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Preparation of Functional Amphiphilic Block Copolymers Micelles and the Application in Drug Controlled Release Systems

Author: WangPan
Tutor: GaoQingYu
School: Henan University
Course: Polymer Chemistry and Physics
Keywords: Amphiphilic block copolymers Micelle Preparation High load drugs capacity Folic acid controlled release pH-sensitive
CLC: R943
Type: Master's thesis
Year: 2011
Downloads: 185
Quote: 1
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Abstract

In recent decades, the self-assemble to form polymeric micelles for drug carrier made good results in more and more people's attention. Loaded micelles capable of forming a unique core-shell structure, the drug wrapped in the micelles the kernel, to protect the loaded drug, to avoid human body biological Enzymes and other impact of the human body environment, but also enables the drug in lesion slow release. The drug-loaded micelles have targeted delivery, the nano-size and high stability, these properties so that the drug-loaded micelles able to prevent drug absorption and excreted by the human reticuloendothelial system, thereby reducing the drug to normal human cells and the organization of drug side effects. Most of the polymer micelles by amphiphilic block copolymers self-assemble to form, it has a small particle size, good biocompatibility, high stability, but there is a drawback in the amphiphilic polymer loaded micelles that can not load the ionic drug. Another way is through the composite two oppositely charged polymer to form micelles, the formation of micelles is called the \Polyion complex micelles not only through hydrophobic interaction kernel load hydrophobic drugs, and the ability to load through its electrostatic interaction ionic drugs and charged biological macromolecules. Polyion complex micelles also be able to respond to changes in pH and ionic strength. But a drawback of polyion complex micelles under strong acidic or basic conditions can be prolonged stability exists. In this article, we modified polymer micelle formation, so that the polymer formed not only has the advantages of two polymer micelle, while avoiding their defects. We work mainly includes the following two aspects: 1. Reversible addition - fragmentation chain transfer (RAFT) polymerization synthesized acrylate, iso-butyl (IBA), methacrylic acid dimethylaminoethyl methacrylate (DMAEMA) Regulation copolymeric blocks with polyacrylic acid -2 - hydroxypropyl acrylate (PHPA) composed of amphiphilic diblock copolymers (P (IBA-co-DMAEMA)-b-PHPA), and gel permeation chromatography (GPC), Nuclear magnetic resonance spectroscopy (1H NMR) and infrared spectroscopy (FTIR) was carried out the characterization of the structure and composition. This copolymer self-assembly in an aqueous medium to form a stable polymer micelles by fluorescent probe technique measured obtaining low critical micelle concentration (CMC) of approximately 2.1 mg / L Transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurement results show that P (IBA-co-DMAEMA)-b-PHPA in aqueous self-assembly to form micelles are spherical core-shell structure, the average kinetic diameter is between 110-136nm, and were evenly narrow distribution. The polymer micelles as a carrier, folic acid (FA) as a model drug, drug release in vitro studies simulated biological environment. The results show that the amount of folic acid load and load efficiency up to 38% and 76% respectively. At a temperature of 37 ° C, the ionic strength I = 0.15 M, pH value 2.0,7.4,9.2 phosphate buffer solution (PBS), the relatively rapid release of the FA within 40h, the release rate increases with increasing pH of sequentially. The subsequent release of slowing down, the maximum cumulative release rate of 36%, 61% and 80%, respectively. The polymer micelle is expected to become a new kind of pH-sensitive drug capacity of the high load and the system controlled drug release carrier material. 2, we will triblock copolymer polyacrylic acid -2 - hydroxypropyl acrylate-b-poly methyl methacrylate-b-poly methyl acrylate, dimethylaminoethyl methacrylate (PHPA-b-PMMA-b-PDMAEMA) and polyacrylic acid -2 - hydroxypropyl acrylate-b-poly (methyl methacrylate)-b-polyacrylic acid (PHPA-b-PMMA-b-PAA) was dissolved in acetone, and then dialyzed in deionized water to obtain a new multilayer micelles. Such polymeric micelles having PAA and PDMAEMA composite-forming the hydrophobic core and the hydrophilic shell formed by the hydrophobic PMMA formed the outer core and PHPA. Its low critical micelle concentration (CMC), aqueous micelle size and micelle surface morphology by fluorescence spectroscopy, dynamic light scattering (DLS) and transmission electron microscopy (TEM) measured. Low critical micelle concentration of about 2.42 mg / L, dynamic light scattering and transmission electron microscopy measurement results show that the polymer micelles rendered as a regular spherical structure, and an average diameter of about 110nm. In order to study the application of the polymer micelles in the biological field, we folic acid loaded polymeric micelles, studied the behavior of the controlled release of folic acid, results showed that the pH value changes can affect the rate of release of folic acid. All of these features indicate that the polymer micelles hope to become a new type of intelligent drug carrier material.

Preparation of Functional Amphiphilic Block Copolymers Micelles and the Application in Drug Controlled Release Systems

Abstract

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