Figure 5 . Trends of NPC43 cell migration speed in 100×100 μm2 microwells (a) without cover and (b) with cover after different treatments. These groups include control without any treatment, NPC43 cells treated with PTX, and NPC43 cells treated with PEG-PTX NPs. t0.1 represents time when migration speed was equal to 0.1 μm/min.
NPC43 cell migration speed in different microwells without and with the covers are shown in Figure. 5 and Supporting Figure. S8-S9. 100×100 μm2 microwells were used for further explanation because the trends of NPC43 cell migration speed were similar for different microwell sizes after the same treatment. As shown in Figure. 5a, in 100×100 μm2 microwells without a cover, cell migration speed for cells treated with PTX for 16 h decreased quickly, and the t0.1 was 4.0 h. On the other hand, cell migration speed decreased continuously and t0.1 was 10.6 h after the NPC43 cells were treated with PEG-PTX NPs. However, in 100×100 μm2 microwells with covers, the migration speed fell to 0.2 μm/min in the first 5 h then the migration speed decreased very slowly in following 11 h for the control group without any drug treatment as shown in Figure. 5b. The trends of migration speed in microwells with covers were similar to the trends in microwells without covers after NPC43 cells were treated with PTX for 16 h. However, the trends of migration speed were different in microwells without and with covers after the NPC43 cells were treated with PEG-PTX NPs for 16 h and two different curves were required to fit their trends. After the cells were treated with PEG-PTX NPs, the migration speed fell fast in the first several hours, then maintained a very slow decline when cells were in microwells with covers. Hence, t0.1for cells treated with PEG-PTX NPs in 100×100 μm2microwells with covers was 8.3 h, which was 2.3 h less than t0.1 for cells treated with PEG-PTX NPs in 100×100 μm2 microwells without covers. These results demonstrated that the covers provided additional confinement and would decrease the migration speed of NPC43 cells. Cells treated with small molecule anticancer drug PTX and PEG-PTX NPs showed different trends of cell migration speed. In 50×50 μm2 and 150×150 μm2 microwells, similar drug induced cell migration speed reduction was obtained as shown in Supporting Figure. S8-S9.