Speaker
Ms
Jelena Krstić
(Vinča Institute of Nuclear Sciences, University of Belgrade, Serbia)
Description
Hydrogels have been used successfully in many biomedical applications
including scaffolds for wound healing applications or soft tissue
implants. A problem for the biomedical application of hydrogels is
that microorganisms may grow in hydrogels due to their natural
biocompatible properties. Improvement in application of hydrogels is
often achieved by the addition of natural polysaccharide or
non-specific antimicrobial species such as Ag nanoparticles. The
antibacterial bio-synthetic hydrogel nanocomposites consist of blends
between water soluble derivatives of radiation processed chitosan
(ws-chitosan) and poly(vinyl alcohol) cross-linked by
$\gamma$-irradiation (via $^{60}$Co source) and radiation
in situ incorporated Ag nanoparticles (AgNPs). Chitosan is a
copolymer composed of glucosamine and N-acetyglucosamine sugars,
linked by $1$–$4$ glucosidic bonds, both of which are constituents of
mammalian tissues. Chitosan degradation by ionizing radiation gives
structural diversity which contributes to its wide application in
biomedicine. The radiation technology platform allows synthesis by
environmentally friendly and biocompatible radiolytic products of
water. The postirradiation hydrogel freeze-thaw procedure was
performed to enhance mechanical properties and to prevent liking of
un-grafted ws-chitosan during AgNPs synthesis. The thus obtained
ws-chitosan, poly(vinyl alcohol)/ws-chitosan polymer matrix and
nanocomposites were subjected to molecular weight determination (by
Zetasizer), FT-IR, NMR, SEM, elemental analysis and mechanical
characterization by thermomechanical analysis, in static stress/strain
and dynamic mode. The antibacterial properties against *Escherichia coli* and *Staphylococcus aureus* were assessed
by using the agar diffusion test.
Results revealed the partial formation of Maillard reaction products
during radiation degradation of chitosan. The non-linear
stress-strain data from unconfined compression test were fit by the
Kennedy equation and by an elastic model (Rige and Wright). The
results indicated changes in matrix mechanical resistance upon
incorporation of ws-chitosan. In contrast, AgNP incorporation
decreased the polymer matrix elasticity while increasing the
cross-linking density of polymer network and provides more rigidity to
the structure which increases the values of storage modules (obtained
in dynamic mode) and, as a consequence, causes a better mechanical
stiffness of the network. The antibacterial activity of Ag-poly(vinyl
alcohol)/ws-chitosan hydrogels show enhanced antibacterial potential
in comparing with poly(vinyl alcohol)/ws-chitosan hydrogel matrix
only. For investigated hybrid hydrogel, zone of inhibition is greater
against *Staphylococcus aureus* than for *Escherichia coli*. This is important for the treatment of wound
infections in diabetic patients which are dominantly caused by aerobic
Gram-positive cocci. These promising results give possibility for
development and optimization of synthesized antibacterial Ag-hydrogel
nanosystems.
| Country/Organization invited to participate | Serbia |
|---|
Primary author
Ms
Jelena Krstić
(Vinča Institute of Nuclear Sciences, University of Belgrade, Serbia)
Co-authors
Ms
Aleksandra Radosavljević
(Vinča Institute of Nuclear Sciences, University of Belgrade, Serbia)
Mr
Dragutin Jovanović
(Institute of Microbiology, Military Medical Academy, Serbia)
Ms
Jelena Spasojević
(Vinča Institute of Nuclear Sciences, University of Belgrade, Serbia)
Mr
Srđan Popović
(Vinča Institute of Nuclear Sciences, University of Belgrade, Serbia)
Mr
Zorica Kačarević-Popović
(Vinča Institute of Nuclear Sciences, University of Belgrade, Serbia)
