U.P.B. Sci. Bull., Series B, Vol. 76, Iss. 1, 2014 ISSN 1454 – 2331 HIGHLY SELECTIVE AND STABLE GLUCOSE BIOSENSORS BASED ON POLYANILINE / CARBON NANOTUBES COMPOSITES Luisa PILAN 1 , Matei RAICOPOL 2 In this paper, a new selective and stable glucose biosensor based on polyaniline (PANI) / functionalized single-walled carbon nanotubes (SWCNTs) / Prussian Blue (PB) composite films was investigated. For biosensor synthesis we combined two widely used techniques to produce modified electrodes that are the electroreduction of diazonium salts and the electropolymerization. Thus, in a first step, SWCNTs deposited at a PB modified glassy carbon (GC) electrode were functionalized with p-nitrophenyl group by electrochemical reduction of p- nitrobenzenediazonium salt in nonaqueous media. Then, the nitro group was reduced electrochemically to amine functionality. The enzyme doped PANI film can easily be grafted onto the surface of such obtained aminophenyl-modified SWCNTs electrodes. The marked synergistic electrocatalytic activity of SWCNTs and PB film toward H 2 O 2 produced during enzymatic reaction of glucose oxidation permitted effective low-potential amperometric measurement of glucose. Keywords: diazonium salt, amperometric biosensor, carbon nanotubes, conductive polymers, nanocomposite, selectivity 1. Introduction During recent years, enzymatic biosensors have received much attention by many researchers due to their rapid response, high sensitivity and intrinsic selectivity [1,2]. Research in this field is still focused on the improvement of sensor properties by new sensing approaches. The biosensor based on glucose oxidase (GOx) for glucose sensing continues to be the primary model system in the development of new sensing materials and methods [3,4]. The glucose concentration can be determined by amperometric detection of the oxidation current of hydrogen peroxide (H 2 O 2 ), a side product during the enzymatic reaction. A great drawback for this model is represented by high overpotential (usually 0.6V vs. Ag/AgCl) [5] required for H 2 O 2 oxidation. In clinical application the high positive working electrode 1 Lecturer, Faculty of Applied Chemistry and Material Science, University “Politehnica” of Bucharest, Romania, e-mail: luisa_pilan@yahoo.com 2 Assistant Professor, Faculty of Applied Chemistry and Material Science, University “Politehnica” of Bucharest, Romania