title: Watching individual molecules flex within lipid membranes using SERS.
abstract: Interrogating individual molecules within bio-membranes is key to deepening our understanding of biological processes essential for life. Using Raman spectroscopy to map molecular vibrations is ideal to non-destructively 'fingerprint' biomolecules for dynamic information on their molecular structure, composition and conformation. Such tag-free tracking of molecules within lipid bio-membranes can directly connect structure and function. In this paper, stable co-assembly with gold nano-components in a 'nanoparticle-on-mirror' geometry strongly enhances the local optical field and reduces the volume probed to a few nm(3), enabling repeated measurements for many tens of minutes on the same molecules. The intense gap plasmons are assembled around model bio-membranes providing molecular identification of the diffusing lipids. Our experiments clearly evidence measurement of individual lipids flexing through telltale rapid correlated vibrational shifts and intensity fluctuations in the Raman spectrum. These track molecules that undergo bending and conformational changes within the probe volume, through their interactions with the environment. This technique allows for in situ high-speed single-molecule investigations of the molecules embedded within lipid bio-membranes. It thus offers a new way to investigate the hidden dynamics of cell membranes important to a myriad of life processes.
authors.affiliation: 1] NanoPhotonics Centre, Cavendish Laboratory, Department of Physics, JJ Thompson Ave, University of Cambridge, Cambridge, CB3 0HE, UK [2].
authors.forename: Richard W
authors.initials: RW
authors.lastname: Taylor
authors.affiliation: 1] NanoPhotonics Centre, Cavendish Laboratory, Department of Physics, JJ Thompson Ave, University of Cambridge, Cambridge, CB3 0HE, UK [2].
authors.forename: Felix
authors.initials: F
authors.lastname: Benz
authors.affiliation: NanoPhotonics Centre, Cavendish Laboratory, Department of Physics, JJ Thompson Ave, University of Cambridge, Cambridge, CB3 0HE, UK.
authors.forename: Daniel O
authors.initials: DO
authors.lastname: Sigle
authors.affiliation: NanoPhotonics Centre, Cavendish Laboratory, Department of Physics, JJ Thompson Ave, University of Cambridge, Cambridge, CB3 0HE, UK.
authors.forename: Richard W
authors.initials: RW
authors.lastname: Bowman
authors.affiliation: Department of Physics, University of Leeds, Leeds, UK.
authors.forename: Peng
authors.initials: P
authors.lastname: Bao
authors.affiliation: Department of Physics, University of Leeds, Leeds, UK.
authors.forename: Johannes S
authors.initials: JS
authors.lastname: Roth
authors.affiliation: Department of Physics, University of Leeds, Leeds, UK.
authors.forename: George R
authors.initials: GR
authors.lastname: Heath
authors.affiliation: Department of Physics, University of Leeds, Leeds, UK.
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Evans
authors.affiliation: NanoPhotonics Centre, Cavendish Laboratory, Department of Physics, JJ Thompson Ave, University of Cambridge, Cambridge, CB3 0HE, UK.
authors.forename: Jeremy J
authors.initials: JJ
authors.lastname: Baumberg
mesh_terms: D005229:Fatty Acids, Monounsaturated / Q000737:chemistry; D006046:Gold / Q000737:chemistry; D008051:Lipid Bilayers / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry; D010713:Phosphatidylcholines / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D013059:Spectrum Analysis, Raman
chemical_list: D005229:Fatty Acids, Monounsaturated; D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D000644:Quaternary Ammonium Compounds; D006046:Gold; C070046:1,2-dioleoyloxy-3-(trimethylammonium)propane; C028694:1-palmitoyl-2-oleoylphosphatidylcholine
references.citation: Anal Sci. 2013;29(9):865-9
references.pmid: 24025569
references.citation: Opt Express. 2006 Oct 16;14(21):9988-99
references.pmid: 19529393
references.citation: Nat Rev Mol Cell Biol. 2008 Feb;9(2):112-24
references.pmid: 18216768
references.citation: Biophys J. 2007 Feb 15;92(4):1306-17
references.pmid: 17142265
references.citation: Nano Lett. 2013 Nov 13;13(11):5033-8
references.pmid: 24059599
references.citation: Nat Rev Mol Cell Biol. 2003 May;4(5):414-8
references.pmid: 12728275
references.citation: Nature. 2012 Nov 22;491(7425):574-7
references.pmid: 23135399
references.citation: Nat Cell Biol. 2007 Jan;9(1):7-14
references.pmid: 17199125
references.citation: Proc Natl Acad Sci U S A. 2005 Jun 28;102(26):9118-21
references.pmid: 15967988
references.citation: Nature. 2013 Jun 6;498(7452):82-6
references.pmid: 23739426
references.citation: Science. 1997 Feb 21;275(5303):1102-6
references.pmid: 9027306
references.citation: Small. 2011 Jan 17;7(2):209-14
references.pmid: 21213383
references.citation: J Am Chem Soc. 2009 Apr 8;131(13):4616-8
references.pmid: 19292448
references.citation: Analyst. 2013 Aug 21;138(16):4574-8
references.pmid: 23748709
references.citation: Biophys J. 2001 Mar;80(3):1417-28
references.pmid: 11222302
references.citation: Phys Rev E Stat Phys Plasmas Fluids Relat Interdiscip Topics. 2000 Sep;62(3 Pt B):4318-24
references.pmid: 11088961
references.citation: J Biophotonics. 2010 Jul;3(7):455-61
references.pmid: 20535731
references.citation: Biophys J. 1978 May;22(2):191-207
references.pmid: 580768
references.citation: Biophys J. 2004 Jun;86(6):3783-93
references.pmid: 15189874
references.citation: Nature. 2003 Oct 23;425(6960):821-4
references.pmid: 14574408
references.citation: J Am Chem Soc. 2013 Nov 13;135(45):17187-92
references.pmid: 24079659
references.citation: Int J Mol Sci. 2013 Feb 06;14(2):3514-39
references.pmid: 23389046
references.citation: Biochim Biophys Acta. 1977 Nov 24;489(2):191-206
references.pmid: 579158
references.citation: Nat Rev Mol Cell Biol. 2001 Jul;2(7):504-13
references.pmid: 11433364
references.citation: Nat Nanotechnol. 2012 Sep;7(9):583-6
references.pmid: 22902959
references.citation: Nano Lett. 2013;13(12):5985-90
references.pmid: 24188432
references.citation: Science. 2010 Jan 1;327(5961):46-50
references.pmid: 20044567
references.citation: Biochemistry. 1977 Feb 22;16(4):642-7
references.pmid: 836805