2009 Volume 58 Issue 8 Pages 753-756
A cup-stacked carbon nanotube (CSNT) was formed by stacking cup-shaped carbon units with a hollow open channel of 80 to 100 nm in diameter, in contrast to the structure of a conventional multi-walled carbon nanotube (MWNT) made up of some seamless cylinders. The side of the cup is hydrophobic and the edge is hydrophilic due to the presence of carboxyl groups. Thus, a CSNT has a large hollow space in which one can incorporate enzyme molecules based on a physical adsorption. In this work, CSNT and other nanosize supports [MWNT, graphite, activated carbon and aminopropyl CPG (APCPG)] were packed into similar stainless-steel columns (4 × 3 mm), and glucose oxidase (GOD) was adsorbed by circulating an enzyme solution into each column. The CSNT adsorbed GOD both strongly and rapidly. The adsorbed amount was significantly larger than those onto MWNT, graphite, and activated carbon, and equivalent to that immobilized onto APCPG by a glutaraldehyde crosslinking reaction. As a result, it was found that CSNT has a high adsorptive activity for GOD. The flow-injection system with a GOD adsorbed CSNT packed column responded linearly to the concentration of glucose over a dynamic range of 5 × 10−7∼1 × 10−3 M.
