Presentation on theme: "Gold Nanorod Biosensors and Single Particle Spectroscopy Jason H. Hafner MURI site visit July 27, 2005."— Presentation transcript:
Gold Nanorod Biosensors and Single Particle Spectroscopy Jason H. Hafner MURI site visit July 27, 2005
Gold Nanorods longitudinal transverse -Sharp, localized plasmon resonance. -Molecular size in short dimension
Localized Surface Plasmon Resonance Sensors Silver nanoparticles on substrate Antibodies conjugated to nanoparticles. wavelength absorbance
Localized Surface Plasmon Resonance Sensors wavelength absorbance Upon analyte binding, the resonance wavelength shifts: Silver nanoparticles on substrate By Nanosphere Lithography Antibodies conjugated to nanoparticles.
Localized Surface Plasmon Resonance Sensors Haes, Van Duyne Exper Rev. Mol. Diagn. 4, p. 528 (2004). -Simple physical mechanism: no surface enhancement, no aggregation. -Low cost technology: label-free, no purification or amplification of analyte. Use Gold Nanorods: More facile surface chemistry (gold). Entire substrate created by self assembly. Elongated shape and small size increases sensitivity (higher nm/RIUs).
Seed-Mediated, Surfactant Directed Gold colloid grows while surrounded by a surfactant bilayer which regulates the growth rate… Gold Nanorods Synthesis N + Br - CTAB Murphy, Langmuir 20, p. 6414 (2004). … a defect forms with poor surfactant binding to create anisotropic growth… … which results in an elongated structure. 50 mL of nanorod solution with OD=2 can be produced, but it is only stable in saturated surfactant.
PEG-SH displaces the CTAB, creating a strongly-bound buffer layer so nanorods may be put in arbitrary solutions. Nanorod PEGylation + 5000 MW PEG-thiol 400 500 600 700 800 900 1000 Nanorods in CTAB Nanorods in buffer PEG-Nanorods in buffer
Nanorod-Antibody Conjugation LC-SPDP IgG conjugated nanorods bind a complementary strip plate (left), while nanorods that are only PEGylated do not (right). +
Absorbance of Nanorods on a glass substrate 50:15 = 4.4 +/- 0.5 x 10 9 cm -1 M -1. air water SPR sensitivity = 150 nm/RIU (similar to nanosphere lithography)
Single Particle Spectroscopy To camera, CCD spectrometer, InGaAs spectrometer. Individual Gold Nanoshells, Dark Field 1. Determine more accurate optical properties of nanostructures. 2. Study complex nanostructure shapes. 3. Characterize tips for near field microscopy. 4. Find ultimate limit of LSPR biosensing. Completely removes effects of structural inhomogeneity
Single Molecule LSPR Sensing? time peak Inject analyte *Analytes (proteins) similar size to nanoparticle. *Elongated particles: optimized for LSPR. *Admit analyte at very low concentration. *Observe spectral shifts at a rapid rate.
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