Biochemical Sciences Division, Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899-6312, USA.
Lab Chip. 2011 Dec 7;11(23):4041-6. doi: 10.1039/c1lc20505f. Epub 2011 Oct 14.
Carbon dioxide partial pressure (P(CO(2))) was controlled on-chip by flowing pre-equilibrated aqueous solutions through control channels across the device. Elevated P(CO(2)) (e.g. 0.05 atm) was modulated in neighboring stagnant channels via equilibration through the highly gas permeable substrate, poly(dimethylsiloxane) (PDMS). Stable gradients in P(CO(2)) were demonstrated with a pair of control lines in a source-sink configuration. P(CO(2)) equilibration was found to be sufficiently rapid (minutes) and stable (days) to enable long-term microfluidic culture of mammalian cells. The aqueous solutions flowing through the device also mitigated pervaporative losses at sustained elevated temperatures (e.g. 37 C), as compared to flowing humidified gas through the control lines to control P(CO(2)). Since pervaporation (and the associated increase in osmolality) was minimized, stopped-flow cell culture became possible, wherein cell secretions can accumulate within the confined environment of the microfluidic culture system. This strategy was utilized to demonstrate long-term (> 7 days) microfluidic culture of mouse fibroblasts under stopped-flow conditions without requiring the microfluidic system to be placed inside a cell culture incubator.
二氧化碳分压（P（CO（2）））通过在设备上流动预平衡的水溶液来控制芯片上的二氧化碳分压。通过高度透气的聚二甲基硅氧烷（PDMS）通过平衡来调节相邻静止通道中的升高的 P（CO（2））（例如 0.05 大气压）。通过源-汇配置中的一对控制线证明了 P（CO（2））的稳定梯度。发现 P（CO（2））的平衡足够快（分钟）且稳定（天），从而能够进行哺乳动物细胞的长期微流控培养。与通过控制线流动加湿气体以控制 P（CO（2））相比，流经设备的水溶液还减轻了持续升高温度（例如 37°C）下的渗透蒸发损失。由于最小化了渗透蒸发（以及相关的渗透压升高），因此可以进行停流细胞培养，其中细胞分泌物可以在微流控培养系统的封闭环境中积累。该策略用于在停流条件下证明了长达 7 天以上的小鼠成纤维细胞的长期微流控培养，而无需将微流控系统放置在细胞培养孵育箱内。
