Study of Langmuir and Langmuir-Blodgett films of odorant-binding protein/amphiphile for odorant biosensors.

Yanxia Hou, Nicole Jaffrezic-Renault, Claude Martelet, Chaker Tlili, Aidong Zhang, Jean-Claude Pernollet, Loïc Briand, Gabriel Gomila, Abdelhamid Errachid, Josep Samitier, Ludovic Salvagnac, Benoit Torbiéro, Pierre Temple-Boyer

Index: Langmuir 21(9) , 4058-65, (2005)

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Abstract

To make ultrathin films for the fabrication of artificial olfactory systems, odorant biosensors, we have investigated mixed Langmuir and Langmuir-Blodgett films of odorant-binding protein/amphiphile. Under optimized experimental conditions (phosphate buffer solution, pH 7.5, OBP-1F concentration of 4 mg L(-1), target pressure 35 mN m(-1)), the mixed monolayer at the air/water interface is very stable and has been efficiently transferred onto gold supports, which were previously functionalized by self-assembled monolayers (SAMs) with 1-octadecanethiol (ODT). Atomic force microscopy and electrochemical impedance spectroscopy were used to characterize mixed Langmuir-Blodgett (LB) films before and after contact with a specific odorant molecule, isoamyl acetate. AFM phase images show a higher contrast after contact with the odorant molecule due to the new structure of the OBP-1F/ODA LB film. Non-Faradaic electrochemical spectroscopy (EIS) is used to quantify the effect of the odorant based on the electrical properties of the OBP-1F/ODA LB film, as its resistance strongly decreases from 1.18 MOmega (before contact) to 25 kOmega (after contact).