Poly(dimethylsiloxane) (PDMS) is one of the most popular polymer materials for microfluidic devices. However, it still remains a challenge to rapidly fabricate PDMS microfluidic devices with micrometerscale feature sizes. In this paper, we present a gray-scale digital photolithography technology for direct patterning of large-area high-resolution PDMS microstructures for biomicrofluidic applications. With the positive-and negative-tone photosensitive PDMS (photoPDMS), we rapidly fabricated various PDMS microstructures with complex geometries by using an one-step patterning process. The positive-tone PDMS has been used to pattern large-area microfluidic chips, while the negative-tone PDMS has been utilized to fabricate high-resolution on-chip microstructures and components. In particular, a large-area microfluidic chip of 5.5 × 2.8 cm 2 with complex three-dimensional (3D) staggered herringbone mixers (SHMs) was fabricated from the positive-tone PDMS by using a single-step optical exposure process; a small microfluidic chip with feature size as small as 5 µm was prepared with the negative-tone PDMS. Furthermore, 3D surface engineering of PDMS microchannels was demonstrated to customize extracellular microenvironments for investigating cell migration.
Guidance of postinfarct myocardial remodeling processes by an epicardial patch system may alleviate the consequences of ischemic heart disease. As macrophages are highly relevant in balancing immune response and regenerative processes their suitable instruction would ensure therapeutic success. A polymeric mesh capable of attracting and instructing monocytes by purely physical cues and accelerating implant degradation at the cell/implant interface is designed. In a murine model for myocardial infarction the meshes are compared to those either coated with extracellular matrix or loaded with induced cardiomyocyte progenitor cells. All implants promote macrophage infiltration and polarization in the epicardium, which is verified by in vitro experiments. 6 weeks post‐MI, especially the implantation of the mesh attenuates left ventricular adverse remodeling processes as shown by reduced infarct size (14.7% vs 28–32%) and increased wall thickness (854 µm vs 400–600 µm), enhanced angiogenesis/arteriogenesis (more than 50% increase compared to controls and other groups), and improved heart function (ejection fraction = 36.8% compared to 12.7–31.3%). Upscaling as well as process controls is comprehensively considered in the presented mesh fabrication scheme to warrant further progression from bench to bedside.
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