Broadband Plasmon Waveguide Resonance Spectroscopy for Probing Biological Thin Films

Abstract

A commercially available spectrometer has been modified to perform plasmon waveguide resonance (PWR) spectroscopy over a broad spectral bandwidth. When compared to surface plasmon resonance (SPR), PWR has the advantage of allowing measurements in both s-and ppolarizations on a waveguide surface that is silica or glass rather than a noble metal. Here the waveguide is a BK7 glass slide coated with silver and silica layers. The resonance wavelength is sensitive to the optical thickness of the medium adjacent to the silica layer. The sensitivity of this technique is characterized and compared with broadband SPR both experimentally and theoretically. The sensitivity of spectral PWR is comparable to that of spectral SPR for samples with refractive indices close to that of water. The hydrophilic surface of the waveguide allows supported lipid bilayers to be formed spontaneously by vesicle fusion; in contrast, the surface of an SPR chip requires chemical modification to create a supported lipid membrane. Broadband PWR spectroscopy should be a useful technique to study biointerfaces, including ligand binding to transmembrane receptors and adsorption of peripheral proteins on ligand-bearing membranes.

Sensitivity comparison of surface plasmon resonance and plasmon-waveguide resonance biosensors

“…The idea was later implemented by Salamon et al who developed the first plasmon-waveguide resonance biosensor and extensively studied the applications in membrane systems (Salamon et al 1997; Salamon Z. and Tollin G. 2001). Since then, many research groups proposed modified designs (Toyama et al 2000; Zhang et al 2009; Zourob and Goddard 2005; Zourob et al 2005b) and applied the concept to a variety of biological targets (Hruby et al 2010; Hruby and Tollin 2007; Zourob et al 2005a). Plasmon-waveguide resonance is based on the deposition of a dielectric layer over a gold or silver film.…”

“…Guided modes are highly sensitive to changes in the refractive index with both polarizations. This advantage is used to investigate the birefringence and optical dichroism of anisotropic materials such as lipid bilayer membranes, self assembled monolayers and thin films (Salamon Z. and Tollin G. 2001; Zhang et al 2009). This is mainly achieved by dealing with four optical parameters (two refractive indices and two extinction coefficients) rather than two in conventional SPR (Fig.…”

ITO/Poly(Aniline)/Sol-Gel Glass: An Optically Transparent, pH-Responsive Substrate for Supported Lipid Bilayers

“…Fluorescence imaging and fluorescence recovery after photobleaching (FRAP) measurements on PSLBs deposited on ITO/PANI/sol-gel electrodes were performed as described in [28, 32] and in Supplementary Material. For FRAP, PSLBs composed of egg PC (the blank) or NBD-PC/egg PC (the sample, 0.05/0.95 mol/mol)) were formed on pairs of ITO/PANI/sol-gel electrodes mounted in the two compartments of a liquid cell.…”

Plasmon Waveguide Resonance: Principles, Applications and Historical Perspectives on Instrument Development

“…For the moment, no other company has taken over the development of PWR as far as we know. Instruments have been developed in laboratories at the University of Arizona (Saavedra lab; [28]) and in the Alves laboratory, as described below.…”