Spectroscopic characterization of CNTs

In this chapter, we will discuss electrochemical sensors based on CNTs. First, the properties and structures of CNTs, the preparation and purification of CNTs, and the advantages of electrochemical sensors based on CNTs are described, then, the fabrication of electrochemical sensors based on CNTs, applications of electrochemical sensors based on CNTs, and the spectroscopic characterization of CNT sensors are described. In conclusion, we will look into some aspects of the future direction for CNT sensors in clinical and biomedical research. 

Sidewalls of CNTs were coated with PEG [241], preventing the nonspecific adsorption of proteins [242, 243], The polymeric layer was subsequently used as an interface for the specific coupling or affinity binding of proteins [242]. By a diamine-terminated oligomeric PEG functionalization, the solubilization of as-prepared and purified SWCNTs was achieved [244], The soluble tubes were characterized by spectroscopic, microscopic and gravimetric techniques. 

Within materials science, the optical properties of ICP-CNT composites refer specifically to the absorption, photo luminescence, Raman and FTIR spectroscopy of ICP-CNT composites. Spectroscopic methods offer the possibiUty of quick and nondestructive characterization of relatively large amounts of ICP-CNT composites. There is a strong demand for such characterization from the industrial point... 

At first, an overview of the experimental methods which are suitable to characterize the CNT aggregation state in general, and thus are suitable to monitor CNT debundling in aqueous medium and in presence of surfactant, will be reviewed. Three main streams will be presented (i) "direct imaging of the CNT dispersions by m icroscopic techniques (ii] spectroscopic techniques, such as Raman spectroscopy, which exploit the difference in electronic properties between bundled and individualized CNTs and (iii] depolarized dynamic light scattering which is commonly used to characterize colloidal systems. 

Prato and coworkers succeeded in the 1,3-dipolar addition of azomethine ylides to CNTs [161], Treatment of pristine SWCNTs with an aldehyde and an N-substi-tuted glycine derivative resulted in the formation of substituted pyrrolidine moieties on the SWCNT surface (Scheme 1.22). The approach works effectively with both SWCNTs, prepared by several different methods, and MWCNTs. The pyrro-lidino-functionalized CNTs were sufficiently soluble in common organic solvents and were characterized by several spectroscopic techniques and TEM [161]. The... 

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