The use of gold and silver nanoparticles for surface enhanced fluorescence (SEF) of Dyes

Öztürk, Tacettin
This study focuses on preparing surface enhanced fluorescence (SEF) substrates for use in the enhancement of the emission signal of rhodamine B and fluorescein dyes. Fluorescence spectroscopy has been widely utilized owing to its high sensitivity. SEF is a process where the interactions of fluorophores with the localized surface plasmons of metal nanoparticles results in fluorescence enhancement, increased photostability and rates of system radiative decay which leads to a decreased lifetime. One of the most important factors of SEF studies is to provide a uniform distance between fluorophore and metal nanoparticle in a controlled manner; otherwise, Förster resonance energy transfer takes place from fluorophore to metal nanoparticle and emission intensity of fluorophore is quenched. The spherical gold and silver nanoparticles were prepared using the well known and straightforward chemical reduction method, in which sodium citrate acted both as a reducing agent and a stabilizer around the formed nanoparticles. Silver and gold were chosen because of their high plasmon field enhancement. Since plasmon field strongly depends on the shape and size of the nanoparticles, the prepared nanoparticles were characterized using absorption spectroscopy and field emission scanning electron microscopy (FE-SEM). Prior to deposition of silver or gold nanoparticles on glass slides, the slides were derivatized by immersing them into an aqueous solution of 3-Aminopropylethoxysilane (APTES). Following derivatization, silver or gold nanoparticles were deposited by immersing the slides into the colloid mixture. Metal nanoparticle coated slides were characterized using absorption spectroscopy and field emission scanning electron microscopy (FE-SEM). Surface enhanced Raman scattering (SERS) measurements were carried out to observe the plasmon efficiency of the deposited nanoparticles. The SERS measurements were repeated for the duration of two weeks in order to check the stability of the plasmon efficiency. In this study, different types of materials (silica, zinc oxide, gold, stearic acid.) were employed as spacers to observe their effects on fluorescence enhancement. Physical vapor deposition (PVD) and Langmuir-Blodgett (LB) film deposition techniques were used for the formation of the spacer within the substrate. Fluorescence enhancement of rhodamine B and fluorescein was observed on the prepared SEF substrates. Obtained enhancement factors indicate that SEF substrates have the potential for sensitivity improvements of fluorescence sensing in many fields.


Production and characterization of activated carbon from hazelnut shell and hazelnut husk
Çuhadar, Çiğdem; Yücel, Hayrettin; Department of Chemical Engineering (2005)
In this study, the pore structures and surface areas of activated carbons produced from hazelnut shell and hazelnut husk by chemical activation technique using phosphoric acid (H3PO4), at relatively low temperatures (300, 400 and 500oC), were investigated. Raw materials were impregnated with different H3PO4 solutions of 30%, 40%, 50% and 60% by weight. To produce activated carbon, acid impregnated samples were heated; at a heating rate of 20 oC/min to the final carbonization temperature and held at that tem...
A Solution to the Adhesion Problem of Oxide Thin Films on Zinc Selenide Optical Substrates
Cosar, M. B.; Aydogdu, G. H.; Batman, H.; Ozhan, A. E. S. (2016-05-13)
Zinc selenide optical substrates have high transparency within the 0.5- to 14.0-mu m wavelength range. This makes them an attractive candidate for multiband imaging applications in optical components. In order to minimize reflection loss in visible, near-infrared, and mid-infrared applications, zinc selenide lenses are coated with multi-layered oxide thin films by physical vapor deposition method or ion beam deposition. In this study, a four-layer anti-reflective filter at 1.064 gm and between 3.6 and 4.9 g...
Enhanced peak separation in XPS with external biasing
Ertaş, Gülay; Suzer, S (Elsevier BV, 2005-08-15)
We have demonstrated that the An 4f peaks of the capped gold nanoparticles deposited on a SiO2 (20 nm)/Si substrate can be separated form the An 4f peaks of a gold metal strip, in contact with the same sample, by application of an external voltage bias to the sample rod while recording the XPS spectra. The external bias controls the flow of low-energy electrons falling on to the sample which in-turn controls the extent of the differential charging of the oxide layer leading to shifts in the binding energy o...
Preparation and characterization of a new CdS-NiFe2O4/reduced graphene oxide photocatalyst and its use for degradation of methylene blue under visible light irradiation
Bagherzadeh, Mojtaba; Kaveh, Reyhaneh; Özkar, Saim; AKBAYRAK, SERDAR (Springer Science and Business Media LLC, 2018-10-01)
In this paper, CdS nanoparticles as a visible light active photocatalyst were coupled by NiFe2O4 and reduced graphene oxide (rGO) to form CdS-NiFe2O4/rGO nanocomposite by facile hydrothermal methods. The CdS-NiFe2O4/rGO nanocomposite shows enhanced photocatalytic activity for the degradation of methylene blue (MB) under visible light illumination. In addition to improved photocatalytic performance, this prepared nanocomposite shows increased photostability and is magnetically separable from the aqueous medi...
A new NIR absorbing DPP-based polymer for thick organic solar cells
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Sunlight covers a broad spectrum from ultra-violet to infrared, and low band gap materials are required to utilize the near infrared region (NIR) for better photon harvesting in organic solar cells. It has been shown that copolymers comprising diketopyrrolopyrrole-based acceptors and simple donors (thiophene or furan) achieve an absorption maximum at around 800 nm. In this study, selenophene was coupled with a diketopyrrolopyrrole based acceptor to yield a polymer (PFDPPSe) with an absorption maximum at 830...
Citation Formats
T. Öztürk, “The use of gold and silver nanoparticles for surface enhanced fluorescence (SEF) of Dyes,” M.S. - Master of Science, Middle East Technical University, 2010.