We have investigated non-destructive, non-contact single-cell based differential cell screening method using on-chip microcultivation and optical tweezers. The four-room microchamber for cultivating four single cells consists of 5μm high microstructure on the glass slide and is covered with semipermeable membrane to cultivate those cells under contamination-free condition. The number of cells in microchambers is controlled by using optical tweezers to pick out excess cells. For studying the actual changes occurring in cells under isolated condition, we measured and compared four cells in four microchambers simultaneously for more than 10 generations. To examine the potential of this method, we observed single cells of Escherichia coli for more than 10 generations. The results of these observations showed that they keep their mean values even though there exist large dynamic variations in interdivision time and growth speed. The simultaneous observations of four cells also confirmed that these variations in cells are not derived from the time-course changes of environmental conditions because those variations in four cells did not synchronized. The results suggested the potential use of our method for cell assay to predict whether the cells' variation is in permissible range or is caused by drugs or other environmental effects.
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