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J.-H. Yoon, L. Langolf, W. Xie,R. Grzeschik, E. Stepula,
X. Wang, Y. Zhang, Sebastian Schlücker
University Duisburg-Essen
Department of Chemistry
www.uni-due.de/schluecker-lab
Surface-enhanced Raman Spectroscopy and Imaging with Molecularly Functionalized Noble Metal Nanoparticles
Raman Workshop@ETHZ13th June 2018
ω0 ωvib
Modulated electricfield with angular frequency ω0 ωvib+-
ω0 ωvib-ω0 ωvib+ ω0
Classical Description of Raman Scattering
Induced dipole moment:
Nano-Antenna: Receiver and Transmitter
Localized Surface Plasmon Resonance (LSPR) Excitation on AuNP
Normal versus Surface-Enhanced Raman Scattering (SERS)
Normal Raman:IR ∝ E2
The Electromagnetic Enhancement (EM) Contribution
SERS:ISERS ∝ │EL(ω0)│2
E∝ 1/d3
∝ 1/d12 Sensitivity
· │EL(ωR)│2 ≈ E4
Surface selectivity
Normal versus Surface-Enhanced Raman Scattering (SERS)
A Short History of Surface-enhanced Raman Scattering (SERS)
1973 - First observation (Fleischmann) 1977 - First explanation & quantitative measurement (Van Duyne)1978 - Electromagnetic model for SERS (Moskovits)1997 - First observation of single-molecule SERS (Nie, Kneipp)
SERS Enhancement Factor (EF):SERS Signal/Number of Molecules on Surface
Normal Raman Signal/Number of Molecules in Solution
EM = plasmonic (up to ~1011) × CM (non-plasmonic up to ~102-3)
SERS labels (nanotags)
NP
= Raman label= Raman reporter
SERSlabel
vs. Label-free
NP
= analyte moleculein solution
SERS Applications with Noble Metal Colloids
• Detection of Analytesbiomolecules, drugs, explosives, food components, pharmaceuticals, pigments (e.g., in paintings)
• Chemical Reaction Monitoring
• Immunoassays• iSERS Microscopy
SERS Literature: From Fundamentals to Applications
Surface-Enhanced Raman Spectroscopy: Concepts and Chemical Applications
Angew. Chem. Int. Ed. 2014, 53, 4756-4795.
Maximum Signal Enhancement: Dimers for Ultrasensitive SERS
DimerMonomer
Hot SpotDependent on Gap Distance
Dimers: Generating a HOT SPOT
Inter-gap
Intra-gap
Crevice
Physical Chemistry I @ UDE
Precision Plasmonics
SERS nanotags/labelsimmuno-SERS (iSERS)
Chemical Energy Conversion
Small 2018
Angew. Chem. 2009
Chem. Comm. 2014
Small 2010
Nanoscale 2013
Small 2011
PCCP 2015Analyst 2016
Anal. Chem. 2018
Chem. Comm. 2012 JACS 2011
JACS 2013
Angew. Chem. 2016
Nature Comm. 2017
Nature Comm. 2015
Anal. Chem. 2017
Theory: Ideal Dimers of Gold Nanospheres
Plasmon Hybridization(cf. LCAO theory)
Nordlander et al.
kE
Two spheres separated by a very small defined gap
Towards Ideal Dimers: Experimental Challenges
Colloidal AuNPs
Gold nanoparticles are not perfectly spherical
but are nanocrystals
NPs by EBL
kE
Two spheres separated by a very small defined gap
Halas et al. Nano Lett. 2013, 13, 3281.
Non-Spherical Particles with Controlled Gap Distance
Single particle dark fieldscattering spectra
Controlled short gap distance:C8 dithiol (ca. 1.3 nm)
Non-idealdimers
Precision Plasmonics: Ideal Dimers of Gold Nanospheres
Non-idealdimers
idealdimers
Precision Plasmonics: Ideal Dimers of Gold Nanospheres
idealdimers
Small 2018
Correlative Single-Particle Rayleigh/SERS Imaging in Suspension
Rayleigh
Raman
Anal. Chem. 2018
Single-Particle SERS of Dimers in Suspension
100 ms / frame
Rayleigh
Raman Raman
Rayleigh
10 ms / frame
Anal. Chem. 2018
Summary 1: Precision Plasmonics with AuNP Dimers
Correlative Rayleigh/SERS video rate imaging of single NPs in suspension
uniform structure (gap morphology) uniform scattering spectra
2: Rayleigh/Mie
1: Raman orFluorescence
100 % (Ref.)
x % (?!)
