Experimental Section General. Single-walled carbon nanotubes (SWNTs) were purchased from Carbon Nanotechnologies, Inc. (Houston, TX). D-(+)-Glucose, and glucose oxidase (GOx, EC 1.1.3.4, type X-S, lyophilized powder, 130~190 units/mg, from Aspergillus niger) were purchased from Sigma-Aldrich. Glucose stock solutions were mutarotated overnight at room temperature before use. All reagents and solvents were purchased from commercial suppliers and used as received. UV-Visible spectra were measured by using a Cary 50 UV-visible spectrophotometer. Ultrasonication was carried out in a Banson Ultrasonics B1510, and B2500 bath sonicator. Beckman Allegra [TM] X-22R Benchtop centrifuge was used for centrifugation. Raman spectra from all samples were collected with a Renishaw Ramanscope at an excitation laser wavelength of 785 nm. NMR spectra were measured on Bruker Avance 200 spectrometers. SEM was performed using a JEOL JSM-7000F scanning electron microscope. The Circular dichroism (CD) measurements were performed on an AVIV Circular Dichroism Spectrophotometer Model 410 (Biomedical Inc) at 25 °C. The samples were prepared from corresponding solid films dissolved in dilute acetic acid solutions in DI H 2 O (pH 4.5).
The interaction between single-walled carbon nanotubes and two anionic conjugated polyelectrolytes, poly[2,5-bis(3-sulfonatopropoxy)-1,4-phenylene-alt-1,4-phenylene) sodium salt and poly[2,5-bis(3sulfonatopropoxy)-1,4-ethynylphenylene-alt-1,4-ethynylphenylene] sodium salt, was investigated. It was found that the supramolecular polymer-nanotube assembly occurred efficiently and produced stable complexes that could be purified from excess free polymer in solution. These complexes were characterized using absorption spectroscopy, fluorescence spectroscopy, Raman spectroscopy, and electron microscopy. It was further found that patterning of these polymer-nanotube complexes could be accomplished by utilizing electrostatic attraction with a prepatterned, cationically charged surface. Patterned features were found to be electrically conducting with a measured sheet resistance value of 0.68 ( 0.01 MΩ for features having a thickness on the order of several nanometers.
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