Dispersions Based on Carbon Nanotubes – Biomolecules Conjugates

Abstract

The discovery of carbon nanotubes (CNTs) [1] followed by their large-scale production have paved the way to wide CNT integration into modern nanotechnology by taking advantage of their excellent mechanical properties and high electrical and thermal conductivities [2]. Carbon nanotubes have emerged as new class nanomaterials that are receiving considerable interest because of their unique structure, high chemical stability and high surface-tovolume ratio. Composite nanomaterials based on integration of CNTs and some other materials to possess properties of the individual components with a synergistic effect have gained growing interest [3]. The use of carbon nanotubes as “building blocks” in nano-/microelectronic devices could revolutionize the electronic industry in the same way that the microchips have revolutionized the computer industry. However, it has been a long-standing big challenge to efficiently integrate the carbon nanotube “building blocks” into multicomponent/ multifunctional structures or devices. It has been shown that carbon nanotubes could promote electron transfer with various redox active proteins, including glucose oxidase, cytochrome c, and horseradish peroxidase. Li and co-workers have demonstrated that carbon nanotubes can promote electron transfer with certain proteins and enzymes, and the electrochemical behavior with cytochrome c [4]. The CNT is nearly inert and therefore its functionalization is needed to increase its reactivity and to form with other components conjugates or hybrids. Chemical functionalization of CNTs usually destroys the sp2 structure of CNTs, therefore, damages the intrinsic properties of them. Thus, non-covalent modification of CNTs is of great significance. Surfactants can disperse CNTs in water, however, which needs relatively higher amount and cannot be used for possible biological and chemical application [5]. Pioneering studies have reported on the use of single-walled carbon nanotubes (SWCNTs) as atomic force microscopy (AFM) imaging tips of biomacromolecules, such as antibodies, DNA, proteins, viruses... [6] The integration of biomaterials (e.g., DNA, proteins/enzymes, or antigens/antibodies) with CNTs provides new hybrid systems that combine the conductive or semiconductive properties of CNTs with the recognition or catalytic properties of the biomaterials. This may