Surface plasmon resonance characteristics

Kim, K.-P., Jagadeesan, B., Burkholder, K. M., Jaradat, Z. W., Wampler, J. L., Lathrop, A. A., Morgan, M. T., and Bhunia, A. K. (2006a). Adhesion characteristics of Listeria adhesion protein (LAP)-expressing Escherichia coli to Caco-2 cells and of recombinant LAP to eukaryotic receptor Flsp60 as examined in a surface plasmon resonance sensor. FEMS Microbiol. Lett. 256,324-332. 

The use of optical immune biosensors based on surface plasmon resonance (SPR) for the diagnostics of human and animal diseases as well as for environmental pollution monitoring, is one of prospective directions in biosensorics. The sensitivity of immune biosensors is similar to the ELIS A-method but the simphcity of obtaining results in the real time regime and the speed of the analysis are the main advantages of the biosensor approach. Performance of optical biosensors based on SPR depends on the state of the metallic surface as well as on the density, structure and the space volume of the immobilized molecules. It was demonstrated that the application of intermediate layers between the transducer surface and the sensitive biological molecules can optimize the working characteristics of the immune biosensor [7-14]. 

Table 4 Structural formulas of analytes and functional monomers, accompanied by characteristic values of merit, used in the MIP surface plasmon resonance... 

In addition to the fluorescence platform, several other novel detection techniques, including electrochemical and optical approaches, have been developed in order to alleviate the need for target labeling (36-44). Table 1 summarizes some of these approaches and their characteristics are compared with conventional fluorescence detection. Surface plasmon resonance imaging... 

In Chap. 1 by J. Homola of this volume [1] surface plasmons were introduced as modes of dielectric/metal planar waveguides and their properties were estabhshed. It was demonstrated that the propagation constant of a surface plasmon is sensitive to variations in the refractive index at the surface of a metal film supporting the surface plasmon. In this chapter, it is shown how this phenomenon can be used to create a sensing device. The concept of optical sensors based on surface plasmons, commonly referred as to surface plasmon resonance (SPR) sensors, is described and the main approaches to SPR sensing are presented. In addition, the concept of affinity biosensors is introduced and the main performance characteristics of SPR biosensors are defined. 

Surface plasmon resonance (SPR) sensors are optical sensing devices that take advantage of the sensitivity of a special type of electromagnetic field, a surface plasmon, to changes in refractive index. SPR sensors can be classified based on the method for optical excitation of surface plasmons and the measured characteristic of the light wave interacting with the surface plasmon. 

On a basis of the comparative analysis of the references the correlated dependencies between the optical characteristics of aqueous sols of spherical nanoparticles and their diameter have been discovered. As a result, the empirical dependencies between the values of the square of wave frequency in the adsorption maximum of the surface Plasmon resonance and average diameter of the nanoparticles were determined as well as between the values of the adsorption band width on a half of its height and silver nanoparticles distribution per size. Proposed dependencies are described by the linear equations with the correlation coefficients 0.97 and 0.84, respectively. 

In order to identify the obtained silver nanoparticles, their spectral characteristics were investigated (Fig. 4, a). The spectrum of silver nanoparticles adsorption is characterized by one maximum corresponding to their spherical form. Analyzing the references [5-7], it was discovered that the value of the square of wave fiequency in adsorption maximum of the surface Plasmon resonance of silver nanoparticles linearly depends on their size (Fig. 4, b), that gives the possibilities to calculate an average diameter of the obtained silver nanoparticles. Calculated values of the average diameter of silver nanoparticles consist of 12 - 35 nm. 

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