Infra-Red Surface Plasmon Resonance - a novel tool for real-time sensing of variations in living cells

¹ Hebrew University of Jerusalem

^* To whom correspondence should be addressed. E-mail: aroeti{at}cc.huji.ac.il.

Submitted on August 5, 2005
Revised on September 29, 2005
Accepted on 12 December 2005

	Abstract

We developed a novel Surface Plasmon Resonance (SPR) method, based on Fourier-Transform-Infra-Red (FTIR), as a label-free technique for studying dynamic processes occurring within living cells, in real time. With this method, the long (micrometer) infra-red wavelength produced by the FTIR generates an evanescent wave that penetrates deep into the sample. In this way, it enables increased depth of sensing changes, covering significant portions of the cell-height volumes. HeLa cells cultivated on a gold-coated prism were subjected to acute cholesterol enrichment or depletion using cyclodextrins. Cholesterol insertion into the cell plasma membrane resulted in an exponential shift of the SPR signal towards longer wavelengths over time, whereas cholesterol depletion caused a shift in the opposite direction. Upon application of the inactive analog -cyclodextrin (-CD), the effects were minimal. A similar trend in the SPR signal shifts was observed on a model membrane system. Our data suggest that FTIR-SPR can be implemented as a sensitive technique for monitoring in real time dynamic changes taking place in living cells.

Key Words: cell biophysics, cell membranes, cholesterol, infra-red, surface plasmon resonance