Soft Matter Composites Interfacing with Biomolecules, Cells, and Tissues - Bioinspired Approaches for Human-Centric Technologies - page 51

allowing controlling both the capacity and rate of oxygen delivery, providing
beneficial oxygen levels for days in a wound (Wijekoon et al. 2013 ). Since these
systems are capable of reloading oxygen more than once, they can be utilized for
long periods of time potentially weeks for treatment and cell regeneration. Fibro-
blast cells were shown to respond favorably to such enhanced oxygen environments
even without supplemental oxygen which should directly translate to accelerated
wound healing in vivo.
Another material of choice for construction is cyclodextrins (CD) towards
biopolymer hydrogels with antimicrobial properties (Glisoni et al. 2013 ). For
instance, two types of hydrophilic networks with conjugated beta-cyclodextrin
( -CD) were recently developed with the aim of engineering useful platforms for

the localized release of an antimicrobial 5,6-dimethoxy-1-indanone N4-allyl
thiosemicarbazone (TSC) in the soft and moist tissue such as the eye and its
potential application in ophthalmic diseases. Poly(2-hydroxyethyl methacrylate)
soft contact lenses (SCLs) coated with

ʲ

-CD, and
superhydrophilic hydrogels (SHHs) of directly cross-linked hydroxypropyl-

ʲ -CD, namely, pHEMA-co- ʲ

-CD
were synthesized and characterized regarding their structure (ATR/FT-IR), drug
loading capacity, swelling, and in vitro release in artificial lacrimal fluid. Incorpo-
ration of TSC to the networks was carried out both during polymerization
(DP method) and after synthesis (PP method). The first method led to similar
drug loads in all the hydrogels, with minor drug loss during the washing steps to
remove unreacted monomers, while the second method evidenced the influence of
structural parameters on the loading efficiency (proportion of CD units, mesh size,
swelling degree). Both systems provided a controlled TSC release for at least
2 weeks, TSC concentrations (up to 4000

ʲ

g/g dry hydrogel) being within an
optimal therapeutic window for the antimicrobial ocular treatment. Microbiological
tests against P. aeruginosa and S. aureus confirmed the ability of TSC-loaded
pHEMA-co-

ʼ

ʲ

-CD network to inhibit bacterial growth as demonstrated in Fig. 2.14 .
As we exemplified in this section, hydrogels are playing an increasing role in
regenerative medicine and wound care owing to their growing functional sophisti-
cation. This is being fortified by advances in hydrogel synthesis, particularly
through molecular and genetic engineering, which provide greater control of
hydrogel structure and hence the emergence of hydrogels with new functionalities
particularly existence of multifunctional aspects such as antimicrobial properties as
well as cell proliferation and structural stability. In order to exploit and expand
biomedical uses of hydrogels based on biopolymers, it is necessary to fully under-
stand the relationship between hydrogel structure and function. This section is by
no means a comprehensive review of such materials but aimed to highlight the key
attributes of biopolymer hydrogels that modulate their function, with discussions
and examples on the link between these attributes and hydrogel behavior, and
identifying possible future applications to elucidate them.