BOC tutorial 12/10/2015

Wood, R W Philosophical Magazine 4: 269–275. angle grating silver Wavelength (Å) Angle of Incidence

Rayleigh, L “On the Dynamical Theory of Gratings.” Proceedings of the Royal Society A 79 (532) (August 2): 399–416.

 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

 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 Sensors and Actuators 4: 299–304. Kretschmann, E, and H Raether Zeitschrift Für Naturforschung 23a: 2135–2136.

 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 Sensors and Actuators 4: 299–304.

 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

 Saturation measurement  Similar to other techniques (ITC, ELISA) [AB]

 Finding the proper conditions ◦ Immobilization ◦ Buffers, flow rate ◦ Regeneration  Non-specific binding & Referencing  Surface effects  Modelling: Does the model describe the experiment?

 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

 Initially: it does not fit  Two phases visible in sensorgram  Likely cause: Mass transport limitation

Wild-type antibody Non-glycosylated antibody K D = 60 nMK D = 10 nM