An improved wound dressing with a long-term drug diffusion-efficacy has been developed by UV-radiation technique. It involves incorporation of ciprofloxacin (CIP), at the concentration of 0.5-2.0% (w/v), into a water mixture of 2-hydroxymethacrylate (HEMA) monomer, benzoin isobutyl ether (BIE) initiator and different content of ethylene glycol dimethacrylate (EGDMA) cross-linker. Increasing the concentration of EGDMA would reduce the releasing ratio of CIP from pHEMA. T1/2 is increased from 2.64 to 45.67 h when the EGDMA is added from 1 to 8%. In the ranges of 0< or = F < or = 0.6, the n value of 1%CIP-pHEMA membranes is increased from 0.48 to 0.81. It indicates that the mechanism of drug release falls between the Fickian and Case II diffusion model. The antibacterial activity of the drug impregnated into the membrane was evaluated by in vitro drug kinetic agar plate method. Higher concentration of EGDMA, up to 8% of the cross-linker, extends the drug release. Comparison with the drug-soaked membranes, the newly synthesized 1% CIP-pHEMA membrane (cross-linked with 4% EGDMA) sustains the release of the entrapped drug and maintains the antibacterial activity up to 12 days.
Porous scaffolds for dermal tissue engineering were fabricated by freeze-drying a mixture of chitosan and gelatin (CG) solutions. Different crosslinking agents including glutaraldehyde, 1-(3-dimethylaminopropyl)-3-ethyl-carbodimide hydrochloride (EDC), and genipin were used to crosslink the scaffolds and improve their biostability. The porous structure and mechanical properties were determined for the scaffolds. The proliferation of human fibroblasts in the scaffolds was analyzed. It was found that EDC crosslinked scaffolds had the greatest amount of cells after four days. EDC crosslinked CG scaffolds had tensile modulus in a dry state and compressive modulus in a wet state similar to commercial collagen wound dressing. They also showed appropriate pore size, high water absorption, and good dimensional stability during cell culture. When human fibroblasts were seeded on acellular porcine dermis (APD), acellular human dermis (AHD), and CG scaffolds for 3D cell culture, they were well-distributed in the centre of the CG scaffolds but stayed only on the superficial layer of APD or AHD after seven days. A gelatin-based bioglue was applied to the CG scaffolds where the keratinocytes were seeded to mimic epidermal structure. After 14 days, the bioglue degraded and keratinocytes grew to form monolayers on the scaffolds. This study showed that CG scaffolds crosslinked by EDC and seeded with human fibroblasts could serve as dermal constructs, while the bioglue coating seeded with keratinocytes could serve as an epidermal construct. Such a combination could help regenerate skin with integrated dermal and epidermal layers and a have potential use in tissue-engineered skin.
In order to obtain much slower biodegradable films, which are often required for biomedical applications, we have developed a series of studies on heterogeneous cross-linking of hyaluronic acid (HA) films by using 2-chloro-1-methylpyridinium iodide (CMPI) or 1-ethyl-(3,3-dimethylaminopropyl)carbodiimide (EDC) as cross-linking reagents. From the in vitro degradation rate, we found that EDC cross-linked HA films completely dissolved in PBS at 37 degrees C during the period of 4-6 days. However, CMPI cross-linked HA films showed only a low percentage of weight loss over 30 days. This phenomenon could be explained from the mechanism of reaction between carboxyl group of HA and EDC. The latter reacted with carboxyl group to form an unstable intermediate O-acylurea, which showed a relatively low reactivity and quickly rearranged to form a stable N-acylurea. Thus, most of the EDC-activated carboxyl groups in HA were chemically transferred into N-acylurea or left as unreactive O-acylurea, and only a few of cross-linking bonds were formed between HA. On the other hand, the intermediate obtained from the reaction between carboxyl group and CMPI showed a relatively high reactivity and reacted with the hydroxyl group of the same and/or different molecules of HA to form an inter- and intramolecular esterification. Apparently, CMPI cross-linked HA films have a much higher cross-linking density and constructed a more rigid three-dimensional network. Therefore, it produced HA films, which dramatically increased its enzymatic stability in aqueous solution of hyaluronidase. The obtained results from elemental analyses, FT-IR spectra and NMR spectra also indicate that acylurea groups were introduced into EDC-cross-linked HA films.
An accurate and reproducible method for the simultaneous determination of ampicillin (AMP), sulbactam (SUL), and cefoperazone (CFP) in pharmaceutical formulations by using HPLC with beta-CD stationary phase was developed. It involved the use of the added tetraethylammonium acetate (TEAA) reagent, pH, and methanol as the significant parameters to find the optimum separation condition. A high resolution and selectivity of analytes was obtained by running the mobile phase in methanol-5 mM TEAA buffer = 35:65 (v/v, pH 4.5) at 280 nm. The mean recoveries ranged from 96.6 to 103.3% for AMP in the synthetic mixture, 97.6 to 103.0% for SUL, and 97.0 to 104.0% for CFP. The low LOD (<1.8 microg/mL) and low CV (<0.9%) assured that this method was sensitive and reproducible. The assay of analytes in commercial products exhibited that it was convenient and reproducible for routine analyses of these components in sterilized H(2)O, saline, or 5% dextrose injection solutions.
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