| Shellac which is also known as lac is a natural brown resin secreted by lac insects grown in tropical plants. After rinsing and filtered, the crude materials can become purified products. The shellac is widely used in food, phannaceuticals, military, dyes and other industries because of its excellent properties (such as good properties of film-forming, waterproofness, color fixing and biocompatibility). In pharmaceutical industry, shellac was often used as enteric-coated excipient when there was no polyacrylic acid yet. However, as a result of the emergence of a variety of the synthetic materials since the fifties, shellac was slowly fading out many fields. With the development of biomedicine, people found that there were many limitations of the synthetic materials, such as irritant and carcinogenicity. So lac returns to the people’s attention for its unique properties now.The medicated shellac nanofiber mats with different drug release characters were prepared via single and blend electrospinning technology. The spinning process was optimized by analysis the diameter distributions, surface morphologies and in vitro drug release characters of different nanofiber mats which were prepared by adjusting the concentration of spinning solutions, the mass ratio of different polymers and other parameters. The results indicated that the electrospun shellac nanofibers had uniform diameters and good performance in drug loading, drug controlled release and so on.Shellac drug-loaded microspheres were prepared by electrospray process. The factors (eg, concentration of shellac solution and the distance between needle and collector) were investigated to optimize the preparation process. The performance of the microspheres were studied by analysis the size distribution, encapsulation efficiency, drug loading, surface morphology, and in vitro drug release characters of the microspheres. Results showed the microspheres prepared via the optimal process had excellent properties, such as the smaller particle size, the more concentrated size distribution, the higher drug loading and encapsulation efficiency as well as the better property of sustained drug release.Modified medicated shellac membrane was directly casting by solution of the drug the shellac which was modified by sodium carbonate. By the means of testing the pH values and conductivities of reaction systems, the optimal reaction time and the concentration of sodium carbonate were selected. The property of the modified shellac and the drug-loaded membrane was identified by fourier-transform infrared and the results showed that the modified shellac became salt and pKa value decreased. The modified material can be applied as a better enteric-coated excipient.Fourier-transform infrared (FTIR), UV-VIS spectrophotometer, X-ray diffraction (XRD) and differential scanning calorimetry (DSC) were carried out to characterize the drug loaded fibers, microspheres and membranes mentioned above. The results showed that the matrix-shellac can encapsulate the drug well and the drug was also distributed well in shellac. In addition, the drug release behaviors of these drug delivery systems almost achieved ideal results. Although confined to the time and limitation of the author some problems weren’t interpreted well, the results of this study can to some extent enlarge the range of application and provided some new drug delivery systems involving shellac. |
