Lecture 12 - Plasmonic Nanostructures in Sensing Molecules

Lecture 12 - Plasmonic Nanostructures in Sensing Molecules...

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1 Plasmonic Nanostructures in Sensing Molecules
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2 Presentation Outline ± Introduction ± Surface Plasmon Resonance (SPR) ± Localized SPR / Nanoshells ± Surface Enhanced Raman Scattering (SERS) ± Challenges ± Conclusions / Summary You are here
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3 Introduction Abundance Variety Precise Control Easy binding to Bio Molecules Sensing Cancer Therapy Promise of more and more advanced applications than conventional techniques: Fluorescence, Chromatography, Mass Spectrometry
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4 Introduction – Motivation Proc. Nat. Ac. Sci. vol. 97, pp. 996-1001 (2000) Plasmon resonances give specific metallic nanoparticles a strong and well defined color. This effect was already used in the Middle Ages to fabricate stained-glass windows. More recently, plasmon Resonant nanoparticles have been used as biomarkers
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5 Plasma Resonance Single atom 1 2 2 0 p Ne m ω ε ⎛⎞ = ⎜⎟ ⎝⎠ 0 2 = + x x p & & () E m e x = & & P E π 4 = Nex P = ω p = plasma frequency γ = restoring force (spring) constant Material Resonance condition Resonance Frequency Bulk Metal Planar Surface Sphere Ellipsoid Plasma resonances for various geometries Optical Properties of Metal Clusters Kreibig and Vollmer,1995 0 eff = eff d = − 2 eff d = − 1 M eff M L L =− p 2 p 3 p p M L
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6 Types of Plasmonic Structures 200nm Nanoshells (LSPR) Structured LSPR or SERS films Metal-dielectric semicontinuous films Surface Plasmon Resonance (SPR)
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7 Presentation Outline ± Introduction ± Surface Plasmon Resonance (SPR) ± Localized SPR / Nanoshells ± SERS ± Challenges ± Conclusions / Summary You are here
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8 First Publication of SPR Effects (1902) The phenomenon of anomalous diffraction on diffraction gratings due to the excitation of surface plasma waves was first described by Wood in 1902.
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9 What is a surface plasmon-polariton? Plasmon: Electron density wave excited by photons of light Occurs on the metal-dielectric surface Wave vectors must satisfy: 1/2 sp = = sin εε ω ε θ ⎛⎞ ⎜⎟ + ⎝⎠ md d kk c ε m ε d
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10 SPR - Introduction ± Plasmon-polariton excitation produces absorbance peak at specific frequency ± Shift in the absorbance spectrum indicates presence of analyte molecules (change in dielectric refractive index) First experiments on biosensing using SPR method Liedberg et al, 1983
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11 SPR Excitation Techniques Kretschmann Geometry The periodic structure translates to a 2 m=0,1,2. .. eff sp kk m a π ⎛⎞ ⎜⎟ ⎝⎠ The sensor structure is irradiated from waveguide
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12 SPR Applications Chemical 1. Sensing 2. Reaction kinetics 3. Concentration measurement 4. Mass Spectrometry 5. Equilibrium properties … and many more Biological 1. Real time sensing 2. Detection of binding reactions 3. Proteomics 4. Plasma membrane studies 5. Drug delivery techniques …..and many more
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13 Applications – Industry interest/ products Surface Plasmon Resonance Biosensor Spreeta from NOMADICS SPR based sensor Texas Instruments Beverages Medical Diagnostics Food Safety National Defense Water Quality Research www.nomadics.com
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14 SPR Applications: Multi Component Analysis a. CheA alone bound to the surface c. Injection of Tar… no appreciable
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Lecture 12 - Plasmonic Nanostructures in Sensing Molecules...

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