(397ah) Inhibiting Bacterial Growth --- a Novel Biomedical Application of Ceria Nanoparticles

Inhibiting Bacterial Growth
--- a Novel Biomedical Application of Ceria Nanoparticles

Qi Wang¹, J. Manuel Perez², Thomas J. Webster^1,3

¹Bioengineering Program, ³Department
of Chemical Engineering, College of Engineering, Northeastern University, Boston,
MA 02115

²Nanoscience Technology Center, University
of Central Florida, Orlando, FL 32826

As a highly abundant material, ceria (or cerium
oxide, CeO₂) is technologically important due to its wide-range of applications,
for example in catalysts for the elimination of toxic auto-exhaust gases,^[1-2] oxygen sensors,^[3]electrochromic thin-films^[4] and so on. Upon the
transition from a macro-sized particle into a nanocrystalline
particle, ceria significantly changes its physicochemical properties to usually
possess a high density of nanocrystalline ceria
interfaces.^[5] Thus, nanostructured ceria has attracted extensive attention in
such applications due to improvements in 
redox properties, transport properties, and
high surface to volume ratios.

However, although ceria nanoparticles have
been studied for numerous applications in traditional science and engineering
applications, there have been almost no studies regarding the potential
biomedical applications of ceria until recently when researchers demonstrated
that ceria nanoparticles possess antioxidant properties at physiological pH
values. The ability of these nanoparticles to act as an antioxidant lies in
their ability to reversibly switch from Ce³⁺ to Ce⁴⁺.^[6]
In recent studies, this antioxidative ability enables
the application of ceria nanoparticles to protect against radiation damage,
oxidative stress and inflammation.^[7]

To build off of these exciting applications of ceria
nanoparticles, the present study investigated for the first time the influence
of ceria nanoparticles on bacteria growth. Specifically, dextran or polyacrylic acid coated ceria nanoparticles were studied in
the bacterial experiments involving Pseudomonas aeruginosa. Results showed that the growth of P. aeruginosa
was significantly inhibited in the presence of dextran
or polyacrylic acid coated ceria nanoparticles. Ceria nanoparticles with either coating inhibited
bacteria growth by about 20% compared with blank controls after treatment for 1 hour. After 6 hours
of treatment, the inhibition of bacterial growth reached 99.94% and 98% for dextran coated ceria nanoparticles and polyacrylic acid
coated ceria nanoparticles, respectively, compared with blank controls. After
24 hours of treatment, there were at least 98.69% bacteria inhibition for polyacrylic acid coated ceria nanoparticles and almost
complete (~100%) inhibition for dextran coated ceria nanoparticles. This study revealed a
promising biomedical application of ceria nanoparticles to prevent bacterial
infections that is worthwhile to be further explored.

Reference:

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Trovarelli, Catalytic properties of ceria and CeO₂-containing
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1996, 38, 439-520.

[2]    
J. Kaspar, P. Fornasiero and M. Graziani, Use of CeO₂-based oxides in the
three-way catalysis, Catal. Today, 1999, 2, 285-298.

[3]    
P. Jasinski, T. Suzuki and H. U. Anderson, Nanocrystalline
undoped ceria oxygen sensor, Sens. Actuators, B, 2003, 95, 73-77.

[4]    
N. Ozer, Optical properties and electrochromic
characterization of sol-gel deposited ceria films, Sol. Energy Mater. Sol. Cells, 2011, 68, 391-400.

[5]    
V. K. Ivanov, A. B. Shcherbakov, and A.
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[6]    
R. W. Tarnuzzer, J. Colon, S. Patil and
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radiation-induced cellular damage, Nano Lett., 2005, 5, 2573-2577.

[7]    
A. Asati, S. Santra, C. Kaittanis, S. Nath and J. M.
Perez, Oxidase-like activity of polymer-coated cerium
oxide nanoparticles, Angew. Chem., Int. Ed., 2009, 48, 2308-2312.