Physical Chemistry I @ UDE
Precision Plasmonics
SERS nanotags/labelsimmuno-SERS (iSERS)
Chemical Energy Conversion
Small 2018
Angew. Chem. 2009
Chem. Comm. 2014
Small 2010
Nanoscale 2013
Small 2011
PCCP 2015Analyst 2016
Anal. Chem. 2018
Chem. Comm. 2012 JACS 2011
JACS 2013
Angew. Chem. 2016
Nature Comm. 2017
Nature Comm. 2015
Anal. Chem. 2017
Applications of SERS with Plasmonic Nanoparticles
Label-free SERS
NP
= analyte moleculein solution
SERS NP labels = Nanotags
NP
= Raman label= Raman reporter molecule
SERSlabel
vs.
vs.
Spectral Multiplexing: Small Width of Raman Peaks
Nanoscale 2014
Spectral Multiplexing with SERS Labels
Detection of multiple labelsin a single measurement!
# 1label
# 2 label
# 3 label
# 4 label
Wavenumber (cm-1)
Anal. Bioanal. Chem. 2009
SERS Multiplexing: Quantitative 6-plex
400 600 800 1000 1200 1400 1600 18000.0
0.2
0.4
0.6
0.8
1.0 Mixture (measured) Mixture (calculated) Difference
norm
. SER
S In
tens
ity
wavenumber [cm-1]
BMBATFMBATN MMTAA MNBAMMC+ + + + +111 1 11: : : : :
Quantitative 6-Color SERS Experiments (Cuvette)
1 2 3 4 50
0.5
1
1.5
2
2.5
3
3.5
1:1:1:1:1:1 1:1:1:3:3:3 1:3:1:3:1:3 3:1:3:1:3:1 3 :3:3:1:1:1
J. Raman Spectrosc. 2016
Example: Benign vs. Cancerous Prostate Biopsies
Benign: (+)-P63 (tumor suppressor; cancer-specific)
Cancerous: (-)-P63iSERSBF & iSERS iF iF & iSERS
Benign
PSA
P63
+
+
+
-
Cancerous
2-Color-iSERS: Benign vs. Cancerous Prostate Biopsies
Benign
PSA
P63
+
+
+
-
Cancerous
2-Color-iSERS: Benign vs. Cancerous Prostate Biopsies
Summary 2: SERS nanotags for iSERS microscopy & assays
SERS label= plasmonic NP & Raman reporter& shell (optional)
Multiplexing (colours) & Quantification
photostable& bright (single NPs!)
Long term goal: Personalized diagnostics(quantitative, multi-marker)
iSERS= immuno-SERS microscopy
Physical Chemistry I @ UDE
Precision Plasmonics
SERS nanotags/labelsimmuno-SERS (iSERS)
Chemical Energy Conversion
Small 2018
Angew. Chem. 2009
Chem. Comm. 2014
Small 2010
Nanoscale 2013
Small 2011
PCCP 2015Analyst 2016
Anal. Chem. 2018
Chem. Comm. 2012 JACS 2011
JACS 2013
Angew. Chem. 2016
Nature Comm. 2017
Nature Comm. 2015
Anal. Chem. 2017
Plasmonic NPs for Chemical Energy Conversion
J. Am. Chem. Soc. 2011
Au
Pt
BifunctionalAu/Pt/Au
nanoraspberries
Microfluidic SERS: Label-free Kinetic Reaction Monitoring
4-NTP 4-ATPNO2
S
NH2
S
NaBH4, Pt-Kat.
NP NP
4-ATP
Angew. Chem. Int. Ed. 2016, 55, 13729.
NO2
S
NH2
S
NaBH4, Pt-Kat.
NP NP
NO2
S
NaBH4, Pt-
NP
Model Reaction: Nitro to Amino Reduction (NaBH4, Pt-cat.)
4-NTP
4-ATP
AgS
NO2
AgS
NH2hν
HCL
Wavenumber / cm-1
H2SO4
HCl
NaCl
H2SO4 + NaCl
Ram
an In
tens
ity
νs(NO2)
νs(C−C)(4-ATP)
νs(C−C)(4-NTP)
H2O
Surprise: Hydride Reduction without Hydride Reagents!
no NaBH4 !
4-NTP
Ag core/Ag satellite NPs
4-ATP
Hot Electrons & Photorecycling (AgX)
Formally: Hydride reduction without hydridesH- equivalent in protic environment: H- = H+ + 2e-
-
Nature Comm. 2015
Hot Electrons Drive Nano-Localized Chemistry
Nature Comm. 2017
d)
Plasmon
Radiative channelScattering
Non-radiative channel
Electron-phonon coupling
Heat
Hot electrons
Absorption
Charge carrier generation
Label-freeSERSOR
iSERS labels
ReductionChemistry;
Photorecycling
Photothermaleffect
Decay
Summary 3: from label-free SERS to plasmonic chemistry
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