Wax patterned microwells for stem cell fate study†
The fabrication of cost effective paper-based analytical devices by wax printing has recently become popular, by and large, using cellulose filter papers. Paper-based devices need higher temperature to form hydrophobic barrier across paper substrate, rely on large working channels (≥500 μm) for liquid handling, and exhibit lower efficiency (∼50%) of sample mobility. Such limitations confine applications of wax based fabrication. In this work, we report printability, fidelity, and application of wax micropatterns on a non-cellulosic, non-fibrous, and non-porous polyethylene terephthalate based substrate (mPET). Resolution of wax printing on mPET was found to be 120 μm for line and 60 μm for channel micropatterns. The wax micropatterns can sustain heat and retain their structural integrity at melting temperature of wax and above (≥120 °C). In application, wax microwells were patterned on the new substrate in a high throughput fashion, which formed a suitable niche for mouse embryonic stem cell (mESC) culture either to maintain self-renewal or direct differentiation. This study will open a new direction in wax printing applications not only as a low-cost but a multipurpose fabrication tool.