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Biophys J. 2007 Jun 15;92(12):4466-72. Epub 2007 Mar 30.

Detection of protein orientation on the silica microsphere surface using transverse electric/transverse magnetic whispering gallery modes.

Author information

1
Microparticle Photophysics Laboratory, Polytechnic University, Brooklyn, New York 11201, USA.

Abstract

The state of adsorbed protein molecules can be examined by comparing the shifts in a narrow line resonance wavelength of transverse electric (TE) and transverse magnetic (TM) whispering gallery modes (WGM) when the molecules adsorb onto a transparent microsphere that houses WGM. In adsorption of bovine serum albumin (BSA) onto an aminopropyl-modified silica microsphere, the TM/TE shift ratio indicated highly anisotropic polarizability of BSA in the direction normal to the surface, most likely ascribed to anchoring the heart-shaped protein molecule by one of its tips. The polarization-dependent resonance shift was confirmed when the surrounding refractive index was uniformly changed by adding salt, which would simulate adsorption of large objects.

PMID:
17400701
PMCID:
PMC1877779
DOI:
10.1529/biophysj.106.103200
[Indexed for MEDLINE]
Free PMC Article

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