| Chitosan is obtained on an industrial scale by the alkaline deacetylation of chitin. It is a biodegradablely cationic polysaccharide with good physicochemical properties and biocompatible properties. It has been widely used in the field of artifical skin, drug delivery, artifical vessel, gene therapy and cancer therapy. Carboxymethyl chitosan (CMCS) was a water-soluble CS derivative and functional biomaterial that possessed histological affinity, promoting the wound healing and inhibiting the keloid formation. In this paper, a novel CS/ PVA/CMCS-SA (C-P-CA) composite film was prepared with CS, CMCS, PVA and Sodium alginate (SA) for treatment of the oral ulcer. Ornidazole (OD) was incorporated into the films as model drug. In order to select an optical composite film, the physicochemical properties and in vitro release rate of OD from the films was studied. The effect of composite films on rabbit oral ulcer induced by acetic acid was observed.The composite films were prepared using casting/solvent evaporation technique. The scanning electron microscopy (SEM) photographs of the films indicated that there was good molecular compatibility of the polymers.The homogenous crystals of OD were visible on scanning electron micrographs. The water uptake degree and bioadhesive strength of films increased as the concentration of SA in the films increased. However, the tensil strength decreased. The OD–incorporated films showed more persistent antibacterial abilities than those blank films. And the antibacterial capability of the OD–incorporated composite films was observed to be more effective against the Staphylococus aureus (S. aureus) than Escherichia coli(E. coli). No significant difference was observed in cumulative released percent when concentration of SA in the films increased. And the CMCS:SA=1:1 was selected for the next experiments.The C-P-CA composite films OD-loaded with 0.5, 1.0 and 1.5mg/ cm~2 were prepared according to the D (CMCS:SA=1:1). The FTIR showed a strong evidence of the intermolecular interactions and good molecular compatibility of the polymers. The results of stability test revealed that there was no significant change of the color, shape and drug loading of OD-incorporated films stored at temperatures 4, 25℃for 90 days respectively. The water uptake of the OD-incorporated films was influenced by the solvent agent environment pH, and ionic intensity. There was no significant difference in cumulative released percent when concentration of OD was increased from 0.5 to 1.5mg/ cm~2. And the film (D1) which contained 1.0mg/ cm~2 OD was selected for the next experiments.The biocompatibility of OD-incorporated films was evaluated by Skin Sensitization test and tissue implanted. The Skin Sensitization test showed that the films were not contact allergenic activity on rat skin. It was found that the tissue reaction of the films was similar to that of the silk threads after implanted into dorsal muscles. The results suggested that the films had good biocompatibility.The oral ulcer area treated with D1 films and D1-EGF films was smaller than controlled group (P<0.05); the degree of edema was less serious than controlled group(P<0.05). However, statistical analysis showed that there was no significant difference (p>0.05) in the ulcer size reduction between group treated with D1 and D1-EGF. As the presence of oral ulcer adversely affected eating, change in food-intake provide objective measurements of function. Animals treated with D1 films and D1-EGF films, the onset of food-intake recovery was noted at about day 5, whereas it appeared after day 9 for the control group. The histological examination showed that the amount of inflammatory cells was less than than controlled group in various stage (P<0.05). The results suggested that the D1 film could accelerate the rate of ulcer healing. And the presence of EGF in the buccal film further enhanced the ulceration-healing efficiency. And it provided the basic theory basis for further clinical test.
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