Scientists develop low-cost, ‘green’ antimicrobial paint

Scientists develop low-cost, ‘green’ antimicrobial paint
Rice, CCNY research appears in March issue of Nature Materials

BY JADE BOYD
Rice News Staff

Researchers at Rice University and the City College of New York
(CCNY) have developed a low-cost, environmentally friendly technique
for embedding antimicrobial silver nanoparticles into vegetable
oil-based paints. The research, which is available online and slated to
appear in the March issue of Nature Materials, could provide homes and
workplaces a new defense against germs via the application of a fresh
coat of paint.

PULICKEL AJAYAN

“The simplicity of the process and economics
should allow us to commercialize these paints as a versatile coating
material for health and environmental applications,” said study
co-author Pulickel Ajayan, Rice’s Benjamin M. and Mary Greenwood
Anderson Professor in Mechanical Engineering and Materials Science.

Silver’s
antibacterial properties have been known for thousands of years, and
silver nanoparticles offer superior antibacterial activity while being
non-toxic. However, coatings containing antimicrobial agents have
failed commercially in the past due to their complex, multi-step
preparation methods and high cost of production.

The CCNY-Rice
team developed a “green chemistry” approach to synthesize metal
nanoparticles in common household paints in situ without using
hazardous reagents and solvents.

“We extensively worked on
poly-unsaturated hydrocarbon chain-containing polymers to devise a
novel approach to nanoparticle formation,” said lead author George
John, professor of chemistry at CCNY.

Polyunsaturated
hydrocarbons undergo auto-oxidation-induced cross-linking, which is
similar to lipid peroxidation, the process by which fatty acids are
oxidized in biological systems. During this process a variety of
chemically active species called ‘free radicals’ are generated. These
were used by the group as a tool to prepare metal nanoparticles in situ
in the oil medium.

“Using the same approach we should be able to
produce a large variety of nano-particle dispersions useful in
applications ranging from healthcare to catalysis,” added
co-investigator Ashavani Kumar, a postdoctoral research associate at
Rice.

The nanoparticle embedded coating can be applied like
traditional paints to such surfaces as metal, wood, polymers, glass,
and ceramics. The metal nanoparticles show characteristic color but
avoid the use of short shelf-life organic pigment paints.

In
addition, these coatings exhibited efficient antibacterial activity
toward Escherichia coli (E. coli) and Staphylococcus aureus (S.
aureus). The antibacterial property is important for hospitals and
other public buildings that are prone to bacterial growth, a main cause
of infection and disease.

“We have been working on developing
various in situ methods for organic soft matter-mediated metal
nanoparticle synthesis,” said Praveen Kumar Vemula, one of the
investigators. “However, to date, the present approach is the smartest
as it is devised based on utilization of naturally occurring process.”