Fabrication Of Drug Release Barrier Layers Based On Free-Standing Polymer Nanosheet

In recent years,the research about drug delivery systems has developed rapidly and obtained a reliable clinical efficacy. A number of controlled release drug delivery systems have been produced. They have many properties such as targeting, controllable drug release, pharmacology stable and easy drug release. With the development of nanomaterials and nanotechnology, nano drug delivery system has showed more obvious advantage than traditional carrier material. Nowadays, the free-standing nanosheets have become an attractive topic of research. For example, the free-standing nanosheets of polylactic acid (PLA) have good quality of biocompatibility, biodegradability, plasticity, adhesion and so on. It has been reported that the PLA free-standing nanosheets had been used in bone material, surgical sutures, drug delivery and wound dressings. In this dissertation, we used a PLA free-standing nanosheet to cover a drug coating prepared by layer-by-layer technology. It could reduce the burst release of the drugs, obtaining the control of drug release. The combination of drug controlled release coating and medical implanted devices can solve the problem about the medical implants and enhance the function of medical implants.First, we prepared polyallylamine hydrochloride dextran microgel by covalent cross-linked poly (allylamine hydrochloride) and dextran and used it and hyaluronic acid as building blocks to deposited multilayer thin films. Afterwards, the methyl orange or ibuprofen were loaded in multilayer thin films. Assembly process of the multilayer and the drug load was followed by UV spectrophotometer. The morphology and the thickness of the drug coating were characterized by scanning electron microscope. Next, the PLA free-standing nanosheet was prepared by spin-coating with a water-soluble polyvinyl alcohol as sacrificial layer and then was transferred to cover the drug coating. In this process, the release of the drug was measured by UV spectrophotometer. The surface morphology and thickness of different PLA free-standing films were characterized by scanning electron microscope. Finally, a further study was done about the whole drug carrier releasing in a simulated physiological environment. The result indicated that PLA free-standing nanosheet as barrier layer can effectively control the fast release of model drugs.