World Journal Of Engineering
SILVER NANOPARTICLES BASED MATERIALS FOR ANTIMICROBIAL
TREATMENT OF MEDICAL LEATHERS AND SHEEPSKINS
1
2
Carmen Gaidau , Aurora Petica , Wuyong Chen3 and Lucretia Miu1
1
Leather and Footwear Research Institute, Bucharest, 031215, Romania, carmen_gaidau@icpi.ro
2
INCDIE-ICPE CA, Bucharest, 03013, Romania, petica@icpe-ca.ro
3
Department of Biomass and Leather Engineering (DBLE),
Sichuan University, College of Light Industry Textile and Food Chengdu, R.P.China
Trichoderma containing different micotoxines (e.g.
aflatoxins). To evaluate the antimicrobial efficiency, the
minimal inhibitorial concentration (MIC) was
determined upon the: Staphylococcus aureus (ATCC),
Pseudomonas aeruginosa (ATTC), Escherichia coli
(ATCC). Antibacterial and antifungal properties of new
collagen materials doped with SNPs were assessed using
different methods such as difusimetric, MIC and
antibiogram methods.
The collagen based materials were the sheepskins
and furskins originating from raw sheepskins, which
were processed with specific technologies for medical
use [8]. The main kinds of the treatment applied for
interaction with SNPs were immersion, spraying,
tanning, and retanning. AFM and SEM images revealed
nanomaterials deposition on leather structure. Ag
concentration from collagen based materials was done
by AAS technique.
Results and discussion
Characteristics of electrochemically obtained CSS
Introduction
Silver nanoparticles (SNPs) synthesis attracts an
increasing interest due to their new and different
characteristics as compared with those at macroscopic
phase, with attractive applications in various domains,
such as: optics, microelectronics, catalysis, information
storage, energy conversion. The success of the
introduction of silver nanoparticles (SNPs) in different
forms in bioscience, healthcare and consumer goods is
already known [1 – 5].
The SNPs with antimicrobial and antifungal
properties against a great number of bacteria and fungi
may be used in form of colloidal sols or doping agents
for a lot of composite materials with polymer matrix.
Recently, various antibacterial finishes and disinfecting
techniques have been developed for different types of
textiles, cellulosic and synthetic materials [6].
It is believed that the mechanism of the antibacterial
effect of silver ions (Ag+) involves interaction with the
thiol groups of proteins, blocking the S-H bounds, which
induces the inactivation of bacterial proteins [7].
Silver nanoparticles as ecological alternative for
organic biocides, which are mainly volatile organic
compounds (VOC), represent an innovative challenge
for treatment of collagen and keratin based materials
such as medical leathers and furskins.
Experimental
SNPs were obtained as colloidal silver solution (CSS),
by electrochemical way, with so-called “sacrificial anode
method”, using a constant current pulse generator, with
stirring and alternating polarity and electrodes of 99.999
Ag. To prepare stable and concentrated CSSs, a mix of
stabilizer and co-stabilizer agents has been used, namely
PVP [poly (N-vinylpyrrolidone)] and Na-lauryl sulfate.
The experiments were carried out using the following
materials:
 deionized water with conductivity < 1 S, resistivity
of 18 .cm and pH = 5– 7;
 poly [1-vinyl-2-pyrrolidone] (C6H9NO)n (PVP10 with
M = 10,000 from Sigma – Aldrich);
 Na-lauryl sulfate, provided from Sigma – Aldrich.
The Ag concentration of the obtained CSS was
determined by UV-Vis absorbance spectra recording
using a JASCO V 570 spectrophotometer. The
nanoparticles sizes were analyzed by DLS technique
(Dynamic Light Scattering) using Brookhaven 90 Plus
equipment. The SNPs morphology was evidenced by
TEM measurements. To evaluate the antifungal effect,
the antibiogram method was used, with a fungi mix from
the following species: Aspergillus, Penicillium,
Electrosynthesis of SNPs in aqueous media is an
efficient and ecological process, which offers the
advantage of a high purity of the final formed solution
and a broad spectrum of antibacterial and antifungal
activity [9, 10]. A CSS containing 29.27 ppm Ag,
obtained in the presence of a mix of PVP 10 and Na-LS,
as steric and electrostatic stabilizers was used for the
treatment of medical leather and furskins. The
characteristics of this solution are presented in Figures 1
and 2.
