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To create a moist environment for rapid wound healing, a new C-P-A film with sustained antibacterial capacity had been developed by the casting/solvent evaporation method. This new type of C-P-A film consists of a chitosan top layer and sodium alginate sublayer separated by an ornidazole-incorporated poly(vinyl alcohol) layer, exhibited perfect binding characteristics among the three layers. Physical characterization of the C-P-A film showed that the triple-layerd film had excellent light transmittance, control of water vapor transmission rate, and fluid drainage ability promotion, compared with the single-layer film. From the in vitro release studies, about 90% of OD was released from the composite films within 60 min, and no significant difference was observed in cumulative release percentage with increases in the drug content. The composite film at low concentration of OD (1.0 mg/cm2) showed effective antimicrobial activity in the cultures of Staphylococcus aureus and Escherichia coli in agar plates. The results obtained in this work indicated that the new type of C-P-A composite film incorporated with ornidazole has the potential for wound dressing application.

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Several carboxymethyl‐chitosan (CMCS) samples with different deacetylation degree and/or substituted degree were prepared from the carboxymethylation reaction of chitosan under soft conditions. The products were dissolved in standard HCl aqueous solution to carry out potentiometric titration by using NaOH as titrating solution at different ionic strengths. Then the dissociation behaviors of protonated carboxyl and amine groups were investigated under their degree of dissociation (α) and protonation constant (pKα) had been calculated. Moreover, influences of the intrinsic and extrinsic parameters on the dissociation behavior of CMCS were also considered in this article. As a result, dissociations of carboxyl and amine on CMCS exhibited unusual behaviors in comparison with carboxyl of carboxymethyl‐cellulose and amine groups of chitosan, respectively. The pKα values of carboxyl declined slightly at early dissociation stage but subsequently maintained constant. In contrast, the pKα of ammonium increased with its dissociation degree despite that there was an inflexed change on its dissociation curve. The potentiometric behavior of carboxyl was hardly affected by variation of deacetylation degree or substituted degree. However, these intrinsic parameters played more important role on dissociations of ammonium on CMCS. The ionic strength of media could bring screening effect on dissociaciation of both sorts of ionizable groups of CMCS. By increasing the ionic strength of media, screening effect on dissociations increased significantly. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1419–1429, 2008