Photonic crystals in biology

Poster Session, Tuesday, June 15
Theme A1 - B702
Performance of Silver Doped PEDOT Polymer Film as a SERS Substrate
Üzeyir Doğan, 1* Murat Kaya, 1 Atilla Cihaner 2 and Mürvet Volkan 1
1 Department of Chemistry, Middle East Technical University, Ankara, Turkey
2 Department of Materials Engineering, Atılım University, Ankara, Turkey
Abstract - A new and simple polymer substrate for inducing Surface Enhanced Raman Scattering (SERS) has been
investigated. This new SERS substrate consists of an ITO slide as a solid support electrochemically covered with poly (3,4
ethylenedioxythiophene) (PEDOT) and fine silver particles.
Raman spectroscopy is an analytical technique that is
widely used to characterize chemical substances in samples
[1] because of having different signal patterns for different
Raman active substances. However, the sensitivity of the
technique is very low. Surface enhanced Raman scattering
(SERS) overcomes this disadvantage of Raman
spectroscopy. A major factor in the large enhancement
associated with SERS is the strong electromagnetic field
enhancement close to the surface produced by surface
plasmons, which are the result of the coupled oscillations of
the conductance electrons of metals and the electromagnetic
field component of the incident light [2,3]. When an analyte
is brought into contact with nanoparticles of metals such as
silver [4] or gold [5] the strong field enhances the Raman
effect.
Conducting polymers have a wide range of applications
in the field of optical, electronic, electro-chromic devices,
and sensors etc. Among them, poly (3,4
ethylenedioxythiophene) (PEDOT) (Figure 1) is considered
to be a good applicant for its regioregular polymerization,
low bandgap, stability and optical transparency. The recent
technological interests are in the synthesis of conducting
polymers incorporated with metal nanoparticles for varied
applications. Conducting polymers are widely employed as
support materials for dispersing the metal particles [6].
Figure 2. Raman spectrum of 10 -7 M BCB
Additionally, the homogeneity of the surface in terms of
its SERS activity (Figure 3) and shelf life of the substrates
were examined.
Figure 3. Raman spectrum of 10 -7 M BCB at different points on the
same substrate.
Figure 1. Poly(3,4-ethylenedioxythiophene) or PEDOT
In this study, we investigated a new SERS active
substrate using electrochemical method. Briefly, the surface
of indium tin oxide (ITO) coated glass surface covered
with variable amounts of PEDOT polymer and doped with
variable amounts of silver nanoparticles. The effects of
several experimental conditions of preparation were
investigated using low concentrations of brilliant cresyl blue
(BCB). Figure2 shows the characteristic SERS signal of 10 -7
M BCB acquired with the prepared substrate. The spectral
evaluations of this compound closely matched with those
reported in literature.
* murvet@metu.edu.tr
[1] Smith, E., Dent, G., 2005. Modern Raman spectroscopy. A
practical approach. Wiley, England
[2] Raether, H., 1988. Surface Plasmons. Springer-Verlag, Berlin
[3] Schatz, G-C., Van Duyne, R.P., 2002. Handbook of Vibrational
Spectroscopy. Wiley, Chichester
[4] Li, S-Y., Cheng, J., Chung, K-T,. 2008. Surface-enhanced
Raman spectroscopy using silver nanoparticles on a precoated
microscope slide, Spectrochimica Acta, Part A 69: 524–527
[5] Joo, S-W., 2004. Surface-enhanced Raman scattering of 4,4-
bipyridine on gold nanoparticle surfaces, Vibrational
Spectroscopy, 34: 269–272
[6] S. Harish , J. Mathiyarasu , K. L. N. , V. YegnaramanJ Appl
Electrochem (2008) 38:1583–1588
6th Nanoscience and Nanotechnology Conference, zmir, 2010 335