Semi-Egg-Like Heterogeneous Compartmentalization of Cells Controlled by Contact Angle Hysteresis

Precise control of liquid inside compartments is critically important in bioreactors, combinatorial analysis, and tissue engineering. A contact angle hysteresis (CAH)-based strategy is demonstrated to construct a semi-egg-like hydrogel architecture, leading to spatial heterogeneous compartmentalization of cells. The semi-egg-like architecture is fabricated by successively capturing and gelling prehydrogel liquids using a substrate with controlled-CAH pattern and ultralow-CAH background. The controlled-CAH pattern could capture liquid with tunable size, while ultralow-CAH background prevents liquid sticking. It is envisioned that this CAH-based strategy would be promising in designing functional surface for engineering complicated architectures of either biomedical or nonbiomedical systems. From bad to good: Large contact angle hysteresis (CAH, defined by θ_A - θ_R) that causes pinning of droplet on surface is often an unfavorable factor in surface chemistry. It is, however, harnessed in constructing a semi-egg-like hydrogel for 3D heterogeneous compartmentalization of cells. By designing surface with controlled-CAH patterns and ultralow-CAH background, the semi-egg-like architecture is fabricated by dip-coating in a facile way.