An Absorption-Based Surface Plasmon Resonance Sensor Applied to Sodium Ion Sensing Based on an Ion-Selective Optode Membrane

Abstract

A surface plasmon resonance (SPR) sodium ion sensor using an ion optode membrane film was experimentally and theoretically described based on an absorption-based SPR principle proposed in our previous article (Kurihara, K; Suzuki, K. AnaL Chem. 2002, 74, 696-701). The sodium ion concentrations from 10(-6) to 10(-1) have been successfully determined not only by the resonance angle diagnosis of the SPR curve but also by the minimum reflectance one. The ion optode film was plasticized poly(vinyl chloride) including a neutral sodium ionophore, a pH-sensitive cationic dye, and an anionic additive. Its optical absorption intensity changed with the sodium ion concentrations. The SPR ion sensor physically measured the complex refractive index caused by the absorption in the ion optode film. We have exhaustively investigated the experimental response behavior of the SPR curve relative to the sodium ion concentrations by comparison with numerically simulated SPR curves using a three-layer Fresnel equation including experimental values for the sodium ion optode membrane film. As predicted by the absorption-based SPR principle, the SPR curve behavior of the SPR ion sensors depended on two factors: one was the relation between the excitation frequency of the light source and the absorption maximum frequency in the ion optode film while the other was the gold metallic thickness in the Kretchmann configuration. The concept and practical theory of an absorption-based SPR sensor not only have been proved by the experimental results of the SPR sodium ion sensor but also have successfully allowed flexible ion sensing in an SPR sensor, which would be very difficult without the absorption mechanism in the ion optode film.

Dependence of the signal amplification potential of colloidal gold nanoparticles on resonance wavelength in surface plasmon resonance-based detection

“…The SPR signal (reported as a function of particle surface coverage), varies for the resonance wavelengths of approximately 650 nm, 770 nm, and 920 nm, and is greatest at 770 nm. Modeling results using a simple absorptive Lorentz model [11,12] are shown to be in good agreement with the experimental data and are consistent with a red-shifted localized surface plasmon resonance (LSPR) absorption peak of 650 nm for the colloidal gold nanoparticles on planar gold. The results indicate that the resonance wavelength dependence of the colloidal gold nanoparticles on planar gold is a balance between this LSPR absorption peak in the visible range and the inherent sensitivity increase of SPR on planar gold in the NIR [13,14].…”

“…The set of best fit parameters obtained for the five-layer system in the first stage was fixed, and the MEA-plus-colloidal gold samples were modeled at the three resonance wavelengths and for each of the particle surface coverages. The colloidal gold layer was modeled as a collection of independent Lorentz oscillators after Kurihara et al [11,12] The expression used for the permittivity of the colloidal gold layer follows. (2) Here ε ns background is the background permittivity of the sensing layer, ω is the angular frequency of incident light, ω 0 is the peak absorption angular frequency, A(ω 0 ) is the absorbance at the peak absorption frequency, d is the effective thickness of the colloidal gold layer, γ is the absorption damping frequency, and c is the speed of light in vacuum.…”

SPR sensor signal amplification based on dye-doped polymer particles

“…A simulation of the SPR curve change based on absorption changes of the sensing layer was performed in order to estimate the effect of the dye [17][18][19][20].…”

“…Ion-optode membranes [14][15][16] were used as SPR-sensing layers. Based on the change of the color of a membrane-incorporated indicator dye, small molecules were successfully measured due to the change of the imaginary part of the surface refractive index [17][18][19][20].…”

A survey of the year 2002 commercial optical biosensor literature

“…[794][795][796][797][798][799][800][801][802] Seven articles described work using the Windsor Scientific Ltd IBIS (www.windsor-ltd.co.uk) [803][804][805][806][807][808][809] and six articles reported data from a new platform developed by DKK-TOA Corp. (www.dkktoa.net). [810][811][812][813][814][815] In addition, four articles described work performed using an instrument produced by Analytical m-Systems (www.micro-systems.de). [816][817][818][819] …”