Vertically aligned carbon nanotube probes for monitoring blood cholesterol

Abstract

Detection of blood cholesterol is of great clinical significance. The amperometric detectiontechnique was used for the enzymatic assay of total cholesterol. Multiwall carbonnanotubes (MWNTs), vertically aligned on a silicon platform, promote heterogeneouselectron transfer between the enzyme and the working electrode. Surface modification ofthe MWNT with a biocompatible polymer, polyvinyl alcohol (PVA), converted thehydrophobic nanotube surface into a highly hydrophilic one, which facilitates efficientattachment of biomolecules. The fabricated working electrodes showed a linearrelationship between cholesterol concentration and the output signal. The efficacy ofthe multiwall carbon nanotubes in promoting heterogeneous electron transferwas evident by distinct electrochemical peaks and higher signal-to-noise ratio ascompared to the Au electrode with identical enzyme immobilization protocol.The selectivity of the cholesterol sensor in the presence of common interferentspresent in human blood, e.g. uric acid, ascorbic acid and glucose, is also reported.