磁各向异性水凝胶的制备及其作为肿瘤细胞三维培养基质的应用

发布时间：2018-12-23 19:04

【摘要】：作为交叉学科,生物医学工程领域所研究的问题较为复杂,结构功能单一的材料往往无法满足研究者的需求。同时研究者们也发现将多种具有不同性质的材料进行复合,往往能为材料赋予新的结构或者功能,而这些具有新功能的材料能更好的解决生物医学领域所面临的一些复杂问题,因此通过复合的方法制备具有新结构或者功能的材料成为生物医用材料的研究热点之一。作为纳米材料的分支之一,磁性纳米材料因其较好的生物相容性和响应外加磁场的特性受到研究者们的持续关注。近些年基于磁性纳米材料的复合材料发展势头迅猛,而在与其复合的众多材料中,水凝胶因其各方面的优秀特性受到研究者们的普遍亲睐。这两种特性迥异的材料复合后产生了具有磁响应功能的水凝胶复合材料。在此基础上进一步复合过程中外加磁场,可以使得复合材料获得单一材料不具备的新结构与功能。本文利用外加磁场辅助调控制备了一系列具有各向异性结构和特性的磁性纳米材料-水凝胶复合材料,研究了磁各向异性水凝胶的各向异性结构与特性之间的相互关系,初步探究了其作为体外三维细胞培养基质的应用。论文的具体内容包含以下几个部分:1.结合静磁场辅助组装、磁性纳米材料和水凝胶,制备了一种具有特殊取向结构的新型磁各向异性水凝胶,该方法简便易行,具有较好的普适性。根据模拟计算结合实验,探究了用于制备磁各向异性水凝胶的磁性纳米材料和水凝胶体系的基本要求;研究了磁性纳米材料的种类、尺寸及浓度;水凝胶单体浓度及交联剂浓度;外加磁场强度及组装时间对磁各向异性水凝胶结构的影响,并首次使用高分辨显微CT原位表征并重建了磁各向异性水凝胶中磁性纳米材料组装结构在空间中的分布。2.对基于静磁场制备的磁各向异性水凝胶的力学,光学,磁学和在交变磁场中的发热特性进行了研究。具有特定取向的磁性纳米材料组装结构对磁各向异性水凝胶在不同方向上的弹性模量有不同程度的影响,其在空间中的分布方式使得复合材料具有类似三维光栅的衍射能力。首次发现并报道了具有磁各向异性水凝胶在交变磁场中的可控发热增强效应,并对通过研究磁各向异性水凝胶的磁学效应对其机制进行了初步阐释,结果显示这种独特的发热性质可能是由磁性纳米颗粒之间的相互作用引起的。这种可以通过改变磁各向异性水凝胶与外加交变磁场交角进行控制的发热方式使得其可以作为具有药物控制释放能力的载体等,结合磁各向异性水凝胶的发热特性在肿瘤热/化疗协助作用方面具有较好的潜在应用前景。3.首次利用交变磁场/旋转磁场辅助制备磁各向异性水凝胶。初步探究了交变磁场/旋转磁场对磁各向异性水凝胶结构和特性的影响,研究了交变磁场频率、旋转磁场转速等因素对磁各向异性水凝胶的影响。结果显示交变磁场组装可能有助于提高磁性纳米材料间的相互作用;旋转磁场能在水凝胶内部形成类似圆饼状的磁性纳米材料组装结构,具有这种特别结构的磁各向异性水凝胶同样在交变磁场中具有各向异性的发热特性;增大旋转磁场的转速能提高旋转磁场辅助制备的磁各向异性水凝胶在交变磁场中的发热能力。4.首次利用抗细胞粘附的水凝胶和细胞粘附的磁性纳米材料结合制备磁各向异性水凝胶,利用物理切割的方法将磁性纳米材料组装结构暴露在界面上,细胞可以粘附在复合材料的表面上,通过粘附、增殖、迁移和聚集,自主形成多细胞聚集体,多细胞聚集体进一步通过增殖和融合形成具有紧实结构的多细胞球。细胞增殖结果显示在此模型上生长的细胞其增殖速度远低于在细胞孔板上生长的细胞,与细胞在体内生长的速率更接近;活\死细胞染色显示培养一段时间后在多细胞球的中心部分有初步形成的死核,抗药性测试结果显示具有这种结构的多细胞球可以有效的被用于肿瘤细胞体外药物和治疗手段的评价;不同细胞株(正常细胞或肿瘤细胞)在磁各向异性水凝胶表面形成多细胞球的效率存在一定差异,而且可以促使一些无法在传统三维细胞培养系统中形成多细胞球的细胞株形成多细胞球。这种促进肿瘤细胞自发形成多细胞球的功能使得磁各向异性水凝胶在肿瘤体外诊断上具有良好的应用前景。
[Abstract]:As a cross-discipline, the problems in the field of biomedical engineering are complex and the material with a single structural function is often unable to meet the needs of the researchers. At the same time, the researchers have also found that a variety of materials with different properties can be compounded, and new structures or functions can be imparted to the material, and the materials with the new function can better solve the complex problems of the biomedical field, so that the preparation of the material with the new structure or function by the composite method becomes one of the research hotspots of the biomedical materials. As one of the branch of the nano-material, the magnetic nano-material is subject to the constant attention of the researchers because of its good biocompatibility and response to the characteristics of the applied magnetic field. In recent years, the development of the composite material based on the magnetic nano-materials has developed rapidly, and in the many materials compounded with it, the water-gel is subject to the general affinity of the researchers because of the excellent characteristics of its various aspects. The two types of materials with different characteristics result in a hydrogel composite with a magnetic response function. on the basis of which, a magnetic field is added to the composite material, so that the composite material can obtain a new structure and a function that a single material does not have. In this paper, a series of magnetic nano-material-hydrogel composites with anisotropic structure and properties were prepared by external magnetic field-assisted regulation, and the relationship between the anisotropic structure and the properties of the magnetic anisotropic hydrogel was studied. The application of it as a three-dimensional cell culture matrix in vitro was studied. The specific contents of the thesis include the following parts: 1. The novel magnetic anisotropic hydrogel with special orientation structure is prepared by combining the static magnetic field auxiliary assembly, the magnetic nano material and the hydrogel, and the method is simple and convenient, and has good universality. In this paper, the basic requirements of the magnetic nano-materials and the hydrogel system for preparing the magnetic anisotropic hydrogel are investigated, and the species, the size and the concentration of the magnetic nano-materials, the concentration of the water-gel monomer and the concentration of the cross-linking agent are studied. The influence of the magnetic field strength and the time of assembly on the