chapter  7
34 Pages

Ion Channel Switch- and Lipid Film-Based Biosensors

ByTibor Hianik, Dimitrios P. Nikolelis, Georgia-Paraskevi Nikoleli

Lipids are amphiphilic molecules, which possess both hydrophilic head groups and hydrophobic chains. Depending on the concentration and the ratio of the sizes of the head groups and tails, they can spontaneously form different structures such as bilayer or multilayer sheets, micelles, and liposomes

CONTENTS

7.1 Introduction ................................................................................................ 197 7.2 Methods for Preparation of Biosensors Based on Lipid Films ............ 199

7.2.1 Metal-Supported Lipid Layers ..................................................... 199 7.2.2 BLM Formed on a Surface of Glassy Carbon Electrode ........... 201 7.2.3 Stabilized Lipid Films Formed on a Glass Fiber Filter and

on an Agar Support ....................................................................... 202 7.2.4 Bilayers Stabilized by Polymerization and Formed

on Semiconductor and Carbon Nanotube Surfaces .................. 204 7.2.4.1 Polymer-Supported Bilayer Lipid Membranes ........... 204 7.2.4.2 Lipid Films Supported on Semiconductors ................. 205 7.2.4.3 Lipid Films Supported on Carbon Nanotubes ........... 205

7.2.5 BLM Formed on Microporous Materials .................................... 206 7.3 Biosensors Based on Ion Channel Switch .............................................. 208 7.4 Biosensors Based on Supported Lipid Films and Their Analytical

Applications ................................................................................................ 210 7.4.1 Ion-Selective sBLM Modied by Carriers and Ion Channels ......212 7.4.2 Enzyme Biosensors ........................................................................ 213 7.4.3 DNA Biosensors ............................................................................. 218 7.4.4 Afnity Biosensors Based on Articial and Natural

Receptors ......................................................................................... 220 7.5 Conclusions ................................................................................................. 226 Acknowledgments .............................................................................................. 226 References .............................................................................................................227

in aqueous media. In these structures, the hydrophobic chains are hidden from water and the hydrophilic groups remain in the solution. Natural cell membranes consist mainly from different lipids such as phospholipids, glycolipids, cholesterol, and proteins. The protein fraction varies from 20% to 80% depending on the type of membrane. The peripheral proteins such as cytochrome c (cyt c) are embedded to the surface of the membrane, while integral proteins, for example, bacteriorhodopsin, span the hydrophobic part of the lipid bilayer.