Materials Letters 65 (2011) 2745–2747

Contents lists available at ScienceDirect

Materials Letters
j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / m a t l e t

Biosynthesis of titanium dioxide nanoparticles using bacterium Bacillus subtilis

A.Vishnu Kirthi, A. Abdul Rahuman ⁎, G. Rajakumar, S. Marimuthu, T. Santhoshkumar, C. Jayaseelan,
G. Elango, A. Abduz Zahir, C. Kamaraj, A. Bagavan
Unit of Nanotechnology and Bioactive Natural Products, Post Graduate and Research Department of Zoology, C.Abdul Hakeem College, Melvisharam-632 509, Vellore District,
Tamil Nadu, India

a r t i c l e i n f o a b s t r a c t

Article history: The present study reports a low-cost, new material, eco-friendly and reproducible microbes Bacillus subtilis
Received 28 October 2010 mediated biosynthesis of TiO2 nanoparticles. Titanium dioxide nanoparticles synthesized from titanium as a
Accepted 21 May 2011 precursor, using the bacterium, B. subtilis. The synthesized nanoparticles were characterized and confirmed as
Available online 30 May 2011
TiO2 nanoparticles by using the UV spectroscopy, XRD, FTIR, AFM and SEM analysis. The morphological
characteristics were found to be spherical, oval in shape, individual nanoparticles as well as a few aggregates
Keywords:
Biosynthesis
having the size of 66–77 nm. The XRD shows the crystallographic plane of anatase of TiO2 nanoparticles,
Bacillus subtilis indicating that nanoparticles structure dominantly correspond to anatase crystalline titanium dioxide.
Titanium dioxide © 2011 Elsevier B.V. All rights reserved.
Atomic force microscopy
XRD
FTIR

1. Introduction understand the mechanism of nano transformation of accomplishing

biosynthesis at the extra-cellular level.
Nanoparticles have demonstrated antimicrobial activities; the
development of novel applications in this field makes them an 2. Materials and methods
attractive alternative to antibiotics. The recent discovery of the
biosynthesis of metal nanoparticles points towards new biotechno- 2.1. Synthesis of TiO2 nanoparticles using B. subtilis
logical methods in materials science [1,2].Titanium dioxide (TiO2)
nanoparticles form may be one of the most important materials for B. subtilis cells were allowed to grow as suspension culture in
photocatalysts [3], cosmetics, and pharmaceuticals [4]. Bacillus subtilis sterile distilled water containing suitable carbon and nitrogen source
is an aerobic, oxygen tolerant, spore forming bacteria which can for 36 h and this was treated as source culture. 25 ml of culture was
survive even in the harsh unfavorable conditions, which makes it a taken and diluted four times by adding 75 ml of sterile distilled water
suitable candidate for the biosynthesis of the metal nanoparticles like containing nutrients. This diluted culture solution was again allowed
TiO2. Lengke et al. [5]demonstrated the synthesis of gold nanoparticles to grow for another 24 h. 20 ml of 0.025 M TiO(OH)2 solution was
from B. subtilis and an airborne Bacillus sp. used to reduce Ag + ions to added to the culture solution and it was heated on steam bath up to
Ag 0 [6]. 60 °C for 10–20 min until white deposition starts to appear at the
As such they are extremely energetic, adaptable and promising bottom of the flask, indicating the initiation of transformation. The
due to their potential metabolic fluxes. The capabilities of this culture solution was cooled and allowed to incubate at room
benevolent microbe have not been taken into full use in terms of temperature in the laboratory ambience. After 12–48 h, the culture
synthesizing metallic and/or oxide nanoparticles. In the present effort, solution was observed to have distinctly markable coalescent white
B. subtilis has been taken in order to assess its potentiality as a putative clusters deposited at the bottom of the flask [7].
candidate bacterium for the synthesis of TiO2 nanoparticles. It is an
attempt to explore and establish a cost effective, eco-friendly and 2.2. Characterization of TiO2 particles
amenably reproducible approach for the purpose of scaling up and
subsequent downstream processing. This effort has also been made to The UV absorbance of the synthesized TiO2 nanoparticles was
measured in Schimadzu 1601 spectrophotometer operated at a
resolution of 1 nm. The synthesized nanoparticles were freeze dried,
⁎ Corresponding author. Tel.: + 91 94423 10155, + 91 04172 269009; fax: + 91
powdered and used for XRD analysis. The spectra were recorded in
04172 269487. Bruker AXS D8 Advance X-ray diffractometer with Philips® PW 1830
E-mail address: abdulrahuman6@hotmail.com (A.A. Rahuman). X-ray generator. The diffracted intensities were recorded from 0° to

0167-577X/$ – see front matter © 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.matlet.2011.05.077
2746 A.V. Kirthi et al. / Materials Letters 65 (2011) 2745–2747

Fig. 1. (A) UV absorption spectrum for the synthesized TiO2 nanoparticles showing peak at 366 nm, (B) indexed X-ray diffraction patterns of TiO2 at room temperature.

