| Developing wound dressings with sustained antimicrobial efficacy was considered as main focus of this paper. Ciprofloxacin hydrochloride (CP) was selected as the therapeutic drug for its broad antimicrobial spectrum. The drug loading Chitosan/Alginate (Chs/Alg) bi-layer composite membrane and Chitosan/Gelatin (Chs/Gel) sponge with sustained antimicrobial efficacy were prepared and expected to decrease the frequency of changing dressings, improving the patients’ compliance and to improve the wound healing process.The solubility of CP in phosphate buffer saline was 5.5 mg/mL. The intrinsic viscosity of Chs and Alg were determined with Ubbelohde viscometer, and the molecular weights were calculated. The deacetylation degree (DD) of Chs was determined through acid base titration. The relationship between the properties of the membranes and the physical-chemical properties of the Chs and Alg were detected. The results indicated that the relative water vapor transmission rate decreased with the increasing of the DD of the Chs. Besides, the increasing of the DD and the molecular weight of Chs led to the increasing of the mechanical property and water uptake capacity of the membranes. While, high TPP concentration resulted in low relative water vapor evaporation rate and water uptake capacity but high mechanical property of the membranes. It showed that Alg with high molecular weight has the largest water uptake capacity.The influence of crosslinking condition and plasticizer on the properties of the Chs/Alg bi-layer composite membranes was investigated. Central composite design (CCD)-Response Surface Methodology (RSM) was employed to optimize the formulation of the membrane. The best formulation of the composite membrane was GLY concentration (4.7%), CaCl2 concentration (9.5%) and crosslinking time (4.6 min). The best formulation was verified as the relative water vapor transmission rate of 60.7%, water uptake capacity of 506.9%, tensile strength of 17.1MPa, and breaking elongation of 51.8%. The cumulative drug release degree was 58.2% at 12h,72.0% at 24h and 94.0% at 48h. SEM, IR, X-Ray diffraction, and DSC were combined to characterize the composite membrane. The results showed that the thickness of the two layers was uniform. A perfect binding between the Chs layer and the Alg layer was achieved by the consequent casting and evaporating of Alg and Chs solutions. The reduction of the inhibition zones of agar plates inoculated with Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), and Pseudomonas aeruginosa (P. aeruginosa) strain suggested that the antimicrobial activity of the membrane could last for at least 1 week.The pharmacodynamics of the membranes was tested using a full-thickness wound model in rabbits. The results showed that the blank and the drug loading membrane were effective in improving the healing process compared with the control gauze group. However, there’s no significant difference between the blank membrane and the drug loading membrane for the wounds that didn’t got infected. The concentration of CP in plasma and wound tissue was determined by HPLC. After CP was administered to rats at a dose of 36mg/kg by oral and topical administration, respectively, the results showed that the drug concentration in blood was very low after topical administration. However, the concentration of CP in wound tissue was higher after topical administration. Topical administration of CP Chs/Alg bi-layer composite membrane could produce low plasma concentration and high concentration in target tissues. It can be concluded that the drug in target tissues was mainly by direct penetration.Chitosan/gelatin (Chs/Gel) skin scaffolds were fabricated and the pore size, porosity, water uptake capacity, water retention capacity, degradation rate and drug release rate of the sponges were investigated. The best formulation of the sponge was HAc concentration (1%), weight of chitosan and alginate (0.6g), ratio of gelatin to chitosan (7:3) and glutaraldehyde (4.5mL). Chs microspheres containing CP was incorporated into the sponges in a "sandwiches style". The results indicated that the drug releasing rate was delayed and about 90% drug released from the sponge sponge at 48h.To further analyze the ability of a sponge to influence the growth of cultured cells, human skin fibroblasts (HSF) and human keratinocytes (Hacat) were cultured in Chs/Gel sponges. Cell ability was assayed with MTT methods and the morphology of the cells was observed with AO/EB staining methods. The results indicated that the HSF could grow into the sponges and the Hacat cultured on HSF-containing sponges proliferated well and formed a thick layer after incubation for 7 days. The pharmacodynamics of the sponge was tested using a full-thickness wound model in rabbit. The cells could migrate into the sponge and proliferated well. Fortunately, the drug loaded sponge could inhibit the inflammation reaction at the early stage and improve the wound healing process.It was showed that the CP Chs/Alg bi-layer composite and CP Chs/Gel sponge with sustained antimicrobial efficacy were with good biocompatibility and suitable for topical delivery of CP. It can be concluded that topical administration could produce low plasma concentration and relatively high concentration in target tissues, which improved the wound healing process. Reliable scientific basis was provided for the new wound dressing with antimicrobial efficacy research and development. |
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