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Carbon nanotube-based optical platforms for biomolecular detection

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Abstract

Carbon nanotubes are exceptionally photostable fluorophores that emit in the near infrared range. Their novel optical properties make them particularly appealing for applications in biosensing. This chapter focuses on the state-of-the-art development of optical biosensors based on single-walled carbon nanotubes (SWCNTs); also, it draws attention to the basic photophysics of SWCNTs, optical-sensing mechanisms, and surface functionalization principles. The concerted efforts from the research community in the past decade have enabled the realization of several SWCNT-based optical biosensors that provide real-time, non-invasive analyte detection. We review the performance of these biosensors with regard to their sensitivity, selectivity and response time, and highlight the prospects and challenges of constructing biosensors for more advanced sensing applications.

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... Optical sensors are powerful tools equipped for providing information on an analyte remotely [19]. They are composed of signal transducers and molecular recognition elements. ...
... SWCNTs are sensitive to changes in the surface chemistry and 800-1600 nm wavelength range in near-infrared (NIR) emissions. The near-infrared window in biological tissue called the "biological window" lies in the range of 700-1300 nm, in which scattering, absorption, and autofluorescence by water, blood, and tissues are minimal [19]. Also, they do not blink or bleach for a long period of time, thus making SWCNTs applicable for use in biological environments. ...
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Article
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Article
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Article
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Article
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Article
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Article
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Article
Peptides selected from phage-displayed libraries have been found to exhibit high-affinity binding to carbon nanotubes including single-walled carbon nanotubes (SWNTs), multi-walled carbon nanotubes, and single-walled carbon nanohorns. One unique feature of these peptides is that their amino acid sequences are rich in tryptophan and histidine residues. The aim of this study was to investigate the importance of the tryptophan residue in a newly identified SWNT-binding peptide, UW-1, which contains the motif, XTHXXPWTX, where X is any amino acid. Tryptophan was altered in the following ways: mutation to alanine or substitution with three unnatural tryptophan analogues, i.e., 5-fluorotryptophan, 5-hydroxytryptophan, and 7-azatryptophan. Analysis of experimental and computational data suggests that the highest occupied molecular orbital of the tryptophan residue in the peptide interacts with the lowest unoccupied molecular orbital from the SWNT. This information should be important in permitting modulation of peptide affinities to these nanomaterials.
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