gel matrix, it becomes imperative to determine if these nanostructured materials still remain amenable to interactions with external reagents. This issue assumes central importance because the functional relevance of nanoconfined proteins and enzymes is contingent upon their reactions with suitable substrates or ligands. 

From a different point of view, wet hydrophobic ILs have been described as nanostructured materials, where cations and anions are connected together with hydrogen bonds, forming an extended network of polar and nonpolar regions [110]. In concentrated aqueous solutions of ILs, these organized structures can be maintained, and under these conditions, Hofmeister series concept could not be properly applied [82]. Moreover, enzyme molecules have been considered to be included into these IL networks, thus maintaining their native structures and the essential water molecules. In a sense, these ILs could be considered both as solvents and liquid immobilization supports in which high enzyme stability can be achieved [45, 70,90,110,111]. 

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