Biosensors and Bioelectronics 21 (2005) 1–20 Review Structured thin films as functional components within biosensors Frank Davis ∗ , Seamus P.J. Higson Institute of Bioscience and Technology, Cranfield University at Silsoe, Silsoe, Bedfordshire MK45 4DT, UK Received 2 July 2004; received in revised form 4 October 2004; accepted 5 October 2004 Available online 18 November 2004 Abstract This review provides an introduction to the field of thin films formed by Langmuir–Blodgett or self-assembly techniques and discusses applications in the field of biosensors. The review commences with an overview of thin films and methods of construction. Methods covered will include Langmuir–Blodgett film formation, formation of self-assembled monolayers such as gold–thiol monolayers and the formation of multilayers by the self-assembly of polyelectrolytes. The structure and forces governing the formation of the materials will also be discussed. The next section focussed on methods for interrogating these films to determine their selectivity and activity. Interrogation methods to be covered will include electrochemical measurements, optical measurements, quartz crystal microbalance, surface plasmon resonance and other techniques. The final section is dedicated to the functionality of these films, incorporation of biomolecules within these films and their effect on film structure. Species for incorporation will include antibodies, enzymes, proteins and DNA. Discussions on the location, availability, activity and stability of the included species are included. The review finishes with a short consideration of future research possibilities and applications of these films. © 2004 Elsevier B.V. All rights reserved. Keywords: Langmuir–Blodgett; Thin films; Biosensors Contents 1. Introduction ........................................................................................................ 2 2. Methods of thin films formation ...................................................................................... 2 2.1. Langmuir–Blodgett (LB) films ................................................................................. 2 2.2. Polyelectrolyte multilayers .................................................................................... 3 2.3. Self-assembled monolayers .................................................................................... 3 2.3.1. Alcohols, acids and siloxanes .......................................................................... 3 2.3.2. Gold–thiol monolayers ................................................................................ 4 3. Interrogation techniques for the study of thin films ..................................................................... 5 3.1. Monolayers at air–water interface .............................................................................. 5 3.2. Spectroscopy and microscopy .................................................................................. 5 3.3. Mass-sensitive techniques ..................................................................................... 5 3.4. Surface plasmon resonance (SPR) .............................................................................. 6 3.5. Electrochemical techniques .................................................................................... 6 ∗ Corresponding author. Tel.: +44 1525 863455; fax: +44 1525 863533. E-mail address: f.davis@cranfield.ac.uk (F. Davis). 0956-5663/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.bios.2004.10.001