Photonic crystals in biology

Poster Session, Tuesday, June 15
Theme A1 - B702
Facile preparation method to tune size (12 - 500 nm) of luminescent silica nanoparticles
Gülay Durgun 1 , Özlem Gezici 1 , Serdar Özçelik 1 *,
Izmir Institute of Technology, Faculty of Science, Department of Chemistry, Urla-Izmir 35430
Abstract-We report a simple method to systematically prepare dye doped silica nanoparticles with continuously tunable size in the range
from 12 to 500 nm. The results of dynamic light scattering and electron microscopy proved that nanoparticles are highly monodisperse even
at the scale of 12 nm. We showed that initial amounts of ethanol and ammonia are instrumental to tune the size of particles. We
demonstrated silica network providing photostability as protective layer for dye molecules against solvents, fluorescence quenchers and pH.
Moreover, we found that the particles are not cytotoxic upto 1 mg/ml with 72 hours of incubation period.
The dye-doped silica nanoparticles are one of the most
widely preferred material for labeling in bioanalysis and
biotechnological applications. Silica shell which is
thought to be biocompatible and non-toxic [1] protects dye
molecules from the surrounding environment and
encapsulates thousands of fluorescent dye molecules in its
network [2], providing photostability and signal
enhancement respectively [3].
In general, two main methods have been used for the
synthesis of silica-based nanoparticles (Np); reverse
microemulsion and Stöber method. These methods offers
certain advantages with some limitations.
In our study, we report a facile synthesis method to
produce uniform Nps in the range from 12 to 466 nm by
using Stöber method (Figures 1 and 2). The influence of
the amount of reagents on the particle size, monodispersity
and photophysical properties of the Nps are investigated in
detail.
Figure 3. Absorption and fluorescence spectra of FITC doped
silica Nps, showing linear realtionship between the size and the
amount of FITC encapsulated.
In the second part of the our study, we showed that the
silica network provided photostability. The FITC doped
silica Nps within the size range from 12 to 250 n m are not
toxic against MCF7 and PC3 cell lines. This project is
supported by DPT and TUBITAK (Grant No: 108T446)
(a)
(b)
Figure 1. SEM images of silica Nps with size of 450 and 40 nm.
Figure 2. DLS results of Nps with size of 466, 255, 31 and 12
nm, respectively.
We determined the amount of dye (0.02-
encapsulated in the Nps by disintegrating the silica
network at high pH (0.1M NaOH). When we compared
size of Np and its dye content, we observed a linear
relationship (Figure 3).
Figure 4. MTT assay of the silica Nps for the cell lines of MCF7
and PC3.
*Corresponding Author: serdarozcelik@iyte.edu.tr
[1] Rosi, N.L., Mirkin, C.A., Chem. Rev. 2005,105,1547.
[2] Zhao, X., Bagwe, R. P., Tan, W., Adv . Mater. 2004, 16, 173-
176.
[3] Bringley, J. F., Penner, T.L., Wang, R., Harder, J. F.,
Harrison, W. J., Buonemani, L., Journal of Colloid and Interface
Science , 2008, 320, 132–139.
6th Nanoscience and Nanotechnology Conference, zmir, 2010 310