动态磁场对磁转染行为的影响及转染效率的增强机制研究

Magnetic nanoparticles assisted gene transfection is an effective approach to overcome the defect of low transfection efficiency based on non-viral agents. This technology has shown important practical value in functional genomics and gene therapy. The past researches have demonstrated the significant advantages of dynamic magnetic fields on enhancing transfection efficiency comparing to static fields, however, the factors and action mechanism of dynamic magnetic fields on transfection behavior are still not well known. Therefore, this project proposes to explore a key scientific problem: how the dynamic magnetic field and its interaction mode with magnetic complexes improve magnetofection efficiency. For this purpose, the project will design and develop a guidance and regulatory system of magnetic targeting by application of permanent magnet with a combination of quadrupole magnet, which is used to generate and control dynamic magnetic fields with some key variable parameters including magnetic field strength, gradient, frequency and actuation duration. On this basis, the dynamic behavior of magnetic complexes under the action of different dynamic fields will be analyzed. Then the influencing rule and action mechanism of dynamic fields in the transfection progress acting on the magnetic complexes enrichment on the cell surface, endocytosis and transport behavior inside the cell will be investigated. All these will provide a theoretical foundation and experimental basis for obtaining optimal magnetic field to achieve high efficiency transfection.

基于磁性纳米颗粒载体的基因转染技术是突破目前非病毒载体转染效率低下这一瓶颈的重要途径，在功能基因组学和疾病基因治疗领域具有重要的应用价值。现有研究表明，相比于静态磁场，动态磁场对于进一步提高磁转染效率具有显著优势，但其影响转染行为的因素及作用机理不明。为此，本项目拟围绕动态磁场及其与磁性复合物间的作用模式是如何增强磁转染效率这一关键科学问题，设计和研制基于永磁体和四极电磁体的组合电磁靶向引导和调控系统，实现磁场大小、方向、变化频率及作用时间等关键电磁参数可调的动态磁场，在此基础上，探讨不同磁场作用形式下磁性复合物的动力学行为，明确动态磁场在转染过程中对磁性复合物在细胞表面的富集特性、内吞特性和在胞内输运特性的影响规律及作用机制，为探求实现高效转染的最佳磁场作用模式提供理论基础和实验依据。

基于磁性纳米颗粒载体和动态磁场的基因转染技术是实现非病毒载体高效转染的重要途径，在功能基因组学和疾病基因治疗领域具有重要的应用价值。然而，动态磁场作用模式下磁转染效率的增强机制尚未被有效揭示。为解决上述问题，本项目在动态磁场、磁性复合物及细胞间的相互影响和作用规律等方面开展了系统研究，所取得的主要研究成果有：1）提出并研制了一种可产生多类静态和动态磁场的新型共轴式双线圈磁体-电源-控制系统，并构建了相应的微粒操控实验平台，为开展不同磁场作用形式下的磁性粒子靶向特性和磁转染特性研究提供了平台支撑；2）明确了静态和动态磁场下粒子间磁相互作用力对粒子分布形态的影响规律，发现动态磁场可显著提高粒子的覆盖率和分散均匀性，为动态磁场可改善粒子富集特性进而提高转染效率这一新的阐释机制提供了依据；3）提出了一种基于离子修饰的磁性纳米粒子表面电性的调节方法，并在此基础上，以聚乙烯亚胺（PEI）作为载体，探明了三元转染复合物中磁性纳米粒子、PEI与核酸的不同配比以及不同外加梯度磁场（静/动态）对磁转染特性的影响规律。