Supplementary information for:
Nanoparticle Surface-Enhanced Raman Scattering of Bacteriorhodopsin Stabilized by Amphipol A8-35
Vitaly Polovinkin1,2,3,4, T. Balandin5, O. Volkov5,6, E. Round5, V. Borshchevskiy4,5, P. Utrobin1,2,3, D. von Stetten7,
A. Royant1,2,3,7, D. Willbold5,8, G. Arzumanyan9, J.-L. Popot10 and V. Gordeliy1,2,3,4,5,*
1
Institut de Biologie Structurale J.-P. Ebel, Université Grenoble Alpes, F-38000 Grenoble, France;
2
Institut de Biologie Structurale J.-P. Ebel, Centre National de la Recherche Scientifique, F-38000 Grenoble, France;
3
Institut de Biologie Structurale J.-P. Ebel, Direction des Sciences du Vivant, Commissariat à l'Énergie Atomique,
F-38000 Grenoble, France;
4
Laboratory for Advanced Studies of Membrane Proteins, Moscow Institute of Physics and Technology, 141700
Dolgoprudny, Moscow Region, Russia;
5
Institute of Complex Systems (ICS), ICS-6: Structural Biochemistry, Research Centre Juelich, 52425 Juelich,
Germany;
6
Institute of Crystallography, University of Aachen (Rheinisch-Westfälische Technische Hochschule), 52056 Aachen,
Germany;
7
European Synchrotron Radiation Facility, 38027 Grenoble, France;
8
Institut für Physikalische Biologie, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany;
9
Multi Access Centre "Nanobiophotonics", Joint Institute for Nuclear Research, 141980 Dubna, Moscow Region,
Russia;
10
Laboratoire de Physico-Chimie Moléculaire des Membranes Biologiques, UMR 7099, Institut de Biologie PhysicoChimique (CNRS FRC 550), Centre National de la Recherche Scientifique and Université Paris-7, 13 rue Pierre et
Marie Curie, F-75005 Paris, France.
*
Corresponding author. E-mail: valentin.gordeliy@ibs.fr. Address: 6 rue Jules Horowitz, F-38000 Grenoble, France.
Tel.: +33 457 42 8614. Fax: +33 476 50 1890.
Keywords: amphipol, membrane protein, bacteriorhodopsin, SERS spectroscopy, silver nanoparticles
Short communication destined to the special issue
on amphipols of J. Membr. Biol.
1
Figure S1 a. A bright-field optical image of the dried mixture of BR/A8-35 complexes and silver NPs (5-µL drop at a
BR concentration of 0.08 g·L-1), which was used to measure SERS spectra of BR/A8-35. This image is the same image
as presented in Fig. 3a of the main text. b. Scaled UV-visible absorption spectrum of Lee-Meisel Ag NP colloid solution
used for SERS experiments in the present work is drawn as a black line. The silver colloid has an absorption maximum
at ~405 nm with a FWHH of ~102 nm. This spectrum was measured with a spectrophotometer UV2450
(Shimadzu, Japan). Spectra 1 (red line), 2 (blue line), 3 (green line) and 4 (yellow line) are UV-visible spectra recorded
from the areas of the dried drop in Panel a, marked by red spots with corresponding numbers. This variation of UVvisible absorption spectrum along the dried drop is caused mainly by the non-uniform aggregation of Ag NPs upon
drying, since the aggregation of Ag NPs nanoparticles is accompanied by shifts to longer wavelengths and broadening
of plasmon resonance peak (Félidj et al. 1999; Wang et al. 2008). Spectra 1 to 4 were recorded on a UV-visible
absorption microspectrophotometer, equipped with an Ocean Optics QE65 Pro spectrometer (Dunedin, FL), and an
optical system with a focal spot size of about 25-µm diameter (using 100-µm fibres) at the sample position. This setup
has been described in detail by Royant et al. (2007).
2
Figure S2 Resonance Raman spectra of BR/A8-35 complexes (3 g·L-1 BR) in 20 mM Na/K-Pi, pH 7.2 (blue line) and
BR in purple membranes (7 g·L-1 BR) in 20 mM Na/K-Pi, pH 7.2 (red line). Spectra were collected at a laser
wavelength of 514.5 nm, an exposure time of 30 s and 1-mW laser power.
3
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