Evaluation of a photocrosslinkable hydroxyethyl chitosan hydrogel as a potential drug release system for glaucoma surgery.

Hydroxyethyl chitosan (HECTS) is a critical derivative of chitosan that has been widely used as biomedical materials due to great water-solubility and excellent biocompatibility. Here, photosensitive hydroxyethyl chitosan was synthesized by introducing azide group on NH2 of HECTS (HECTS-AZ), afterwards FTIR and 1H NMR spectra were detected to confirm the formation of HECTS-AZ. The solution of HECTS-AZ can achieve a sol-gel transition through UV irradiation for 30 s. The evaluation of biocompability and biodegradability in vivo was conducted in rats, visual and pathological examinations exhibited the HECTS-AZ has excellent biocompability and degradation time of the hydrogel is more than 14 weeks. Furthermore, HECTS-AZ hydrogel as an ocular drug delivery system loading heparin was prepared to implant under sclera of rabbit after glaucoma filtration surgery (GFS). The experimental results demonstrated the heparin loaded hydrogel can effectively maintain filtration bleb and lowing intraocular pressure (IOP) after GFS for prolonged time. Besides, obvious inflammatory reactions and side effects have not been observed in ocular during the experimental period. In conclusion, the HECTS-AZ hydrogel is a potential drug delivery device for the treatment of glaucoma and other ocular diseases.

Study of a new biodegradable hernia patch to repair abdominal wall defect in rats.

A novel biodegradable chitin hernia patch was prepared by acetylation of chitosan fabric in our study. Physicochemical properties, cell compatibility and biodegradability of the chitin patch were quantified. Histopathological study of the functional experiment showed that this newly designed hernia patch promoted collagen deposition and neovascularization by significantly promoting the secretion of FGF1 and TGF-ß1 in the early postoperative (P<0.01). Chitin patch caused less inflammation by inhibiting excessive expression of IL-6 and TNF-α when compared to the polypropylene mesh (P<0.01). Acceptable fibrosis was consistent with the results of immunohistochemistry studies. The density of FGF1 and TGF-ß1 positive cells in the chitin patch group at 7 d was reduced to a lower level at 15 d (P<0.01). With regeneration of the defect abdominal wall, chitin patch degraded gradually, avoiding foreign body response and chronic complications. Our studies demonstrated that the newly designed chitin patch showed good promise for the hernia treatment.