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BOC tutorial 12/10/2015
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Wood, R W. 1902. Philosophical Magazine 4: 269–275. angle grating silver Wavelength (Å) Angle of Incidence
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Rayleigh, L. 1907. “On the Dynamical Theory of Gratings.” Proceedings of the Royal Society A 79 (532) (August 2): 399–416.
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Surface Plasmons: electron oscillations on a dielectric interface Can be excited by coupling to a photon with the same wave vector: ‘disappearing photons’ Excited surface plasmons propagate like a wave over the surface until the energy is absorbed or emitted
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Wavefunction of plasmons on metal-dielectric (k sp ) interface depends on wavelength and dielectric constants Wavefunction of light parallel to the metal surface (k x ) depends on wavelength, dielectric constant and angle of incidence In a thin metal film, the light wave on the surface can affect the plasmon wave on the other side At some angle θ, k x will equal k sp ie. the two waves are equal and the plasmon wave will start to resonate θ Liedberg, B., C. Nylander, I. Lundstrom. 1983. Sensors and Actuators 4: 299–304. Kretschmann, E, and H Raether. 1968. Zeitschrift Für Naturforschung 23a: 2135–2136.
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Resonance is observed as a narrow minimum in intensity of reflected light Changes to the refractive index on the metal-dielectric interface change the dielectric constant of the interface (like different medium or a layer of molecules) If the dielectric constant changes, the wavefunction changes and thus the angle where resonance occurs Liedberg, B., C. Nylander, I. Lundstrom. 1983. Sensors and Actuators 4: 299–304.
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Real-time Label free Quantitative analysis Now also multiplex K D in nM to mM range Needs heavy molecules as analyte Assay in pure or non-pure samples
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Saturation measurement Similar to other techniques (ITC, ELISA) [AB]
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Finding the proper conditions ◦ Immobilization ◦ Buffers, flow rate ◦ Regeneration Non-specific binding & Referencing Surface effects Modelling: Does the model describe the experiment?
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Anti-citrullinated protein antibody from RA patients Specific glycosylation in Fab ◦ Highly present in some patients Effects on affinity? Compare glycosylated and non-glycosylated variant
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Initially: it does not fit Two phases visible in sensorgram Likely cause: Mass transport limitation
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Wild-type antibody Non-glycosylated antibody K D = 60 nMK D = 10 nM
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