title: Nanostructured biosensors built by layer-by-layer electrostatic assembly of enzyme-coated single-walled carbon nanotubes and redox polymers.
abstract: In this study, we describe the construction of glucose biosensors based on an electrostatic layer-by-layer (LBL) technique. Gold electrodes were initially functionalized with negatively charged 11-mercaptoundecanoic acid followed by alternate immersion in solutions of a positively charged redox polymer, poly[(vinylpyridine)Os(bipyridyl)2Cl(2+/3+)], and a negatively charged enzyme, glucose oxidase (GOX), or a GOX solution containing single-walled carbon nanotubes (SWNTs). The LBL assembly of the multilayer films were characterized by UV-vis spectroscopy, ellipsometry, and cyclic voltammetry, while characterization of the single-walled nanotubes was performed with transmission electron microscopy, Raman spectroscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy. When the GOX solution contained single-walled carbon nanotubes (GOX-SWNTs), the oxidation peak currents during cyclic voltammetry increased 1.4-4.0 times, as compared to films without SWNTs. Similarly the glucose electro-oxidation current also increased (6-17 times) when SWNTs were present. By varying the number of multilayers, the sensitivity of the sensors could be controlled.
authors.affiliation: University of Oklahoma Bioengineering Center, School of Chemical, Biological and Materials Engineering, Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, 100 East Boyd, Norman, Oklahoma 73019, USA.
authors.forename: Youdan
authors.initials: Y
authors.lastname: Wang
authors.forename: Pratixa P
authors.initials: PP
authors.lastname: Joshi
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Hobbs
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Johnson
authors.forename: David W
authors.initials: DW
authors.lastname: Schmidtke
mesh_terms: D001234:Aspergillus niger / Q000201:enzymology; D015374:Biosensing Techniques / Q000379:methods*; D005947:Glucose / Q000378:metabolism; D005949:Glucose Oxidase / Q000737:chemistry* / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure*; D010084:Oxidation-Reduction; D010777:Photochemistry; D011108:Polymers / Q000737:chemistry*; D013057:Spectrum Analysis; D055672:Static Electricity
chemical_list: D037742:Nanotubes, Carbon; D011108:Polymers; D005949:Glucose Oxidase; D005947:Glucose