Cell Assembly in Self-foldable Multi-layered Soft Micro-rolls

Multi-layered thin films with heterogeneous mechanical properties can be spontaneously transformed to realise various three-dimensional (3D) geometries. Here, we describe micro-patterned all-polymer films called micro-rolls that we use for encapsulating, manipulating, and observing adherent cells in vitro. The micro-rolls are formed of twin-layered films consisting of two polymers with different levels of mechanical stiffness; therefore they can be fabricated by using the strain engineering and a self-folding rolling process. By controlling the strain of the films geometrically, we can achieve 3D tubular architectures with controllable diameters. Integration with a batch release of sacrificial hydrogel layers provides a high yield and the biocompatibility of the micro-rolls with any length in the release process without cytotoxicity. Thus, the multiple cells can be wrapped in individual micro-rolls and artificially reconstructed into hollow or fibre-shaped cellular 3D constructs that possess the intrinsic morphologies and functions of living tissues. This system can potentially provide 3D bio-interfaces such as those needed for reconstruction and assembly of functional tissues and implantable tissue grafts.