Preparation of Anisotropic Micro-Hydrogels with Tunable Structural and Topographic Features by Compound Interfacial Shearing.

We propose a compound interfacial shearing (CIS) process for versatile production of monodisperse Janus emulsions with controllable structural and topographic features. The process induces an active periodic force to decouple material and process parameters, enables independent control of compartmental features in Janus emulsions, and facilitates inline and on-demand generation of various geometric features for a large variety of process parameters and material properties. Janus emulsions of poly(ethylene glycol) diacrylate (PEGDA) with a controlled number of compartments are produced by CIS and photopolymerized to form micro-hydrogels with designated interfacial curvatures. PEGDA micro-hydrogels can be further modified to achieve anisotropy of surface or internal features by the content of an oily dispersed phase. MCF-7 human breast cancer cells are encapsulated in micro-hydrogels for cell proliferation with satisfactory viability. By modifying PEGDA micro-hydrogels with RGDS-conjugated polystyrene microspheres, we have demonstrated the controlled spatial adhesion of MCF-7 cells and human umbilical vein endothelial cells (HUVECs) on the substrates of different three-dimensional (3D) curvatures. Our pilot study suggests a simple and potentially scalable approach to produce 3D substrates with controllable structural and topographic features for 3D guided cell organization.