Surface plasmon resonance overview

In this section an overview of the numerous methods and principles for the discrimination of enantiomers is given. First, the interaction principles of the polymer-based methods adapted from chromatographic procedures are illustrated. The discrimination of enantiomers was achieved some decades ago by using different types of stationary materials, like cyclodextrins or polymer-bonded amide selectors. These stationary-phase materials have successfully been appointed for label-free optical sensing methods like surface plasmon resonance (SPR) or reflectometric interference spectroscopy (RIfS). Furthermore, various successful applications to optical spectroscopy of the well-established method of fluorescence measurements for the discrimination of enantiomers are described. 

Mainly electrochemical (amperometric, potentiometric, impedimetric, or conductometric) and optical (IR, Raman, fluorescence, absorption, reflection, evanescence field, or surface plasmon resonance) transducers are used as the basis for biosensors. However, beside these there are other, less often employed transducers that make use of the piezoelectric effect, surface acoustic waves, or detection of heat generated in enzyme reactions [40, 41]. In the context of this work, the focus is on the specific features of electrochemical transducers. An overview showing the different fields of apphcation can be found in Sect. 2.11.1.5 (Table 2). 

Shenoy DK (2005) Cavitands container molecules for surface plasmon resonance (SPR)-based chemical vapor detection. Mater Sci Technol 2005 NRL review 171-173 Szetjli J (1998) Introduction and general overview of cyclodextrin chemistry. Chem Rev 98 1743-1753 Valeur B, Leray I (2007) Ion-responsive supramolecular fluorescent systems based on multichromophoric calixarenes a review. Inorg Chim Acta 360 765-774... 

In the first part of this chapter we will briefly discuss the nature of noncovalent interactions, followed by an overview of standard methods for probing them (optical and fluorescence spectroscopy, isothermal titration calorimetry/microcalorimetry, differential scanning calorimetry, and surface plasmon resonance), with particular attention to their application to biomolecules. An overview of mass spectrometric methods suitable for detecting noncovalent complexes will then be presented. The advantages of mass spectrometry compared with conventional analytical methods are sensitivity, speed, and the ability to obtain stoichiometric information directly. 

The goal of this chapter will be to provide an overview of the use of planar, optically resonant nanophotonic devices for biomolecular detection. Nanophotonics23 24 represents the fusion of nanotechnology with optics and thus it is proposed that sensors based on this technology can combine the advantages of each as discussed above. Although many of the issues are the same, we focus here on optical resonance rather than plasmonic resonance (such as is used in emerging local SPR and surface-enhanced Raman spectroscopy-based biosensors). 

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