structure of the magnetic anisotropic hydrogel was studied, and the distribution of the magnetic nano-material in the space was reconstructed in situ by using the high-resolution micro-CT in-situ and the distribution of the magnetic nano-material in the space was reconstructed. The mechanical, optical, magnetic and heat-generating properties of the magnetic anisotropic hydrogel prepared based on the static magnetic field are studied. The magnetic nano-material assembly structure with specific orientation has different influence on the elastic modulus of the magnetic anisotropic hydrogel in different directions, and the distribution mode of the magnetic nano-material in the space makes the composite material have the diffraction capability similar to the three-dimensional grating. The controllable heating enhancement effect of the magnetic anisotropic hydrogel in the alternating magnetic field was first found and reported, and the mechanism of the magnetic anisotropic hydrogel was initially explained. The results show that this unique heating property may be caused by the interaction between the magnetic nanoparticles. this can be controlled by changing the angle between the magnetic anisotropic hydrogel and the applied alternating magnetic field so that it can be used as a carrier with a drug control release capability, etc., The heat-generating property of the combined magnetic anisotropic hydrogel has a better potential application prospect in the treatment of tumor heat/ chemotherapy. the magnetic anisotropic hydrogel is prepared by using an alternating magnetic field/ rotating magnetic field for the first time. The effect of the alternating magnetic field/ rotating magnetic field on the structure and properties of the magnetic anisotropic hydrogel was investigated. The effects of the alternating magnetic field frequency and the rotational speed of the rotating magnetic field on the magnetic anisotropic hydrogel were studied. The result shows that the alternating magnetic field assembly may help to improve the interaction between the magnetic nano-materials, and the rotating magnetic field can form a similar round-cake-like magnetic nano-material assembly structure inside the hydrogel. the magnetic anisotropic hydrogel with the special structure also has an anisotropic heating characteristic in the alternating magnetic field, the rotating speed of the rotating magnetic field is increased, and the heating capacity of the magnetic anisotropic hydrogel in the alternating magnetic field can be improved by increasing the rotating speed of the rotating magnetic field. the magnetic nano-material assembly structure is exposed on the surface of the composite material by physical cutting method for the first time, and the cell can be adhered to the surface of the composite material, and the magnetic nano-material assembly structure can be adhered and proliferated through adhesion and proliferation, migration and aggregation, self-forming multi-cell aggregates, and multi-cell aggregates further forming a multi-cell ball with a compact structure by proliferation and fusion. The cell proliferation results show that the cells grown on this model are far below the cells grown on the cell-well plates, closer to the rate at which the cells grow in vivo, and the live dead cell staining shows a preliminarily formed dead core in the central portion of the multi-cell ball after a period of incubation, the drug resistance test results show that the multi-cell ball with such a structure can be effectively used for the evaluation of the in-vitro drug and treatment means of the tumor cells; the efficiency of forming the multi-cell ball on the surface of the magnetic anisotropic hydrogel by different cell lines (normal cells or tumor cells) is different, but also a number of cell lines that are not able to form multicell spheres in a conventional three-dimensional cell culture system can be promoted to form a multi-cell ball. The function of promoting the spontaneous formation of the multi-cell ball of the tumor cell enables the magnetic anisotropic hydrogel to have a good application prospect in the in vitro diagnosis of the tumor.
【学位授予单位】：东南大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O648.17;R73-3

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