Fabrication of a circular PDMS microchannel for constructing a three-dimensional endothelial cell layer

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ORIGINAL PAPER

Fabrication of a circular PDMS microchannel for constructing a three-dimensional endothelial cell layer Jong Seob Choi • Yunxian Piao • Tae Seok Seo

Received: 27 March 2013 / Accepted: 23 April 2013 Ó Springer-Verlag Berlin Heidelberg 2013

Abstract We describe a simple and efficient fabrication method for generating microfluidic channels with a circular cross-sectional geometry by exploiting the reflow phenomenon of a thick positive photoresist. Initial rectangular shaped positive photoresist micropatterns on a silicon wafer, which were fabricated by a conventional photolithography process, were converted into a half-circular shape by tuning the temperature to around 105 °C. Through optimization of the reflow conditions, we could obtain a perfect circular micropattern of the positive photoresist, and control the diameter in a range from 100 to 400 lm. The resultant convex half-circular photoresist was used as a template for fabricating a concave polydimethylsiloxane (PDMS) through a replica molding process, and a circular PDMS microchannel was produced by bonding two half-circular PDMS layers. A variety of channel dimensions and patterns can be easily prepared, including straight, S-curve, X-, Y-, and T-shapes to mimic an in vivo vascular network. To form an endothelial cell layer, we cultured primary human umbilical vein endothelial cells inside circular PDMS microchannels, and demonstrated successful cell adhesion, proliferation, and alignment along the channel.

J. S. Choi and Y. Piao contributed equally to the work.

Electronic supplementary material The online version of this article (doi:10.1007/s00449-013-0961-z) contains supplementary material, which is available to authorized users. J. S. Choi  Y. Piao  T. S. Seo (&) Department of Chemical and Biomolecular Engineering and Institute for the BioCentury, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701, Republic of Korea e-mail: [email protected]

Keywords Polydimethylsiloxane  Circular microchannels  Cell culture  Reflow of photoresist  Human umbilical vein endothelial cells

Introduction The application of microfabrication technology has expanded from simple biomolecular separation to more complicated genomic, proteomic, and cellular analyses [1]. In particular, the ability of microtechnology for precise control of time and space in microenvironments provides an excellent platform for cell biology and tissue engineering [2, 3]. Microfluidic-based biomimetic devices have demonstrated more reliable and high-throughput drug screening capability compared with the conventional static 2-D cell culture system [4–6]. Research on the construction of an artificial microvascular system on a chip is a good example. Vascular endothelial cells lining the lumina of all blood vessels play an important role in maintaining the homeostasis of the circulatory system, and they are involved in a number of vascular diseases such as atherosclerosis and thrombosis. Study on the vascular endothelium, cardi