Amperometric glucose biosensor based on multilayer films via layer-by-layer self-assembly of multi-wall carbon nanotubes, gold nanoparticles and glucose oxidase on the Pt electrode

A novel amperometric glucose biosensor based on the nine layers of multilayer films composed of multi-wall carbon nanotubes (MWCNTs), gold nanoparticles (GNp) and glucose oxidase (GOD) was developed for the specific detection of glucose. MWCNTs were chemically modified with the H2SO4-HNO3 pretreatment to introduce carboxyl groups which were used to interact with the amino groups of poly(allylarnine) (PAA) and cysteamine via 1-ethyl-3-(3-dimethylaniinopropyl) carbodiiniide/N-hydroxysuccinimide cross-linking reaction, respectively. A cleaned Pt electrode was immersed in PAA, MWCNTs, cysteamine and GNp, respectively, followed by the adsorption of GOD, assembling the one layer of multilayer films on the surface of Pt electrode (GOD/GNp/MWCNTs/Pt electrode). Repeating the above process could assemble different layers of multilayer films on the Pt electrode. PBS washing was applied at the end of each assembly deposition for dissociating the weak adsorption. Film assembling and characterization were studied by transmission electron microscopy and quartz crystal microbalance, and properties of the resulting glucose biosensors; were measured by electrochemical measurements. The marked electrocatalytic activity of Pt electrode based on multilayer films toward H2O2 produced during GOD enzymatic reactions with glucose permitted effective low-potential amperometric measurement of glucose. Taking the sensitivity and selectivity into consideration, the applied potential of 0.35 V versus Ag/AgCI was chosen for the oxidation detection of H2O2 in this work. Among the resulting glucose biosensors, the biosensor based on nine layers of multilayer films was best. It showed a wide linear range of 0.1-10 mM glucose, with a remarkable sensitivity of 2.527 mu A/mM, a detection limit of 6.7 mu M estimated at a signal-to-noise ratio of 3 and fast response time (within 7 s). Moreover, it exhibited good reproducibility, long-term stability and the negligible interferences of ascorbic acid, uric acid and acetan-dnophen. The study can provide a feasible approach on developing new kinds of oxidase-based amperometric biosensors, and can be used as an illustration for constructing various hybrid structures. (c) 2006 Elsevier B.V. All rights reserved.