Abstract
A microfluidic platform to satisfy both 3D cell culture and cell‐based assay is required for credible assay results and improved assay concept in drug discovery. In this article, we demonstrate a microvalve‐assisted patterning (MAP) platform to provide a new method for investigating cellular dynamics by generating a linear concentration gradient of a drug as well as to realize 3D cell culture in a microenvironment. The MAP platform was fabricated by multilayer soft lithography and several microvalves made it possible to pattern a cell–matrix (scaffold) and to exchange media solutions without breaking cell–matrix structure in a microchannel. This approach provides not only exact fluids control, bubble removal, and stable solution exchange in a microchannel, but also reliable scaffold fabrication and 3D cell culture. In this study, hepatotoxicity tests with human hepatocellular liver carcinoma cells (HepG2) were also performed in real‐time monitoring where cell morphologies exposed to different drug concentrations were observed at a time. Compared to 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide (MTT) assay, the MAP platform could be used to reduce drug amount and assay time for cell‐based assays as much as 10 and 3 times, respectively. Biotechnol. Bioeng. 2008;101: 1005–1013. © 2008 Wiley Periodicals, Inc.