Surface-enhanced Raman of dopamine and neurotransmitters using sol-gel substrates and polymer-coated fiber-optic probes

Volkan, Mürvet
Vo-Dinh, T
Surface-enhanced Raman spectroscopy (SERS) is used to detect catecholamines-viz., dopamine, norepinephrine, epinine, and isoproterenol-using a new substrate prepared with sol-gel technology. Catecholamines are complexed at the surface by iron(III) ions, which were introduced during the reduction of the silver ions embedded inside the sol-gel matrix. With the use of a He-Ne laser at a power of only 12 mW, it is possible to measure dopamine in the micromolar concentration range. A single-fiber SERS probe system was also introduced that has great potential for sampling in micro-environment applications such as in vivo measurements of dopamine. In this microprobe design both excitation and SERS signals are transmitted through the same fiber simultaneously. The tips of tapered fibers were coated with a polyvinyl alcohol polymer doped with metallic silver particles. The potential of the SERS method and microprobes for medical diagnostics is discussed.


Differentiation of mesophilic and thermophilic bacteria with Fourier transform infrared spectroscopy
Garip, Sebnem; Bozoglu, Faruk; Severcan, Feride (SAGE Publications, 2007-02-01)
In the present study the characterization and differentiation of mesophilic and thermophilic bacteria were investigated by using Fourier transform infrared (FT-IR) spectroscopy. Our results showed significant differences between the FT-IR spectra of mesophilic and thermophilic bacteria. The protein-to-lipid ratio was significantly higher for thermophiles compared to mesophiles. The absorption intensity of the CH3 asymmetric stretching vibration was higher in thermophilic bacteria, indicating a change in the...
Escape of photoelectrons and Compton-scattered photons from an HPGe detector
Can, Cüneyt (Wiley, 2003-07-01)
The response function of a planar HPGe detector due to escape of photoelectrons and Compton-scattered photons was studied for a point source with 59.5 keV energy. It was shown that both mechanisms, in addition to Ge x-ray escape, leading to partial deposition of energy, could be observed in the same experiment. A Monte Carlo program was used to investigate these components of the response function. The results indicate that although the escape of scattered photons and Ge x-rays are of the same magnitude, th...
Surface-enhanced Raman scattering spectroscopy via gold nanostars
Nalbant Esentürk, Emren (Wiley, 2009-01-01)
Anisotropic metallic nanoparticles (NPs) have unique optical properties, which lend them to applications such as surface-enhanced Raman scattering (SERS) spectroscopy. Star-shaped gold (Au) NPs were prepared in aqueous solutions by the seed-mediated growth method and tested for Raman enhancement using 2-mercaptopyridine (2-MPy) and crystal violet (CV) probing molecules. For both molecules, the SERS activity of the nanostars was notably stronger than that of the spherical Au NPs of similar size. The Raman en...
Disorder-induced Raman scattering in ammonium halides
Yurtseven, Hasan Hamit (Informa UK Limited, 1995-01-01)
The mechanism responsible for the lambda-phase transitions in ammonium halides is investigated within the framework of an extended theory of the disorder-induced Raman scattering. The Raman spectra of ammonium halides have been predicted for both the disordered beta phase (NH4Cl and NH4Br) and the ordered gamma phase (NH4Br). It is postulated that those terms which dominate the dynamic distortions of the lattices and thereby cause the bulk of the disorder-allowed Raman scattering, will also dominate the qua...
Photoelectron, compton and characteristic x-ray escape from an HPGe detector in the range 8-52 keV
Yilmaz, E; Can, Cüneyt (Wiley, 2004-11-01)
Escape of photoelectrons, Compton-scattered photons and Ge x-rays from an HPGe detector was studied as a function of energy in the range 8-52 keV. A variable-energy source producing Cu, Rb, Mo, Ag, Ba. and Tb x-rays was used. All three mechanisms for energy loss were observed in the same experiment for Ba and Tb, while only x-ray and photoelectron escapes were evident in the spectra for Ag, Mo, Rb, and Cu. Spectral features and possible mechanisms for partial energy deposition were investigated. A Monte Car...
Citation Formats
M. Volkan and T. Vo-Dinh, “Surface-enhanced Raman of dopamine and neurotransmitters using sol-gel substrates and polymer-coated fiber-optic probes,” APPLIED SPECTROSCOPY, pp. 1842–1848, 2000, Accessed: 00, 2020. [Online]. Available: