Sensor applications of attenuated total reflection infrared spectroscopy

Attenuated total reflection Fourier transform infrared spectroscopy is one of the most powerful methods for recording infrared spectra of biological materials in general, and of biological membranes in particular. It is fast, yields a strong signal with only a few micrograms of sample and recent ATR devices allow the recording of nanogram quantities. Importantly, it allows information about the orientation of various parts of the molecules under study to be evaluated in an oriented system. While mid-infrared radiation has been most used for fundamental research on molecular structure, it is becoming an interesting alternative for sensor research. In addition to the usual sensor response, one of its advantages is its sensitivity to molecular conformation. In turn, the binding of a drug onto a receptor may be monitored as for other detection methods but in addition the evaluation of the structural response of the receptor to this binding is likely to bring invaluable information on the mechanism of action of the drug. The present review focuses only on the ATR-mid IR spectroscopy with a special interest for proteins and biological membranes.