Surface Plasmon Resonance:  Theoretical Evolutionary Design Optimization for a Model Analyte Sensitive Absorbing-Layer System

Abstract

Surface plasmon resonance (SPR) has been widely used in a Kretschmann configuration to study optical thickness changes of layers on a Au surface in response to an analyte. The method has been popularized and optimized for protein layers, but has also been used in the same format for other layers without further optimization including those absorbing at the incident wavelength. In this paper, we examine whether SPR remains the "best"attenuated reflectivity format for absorbing overlayers. Experimental data from the SPR response of a copper phthalocyanine film to nitrogen dioxide are used as an input example for a design process using an evolutionary algorithm. The data showed a trend toward thinner gold layer systems ( approximately 25 nm gave an contrast-enhancement of 42.9% compared with approximately 50-nm Au) or Au-free solutions including a layer with low refractive index. From the evolutionary design predictions, further modification could be tested based on available materials and "redundant layers" could be eliminated from the final selection. By inclusion of the external optics, a design could be selected to accommodate poor precision (+/-0.5 degrees ) in the incident angle and a possible multilayer solution was shown using Teflon AF 1600, with refractive index approximately 1.3. The predicted NO(2) response showed an improvement compared with the classical SPR configuration, and the incident angle chosen by the SGA for the interrogation of these layers was close to a stationary point in the absolute response curve, thus offering very good tolerance to automatic position referencing to the reflectivity minimum.

Novel optical NO2-selective sensor based on phthalocyaninato-iron(II) incorporated into a nanostructured matrix

“…Typical representatives of this class of compounds are phthalocyanines (Pc) [7,9]. In view of the development of NO 2 -sensors, investigations were mainly focused on CuPc and PbPc [10][11][12][13][14][15][16][17][18]. Other Pc used were compounds such as polyfluoro-phthalocyaninato-aluminium [19], Ti(Pc) 2 [20], metal-free octahexyl-substituted [21] and 18-crown-6 substituted phthalocyanine [22] and sublimated films or Langmuir-Blodgett films of phthalocyaninatoiron(II) (FePc) [15,17].…”

Fast protein detection in raw blood by size-exclusion SPR sensing

“…A lter chip has the same SPR angle as a at chip, although the large surface area of the SU-8 wall introduces an uncertainty in the determination of SPR angles due to the small depression at the SPR angle. 17,18 We therefore evaluated the effects of the ratio experimentally and compared it with the results obtained from this model.…”

Size-exclusion SPR sensor chip: application to detection of aggregation and disaggregation of biological particles

“…An SPR angle is determined by a mathematical fitting of the curve, 19 which generally depends on its sharpness. 20 This suggests that a small dip of the filter chip potentially causes a relatively high noise level and low resolution of the angle measurements.…”