NER: Magnetically Activated Nanoporous Structures for Biomedical Applications

本提案是对纳米科学和工程计划NSF 01-157的响应而收到的，属于NER类别。该提案侧重于创新的材料合成策略，以制造无源和磁驱动的机械主动精密分离膜。尤其令人感兴趣的是控制良好、稳定和均匀的纳米维膜的开发和表征，该膜能够在血液分离过程中分离病毒和/或蛋白质，并阻断包裹的异种细胞中的抗体和补体分子。假设高比表面积圆柱形胶囊的壁由纳米孔膜组成，通过两步电场驱动阳极氧化铝或钛而形成，可用于对纳米范围内的生物分子进行绝对过滤或排除。对于给定的胶囊，使用带有阳极化纳米多孔窗口的窗玻璃结构，以及用于结构支撑的非阳极铝支柱。铝阳极氧化工艺能够精确控制孔径，根据阳极氧化电压的不同，孔径可控制在大约10 nm到100 nm之间。除了制造被动膜之外，研究人员还建议制造含有磁弹性元件的圆柱形纳米孔生物胶囊。磁弹性元件的加入使生物胶囊能够通过施加时变磁场远程机械振动，从而能够控制通过膜的传输。在胶囊的铝结构支架上电镀一层磁弹性厚膜层。这种胶囊可能会被用作体内药物输送装置，在这种装置中，所需的药物通过外部施加磁场来精确输送。作为拟议研究的另一个方面，研究人员试图利用他们在制备高均匀性纳米多孔氧化铝薄膜方面的专业知识来制备由垂直取向的镀金磁致伸缩纳米线阵列组成的表面涂层。将调查这些阵列在防止生物污损方面的效用。假设纳米线阵列元件的针状形状，以及磁致伸缩纳米线阵列响应于时变的非均匀磁场的波状运动，将有助于防止蛋白质附着到表面，并最终可用于在表面上移动或转移细胞。这项拟议的研究将确定制造纳米孔胶囊的最佳路线，并关注作为生物过滤器的膜功能。将研究用于细胞包裹和免疫隔离的被动纳米多孔生物胶囊和用于通过纳米孔膜的受控传输和输送的机械活性生物胶囊。此外，还将研究磁致伸缩纳米线阵列在防止生物污垢中的使用。所提出的结果是：(1)通过施加外部时变磁场来确定原位或体内受控给药的路径。(2)确定可防止生物污垢的表面，便于将医疗器械引入人体。

This proposal was received in response to the Nanoscale Science and Engineering Initiative, Program Solicitation NSF 01-157, in the NER category. The proposal focuses on innovative materials synthesis strategies to create both passive, and magnetically-driven mechanically active precision separation membranes. Of particular interest is the development and characterization of well-controlled, stable, and uniform nano-dimensional membranes capable of the separation of viruses and/or proteins during the blood fractionation processes and the blocking of antibodies and complement molecules from encapsulated xenogeneic cells. It is hypothesized that high surface area cylindrical capsules the walls of which are comprised of nanoporous membranes, created via a two-step process of electric-field driven anodization of aluminum or titanium, can be used for the absolute filtration or exclusion of biomolecules in the nanometer range. For a given capsule, a windowpane structure is used with anodized nanoporous windows, and un-anodized aluminum struts for structural support. The aluminum anodization process enables precise control of pore size, with a controllable pore diameter of approximately 10 nm to 100 nm depending upon anodizing voltage. Beyond making passive membranes, the investigators propose fabrication of cylindrical nanoporous biocapsules incorporating magnetoelastic elements. Incorporation of the magnetoelastic elements enable the biocapsule to be mechanically vibrated, remotely from a distance, by application of a time-varying magnetic field that should enable controlled transport through the membrane. A magnetoelastic thick film layer will be electroplated onto the aluminum structural supports of the capsule. Such capsules could possibly find application as in-vivo drug delivery devices, where needed medicine is delivered in precise amounts by external application of a magnetic field. As a further aspect of the proposed research, the investigators seek to build upon their expertise in fabrication of nanoporous alumina films of high uniformity to fabricate surface coatings comprised of perpendicularly oriented gold-coated magnetostrictive nanowire arrays. The utility of these arrays will be investigated for their utility in prevention of biofouling. It is hypothesized that the needle-like shape of the nanowire array elements, and the wave-like movement of the magnetostrictive nanowire array in response to a time-varying non-uniform magnetic field, will help prevent protein attachment to the surface, and could ultimately be used to move or transfer cells across the surface. The proposed research will determine optimal routes for fabrication of the nanoporous capsules with attention to membrane functionality as biological filters. The application of passive nanoporous biocapsules for cellular encapsulation and immunoisolation, and mechanically active biocapsules for controlled transport and delivery through the nanoporous membranes will be investigated. In addition, the use of magnetostrictive nanowire arrays will be investigated for their use in the prevention of biofouling. The proposed outcomes are: (1) Determining a path for in-situ or in-vivo controlled drug delivery by application of an external time varying magnetic field. (2) Determination of a surface that would prevent biofouling, facilitating the introduction of medical devices into the human body.