Surface plasmon resonance principle

Englebienne, P., Van Hoonacker, A., and Verhas, M. Surface plasmon resonance Principles, methods and applications in biomedical sciences. Spectroscopy 17, 255-273 (2003). 

Two major optical techniques are commonly available to sense optical changes at sensor interfaces. These are usually based on evanescent wave and surface plasmon resonance principles. 

More recently, the method of scanning near-field optical microscopy (SNOM) has been applied to LB films of phospholipids and has revealed submicron-domain structures [55-59]. The method involves scanning a fiber-optic tip over a surface in much the same way an AFM tip is scanned over a surface. In principle, other optical experiments could be combined with the SNOM, snch as resonance energy transfer, time-resolved flnorescence, and surface plasmon resonance. It is likely that spectroscopic investigation of snbmicron domains in LB films nsing these principles will be pnrsned extensively. 

Fig. 2 Surface plasmon resonance (SPR) principle. Surface plasmons are excited by the light energy at a critical angle (9) causing an oscillation and the generation of an evanescent wave. Under this condition a decrease in the reflected light intensity is observed. The angle 9 depends on the dielectric medium close to the metal surface and therefore is strongly affected by molecules directly adsorbed on the metal surface. This principle allows the direct detection of the interaction of the analyte and the antibody...

B. Liedberg, I. Lundstrom, and E. Stenberg, "Principles of Biosensing with an Extended Coupling Matrix and Surface Plasmon Resonance," Sensors and Actuators Bll, 63-72 (1993). 

Figure 1. Schematic diagram showing the working principle of a surface plasmon resonance biosensor.

However, the determination of affinity does not necessarily have to rely on labeled ligands. It is also possible with native ligands when using suitable detection methods, as for example nuclear magnetic resonance (NMR), surface plasmon resonance (SPR), acoustic biosensors or calorimetry [48, 49]. A particularly versatile and sensitive detection principle for the investigation of interactions between targets and native ligands is mass spectrometry [50]. 

Figure 37. Principle of an optical Ca ion sensor based on a calmodulin (CaM)-me-diated Ca signaling pathway and surface plasmon resonance. ...

In principle, optical chemosensors make use of optical techniques to provide analytical information. The most extensively exploited techniques in this regard are optical absorption and photoluminescence. Moreover, sensors based on surface plasmon resonance (SPR) and surface enhanced Raman scattering (SERS) have recently been devised. 

The detection and quantification of the presence of biomolecules at the surface is based on specific interactions taking place in the evanescent field, generated by the total internal reflectance or by the surface plasmon resonance. The latter is the key transduction principle in the optical bioanalysis and biosensing area (Narayanaswamy and Wolfbeis, 2004). Launched in the early 1980s in Sweden,... 

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. 

The biosensing devices focus mainly on affinity principles such as antibody -antigen reactions and are based on surface plasmon resonance [25], grating couplers[26] or interferometers [27]. It seems possible to get stable and highly sensitive devices based on these principles [28], and further investigations can lead to miniaturized sensor modules with reduced cost, size and complexity. 

A chemical sensor is a device that transforms chemical information into an analytically useful signal. Chemical sensors contain two basic functional units a receptor part and a transducer part. The receptor part is usually a sensitive layer, therefore a well founded knowledge about the mechanism of interaction of the analytes of interest and the selected sensitive layer has to be achieved. Various optical methods have been exploited in chemical sensors to transform the spectral information into useful signals which can be interpreted as chemical information about the analytes [1]. These are either reflectometric or refractometric methods. Optical sensors based on reflectometry are reflectometric interference spectroscopy (RIfS) [2] and ellipsometry [3,4], Evanescent field techniques, which are sensitive to changes in the refractive index, open a wide variety of optical detection principles [5] such as surface plasmon resonance spectroscopy (SPR) [6—8], Mach-Zehnder interferometer [9], Young interferometer [10], grating coupler [11] or resonant mirror [12] devices. All these optical... 

Liedberg B, Lundstrom I, Stenberg E (1993) Principles of biosensing with an extended coupling matrix and surface plasmon resonance. Sensors Actuators B Chem 11 63-72... 

While it is safe to say that SPR is a mature technique from the historical perspective, new driving forces appear to challenge traditional SPR for various needs that traditional SPR sensors fail to satisfy. In particular, a novel SPR biosensor that attempts to capitalize on the nanotechnology, by which to localize surface plasmons (SPs), has emerged and thus has been appropriately called a localized surface plasmon resonance (LSPR) biosensor. In this chapter, 1 focus on the LSPR biosensor by reviewing its operating principles and properties in a systematic way and venture into future directions along which LSPR biosensors evolve. 

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