Single-walled carbon nanotubes–carboxyl-functionalized graphene oxide-based electrochemical DNA biosensor for thermolabile hemolysin gene detection

Abstract

Illustration of the procedure for the preparation of a CFGO and SWCNTs-based electrochemical DNA biosensor.

Diagnostics Strategies with Electrochemical Affinity Biosensors Using Carbon Nanomaterials as Electrode Modifiers

“…On the other hand, graphene, discovered in 2004, is a two-dimensional nanomaterial, a single-atom-thick sheet of hexagonally arrayed sp 2 -bonded carbon atoms which has tremendous potential to modify electrode surfaces due to its unique physicochemical properties [4,9,10,11,12]. The outstanding properties of graphene include large specific surface area, extremely high thermal conductivity, good mechanical strength and high conductivity and electron mobility at room temperature.…”

“…However, the present graphene possesses the defect of forming irreversible agglomerates through van der Waals interaction and π stacking, which greatly restricts its further application in the preparation of electrochemical sensors. These limitations have been overcome by using graphene oxide (GO) which possesses enhanced solubility and dispersion ability attributed to the abundant oxygen functional groups (epoxy, hydroxyl, peroxy, carbonyl and carboxyl groups) available on the basal planes and edges [11]. Graphene is often used as the building unit for the preparation of nanocomposites as well as for loading various nanomaterials with different morphologies [13,14].…”

“…Fast detection times, high sensitivity (down to several fM and in some cases, aM) and specificity (even for single-base mismatched sequences), easy handling, relatively cheap cost, easy integration into portable platforms, low power consumption and multiplexing capabilities are intrinsic advantages of electrochemical DNA biosensors [3,11,17,18]. They combine the specificity of DNA hybridization with the sensitivity of electrochemical transducers to produce an electroanalytical readout for the analytes.…”

“…DNA manipulation, including hybridization, ligation or conformational change, is the underlying principle of electrochemical DNA biosensors. They usually involve the immobilization of a specific probe DNA, usually termed capture probe, fully complementary to the target DNA (TD) to be detected, onto the electrode surface and the examination of electrochemical response before and after the hybridization reaction occurred with the TD [10,11,19,20]. Since the performance of electrochemical DNA biosensors largely depends upon the amount and stability of immobilized capture probes at the surface of a sensing device, a variety of approaches for the fabrication of DNA biosensors have been reported using electrodes modified with various materials including carbon nanostructures to overcome the limited capture probe immobilization onto bare electrodes [12,18,21].…”

“…While CNTs can provide a high surface area to immobilize DNA molecules and significantly improve the electrochemical properties of the sensors, graphene-related nanomaterials allow direct electrochemical oxidation of DNA bases offering simple detection methods [3]. Moreover, single-stranded DNAs (ssDNA) may be directly immobilized on graphene, GO or carboxyl functionalized GO (CFGO) through π electron interaction as well as covalently through amidation [3,11]. Interestingly, it has been shown that ssDNA exhibits stronger interaction with graphene than dsDNA, and graphene-DNA cannot be easily degraded, the structure remaining stable for a long time [18].…”