Liebschner Michael A K, Wettergreen Matthew
Department of Neurosurgery, Baylor College of Medicine, Houston, TX, USA.
Methods Mol Biol. 2012;868:71-89. doi: 10.1007/978-1-61779-764-4_5.
The goal of this area of research is to manipulate the pore space of scaffolds through the application of an intelligent design concept on dissolvable microparticles. To accomplish this goal, we developed an efficient and repeatable process for fabrication of microparticles from multiple materials using a combination of rapid prototyping (RP) and soft lithography. Phase changed 3D printing was used to create masters for PDMS molds. A photocrosslinkable polymer was then delivered into these molds to make geometrically complex 3D microparticles. This repeatable process has demonstrated to generate the objects with greater than 95% repeatability with complete pattern transfer. This process was illustrated for three different shapes of various complexities. The shapes were based on the extrusion of 2D shapes. This may allow simplification of the fabrication process in the future combined with a direct transfer of the findings. Altering the shapes of particles used for porous scaffold fabrication will allow for tailoring of the pore shapes, and therefore their biological function within a porous tissue engineering scaffold. Through permeation experiments, we have shown that the pore geometry may alter the permeability coefficient of scaffolds while influencing mechanical properties to a lesser extent. By selecting different porogen shapes, the nutrition transport and scaffold degradation can be significantly influenced with minimal effect on the mechanical integrity of the construct. In addition, the different shapes may allow a control of drug release by modifying their surface-to-volume ratio, which could modulate drug delivery over time. While soft lithography is currently used with photolithography, its high precision is offset by high cost of production. The employment of RP to a specific resolution offers a much less expensive alternative with increased throughput due to the speed of current RP systems.
该研究领域的目标是通过将智能设计理念应用于可溶解的微粒来操控支架的孔隙空间。为实现这一目标，我们开发了一种高效且可重复的工艺，利用快速成型（RP）和软光刻相结合的方法，从多种材料制造微粒。相变3D打印用于制作PDMS模具的母模。然后将可光交联聚合物注入这些模具中，以制造几何形状复杂的3D微粒。这一可重复的工艺已证明能够以高于95%的重复性生成物体，并实现完整的图案转移。针对三种不同复杂度的不同形状展示了该工艺。这些形状基于二维形状的挤压。这可能会在未来结合研究结果的直接转移，简化制造工艺。改变用于多孔支架制造的颗粒形状将允许定制孔隙形状，从而定制其在多孔组织工程支架中的生物学功能。通过渗透实验，我们表明孔隙几何形状可能会改变支架的渗透系数，同时对力学性能的影响较小。通过选择不同的致孔剂形状，可以显著影响营养物质传输和支架降解，而对构建体的机械完整性影响最小。此外，不同的形状可以通过改变其表面积与体积比来控制药物释放，从而可以随时间调节药物递送。虽然目前软光刻与光刻一起使用，但其高精度被高生产成本所抵消。由于当前RP系统的速度，将RP应用于特定分辨率提供了一种成本低得多的替代方案，且产量更高。
