Immobilization of enzymes onto carbon nanotubes

Abstract

The discovery of carbon nanotubes (CNTs) has opened a new door in nanotechnology. With their high surface area, unique electronic, thermal and mechanical properties, CNTs have been widely used as carriers for protein immobilization. In fact, carbon nanotubes present ideal support system without diffusional limitations, and also have the possibility of surface covalent functionalization. It is usually the oxidation process that introduces carboxylic acid groups. Enzymes and other proteins could be adsorbed or covalently attached onto carbon nanotubes. Adsorption of enzyme is a very simple and inexpensive immobilization method and there are no chemical changes of the protein. It has also been found that this technique does not alter structure and unique properties of nanotubes. However, a major problem in process designing is relatively low stability of immobilized protein and desorption from the carrier. On the other hand, while covalent immobilization provides durable attachment the oxidation process can reduce mechanical and electronic properties of carbon nanotubes. It can also affect the active site of enzyme and cause the loss of enzyme activity. Bioimmobilization studies have showed that there are strong interactions between carbon nanotubes surface and protein. The retention of enzyme structure and activity is critical for their application and it is of fundamental interest to understand the nature of these interactions. Atomic force microscopy (AFM), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and circular dichroism (CD) spectroscopy provide an insight into the structural changes that occur during the immobilization. The aim of this paper is to summarize progress of protein immobilization onto carbon nanotubes

Dual-Enzyme Cascade Composed of Chitosan Coated FeS2 Nanozyme and Glucose Oxidase for Sensitive Glucose Detection

“…Some carrier materials even limit the contact between the substrate and the enzyme, thereby affecting the catalytic efficiency. Additionally, certain carriers will interact with the enzyme to reduce its ability to catalyze reactions [ 22 , 23 , 24 ]. Therefore, the most important factor for successful enzyme immobilization is the selection of an appropriate carrier material [ 25 ].…”

Enzyme‐Immobilized Metal‐Organic Frameworks: From Preparation to Application

“…[6] For immobilizing enzymes by CNTs, the fixation process may reduce the mechanical and electronic properties of carbon nanotubes, thus affecting the active site of the enzyme and leading to the loss of enzyme activity. [7] Sol-gel fixation is usually accompanied by loss of enzyme activity, due to the damage of enzyme, leakage from the immobilized host, or restricted substrate transport. [8] Metal cations/clusters and organic ligands are important components of MOFs, which have high crystallinity, porosity, diversity, and designability.…”

“…MS contains multiple pores, and in some cases, a given enzyme can be easily accommodated within the channel, but if the enzyme molecules are over‐crowded in the channel, the catalytic activity will be low [6] . For immobilizing enzymes by CNTs, the fixation process may reduce the mechanical and electronic properties of carbon nanotubes, thus affecting the active site of the enzyme and leading to the loss of enzyme activity [7] . Sol‐gel fixation is usually accompanied by loss of enzyme activity, due to the damage of enzyme, leakage from the immobilized host, or restricted substrate transport [8] .…”