Photonic crystals in biology

Poster Session, Tuesday, June 15
Theme A1 - B702
Synthesis and Characterization of CdTeFe 3 O 4 Magnetic Nanoparticles
1 , Tülay Oymak 1 , 1 *
1 Department of Analytical Chemistry, Faculty of Pharmacy, Gazi University, Ankara 06500, Turkey
Abstract- A simple chemical method for the fabrication of magnetic-fluorescent nanocomposite materials composed of magnetic nanoparticles
and quantum dots at room temperature is described. The nanosutructures were characterized with fluorescence spectrometry, TEM, EDAX and
magnetic measurements.
Recent advance in nanotechnology have led to a new class
of labelling based on semiconductor quantum dots (QDs).
Surface passivated QDs exhibit high stablity, large absorption
coefficients, size tunable flurescence. These properties have
made QDs an ideal for labeling with broad applications
especially in in biochemistry [1-2]. The combination of
magnetic and fluorescent properties in one nanocomposite
provides new nanoscale photonic devices which would be
manipulated using an external magnetic field [3]. In
immunoassays, QDs are usually used in labeling of secondary
antibodies. Those QD labeled antibodies can be used after the
IMS of the target molecule in order to detect the target. But the
paramagnetic microparticles used in IMS cause partial or
complete quenching of QDs and lowers the sensitivity of the
analyze. Therefore, development of magnetic nanoparticles
which do not cause any quenching would be favorable in
bioassays and in some applications like fluorescence
resonance energy transfer (FRET) two different fluorescence
molecules are used as a donor and acceptor. Development of a
nanoparticle which has both magnetic and fluorescence
properties would be an important advance for such systems.
In this work, we describe a simple synthesis method for the
magnetic-florescent, CdTeFe 3 O 4 , nanocomposite material in
aqueous medium, at room temperature. Characterization of the
core-shell structured Fe 3 O 4 -CdTe nanoparticle proved that the
resulting nanoparticles composed of Fe 3 O 4 core and the CdTe
shell. Rapid and room temperature reaction synthesis of CdTe
coated magnetic nanoparticle and subsequent surface
modification may provide binding properties for sensing
application.
To synthesize CdTe coated iron nanoparaticle, the seed
mediated synthetic method was carried out. First, The Fe3O 4
nanoparticles were prepared by coprecipitation of Fe (II) and
Fe (III). Fe(II) / Fe(III) ratio is kept as 0.5 in an alkaline
solution. Briefly, 1.28 M FeCl 3 and 0.64 M FeSO 4 7H 2 O were
dissolved in deionized water. The solution was then strirred
vigorously until the iron salts were dissolved. Subsequently, a
solution of 1M NaOH was added dropwise into the mixture
with stirring for 40 minutes.
After the preparation of the of Fe3O 4 core, CdTeFe 3 O 4
nanocomposite particles were prepared by bubling the gaseous
tellerium hydride produced by the hydride generation system
through the solution composed of Fe 3 O 4 , 0.03 M CdCl 2 and
0.03 M citrate for 5 minutes. The magnetically active
nanoparticles were collected by a magnet and the supernatant
solution was discarded. The residue was diluted with 5 mL
ethanol and treated with 3-mercaptopropionic acid and shaked
for four hours. The excess of mercaptopropionic acid was
removed by centrifugation. The magnetic separation of these
nanoparticles was easily accomplished and the resulting
nanoparticles were characterized with Transmission Electron
Microscopy (TEM), UV-Vis, X Ray Diffraction (XRD) and
magnetic properties of the nanoparticles were also examined
by vibrating sample magnetometer.
Typical morphology of resulting nanoparticles is shown in
Figure 1.
Figure 1. TEM image of CdTeFe 3 O 4 , nanoparticle
The fluorescence spectrum of the nanoparticle is given in
Figure 2.
R.I.
120
80
40
0
650 675 700 725 750
Wavelength, nm
Figure 2. The fluorescence spectrum of the CdTeFe 3 O 4
nanoparticle exc = 330 nm
*Corresponding author: 1Tnertas@gazi.edu.tr
[1] Sheikh, S. H.; Abela, B. A.; Muchandani, A., Anal Biochem.
2000, 283(1), 33-38
[2] Chan, W.C.; Nie, S., Science, 1998, 281(5385), 2016-2018
[3]Corr, S. A.;Rakovich Y. P.; Gun’ko Y. K., Nanoscale Res. Lett.,
2008, 3, 87-104
6th Nanoscience and Nanotechnology Conference, zmir, 2010 327