Photonic crystals in biology

Poster Session, Tuesday, June 15
Theme A1 - B702
Microbial Synthesis of Gold Nanoparticles Using Rhodopseudomonas palustris NU51
Strain
Ayfer Caliş 1 ,Ayten Ozturk 2 ,Erhan Piskin 1
1 Department of Bioengineering, Hacettepe University, Ankara 06800, Turkey
2 Department of Biology, Nigde University, Nigde 51100, Turkey
Abstract__ In this study, photosynthetic bacteria Rhodopseudomonas palustrisNU51 strain was screened to produce gold
nanoparticles. R. palustris found successfully produce gold nanoparticles. For controlling size and shape of nanoparticles, pH
values changed ranged from 7 to 4. R. palustris biomass and aqua HAuCl 4 incubated and gold nanoparticles characterised.
Nanotechnology is an emerging field in the area of
interdisciplinary research, especially in biotechnology [1].
Nanotechnology collectively describes technology and
science involving nano scale particles (nanoparticles) that
increases the scope of investigating and regulating the
interplay at cell level between synthetic materials and
biological systems [2]. The current interest in nanomaterials
is focused on the controllable properties of size and shape
because the optical,electronic, magnetic, and catalytic
properties of metal nanoparticles strongly depend on their
sizes and shapes [3]. Currently, there are various chemical
and physical synthetic methods aimed at controlling the
size and distribution of nanoparticles. Most of these
methods, however, utilise toxic and expensive chemicals,
and problems are often experienced with nanoparticle
stability, agglomeration of particles and the inability to
control crystal growth [4].
Figure 1: UV visible spectra of gold nanoparticles by R.palustris (1x10 -3 M
aqueous HAuCl 4,pH 6)
[10]. Phototrophic bacteria are ubiquitous in fresh and
marine water soil, wastewater, and activated sludge. They
are metabolically the most versatile among all procaryotes:
anaerobically photoautotrophic and photoheterotrophic in
the light and anaerobically chemoheterotrophic in the dark,
so they can use a broad range of organic compounds as
carbon and energy sources [11].
In this study we explored phototrophic bacteria
Rhodopseudomonas palustris NU51 strain that isolated
from Akkaya lake have been chosen to synthesize gold
nanoparticles at room temparature through a single step
process (Figure 2b). Photosynthetic bacteria
Rhodopseudomonas palustris were cultured in the
medium containing puryvate, yeast extract, NaCl, NH 4 Cl
and KH 2 PO 4 at pH 7 and room temparature. 1 g wet
weight of bacteria biomass obtained from growth medium
and resuspended in 1x10 -3 M aqueous HAuCl 4 . The
reactants pH were adjusted pH 4, 5, 6, 7 using 0,1 M
NaOH solution. All the experiments were conducted at
room temparature and 48 h. After 48 h reaction colour
change was observed. Different shape and size were
obtained due to pH change. Particle size was measured
with Zeta Sizer. The colour of the reaction turned pale
yellow to pale purple. This colour change indicates gold
nanoparticle. Gold nanoparticles analyzed with UV
spectrophotometer (Figure 1, Figure 2a). The results
indicates that max absorption attributed at surface
plasmon resonance band (SPR) of the gold nanoparticles.
Results show that R.palustris produce gold nanoparticle
extracellularly.
*Corresponding author: ayfercalis@hotmail.com
(a)
(b)
Figure 2: (a) UV visible spectra of gold nanoparticles by R.palustris
(1x10 -3 M aqueous HAuCl 4,pH 7) (b) Rhodopseudomonas palustris NU51
Currently, there is a growing need to develop
environmentally benign nanoparticle synthesis process that
does not use toxic chemicals in the synthesis protocols. An
important aspect of nanotechnology is the development of
synthesis of metal nanoparticles is a big challenge [5]. So
the attractive procedure is using microorganisms such as
bacteria and fungi to synthesize gold nanoparticles recently
[6]. Microorganisms produce gold nanoparticles with
different sizes: Bacillus subtilis 5-25 nm [7];
Rhodopseudomonas capsulata 10-20 nm [8], Escherichia
coli 20-25 nm [9], Pseudomonas aeruginosa 15-30 nm
[1] K. Natarajan, S. Selvaraj, V.R. Murty, Digest Journal of
Nanomaterials and Biostructures, 5, 135-140, (2010)
[2] Du L, Jiang H, Liu X, Wang E, Electrochemistry Communications 9,
1165-1170, (2007)
[3] S. He, Y. Zhang, N. Gu, Biotechnol. Prog., 24, 476-480, (2008)
[4] Y. Govender, T.L. Riddin, M. Gericle, C.G. Whiteley, J.Nanopart
Res, 12, 261-271, (2010)
[5] G. Singaravelu, J.S. Arockiamary, V. G. Kumar, K. Govindajraju,
Colloids and Surfaces B:Biointerfaces, 57, 97-101, (2007)
[6] S. He, Z. Guo, Y. Zhang, S. Zhang, J. Wang, N. Gu, Materials
Letters, 61, 3984-3987, (2007)
[7] D. Fortin, T.J. Beveridge, In: Aeuerien E (ed) Biomineralization, 7-
22, (2000)
[8] S. He, Y. Zhang, Z.Guo, N. Gu, 2008, Biotechnology Progress 24:
476-480, (2008)
[9] K. Deplanche, R.D. Woods, I.P. Mikheenko, R.E. Sockett, L.E.
Macaskie, Biotechnology and Bioengineering 101: 873-880, (2008)
[10] M.I. Husseiny, M.A. Ei-Aziz, Y. Badr, M.A. Mahmoud,
Spectrochimica Acta Part A: Molecular and Biomolecular
Spectroscopy 67: 1003-1006, (2007)
[11] H.J. Bai, Z.M. Zhang, Y. Guo, G.E. Yang, Colloids and
Surfaces B: Biointerfaces, 70, 142-146, (2009)
6th Nanoscience and Nanotechnology Conference, zmir, 2010 284