Carbon nanotubes , label-free

Maehashi et al. (2007) used pyrene adsorption to make carbon nanotubes labeled with DNA aptamers and incorporated them into a field effect transistor constructed to produce a label-free biosensor. The biosensor could measure the concentration of IgE in samples down to 250 pM, as the antibody molecules bound to the aptamers on the nanotubes. Felekis and Tagmatarchis (2005) used a positively charged pyrene compound to prepare water-soluble SWNTs and then electrostatically adsorb porphyrin rings to study electron transfer interactions. Pyrene derivatives also have been used successfully to add a chromophore to carbon nanotubes using covalent coupling to an oxidized SWNT (Alvaro et al., 2004). In this case, the pyrene ring structure was not used to adsorb directly to the nanotube surface, but a side-chain functional group was used to link it covalently to modified SWNTs. 

Maehashi, K., Katsura, T., Kerman, K., Takamura, Y., Matsumoto, K., and Tamiya, E. (2007) Label-free protein biosensor based on aptamer-modified carbon nanotube field-effect transitors. Anal. Chem. 79, 782-787. 

K. Kerman, Y. Morita, Y. Takamura, M. Ozsoz, and E. Tamiya, DNA-directed attachment of carbon nanotubes for the enhanced electrochemical label-free detection of DNA hybridization. Electroanalysis 16,1667-1672 (2004). 

J.E. Koehne, H. Chen, A.M. Cassell, Q. Ye, J. Han, M. Meyyappan and J. Li, Miniaturised multiplex label-free electronic chip for rapid nucleic acid analysis based on carbon nanotube nanoelectrode arrays, Clin. Chem., 50... 

In an effort to increase the sensitivity of label-free voltammetry, we can utilize carbon nanotubes (CNTs) as the transducing surface of our aptasensors. It has been well established that the electrochemical responses of DNA are greatly... 

Figure 7.3 Label-free voltammetry of 10 nM IgE on a multiwalled carbon nanotube (MWCNT)-modified screen-printed carbon electrode (solid line) and on a bare screen-printed carbon electrode (dashed line). Experimental conditions for differential pulse voltammetry were as described in Figure 7.2. MWCNTs (1 mg) were dispersed with the aid of ultrasonic agitation in 10 mL of N, Ai-dimethylformamide to give a 0.1-mg mL black solution. MWCNT film was prepared by pipetting a 2- xL drop of MWCNT solution onto the carbon working electrode of the screen-printed electrode and then evaporating the solvent at room temperature.

Figure 7.4 Label-free aptasensors based on CNT-FETs. (A) The aptamers are attached onto the sidewalls of a single-walled carbon nanotube which connects the source (S) and drain (D) electrodes. The binding of the target protein changes the electrical properties of the CNT-FETs significantly. (B) CNT-FET devices at high resolution. (See insert for color representation.)...

Kerman, K., Morita, Y., Takamura, Y., Tamiya, E. (2005). Escherichia coil single-strand binding protein-DNA interactions on carbon nanotube-modified electrodes from a label-free electrochemical hybridization sensor. Anal Bioanal Chem 381, 1114-1121. 

Star, A., Tu, E., Niemann, J., Gabriel, J.-C.P., Joiner, C.S., Valcke, C., 2006. Label-free detection of DNA hybridization using carbon nanotube network field-effect transistors. Proc. Natl. Acad. Sci. USA 103, 921-926. 

Nanomaterials, such as carbon nanotubes and semiconductor or polymer nanowires, can be functionalized with appropriate chemical or biological capture probes [3, 4], A unique property of these materials is flie very high surface-to-volume ratio. The chemical binding event on their surface causes a change of the crmductance of the nanotube or nanowire and thus can be identified via electrical measurement. Electrical nanobiosensors are capable of realizing sensitive, label-free, and real-time detection of a wide range chemical and biological species. 

Kerman, K Morita, Y. Takamura, Y. Ozsoz, M. Tamiya, E. (2004). DNA-Directed Attachment of Carbon Nanotubes for Enhanced Label-Free Electrochemical Detection of DNA Hybridization. Electroanalysis, 16,1667-1672. 

Wang, J., Kawde, A.-N. and Musameh, M. (2003) Carbon-nanotube-modified glassy carbon electrodes for amplified label-free electrochemical detection of DNA... 

Miniaturized multiplex label-free electronic chip for rapid nucleic acid analysis based on carbon nanotube nanoelectrode arrays. Clin. Chem., 50,1886-1893. 

Li, C.-Z., Karadeniz, H., Canavar, E., Erdem, A., 2012. Electrochemical sensing of label free DNA hybridization related to breast cancer 1 gene at disposable sensor platforms modified with single walled carbon nanotubes. Electrochimica Acta 82,137-142. 

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