XYZ on a Chip: Incorporation of Biological Components into Microsystems via Biomimetic Processing

9980795 Gower这个工程微系统的目标：“XYZ”芯片项目是将联合收割机快速原型技术与仿生加工相结合，用于制造包含生物组件的工程微系统。PI目前正在开发一种称为聚合物诱导液体前体（PILP）工艺的仿生处理技术，用于在低温和水基条件下沉积矿物膜。这些良好的加工条件应适合于掺入热敏成分，这将在拟议的方法中得到利用。PILP工艺的新奇在于酸性结晶剂（聚天冬氨酸）通过螯合离子和诱导矿物前体的相分离将传统的溶液结晶工艺转化为固化工艺。该前体是中等粘性液体的形式，并且可以通过隔室模制和成形。生物矿化的标志是生物体能够在囊泡隔室中“塑造”无机晶体，因此假设这种PILP过程可能在方解石生物矿物的形态发生中发挥重要作用。因此，所提出的工作的第一个目标是演示使用微细加工技术的方解石的“微成型”。无机相的图案化将通过以下两种方法来研究：1）PILP前体的软光刻”微成型，或2）由温度诱导成型（TIF）过程产生的陶瓷前体的固体自由成型制造。图案化的无机层的通道随后将通过用于层的平坦化的第二相的聚合来填充（选择聚肉桂酸作为测试床）。然后将使用快速成型技术依次存款许多薄层，以构建受控建筑的三维复合结构，这是该项目的第二个目标。在许多方面，这种逐层的制造方案类似于生物矿化中自然发生的过程;由此计算机辅助设计（CAD）允许对顺序沉积进行空间控制，这是通过生物系统中的细胞过程来完成的。该项目的第三个目标是演示将生物组分以空间均匀和受控的方式并入支架结构中。尿素酶-尿素酶系统将用于试验台，以确定该过程是否使蛋白质变性。蛋白质的空间分布将通过蛋白质的荧光和免疫金标记来检查。本文提出的工作将证明该方法的可行性，并开始获得必要的工具，以开发用于各种应用的定制复合材料的通用方法，例如：生物受体微系统：生物组分的高度空间调节将是微电子学与生物受体物种杂交的未来的必要特征。一种生物可降解的矿物相，具有最佳的生物相容性，可缓慢释放包裹在矿物相中的药物。细胞和组织工程的微囊化：一种含有骨形态发生蛋白的生物可降解相的多孔框架，其用作骨诱导性骨移植替代物，或用于包封骨祖细胞以用于体外硬组织工程（或其它组织）。同样地，多孔框架可以为胰岛细胞提供笼，使生理介质能够通过流动和生物控制释放胰岛素用于治疗糖尿病，同时分离外来细胞以防止免疫原性反应。骨架的三维结构化将使得能够控制用于尺寸特异性分离和色谱的孔隙率和孔隙率梯度，这沿着与生物组分结合的能力，将特别适合于生物分离。利用良性的仿生过程，酶可以被引入到框架中以制造多孔催化介质，并且可能通过与框架的表面相互作用控制蛋白质的取向，以最佳地呈现催化位点。

9980795GowerThe goal of this Engineering Microsystems: "XYZ" on a Chip project is to combine rapid prototyping techniques with biomimetic processing for the fabrication of engineered microsystems that contain biological components. The biomimetic processing technique, called the Polymer-Induced Liquid-Precursor (PILP) process, is currently being developed by the PI for the deposition of mineral films under low-temperature and aqueous-based conditions. These benign processing conditions should be amenable to the incorporation of thermally sensitive ingredients, which will be capitalized on in the proposed methodology. The novelty of the PILP process is that an acidic polyelectrolyte (polyaspartic acid) transforms a traditional solution crystallization process into a solidification process by sequestering ions and inducing phase separation of a mineral precursor. This precursor is in the form of a moderately viscous liquid, and can be molded and shaped by a compartment. The hallmark of biomineralization is the ability of organisms to "mold" inorganic crystals within vesicular compartments, thus it is hypothesized that this PILP process may play a fundamental role in the morphogenesis of calcitic biominerals. Therefore, the first goal of the proposed work is to demonstrate "micromolding" of calcite using microfabrication techniques.Patterning of the inorganic phase will be investigated by the following two approaches: 1) soft lithography" micromolding of a PILP precursor, or 2) solid freeform fabrication of ceramic precursor generated by a Temperature Induced Forming (TIF) process. The channels of the patterned inorganic layer will subsequently be filled in by polymerization of a secondary phase for planarization of the layer (polycinnamic acid is chosen as the testbed). Rapid prototyping will then be used to sequentially deposit numerous thin layers, in order to construct a three-dimensional composite structure of controlled architecture, the second goal of the project. In many ways, this layer-by-layer fabrication scheme is similar to the processes that occur naturally in biomineralization; whereby computer-aided design (CAD) allows for the spatial control of the sequential depositions, which is accomplished by cellular processes in biological systems.A third goal of the project is to demonstrate the incorporation of biological components into scaffolding structures, and in a spatially uniform and controlled fashion. The Urease-urea enzyme system will be used for a testbed, in order to determine if the process denatures the protein. The spatial distribution of the protein will be examined by fluorescent and immunogold labeling of protein. The work proposed herein will demonstrate feasibility of the approach, and begin to acquire the tools necessary for developing a generalized methodology for customized composites for a variety of applications, such as the following:Bio receptor Microsystems: a high degree of spatial regulation of biological components will be a necessary feature for the future of hybridization of microelectronics with bioreceptor species.Drug Delivery- a biodegradable mineral phase with optimal biocompatibility for the slow release of agents encapsulated within the mineral phase.Microencapsulation of Cells and Tissue Engineering: a porous framework of a biodegradable phase containing bone morphogenetic proteins for application as osteoinductive bone-graft substitutes, or for encapsulation of osteoprogenitor cells for in vitro hard-tissue engineering (or other tissues). Likewise, a porous framework could provide a cage for Islet cells, enabling through flow of physiological media and biologically-controlled release of insulin for treatment of diabetes, while isolating the foreign cells to prevent immunogenic response.Bioseparations: structuring of the framework in three-dimensions will enable controlled porosity and porosity gradients for size-specific separations and chromatography, that along with the capability of incorporation of bioconstituents, will be particularly amenable to bioseparations.Biocatalysis: Using the benign biomimetic process, enzymes could be incorporated into the framework to fabricate a porous catalytic media, and possibly with controlled orientation of the protein through surface interactions with framework for optimal presentation of catalytic site.