Figure 1 . Schematic illustration to study effect of nanomedicines on cell behaviors and cytotoxicity on (a) flat surface and (b) 3D platforms of microwell arrays without and with glass cover. Scanning electron micrographs of (c) 50×50 μm2, (d) 100×100 μm2, and (e) 150×150 μm2 polydimethylsiloxane microwells.
Typically, 2D flat surface such as a petri dish is used to study the effect of nanomedicines on cell behaviors as shown in Figure. 1a . In this work, 3D platforms consisted of microwells with different sizes of 50×50, 100×100, and 150×150 μm2 and with glass covers were used as shown in Figure. 1b. The cover provided the microwells additional confinement on the top. The microwells had flat rather than curved bottoms such that the migratory behavior of cells could be evaluated. PEGylated paclitaxel nanoparticles (PEG-PTX NPs) as the nanomedicine were applied for the first time to treat nasopharyngeal carcinoma (NPC43) cells in microwells without and with a cover. In microwells without and with the cover, NPC43 cells showed different cell behaviors such as cell proliferation, cell migration speed, cell elongation, and cell spreading area. Furthermore, the effect of microwells and 3D confinement on the cytotoxicity of PTX and PEG-PTX NPs was studied in detail.
2. Results and Discussion
2.1. Characterization of microwells and PEG-PTX NPs
Polydimethylsiloxane (PDMS) microwells arrays were fabricated according to our previous work.[47]Microwells with different sizes of 50×50, 100×100, and 150×150 μm2 as shown in Figure. 1c-e were fabricated. The depth of all the microwells were 50 μm and the space between adjacent microwells was 50 μm. These microwells were used as 3D platforms to evaluate the effect of PEG-PTX nanomedicine on NPC43 cells.