(44f) Layer-by-Layer Assembly of Enzyme-Coated Single-Walled Carbon Nanotubes and Redox Polymers

A sodium cholate suspension-dialysis method was used to adsorb two different redox enzymes, glucose oxidase (GOX) and horseradish peroxidase (HRP), onto single-walled carbon nanotubes (SWNT). By this method, solutions of highly dispersed and debundled SWNTs were prepared, that remained stable for 30 days and which retained 70% of the native enzymatic activity. We demonstrate incorporation of these enzyme-SWNT conjugates into amperometric biosensors through a layer-by-layer (LBL) self-assembly process. Incorporation of SWNT-enzyme conjugates resulted in a 5-fold increase in the sensitivity as compared to films without SWNTs. In the case of the GOX-based sensors, current densities as high as 400 &muA/cm2 could be reached, with the sensitivity of the sensors being controlled by varying the number of multilayers.