Figure 4.

Investigation of the metabolic switch of U-251 MG cells cultured in the tumor-on-a-chip platform. (a) 2-NBDG uptake by U-251 MG cells cultured in devices with or without a PMMA sheet. Arrows indicate cells with enhanced 2-NBDG uptake. (b) Representative image of the fluorescence ratio of TAMRA and fluorescein (TR/Fluo) of a dual-labeled dextran as a pH sensor in microfluidic devices loaded with U-251 MG cells with or without a PMMA sheet. Scale bars represent 500 μm. (c) Quantified pH values in the device based on the ratio of the intensities of the two dyes (TR/Fluo) of the dual-labeled dextran for devices as illustrated in panel b. Lines depict averages at distinct positions in the devices and the shaded areas indicate the s.e.m.