ORIGINAL CONTRIBUTION
Synthesis of copolymer-stabilized silver nanoparticles
for coating materials
Jukka Niskanen
&
Jun Shan
&
Heikki Tenhu
&
Hua Jiang
&
Esko Kauppinen
&
Violeta Barranco
&
Fernando Picó
&
Kirsi Yliniemi
&
Kyösti Kontturi
Received: 7 October 2009 / Revised: 3 December 2009 / Accepted: 4 December 2009 / Published online: 7 January 2010
#
Springer-Verlag 2010
Abstract Silver ions being less toxic than silver nano-
particles, a more safe material can be obtained to be used as
antimicrobial coating. This can be achieved by using thiol
chemistry and covalently attach the silver nanoparticles in
the coating. Our aim is to produce a coating having
antimicrobial properties of silver ions but with the silver
nanoparticles firmly attached in the coating. Here, we
present a way to produce silver nanoparticles that can be
used as a component in a coating or as such to produce an
antimicrobial coating. The silver nanoparticles presented
here are stabilized by a copolymer (poly(butyl acrylate–
methyl methacrylate)) that is soft and has well-known
good film-producing properties. The reversible addition-
fragmentation chain transfer radical polymerization technique
used to prepare the polymers provides conveniently a thiol
group for effective binding of the silver nanoparticles to the
polymers and thus to the coating.
Keywords Nanoparticles
.
Block copolymers
.
Antimicrobial coating
Introduction
Nanoparticles are used and investigated widely for medical
and biological applications. In medical research, it has been
shown that gold nanoparticles can interfere with growth
factor proteins that cause angiogenesis. This could be
utilized in cancer treatment since cancer cells release these
proteins for promoting angiogenesis in tumors [1–5].
Another application is to functionalize gold nanoparticles
with, e.g., antibodies for detection of hormones and be used
as sensors for example in pregnancy tests [6].
Silver nanoparticles, on the other hand, are mostly used
in antimicrobial applications since the antimicrobial effect
of silver ions is well known [7–9]. There are many
commercial products for wound treatment that contain
silver as an antimicrobial agent. Nanocrystalline silver in
wound dressings is used to treat ulcers, and silver
sulfadiazine is used as pastes or creams for treating burn
wounds [5].
Even though the antimicrobial effect of silver ions has
been known for long, there is still some discussion about
the actual mechanism of the toxicity of silver. It is widely
believed that the toxicity arises from silver ions interacting
with proteins in the cells [10–12]. Feng et al. [10] have
shown that silver ions interact with thiol groups in proteins
and deactivate enzymes this way. They also found that the
condensed form of DNA loses its ability to replicate in the
presence of silver. Schreurs and Rosenberg [11] reported
that silver ions inhibit the respiratory chain of cells and that
the silver removes chlorine ions from the cytoplasm of cells
as AgCl.
J. Niskanen
:
J. Shan
:
H. Tenhu (*)
Laboratory of Polymer Chemistry, Department of Chemistry,
University of Helsinki,
P.O. Box 55, 00014 Helsinki, Finland
e-mail: heikki.tenhu@helsinki.fi
H. Jiang
:
E. Kauppinen
NanoMaterials Group, Department of Applied Physics and Center
for New Materials, Helsinki University of Technology (TKK),
P.O. Box 5100, 02150 Espoo, Finland
V. Barranco
:
F. Picó
Department of Ionic Solids, Materials Science Institute of Madrid
(ICMM), Spanish National Research Council (CSIC),
Cantoblanco,
Madrid, Spain
K. Yliniemi
:
K. Kontturi
Laboratory of Physical Chemistry and Electrochemistry,
Helsinki University of Technology,
P.O. Box 6100, 02015 Espoo, Finland
Colloid Polym Sci (2010) 288:543–553
DOI 10.1007/s00396-009-2178-x