UNCORRECTED PROOF BIOS 1453 1–8 Biosensors and Bioelectronics xxx (2004) xxx–xxx Study of mixed Langmuir–Blodgett films of immunoglobulin G/amphiphile and their application for immunosensor engineering 3 4 Yanxia Hou a,b , Chaker Tlili a,c , Nicole Jaffrezic-Renault a,∗ , Aidong Zhang b , Claude Martelet a , Laurence Ponsonnet a , Abdelhamid Errachid d , Josep samitier d , Joan Bausells e 5 6 7 a IFoS, UMR CNRS, 5621 Ecole Centrale de Lyon, BP 163, 69131 Ecully Cedex, France 8 b College of Chemistry, Central China Normal University, Wuhan 430079, PR China 9 c Laboratoire de Physique et Chimie des Interfaces (LPCI), F.Sc de Monastir, Monastir 5000, Tunisie 10 d Laboratory of NanoBioEngineering, Barcelona Science Park, Barcelona 08028, Spain 11 e Centro Nacional de Microelectr´ onica (IMB-CSIC), Campus UAB, 08193 Bellaterra, Barcelona, Spain 12 Received 12 November 2003; received in revised form 14 April 2004; accepted 14 May 2004 13 Abstract 14 Langmuir–Blodgett (LB) technique appears to be quite suitable for generating biospecific surfaces and it has potential application for fabricating biosensors. In this work, mixed Langmuir–Blodgett films of immunoglobulin G/amphiphile have been transferred onto hydrophobic silver surface previously modified by 1-octadecanethiol (ODT) SAMs. In order to obtain stable LB films, the influences of different parameters – type of amphiphile, surface pressure and pH – on the properties of mixed IgG/amphiphile monolayer, were investigated. Electrochemical properties of the engineered immunosensor have been measured by impedimetric spectroscopy. The immunosensor obtained exhibits a high sensitivity and a good specificity in a linear dynamic range from 200 to 1000 ng ml -1 . 15 16 17 18 19 20 © 2004 Published by Elsevier B.V. 21 Keywords: LB films; Immunoglobulin G; Octadecylamine; Behenic acid; ac impedance; Immunosensors 22 23 1. Introduction 1 Immunosensors are of great interest because of the po- 2 tential utility, which is due to their main advantages, such 3 as high sensitivity, selectivity and robustness related to the 4 selectivity and affinity of the antibody–antigen binding re- 5 action (Bertold, 1997). With the development of immobiliz- 6 ing biomolecules techniques and analytical techniques, im- 7 munosensors have being attracted numerous researchers, and 8 they have been investigated and employed to various fields: 9 the environment analysis (Suri et al., 2002; Mallat et al., 2001; 10 Van Emon et al., 1998), clinical diagnostics (Luppa et al., 11 2001), food and drink industries (Mello and Kubota, 2002) 12 etc. 13 ∗ Corresponding author. Tel.: +33 472186243; fax: +33 478331140. E-mail address: ncole.jaffrezic@ec-lyon.fr (N. Jaffrezic-Renault). Like other types of biosensors, immunosensors need suit- 14 able techniques to immobilize the active biocomponents and 15 appropriate transducers. Immobilization of antibody is a cru- 16 cial step for fabricating high quality immunosensor, since 17 after immobilization the activity of antibody should remain 18 high and binding of antigen should occur in a manner that 19 reduces interference. The conventional methods for immo- 20 bilization of biocomponents include physical adsorption, co- 21 valent binding, entrapment etc., however, they suffer from 22 a poor spatially controlled deposition (Gerard et al., 2002). 23 Conducting polymers have been used widely as a platform for 24 the fabrication of biosensors including immunosensors. How- 25 ever, it is difficult to control the amount of biocomponents 26 in the active films, and moreover, the thickness of polymers 27 leads to a decrease of the response time of the biosensor. 28 Comparing to these techniques, Langmuir–Blodgett (LB) 29 technique is considered as a desirable immobilization method 30 1 0956-5663/$ – see front matter © 2004 Published by Elsevier B.V. 2 doi:10.1016/j.bios.2004.05.017