Soft Matter Composites Interfacing with Biomolecules, Cells, and Tissues - Bioinspired Approaches for Human-Centric Technologies - page 49

Fig. 2.12 Schematic representation of chitosan-based hydrogel networks derived from different
physical associations: (a) networks of chitosan formed with ionic molecules, polyelectrolyte
polymer, and neutral polymers; (b) thermoreversible networks of chitosan graft copolymer
resulting semisolid gel at body temperature and liquid below room temperature (Bhattarai
et al. 2010 )
polyelectrolytes form electrostatic interactions with chitosan, they are different
from the ions or ionic molecules used in ionic complexation in that they are larger
molecules with a broad molecular weight range, such as polysaccharides, proteins,
and synthetic polymers (Fig. 2.12 ). They are complexed without the use of organic
precursors, catalysts, or reactive agents, alleviating the concern about safety in the
body or cross-reactions with a therapeutic payload. In addition, because PECs
consist of only chitosan and the polyelectrolyte, their complexation is straight-
forward and reversible.
Chitosan-alginate blend-based nanocomposite hydrogels containing sugars (see
Fig. 2.13 ) were also shown to be highly effective in wound treatment (Travan
et al. 2009 ). The role of chitosan is fundamental in the formation and stabilization
of well-dispersed small silver nanoparticles, for instance. Reproducibility of size
distribution together with a demonstrated stability of the nanoparticles over time
can be achieved in chitosan-based polymer matrices. Moreover, the use of sugar-
based additives adds a considerable appeal to the results obtained. The simul-
taneous presence of a sugar-based bioactive polymer for cell stimulation
(Fig. 2.13 ) and of silver nanoparticles in the gel for antibacterial activity represents
a major achievement in would treatment. Such approaches can bridge the gap
between nanotechnology and glycobiology (Travan et al. 2009 ; Morais et al. 2013 ).
In open-wound treatment, there is the major risk of infection that presents
serious consequences, which can compromise the recovery success. To prevent
those infections, several approaches are used such as sterility protocols and anti-
biotics administration. However, these protocols are not always effective, and the
antibiotic activity can even fail due to pathogenic resistance development. There-
fore, recently, studies were made to ascertain the use of certain ions as antimicrobial
agents, such as cerium (Ce), which has revealed antimicrobial properties against
several microorganisms (Morais et al. 2013 ). This way, it can be incorporated in
different biomaterials to grant them antimicrobial ability, contributing to a better