Biomedical Engineering Reference
In-Depth Information
time depended on the pH and ionic strength of the buffer, and was
typically about several minutes in a phosphate buffer solution. The
strengthoftheHAgelsincreasedwiththedegreesoftheiroxidation
and aldehydes.
Thepresenceofgraftedaldehydegroupswasobservedbyamul-
tiphoton confocal microscope on fluorescence staining. The alde-
hyde groups were used for covalent cross-linking with HA-ADH.
The resulting cross-linked networks were highly pliable and had
break strength of 500 Pa elastic modulus at 200%-300% strain.
The mechanical characteristics of these doubly cross-linked hydro-
gel were similar to those of vocal fold lamina propria.
In vitro
cell
proliferation results by the MTT assay showed that the prolifera-
tion of the fibroblasts. After loading a low-molecular-weight model
drug, rhodamine into the HA gel, its release was monitored using
UV-Vis spectroscopy. Rhodamine-loaded HA hydrogels maintained
their ability to form doubly cross-linked networks when mixed with
the HA-ADH solution. Most of the entrapped rhodamine was burst-
liberated from the HA gel in the first several hours and completely
released over 3 days. These novel hydrogels demonstrated poten-
tialasbiodegradable,control-releasedhydrogelsforvocalfoldtissue
regeneration.
Glutaraldehyde was used to cross-link amine-grafted HA to
yield hydrogels with high resistance toward biodegradation.
Tomihata and Ikade used acidic glutaraldehyde solutions to fab-
ricate cross-linked HA films.
69
Hu
et al
. compared glutaralde-
hyde and carbodiimide-mediated reactions of HA and found that
glutaraldehyde-based HA gelation yielded highly cross-linked HA
materials suitable for use as 3-D scaffolds for tissue engineering.
70
Because of HA's proven properties of biocompatibility and biode-
grdation, the hydrogels were evaluated on their further possi-
ble application in prevention of peritoneal adhesions, a serious
consequence of abdominal surgery, which could lead to pain, bowel
obstruction, or even infertility. Yoon Yeo
et al.
71
also synthesized
in
situ
HAhydrogelsbyemployingHAderivativessuchasHA-NH
2
and
HA-aldehyde for the prevention of postoperative abdominal adhe-
sions in a rabbit model.
18
,
71
,
72
They tested degree of HA degrada-
tionbyhyaluronasebymeasuringtheamountofreleasedglucuronic
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