The Synthesis Of Environmentally Responsive Amphiphilic Block Copolymer And The Research Of Its Character And Application

Due to its limitations, traditional medicine of oral and injection method have many drawbacks. Adopting the stimulus responsive polymer micelles as the drug delivery system could give play to the advantage in the control drug release by external environmental stimulation, it both can improve absorption efficiency of the hydrophobic drug and the realization of the slow control release of the drug; also it can reduce drug side effects and improve the drug concentration in the blood and so on, which has a good application prospect in biomedical field. Among in all environmental response types, the light response is a kind of external stimulation that widely used which has the characteristics of clean, noninvasive and effective. Compared with other stimulus types such as pH and DDS, light responsive polymer micelles could also realize the rapid release of drug in a specific location and time which does not require a particular chemical environment. And the chemical environment changes can be divided into two kinds, the first kind is need biology itself to provide environment, such as cancer cells in weak acid environment, the controllability of the release in this kind of circumstance is slow. And the other kind need external regulation, this condition will inevitably involve the biocompatibility, biodegradable and biological toxicity, thus light responsive polymer micelles drug carrier has incomparable advantages compared with other response type drug carrier.This paper designed and synthesized two kinds of responsive polymer micelle in the basis of literature research, and the drug controlled release of the light polymeric micelles were studied.Firstly, we introduced the light responsive spiropyrane structure into the polymer, and prepared a light responsive and biocompatible polymer micelles used as a drug carrier. They are described as below:Synthesized a kind of double bond spiropyrane (SPA) used for RAFT polymerization, then get a PEG based macromolecular RAFT reagent through a esterification reaction between a small RAFT reagent and biocompatible monomer PEG, and at last prepared a light responsive block copolymer PEG113-b-PSPm by the RAFT polymerization. And we used the nuclear magnetic resonance hydrogen spectrum (1H NMR)?nuclear resonance magnetic spectrometry (13C NMR) ?gel permeation chromatography (GPC) to characterize the molecular structure of the polymer. Also the critical micelle concentration (CMC) was tested by the fluorescence probe method. And the self-assembly behavior of copolymer in aqueous solution was detected by the scanning electron microscopy (SEM) and dynamic laser light scattering (DLS). Then the light response properties were characterized by the ultraviolet visible light spectrum and the behavior of the disassembly of the micelles under irradiated by 365 nm UV light was studied by SEM and DLS. At the same time, the fluorescence emission spectrum was used to study the simulation of the polymer micelle drug controlled release of Nile red under ultraviolet light irradiation, and cytotoxicity test (determined by MTT) method is used to evaluate the biological properties of the polymer micelle drug carrier.Secondly, this paper also introduced a temperature responsive NIPAAm monomers into the polymer structure, and we prepared a temperature responsive and biocompatible polymer micelle drug carrier. They are described as below:we used the macromolecular RAFT reagent to polymerize the NIPAAm monomers and got the temperature responsive block copolymer PEG113-b-PNIPAAmn. And we used the 1H NMR,13C NMR and GPC to analyze the molecular structure of the polymer. Then UV-vis absorption spectrometer was used to study the temperature response characteristic in different polymerization degree.