Short description: Analytical technique that probes molecular layers adsorbed to the surface of a waveguide
Dual-polarization interferometry (DPI) is an analytical technique that probes molecular layers adsorbed to the surface of a waveguide using the evanescent wave of a laser beam. It is used to measure the conformational change in proteins, or other biomolecules, as they function (referred to as the conformation activity relationship).
The technique is quantitative and real-time (10 Hz) with a dimensional resolution of 0.01 nm.[1]
Extensions of dual-polarization interferometry also exist, namely multiple pathlength dual-polarization interferometry (MPL-DPI)[2][3][4] and absorption enhanced DPI. In MPL-DPI quantification of both layer thickness and refractive index (density) and therefore mass per unit area can be made for in situ and ex-situ coated films, where normal DPI can only calculate film properties if the interferogram is constantly monitored. Absorption enhanced DPI[5] (AE-DPI) is used to separate the mass of different molecules on the surface, exploiting the absorption of one of the molecular species compared to the other species on the surface.
Applications
A novel application for dual-polarization interferometry emerged in 2008, where the intensity of light passing through the waveguide is extinguished in the presence of crystal growth. This has allowed the very earliest stages in protein crystal nucleation to be monitored.[6] Later versions of dual-polarization interferometers also have the capability to quantify the order and disruption in birefringent thin films.[7] This has been used, for example, to study the formation of lipid bilayers and their interaction with membrane proteins.[8][9]
References
↑Swann, MJ; Freeman, NJ; Cross, GH (2007). "Dual Polarization Interferometry: A Real-Time Optical Technique for Measuring (Bio)Molecular Orientation, Structure and Function at the Solid/Liquid Interface". in Marks, R.S.. Handbook of Biosensors and Biochips. 1. John Wiley & Sons. Pt. 4, Ch. 33, pp. 549–568. ISBN978-0-470-01905-4.
↑Coffey, Paul D.; Swann, Marcus J.; Waigh, Thomas A.; Schedin, Fred; Lu, Jian R. (22 June 2009). "Multiple path length dual polarization interferometry". Optics Express17 (13): 10959. doi:10.1364/OE.17.010959.
↑Coffey, Paul David; Swann, Marcus Jack; Waigh, Thomas Andrew; Mu, Qingshan; Lu, Jian Ren (2013). "The structure and mass of heterogeneous thin films measured with dual polarization interferometry and ellipsometry". RSC Advances3 (10): 3316. doi:10.1039/C2RA22911K.
↑Mashaghi, A; Swann, M; Popplewell, J; Textor, M; Reimhult, E (2008). "Optical Anisotropy of Supported Lipid Structures Probed by Waveguide Spectroscopy and Its Application to Study of Supported Lipid Bilayer Formation Kinetics". Analytical Chemistry80 (10): 3666–76. doi:10.1021/ac800027s. PMID18422336.
↑Sanghera, N; Swann, MJ; Ronan, G; Pinheiro, TJ (2009). "Insight into early events in the aggregation of the prion protein on lipid membranes". Biochimica et Biophysica Acta (BBA) - Biomembranes1788 (10): 2245–51. doi:10.1016/j.bbamem.2009.08.005. PMID19703409.
↑Lee, TH; Heng, C; Swann, MJ; Gehman, JD; Separovic, F; Aguilar, MI (2010). "Real-time quantitative analysis of lipid disordering by aurein 1.2 during membrane adsorption, destabilisation and lysis". Biochimica et Biophysica Acta (BBA) - Biomembranes1798 (10): 1977–86. doi:10.1016/j.bbamem.2010.06.023. PMID20599687.
Freeman, NJ; Peel, LL; Swann, MJ; Cross, GH; Reeves, A; Brand, S; Lu, JR (2004). "Real time, high resolution studies of protein adsorption and structure at the solid–liquid interface using dual polarization interferometry". Journal of Physics16 (26): S2493–S2496. doi:10.1088/0953-8984/16/26/023. Bibcode: 2004JPCM...16S2493F.
Khan, TR; Grandin, HM; Mashaghi, A; Textor, M; Reimhult, E; Reviakine, I (2008). "Lipid redistribution in phosphatidylserine-containing vesicles adsorbing on titania.". Biointerphases3 (2): FA90. doi:10.1116/1.2912098. PMID20408675.