Covalent Attachment of Biomacromolecules to Plasma-Patterned and Functionalized Carbon Nanotube-Based Devices for Electrochemical Biosensing

Abstract

The interface between biomacromolecules and carbon nanotubes (CNTs) is of critical importance in developing effective techniques that provide CNTs with both biomolecular recognition and signal transduction through immobilization. However, the chemical inertness of CNT surfaces poses an obstacle to wider implementation of CNTs in bioanalytical applications. In this paper, we present a review of our recent research activities related to the covalent attachment of biomacromolecules to plasma-patterned and functionalized carbon nanotube films and their application to the fabrication of electrochemical biosensing devices. The SWCNT films were spray-deposited onto a miniaturized three-electrode system on a glass substrate and activated using highly purified atomic oxygen generated in radiofrequency plasma; this introduced oxygen-containing functional groups into the SWCNT surface without fatal loss of the original physicochemical properties of the CNTs. The carboxylated SWCNT electrodes were then selectively modified via amidation or esterification for covalent immobilization of the biomacromolecules. The plasma-treated SWCNT-based sensing electrode had an approximately six times larger effective area than the untreated SWCNT-based electrode, which significantly amplified the amperometric electrochemical signal. Finally, the efficacy of plasma-functionalized SWCNT (pf-SWCNT) as a biointerface was examined by immobilizing glucose oxidase, Legionella pneumophila ( L. pneumophila)-specific antibodies, L. pneumophila-originated DNAs, and thrombin-specific aptamers on the pf-SWCNT-based three-electrode devices. The pf-SWCNT films were found to support direct covalent immobilization of the above-listed biomacromolecules on the films and to thereby overcome the many drawbacks typically associated with simple physisorption. Thus, pf-SWCNT sensing electrodes on which biomacromolecules were covalently immobilized were found to be chemically stable and have a long lifetime.

Carbon nanotube catalysts: recent advances in synthesis, characterization and applications

“…284 Besides reflux with oxidants, the oxygen-containing groups on CNT surfaces can be created by air or O 2 plasma. [285][286][287] O 2 plasma is effective for CNT surface modification without causing any severe CNT structural damage by tuning the plasma treatment conditions. 285 These introduced oxygen surface groups are employed to immobilize bio-macromolecules such as enzymes, antibody and deoxyribonucleic acid for sensing and catalysis applications.…”

Effect of Varying the Semiconducting/Metallic Tube Ratio on the Performance of Mixed Single-Walled Carbon Nanotube Network Gas Sensors

“…The surface chemical composition of the SWCNTs has a strong influence on the gas absorption process and therefore the sensing properties. In previous works [24,43], an O 2 plasma treatment was found to introduce a number of oxygen-containing defects into the surface of the CNT film, and these functional groups are known to significantly increase the sensitivity to gases. Although many workers have studied CNT gas sensors functionalized using a plasma process, no reported effects of a plasma treatment on the SWCNT networks with different / were found in the literature.…”

An electrochemical genosensor for Leishmania major detection based on dual effect of immobilization and electrocatalysis of cobalt-zinc ferrite quantum dots

“…Among them, the electrochemical methods have recently received a good deal of attention due to the inherent specificity and sensitivity, their ease of use, low cost, fast response, and miniaturized and automated devices [8,9,12]. For many years, the appropriate modification of the conductive surfaces to immobilize biomacromolecules (such as DNA) has been one of the important approaches in biotechnology, bioanalysis, nanomedicine, and fabrication of biosensors [13][14][15][16][17][18]; it is also useful in understanding the action mechanism of drugs and origin of some diseases [19][20][21]. In a DNA biosensor, the immobilization of a DNA probe on the surface of an electrode is a key step and up to now, various kinds of nanostructured materials have been devised for the single-stranded DNA (ssDNA) immobilization [8,9,22,23].…”