Figure 1- UV-Vis spectra of a CSS with 29.27 ppm Ag
Figure 2 - Grain size distribution of SNPs
From Figure 2 it is observed that the majority of SNPs
(99.52 %) have a diameter up to 3.56 nm in accordance
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World Journal Of Engineering
with TEM micrographs which show that colloidal
solutions contain Ag nanoparticles smaller than 10 nm,
having a spherical shape, uniformly scattered (fig.3).
Zeta potential value of – 50. 25 mV indicates that the
SNPs are very stable in time.
(Aspergillus niger, Paecilomyces variotii, Trichoderma
viride, Scopulariopsis brevicaulis, Penicillium glaucum)
used for inoculation have shown a good resistance after
7 days.
The silver concentration and nano state conservation
inside leather structure (fig.4) suggest being in close
connection with antibacterial resistance of treated
materials.
Figure 3- TEM image of SNPs
Antibacterial effect of CSS
Bacteriostatic and bactericidal effect of the
electrochemically obtained CSS was evaluated using
minimal concentration with bacteriostatic effect – MCBs
and minimal concentration with bactericidal effect –
MCBc against Escherichia coli, Staphylococcus aureus
and Pseudomonas aeruginosa (Table 1).
Table 1 Minimal concentration with bacteriostatic effect
and minimal concentration with bactericidal effect of the
tested CSS
Fig.4-SEM (left) and AFM (right) images of SNP
based materials deposition inside leather structure
Conclusions
The CSS obtained by electrochemical method has
antibacterial and antifungal activity and can be used for
treatment of very useful materials, such as medical
leather and furskin in order to avoid the use of organic
antibacterial materials, from VOC product’s class.
Silver based materials concentration and nano size
deposition inside leather structure is closely connected to
microbial resistance of treated materials.
This investigation represents a new approach in
treatment of collagen and keratin based material and the
obtained results are promising for further research, in
order to introduce them at industrial scale.
Acknowledgement
This work was supported by the ANCS; Research
projects 199/2009, 458/2010 and 500/2011.
References
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[11] SR Gill , D E Fouts , G.L. Archer , EF Mongodin
& all., J.Bacteriol. 2005, 187, 7, 2426-38
Initial Staphylococcus Escherichia coli
Pseudomonas
CSS
aureus
aeruginosa
concen- MCBs MCBc MCBs MCBc MCBs MCBc
tration
(ppm) (ppm) (ppm)
(ppm) (ppm) (ppm)
(ppm)
29.27 14.635 – 29.27 7.317 – 14.635 7.317 14.635
7.317
3.658
–
3.658
From table 1 it can be seen that in the case of
Staphylococcus aureus, the MIC is higher than the one
for the other two bacteria. This is due to its membrane,
which consists of a thick peptidoglycan layer and creates
biofilms; the results being in agreement with literature
data [11]. Bacteriostatic effect is achieved at a dilution of
1/2 from the initial CSS concentration, in the case of S.
aureus and 1/4-1/8 for E. coli and P. aeruginosa, while
the best bactericidal effect is at 1/2 from the initial CSS
concentration, in the case of E. coli and P. aeruginosa.
The fungistatic properties, according to antibiogram
method, are expressed by the presence and magnitude of
the inhibition area for mould growth around a filter
paper padded with CSS. The used fungi mix contains
Aspergillus, Penicillium and Trichoderma. It was
observed that, even after 14 days of exposure, the
inhibition area around the filter paper was very well
evidenced.
Antibacterial effect of leather and furskins treated with
CSS
The medical leather and furskin treated by immersion in
electrochemically obtained CSS, with a content of
490 ppm Ag for leather and 160 ppm for furskin have
displayed resistance to Staphylococcus aureus,
Escherichia coli and Pseudomonas aeruginosa. In the
case of the spraying treatment, Ag concentration is lower
(4 - 12 ppm) and antibacterial activity is not so good.
The exposure of the same medical leathers and furskins,
according to antibiogram method, to a mix of fungi
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