Highly Conductive Redox Protein–Carbon Nanotube Complex for Biosensing Applications

Abstract

The integration of redox proteins with nanomaterials has attracted much interest in the past years, and metallic single‐walled carbon nanotubes (SWNTs) have been introduced as efficient electrical wires to connect biomolecules to metal electrodes in advanced nano‐biodevices. Besides preserving biofunctionality, the protein–nanotube connection should ensure appropriate molecular orientation, flexibility, and efficient, reproducible electrical conduction. In this respect, yeast cytochrome c redox proteins are connected to gold electrodes through lying‐down functionalized metallic SWNTs. Immobilization of cytochromes to nanotubes is obtained via covalent bonding between the exposed protein thiols and maleimide‐terminated functional chains attached to the carbon nanotubes. A single‐molecule study performed by combining scanning probe nanoscopies ascertains that the protein topological properties are preserved upon binding and provides unprecedented current images of single proteins bound to carbon nanotubes that allow a detailed I–V characterization. Collectively, the results point out that the use as linkers of suitably functionalized metallic SWNTs results in an electrical communication between redox proteins and gold electrodes more efficient and reproducible than for proteins directly connected with metal surfaces.

Probing the Structure of Lysozyme–Carbon‐Nanotube Hybrids with Molecular Dynamics

“…[6,7] They have been used for the development of new sorting and purification techniques, [8,9] in biomedical [10] and electronic devices, [11] and appear promising for the development of novel chemical [12,13] and biological [14] sensing instruments, as well as for controlling binding and assembly on templating surfaces. [15] In spite of the growing number of studies dealing with single-walled nanotubes (SWNTs) and proteins, [16][17][18][19] little is known about the microscopic or atomistic details of the association process or of the structure of the adsorbed proteins. For possible applications and in order to understand the potential toxicity of CNTs, a deeper understanding of these crucial points is required.…”

Recent Advances in Applications of Sorted Single‐Walled Carbon Nanotubes

“…Excellent progress has been made in CNT‐based chemical and biological sensors, and these areas have already been the topic of several reviews . Of particular interest in this review is the application of sorted SWCNTs for a comprehensive range of sensing technologies …”

Efficient covalent functionalisation of carbon nanotubes: the use of “click chemistry”

“…Baldacchini et al 82 reported the covalent linkage between SWNTs and yeast cytochrome C (YCC) redox proteins. The cytochrome was attached to maleimide-terminated nanotubes 78 through the thiol group of a cysteine located in the region opposite to the lysine-rich protein docking site.…”