| Summary: | 碩士 === 國立臺北科技大學 === 化學工程與生物科技系化學工程碩士班 === 107 === The commercial drug-containing dressings cannot effectively control the amount of drug release in the present. If the drug is over released that may cause discomfort in the affected part. On the other hand, the inflammation or bacterial infection will be induced if the drug released too low. Therefore, controlling drug release of the dressing material is an important topic in recent years. By appropriate drug delivery, the drug can be effectively applied to the affected part, and the concentration of the released drug is controlled between the toxic level and the minimum effective concentration for displaying the effect of drug. In addition, it is important that drug-containing dressings reduces side effects while maintaining a long duration of treatment.
Accordingly, the study was divided into 2 group (control group: the porous alginate scaffold; the experimental group: the chitosan was used ionic bond combined with the alginate). The experimental group is not only combining the advantages of the two materials for wound healing, also can effectively delay drug release. In order to make the scaffold have antibacterial ability, three kinds of antibiotics (ampicillin, tetracycline hydrochloride, chloramphenicol) with similar molecular weights and different hydrophobic degrees were added as the research drugs in the control group and the experimental group for testing the drug delivery system carries the amount of drug stored, the release rate and the antibacterial ability. On the other way, DNA and the type I collagen expression were detected in the human fibroblasts that sed on the experimental group and the control group for 1, 4, and 7 days.
Firstly, through scanning electron microscopy (SEM), it was found that the surface morphology of the scaffold coated with chitosan was coarse granular; the scaffold image was observed through a fluorescent microscope, and it was found that the surface of the scaffold emits green fluorescence, which is a few Spontaneous fluorescence of the chitosan, and by the Ninhydrin assay, the amount of chitosan coating on a scaffold, measured about 902.09±52.01 μg of chitosan on a scaffold. In addition, due to the inclusion of chitosan on the scaffold, the Young's modulus and ultimate tensile strength of the scaffold were significantly improved during the tensile test. The Young's modulus was increased from 0.14 MPa to 0.29 MPa; the ultimate tensile strength. Increased from 0.097 MPa to 0.20 MPa. In the degradation test, the degradation rate of the scaffold was reduced, and the degradation rate on the 14th day was reduced from 22.47% to 12.98%.
In addition, different antibiotics (ampicillin, tetracycline hydrochloride, chloramphenicol) were added to the scaffold. In order to confirm the drug content carried on each scaffold, the drug storage amount test was carried out, and the results showed that the storage amount was: The ampicillin group: 98 μg/scaffold, tetracycline hydrochloride group: 102 μg/scaffold, chloramphenicol group: 69 μg/scaffold, no significant difference from the alginate scaffold, because the last step of the scaffold procedure is to replenish the drug lost by the scaffold. Then, the drug release test was carried out, and it was found that the scaffold coated with chitosan could effectively delay the release of the drug. The difference in drug release after one day was: 98% to 89% in the ampicillin group, and tetracycline hydrochloride group. From 96% to 81%, the chloramphenicol group decreased from 29% to 26%.
In order to check whether the scaffold released sufficient antibiotics to achieve bacteriostatic effect, Gram-negative bacteria (E. coli) and positive bacteria (S. aureus) were tested separately for inhibition. One day later, the scaffold coated with chitosan was measured. The inhibition zone was reduced, and the inhibition zone of Gram-negative bacteria was reduced from 3.5 mm to 2.3 mm in the ampicillin group, from 7.7 mm to 6.3 mm in the tetracycline group, and the chloramphenicol group. Reduced from 5.5 mm to 4.6 mm; the difference in inhibition zone against Gram-positive bacteria was: 5.3 mm to 3.1 mm for the ampicillin group, 8.0 mm to 6.6 mm for the tetracycline group, and chloramphenicol group was reduced from 6.2 mm to 4.8 mm, and it was speculated that the scaffold could release sufficient antibiotics to achieve bacteriostatic effects.
Finally, human fibroblasts were seeded on the scaffold and tested on the first, fourth, and seventh days. The scaffolds coated with chitosan were found. After the fourth day, the DNA values of the cells and the secreted type I collagen values were all compared with the uncoated scaffold, there is a statistical difference (p<0.05), which is presumed to be related to the improvement of mechanical properties of the scaffold, the decrease of degradation rate and the delay of drug release.
According to the above experimental results, the application of chitosan to the surface of the sodium alginate scaffold and carrying antibiotics can not only slowly release a sufficient amount of antibiotics, but also prevent skin repair, and can be applied to skin dressing in the future .
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