Download Author`s personal copy European Polymer Journal

Author's personal copy
European Polymer Journal 44 (2008) 3116–3121
Contents lists available at ScienceDirect
European Polymer Journal
journal homepage: www.elsevier.com/locate/europolj
Macromolecular Nanotechnology
Highly-loaded silver nanoparticles in ultrafine cellulose acetate
nanofibrillar aerogel
Nguyen Dang Luong a, Youngkwan Lee b, Jae-Do Nam a,*
a
b
Department of Polymer Science and Engineering, Sungkyunkwan University, Kyonggi-do 440-746, South Korea
Department of Chemical Engineering, Sungkyunkwan University, Kyonggi-do 440-746, South Korea
MACROMOLECULAR NANOTECHNOLOGY
a r t i c l e
i n f o
Article history:
Received 22 October 2007
Received in revised form 26 May 2008
Accepted 17 July 2008
Available online 6 August 2008
Keywords:
Antimicrobial
Silver
Nanocomposite
Nanoparticle
Membrane
a b s t r a c t
A facile method was developed to load a large amount of silver nanoparticles into a biodegradable and biocompatible cellulose acetate (CA) nanofibrillar aerogel in a controlled
manner. The micro-sized CA fibrils were separated into nano-sized fibrils by salt-assisted
chemical treatment in a water–acetone co-solvent to give a nanofibrillar structure with a
diameter of 20–50 nm, BET surface area of 110 m2/g, and porosity of 96%. Using the high
electron-rich oxygen density in the CA macromolecules and the large surface area of the
CA nanoporous structure as an effective nanoreactor, the in-situ direct metallization technique was successfully used to synthesize Ag nanoparticles with an average diameter of
2.8 nm and a loading content of up to 6.98 wt%, which can hardly be achieved by previous
methods. This novel procedure provides a facile and economic way to manufacture Ag
nanoparticles supported on a porous membrane for various biomedical applications.
Ó 2008 Elsevier Ltd. All rights reserved.
1. Introduction
Nano-sized metal particles show different properties
from the bulk metal because of their small sizes and thus
may find various photoelectronic, catalytic, magnetic, sensor, and biomedical applications [1]. In particular, Ag is
known to inactivate microbes by interacting with their enzymes, proteins or DNA to inhibit the cell proliferation or cell
division, and it also binds to the negatively-charged bacterial cells to change the functionality of the cell membrane,
thereby preventing bacterial regeneration [2]. Accordingly,
polymer supported silver nanoparticles have been widely
investigated and used in various biomedical applications,
such as wound dressing materials, body wall repairs, augmentation devices, tissue scaffolds, and antimicrobial filters
[3–10]. For these applications, silver nanoparticles have to
be supported in biocompatible polymer systems [11–14].
For example, a cotton fabric was used to support Ag particles
(41 ± 7 nm in size and loading content of 0.53 wt%) to obtain
an antimicrobial effect on both gram-positive (Staphylococ* Corresponding author. Tel.: +82 31 290 7285; fax: +82 31 292 8790.
E-mail address: [email protected] (J.-D. Nam).
0014-3057/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.eurpolymj.2008.07.048
cus aureus) and gram-negative bacteria (Escherichia coli)
[11]. Although an antimicrobial effect has been proved in
many studies, it should be noted that an increased silver
loading content is desirable to obtain stronger antimicrobial
activity for a broad range of biomedical applications.
The electrospinning technique has often been adopted
for the incorporation of silver nanoparticles into polymer
porous media. For example, silver nanoparticles were prepared by electrospinning a mixture of AgNO3 and polyacrylonitrile (PAN) solutions, and the electrospun fibers were
subsequently reduced by N2H5OH [12,13]. A similar work
was performed for cellulose acetate polymer, in which a cellulose acetate solution containing 0.5 wt% of AgNO3 was
electrospun and reduced to give silver nanoparticles
(21 nm in diameter) with cellulose acetate fibers (average
diameter of 610 nm) [14]. This system was tested against
gram-positive ( S. aureus) and gram-negative bacteria
(E. coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa)
and its antimicrobial activity was confirmed. However,
when the AgNO3 and polymer solutions are electrospun together, unreacted AgNO3 may still remain inside the
electrospun fibers as a contaminant, causing biological side