80° 2θ angles. The dried powder was diluted with potassium bromide crystallites. The main peak of θ = 27.811° (Fig. 1B) matches the (101)
in the ratio of 1:100 and recorded the spectrum in Thermo Nicolet, crystallographic plane of anatase of TiO2 nanoparticles, indicating that
Avatar 370 Fourier Transform Infrared Spectrophotometer using the nanoparticles structure dominantly correspond to anatase crystalline.
diffuse reflectance accessory. The spectrum was subjected to There is a slight increase in the peaks which may be the result of
correction to get back the transmission spectrum. The surface nanoparticles synthesized by microorganisms. The particles size
morphology of the film samples was studied using atomic force estimation was performed by the Scherrer's formula.
microscopy (AFM). The AFM images were also used for the analysis of
the fractal behavior as deposited and annealed films. Porosity, 0:9λ
d=
roughness and fractal dimension were evaluated by analyzing the βcosθ
AFM images using post image processing software (Nanoscope IIIa,
Digital Instruments). Scanning electron microscopy (SEM) analysis where d is the mean diameter of the nanoparticles, λ is wavelength of
was performed on a EOL Model JSM-6390LV. X-ray radiation source, β is the angular FWHM of the XRD peak at the
diffraction angle θ. The FTIR spectra of TiO2 nanoparticles exhibited
3. Results and discussion prominent peaks at 3430, 1578, 1451, 1123 cm − 1 (Fig. 2A). A broad
peak at 3430 cm − 1 shows O\H stretching due to alcoholic group.
The onset wavelength of the optical absorption for uncapped TiO2 Peak at 1578 cm − 1 indicates the presence of C_C ring stretching. The
appears at 366 nm in UV–vis spectroscopy (Fig. 1A), which is blue- band observed at 1451 cm –1 is due to bending vibration of the CH2 in
shifted compared to the bulk anatase TiO2, indicating the formation of the lipids and proteins. The peak at 1123 cm –1 is due to the formation
nanoparticles solution. The surface modification of nanocrystalline of the amide linkages between the bacterial proteins and the TiO2
anatase TiO2 particles with orthosubstituted hydroxylated enediols formed during the reaction period. The AFM was performed in order
ligands which as well improves the optical response in the visible to know the topological map of the surface of the synthesized
region [8]. The XRD pattern of the sample showed the presence of nanoparticles. The surface area of the nanoparticles has increased
peaks (2θ = 27.811° (rutile form), 39.187° (anatase form), 41.236° dramatically showing with the increase in the peaks (Fig. 2B). The
(rutile form) and 54.323° (anatase form)), which is regarded as an AFM clearly depicts the formation of the rutile and anatase forms in
attributive indicator of the biologically synthesized nanoparticles TiO2 the TiO2 nanoparticles, and also the surface morphology of the

Fig. 2. (A) FTIR spectra of the B. subtilis synthesized of TiO2, (B) atomic force microscopic (AFM) image of the synthesized of TiO2 showing increased surface area.
 A.V. Kirthi et al. / Materials Letters 65 (2011) 2745–2747 2747

Fig. 3. (A and B) Scanning electron microscopic images of the TiO2 showing individual and aggregate forms of nanoparticles. (C) Particle size distribution showing size range of the
synthesized TiO2 nanoparticles.

particles is uneven due to the presence of some of the aggregates and isms for the consistent and rapid synthesis of TiO2 nanoparticles. The
individual particles of TiO2. synthesized TiO2 nanoparticles were characterized by using UV–vis,
The SEM images of the B. subtilis synthesized TiO2 nanoparticles XRD, FTIR, AFM and SEM and the bacterial biosynthesis of the titanium
have shown spherical clusters of the nanoparticles (Fig. 3A and B). dioxide provides a fast, purest form of producing nanoparticles.
Nanoparticles were spherical, oval in shape, individual as well as a few
aggregates having the size of 66–77 nm. The particle size distribution
Acknowledgements
is shown in Fig. 3C. It reveals the morphological homogeneity with the
grain size falling mostly in submicron range. The energy yielding
The authors are grateful to C. Abdul Hakeem College Management,
material–glucose (which controls the value of oxidation–reduction
Dr. S. Mohammed Yousuff, Principal, Dr. K. Abdul Subhan, HOD of
potential (rH2)), the ionic status of the medium pH and overall rH2,
Zoology Department, for providing the facilities to carry out this work.
which is partially controlled by the bicarbonate negotiate the
synthesis of TiO2 nanoparticles in the presence of B. subtilis [7]. The
synthesis of n-TiO2 might have resulted due to pH-sensitive Reference
membrane bound oxidoreductases and carbon source dependent [1] Joerger R, Klaus T, Granqvist CG. Adv Mater 2000;12:407.
rH2 in the culture solution. Composition of nutrient media, therefore, [2] Tolles WM, Rath BB. Curr Sci 2003;85:1746.
plays a pivotal role in biosynthesis of metallic and/or oxide [3] Sun D, Meng TT, Loong H, Hwa TJ. Water Sci Technol 2004;49:103.
[4] Gelis C, Girard S, Mavon A, Delverdier M, Pailous N, Vicendo P. Photomed 2003;19:
nanoparticles which is done in the present investigation.
242.
[5] Lengke M, Southam G. Geochim Cosmochim Acta 2006;70:3646.
4. Conclusion [6] Pugazhenthiran N, Anandan S, Kathiravan G, Prakash NKU, Crawford S, Ashokkumar
MJ. Nanopart Res 2009;11:1811.
[7] Jha AK, Prasad K, Kulkarni AR. Colloids Surf B Biointerfaces 2009;71:226.
To conclude, we have used a hitherto unreported, new material, [8] Rajh T, Chen LX, Lukas K, Liu T, Thurnauer MC, Tiede DM. J Phys Chem B 2002;106:
inexpensive, non toxic, eco-friendly, abundantly available microorgan- 10543.