PNNL

Abstract

Carbon nanotubes exhibit interesting electrical, structural and mechanical properties that make them highly promising nanoscale building blocks for the construction of novel functional materials. Many potential applications have been proposed, such as conductive and high-strength composites, field emission displays, fuel cells, sensors, and hydrogen storage media.1,2 In addition, biosensors for detecting abnormalities3–5 and bio-fuel cells6 for embedded devices are among the most exciting applications. In order to create the synergy between the biomolecules and nanotubes required to realize these applications, biomolecules, such as proteins and DNAs, must be connected to the carbon nanotubes. This connection can be non-covalent interaction or covalent bonding. There have been several reports on the immobilization of biomolecules on carbon nanotubes,7–13 and most of them use non-covalent interaction. The best stability, accessibility and selectivity, however, will be achieved through covalent bonding because of its capability to control the location of the biomolecule, improve stability, accessibility and selectivity and reduce leaching. In the present study, we report the covalent bonding of proteins to nitrogen-doped multiwalled carbon nanotubes (CNx MWNTs) via a two-step process of diimide-activated amidation between the carboxylic acid groups on CNx MWNTs and the amine groups on proteins.