Guided‐wave and ellipsometric imaging of supported cells

Abstract

SummaryIn this study, results are reported from guided-wave microscopy and imaging ellipsometry near the angle of resonant excitation of an optical guided mode in planar wave guides with metal and dielectric layers. The main goal was to test their ability to detect micro-organisms (Escherichia coli) attached to a support. For this purpose, images from the two techniques were compared with an optical image and good agreement was found. The reasons for the differences between the pictures obtained with wave-guide microscopy and imaging ellipsometry were investigated and it was found that both the reduced plasmon propagation length and the use of additional polarizing elements contributed to the improved quality of the latter.

Novel application of imaging surface plasmon resonance for in situ studies of the surface exploration of marine organisms

“…6 The extreme surface sensitivity of SPR has also found applications in the visualization of cell/substrate contact 7 as well as for the study of cell adhesion and proliferation. 8,9 Surface plasmons may be described as quantized surfacebound electromagnetic waves confined to and propagating along the interface of a metal and a dielectric. Surface plasmons can be resonantly excited by visible light in a setup known as the Kretschmann configuration wherein light, incident through a prism, is reflected from a thin metal film.…”

Plasmon microscopy and imaging ellipsometry of Artrobacter oxydans attached on polymer films

“…The polarizing elements are adjusted so that the specularly reflected light was almost zero. The system is described in detail in a previous paper [5]. A Zeiss Jenatech microscope was used for dark field optical microscopy.…”

“…The aim of this study is to investigate the potentials of SP microscopy and imaging ellipsometry for detecting microorganisms when metal films with reduced field enhancement associated with plasmon excitation like Al films are used and how the results compare with those obtained with Au layers [5]. Two issues are of main interest: is the sensitivity in structures with Al enough to image biological cells with micron sizes and to what extend the resolution is affected by the plasmon propagation length.…”

“…One way to overcome this problem is to use additional polarizing elements in the optical system thus transforming the prism-based setup for generation and detection of SP into an imaging ellipsometry setup [10]. In a previous paper [5], we showed that imaging ellipsometry under conditions of plasmon excitation reveals more details and gives clearer pictures than plasmon microscopy when imaging unlabeled cells. Still, in some cases two close cells could not be resolved due to the propagation length of the GW, which was substantial because an Au layer was used to couple evanescent waves into GW modes.…”

“…They were used to study microorganisms attached to various types of surfaces [1][2][3][4]. SP and GW microscopes have been also shown to be able to image individual micron-sized biological cells attached to a substrate [5,6] or measure the distance between the substrate and different parts of a larger cell [7]. When using prism-based methods, their lateral resolution is limited by the propagation length of the waves [8].…”