1. Synthesizing Gold Nanoparticle Dimers
Ryan Miller, Yan Zhou, Peng Zhang
Department of Chemistry
University of Cincinnati, Cincinnati, Ohio 45220
BACKGROUND
The research involving gold dimers has been increasing significantly in recent
years. A dimer is formed when two metal particles are close together and have
a combined surface plasma resonance. This will greatly enhance the
molecule’s electric field. This enables a great increase in Raman and
photoluminescence signals. The goal of this experiment is to synthesize gold
dimers using a new method. Testing the results required the use of Surface-
Enhanced Raman Spectroscopy (SERS) to produce a qualitative result.
OBJECTIVES
 Find the right procedure for synthesizing gold dimers
 Use SERS in order to test if the procedure produced the desired dimers
 Take pictures of the gold dimers
RESULTS (continued)
Acetone and TTCA Controls
CONCLUSION
The PMMA method was successful in producing the desired gold
dimers. The method involved self-assembly of the gold particles on a
PMMA template. The gold dimers produced allowed for a greatly
enhanced SERS signal. With high plasmonic enhanced optic properties,
the gold dimers may be useful in studies involving solution based SERS
and plasmonic applications.
REFERENCES
Zhong, Lu B., Jun Yin, Yu-Ming Zheng, Qing Lu, and Gang-
Hong Luo. "Self-Assembly of Au Nanoparticles on PMMA
Template as Flexible,." Analytical Chemistry 86 (2014): 6262.
THANKS
Support from the Chemistry Department, University of
Cincinnati is appreciated.
ILLUSTRATIONS
TTCA
RESULTS
Raman Microscope Raman Spectrum
TTCA Conjugated Gold Nanoparticles on PMMA Template
TTCA Conjugated Gold Dimers on PMMA Template
TTCA Conjugated Gold Dimers
PROCEDURE & MATERIALS
 7.5 mL of freshly prepared Au NPs suspension is transferred to a glass vial, followed by
addition of 4.5 mL of toluene with 4mg of PMMA
 4 mL of ethanol is injected into the Au NPs suspension using a mechanical syringe pump
with a feeding rate of 10 mL/h.
 The glass vial is placed in the hood for 24h. A thin PMMA template will be formed on the
top of the aqueous solution after the evaporation of toluene. The self-assembled Au NPs
layer will be fixed on the newborn PMMA template.
 A pair of tweezers is used to retrieve the prepared Au NPs/PMMA film onto a glass slide.
 Rinse the PMMA film with water to remove any free Au NPs.
 The link molecule (also used as Raman probe) is added by rinsing the PMMA film with a
Trithiocyanuric acid solution(TTCA, 1uM in ethanol). Rinse the PMMA film to remove
unbinding TTCA molecules.
 The Au NP dimers will be formed by adding another portion of Au NPs suspension onto
the prepared TTCA-conjugated Au NPs/PMMA film. Rinse the film with water to remove
any free Au NPs.
 Dissolve the prepared Au dimers/PMMA film in acetone. The final product is collected by
centrifuging the solution at 6000rpm.
 The product is measured using a Raman microscope (pictured below) at wavelengths of
633 nm and 785 nm.
 Using the instruments microscope and Transmission Electron Microscopy (TEM), the
results are photographed.
Poly(methyl methacrylate) (PMMA)Trithiocyanuric Acid (TTCA)
Ethanol
Gold NPs
Toluene
& PMMA
PMMA & Au Film
Conjugation of Gold Dimers on PMMA Template
1000 1500
0
2000
4000
6000
8000
Intensity
Raman shift(cm-1
)
PMMA@Au@TTCA
500 1000 1500
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
B
Raman shift(cm-1
)
Acetone
600 800 1000 1200 1400 1600 1800
0
10000
20000
30000
40000
50000
60000
B
Raman shift(cm-1
)
TTCA
979
TEM Image of Gold Dimers and Single
Atoms
600 800 1000 1200 1400 1600 1800
500
1000
1500
2000
2500
Intensity
Raman shift(cm-1
)
Spot 1
Spot 2
975 1355
600 800 1000 1200 1400 1600 1800
2000
4000
6000
8000
Intensity
Raman shift(cm-1
)
spot 1
spot 2
975 1355
PMMA
Au