Biointerface Characterization by Advanced IR Spectroscopy

C.-M. Pradier, Y.J. Chabal

• Publisher: Elsevier
• Year: 2011
• Print ISBN: 9780444535580
• eBook ISBN: 9780444535597
• Topic: Physical Sciences
• Subtopic: Spectroscopy & Spectrum Analysis

IR spectroscopy has become without any doubt a key technique to answer questions raised when studying the interaction of proteins or peptides with solid surfaces for a fundamental point of view as well as for technological applications. Principle, experimental set ups, parameters and interpretation rules of several advanced IR-based techniques; application to biointerface characterisation through the presentation of recent examples, will be given in this book. It will describe how to characterise amino acids, protein or bacterial strain interactions with metal and oxide surfaces, by using infrared spectroscopy, in vacuum, in the air or in an aqueous medium. Results will highlight the performances and perspectives of the technique. - Description of the principles, expermental setups and parameter interpretation, and the theory for several advanced IR-based techniques for interface characterisation - Contains examples which demonstrate the capacity, potential and limits of the IR techniques - Helps finding the most adequate mode of analysis - Contains examples - Contains a glossary by techniques and by keywords

Chapter 1. RAIRS under ultrahigh vacuum conditions on metal surfaces

V. Humblot¹ and C.-M. Pradier²

¹Laboratoire de Réactivité de Surface, UMR CNRS 7197,

²Université Pierre et Marie Curie - Paris VI, 4 Place Jussieu, F-75252 Paris, France

Short history of rairs 1

How does it work - the physical basis of rairs 2

Description of apparatus and coupling with auhv chamber 8

Selected examples. why is rairs so successful for thin films on metal surfaces? 8

CO on pure metal surfaces: the beginning 8

CO/Pd(110) 9

Lysine and tartaric acid on Cu(110) single crystal surface; glutamic acid on Ag(110) 11

Lysine on Cu(110) 12

Low-coverage phase 12

High-coverage phase 13

(R,R)-tartaric acid on Cu(110) 15

Room-temperature (300 K) adsorption phase 15

High-temperature (400 K) adsorption phase 17

Glutamic acid on Ag(110) 18

Bio-molecules (peptides) adsorbed on metal surfaces, studied by RAIRS 19

Adsorption of tri-alanine on Cu(110) 19

Adsorption of Gly-Pro, GSH (Glu-Cys-Gly), and IGF (Gly-Pro-Glu) on Au(110) 21

Gly-Pro on Au(110) 21

IGF on Au(110) 22

GSH on Au(110) 23

Gly-Pro, IGF, and GSH growth mode comparison 23

Conclusions 24

References 25

Abstract

Fourier transform infrared (FTIR) spectroscopy in the reflection absorption mode at grazing incidence (RAIRS) is a very sensitive and powerful tool to analyze thin films deposited on metal surfaces. This chapter presents a brief description of the birth and of the theory of RAIRS, adapted from the classical FTIR in transmission mode. How RAIRS data can be used to determine the adsorption site, chemical state, as well as orientation of an adsorbed molecule with respect to the surface will then be described. Through various examples, going from CO, simple amino acids, to di- and tri-peptides, we will see the interest of using RAIRS for unraveling the adsorption kinetics and assembling mode of simple bio-molecules on a metal surface.

Short history of rairs

InfraRed Spectroscopy in the Reflection Absorption mode at grazing incidence (RAIRS) uses infrared light to excite the internal vibrations of molecules adsorbed on a reflective surface. The frequency of these vibrations is usually assigned to only one given chemical group in the adsorbate. From RAIRS spectra, one can determine the adsorption geometry and the adsorption site of the molecule.

The historical development of RAIRS has been discussed by several authors [1], [2], [3], [4] and [5] and came up after the infrared transmission work of Eischens et al.[6] and [7] and Terenin et al.[8] in the 1950s. Eischens et al. used transmission infrared spectroscopy to study CO on supported Ni, Pd, and Pt. This technique is still widely used today, especially for studying adsorption on supported metals and dispersed catalysts. However, the use of well-defined single crystals, as model surfaces to address adsorption or reaction mechanisms, requires the experiments to be carried out in a reflection mode. RAIRS was first applied in 1959 by Pickering and Eckstrom [9] and Francis and Ellison [10] using multiple reflections. Although the multiple reflection technique was developed further, by using higher quality metal films, Greenler [11], [12] and [13] first considered the possibility of single reflection experiments. The experimental RAIRS studies of CO on copper films by Pritchard and Sims [14] subsequently supported Greenler's findings.

How does it work – the physical basis of rairs

Classically, the general infrared selection rule states that for a vibration to be infrared active, it must induce a change of the electric dipole moment of the molecule. The intensity resulting from the transition between states

and

is defined by the following equation [15]:

(1)

where E is the electric field vector and

is the transition dipole moment.

Obviously, the intensity will be maximum when the electric field vector and the transition dipole moments are parallel and it is proportional to the square of the transition dipole moment [15].

For a molecule adsorbed on a metal surface, the interaction of the infrared radiation with the adsorbate dipole is influenced by the dielectric behavior of the metal, but the surface selection rule extends to molecules adsorbed in multilayers of thicker films, as illustrated by Poling et al.[16] with a 25 nm thick layer of Cu oxalate on copper.

The influence of a metallic substrate on absorption of infrared radiation by adsorbed molecules was originally examined by Francis and Ellison [10] and the classical electrodynamic macroscopic model was then developed by Greenler [11], [12] and [13], leading to the definition of the optimum conditions for RAIRS experiments. Green...

Table of contents

• Cover image
• Table of Contents
• Front Matter
• Copyright
• Preface
• Contributors
• Chapter 1. RAIRS under ultrahigh vacuum conditions on metal surfaces
• Chapter 2. PM-IRRAS at liquid interfaces
• Chapter 3. Infrared spectroscopy for characterization of biomolecular interfaces
• Chapter 4. Infrared analysis of biomolecule attachment to functionalized silicon surfaces
• Chapter 5. Attenuated total reflection infrared (ATR-IR) spectroscopy, modulation excitation spectroscopy (MES), and vibrational circular dichroism (VCD)
• Chapter 6. Synchrotron infrared interface science
• Chapter 7. IR spectroscopy for biorecognition and molecular sensing
• Chapter 8. Advanced infrared glasses for biochemical sensing
• Chapter 9. AFM-IR: photothermal infrared nanospectroscopy
• Chapter 10. Sum-frequency generation spectroscopy of biointerfaces
• Index