Patterning of plasmonic structures for (bio) sensing
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1 Patterning of plasmonic structures for (bio) sensing Gonçal Badenes, Mark Kreuzer, Petru Ghenuche, Romain Quidant Biosensing in the nanoscale Confining light to the nanoscale Implementing a nanostructured biosensor Fabrication Characterisation Enhancing light-matter interaction
Transcript of Patterning of plasmonic structures for (bio) sensing
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Patterning of plasmonic structures for (bio) sensing
Gonçal Badenes, Mark Kreuzer, Petru Ghenuche, Romain Quidant
Biosensing in the nanoscale
Confining light to the nanoscaleImplementing a nanostructured
biosensorFabricationCharacterisation
Enhancing light-matter interaction
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Diffraction limit
This “diffraction limit” constraint can be expressed as a particular case of Heisenberg’s uncertainty principle:
where px=hkx/2π
Light cannot be confined to linear dimensions much smaller than λ/2
(Abbe 1873)
Surface Plasmon BasicsSurface Plasmon Polariton Localised Surface Plasmon
1ε2ε
a
E0
If a << λ ⇒ dipole:(electrostatic approximation)
• Field localization and enhancement
• Strong scattering and absorption
• Highly sensitive to changes in the environment
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AFM image ASNOM image
3 µm × 3 µm
Sub-wavelength patterning of the optical near field
Theory Experiment
R. Quidant et al., "Sub-wavelength patterning of the optical near-field”, Opt. Express 12, 282-287 (2004)
High sensitivitysensing
Nano-opticaltweezing
Enhanced molecularspectroscopy
Localised surface plasmons can be used for nano- optics, manipulation, sensing, switching, interconnects…
(Localised) plasmonics
Interconnects
See e.g. W.L. Barnes et al., “Surface plasmon subwavelength optics,”Nature 424, 824 - 830 (2003)
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Biosensing in the nanoscale
Confining light to the nanoscaleImplementing a nanostructured
biosensorFabricationCharacterisation
Enhancing light-matter interaction
“Single particle” sensing
Local field enhancement can
be observed around “isolated”
metal nanoparticles when the plasmon
is excited
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Arrangement of Gold
Drop of Liquid
Glass Slide with gold & bioreagents
Bio-modified Gold in the drop
Schematic system setup
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NH
CH2CH2CH2S i
O O O
CH3CH2Si
O O O
CH3CH2Si
O O O
NH
CH2CH2CH2S i
O O O
NH
CH2CH2CH2S i
O O O
APTMS ETMS
Chemical modification of the glass surface
Selective salinization controls density of gold colloid (subsequently
bound to surface)
APTMS binds gold, ETMS doesn’t
Numerous investigation zones
Each drop can be a different solutiondifferent sensor!
RED ARROW/LINE: binding of antibody, no presence of target stanozolol
BLACK ARROW/LINE: antibody bound by target and washed away
NH
CH2CH2CH2Si
O O O
NH
CH2CH2CH2Si
O O O
NH
CH2CH2CH2Si
O O O
Au
NH
CH2CH2CH2Si
O O O
NH
CH2CH2CH2Si
O O O
NH
CH2CH2CH2Si
O O O
Au
NHCH2CH2CH2Si
O O O
NH
CH2CH2CH2Si
O O O
NH
CH2CH2CH2Si
O O O
Au
NH
CH2CH2CH2Si
O O O
NH
CH2CH2CH2Si
O O O
NH
CH2CH2CH2Si
O O O
Au
NH
CH2CH2CH2Si
O O O
NH
CH2CH2CH2Si
O O O
NH
CH2CH2CH2Si
O O O
Au
NHCH2CH2CH2Si
O O O
NH
CH2CH2CH2Si
O O O
NH
CH2CH2CH2Si
O O O
Au
NH
CH2CH2CH2Si
O O O
NH
CH2CH2CH2Si
O O O
NH
CH2CH2CH2Si
O O O
Au
glass
Nor
mal
ised
Extin
ctio
n
540 560 580Wavelength (nm)
1.0
0.9
600520
0.8
0.7
Stanozolol-BSA
Stanozolol
Anti-stanozolol
Sensor working principle
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1c)
background
non-specific
specific
Do we have specific binding?
non-specific binding controls
RED ARROW/LINE: no presence of target stanozolol
BLACK ARROW/LINE: all antibody bound by target and washed away
(■) LPR
(▼) spectrophotometric
Quantifying sensor response
M. Kreuzer et al., Biosensors & Bioelectronics 21 (7) (2006)
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Biosensing in the nanoscale
Confining light to the nanoscaleImplementing a nanostructured
biosensorFabricationCharacterisation
Enhancing light-matter interaction
“Single particle” sensing
Local field enhancement can
be observed around “isolated”
metal nanoparticles when the plasmon
is excited
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Field enhancement:geometry and separation tuning
Previous studies (elongated structures, dimers, particles with different shapes) Field enhancement Г≈103-4
J. Kottmann and O. J. F. Martin, Optics Express, 8, 655 (2001)
E. Hao and G. C. Schatz, Chem. Phys., 120, 357 (2004)
Enhancing sensitivity: arrays
Electric near-field map Influence of the covering layer
D
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S. Enoch et al., Optics Exp. 12, (2004)
Enhancing sensitivity: dimer arrays
Influence of the covering layer
P. Ghenuche et al., Opt. Lett. 30(2005)
Field enhancement:particle arrangements
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Field enhancement innanoparticle chains
100nm
20nm
100nm
~20nm
Sample fabrication
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Dimer arrays
Nanoparticle chains
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Summary
Localised surface plasmons are ideal candidates to be used as biosensors
Random arrangements of gold nanoparticles can achieve competitive sensitivity
Sensitivity and accuracy can be significantly improved by using lithographically patterned samples
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