  Chitosan (CT) is an antibacterial polysaccharide that has been investigated
for drug carriers, haemostats and wound dressings. For these applications,
customised CT devices can often be obtained with specific experimental
conditions, which can irreversibly alter native biopolymer properties and
functions and lead to unreliable material behaviour. In order to investigate
the structure-function relationships in CT covalent networks, monosodium
5-sulfoisophthalate (PhS) was selected as heparin-mimicking, growth
factor-binding crosslinking segment, whilst 1,4-phenylenediacetic acid (4Ph)
and poly(ethylene glycol) bis(carboxymethyl) ether (PEG) were employed as
sulfonic acid-free diacids of low and high crosslinker length respectively.
Hydrogels based on short crosslinkers (PhS and 4Ph) displayed increased
crosslink density, decreased swelling ratio as well as minimal hydrolytic and
lysozymic degradation, whilst addition of lysozymes to PEG based networks
resulted in 70 wt.-% mass loss. PhS-crosslinked CT hydrogels displayed the
highest loss (40 +/- 6 CFU%) of antibacterial activity upon incubation with
Porphyromonas gingivalis, whilst respective extracts were tolerated by L929
mouse fibroblasts.
