This paper reports an approach for the fabrication of shape-changing bilayered scaffolds, which allow the growth of aligned skeletal muscle cells, using a combination of 3D printing of hyaluronic acid hydrogel, melt electrowriting of thermoplastic polycaprolactone-polyurethane elastomer, and shape transformation. The combination of the selected materials and fabrication methods allows a number of important advantages such as biocompatibility, biodegradability, and suitable mechanical properties (elasticity and softness of the fibers) similar to those of important components of extracellular matrix (ECM), which allow proper cell alignment and shape transformation. Myoblasts demonstrate excellent viability on the surface of the shapechanging bilayer, where they occupy space between fibers and align along them, allowing efficient cell patterning inside folded structures. The bilayer scaffold is able to undergo a controlled shape transformation and form multilayer scroll-like structures with cells encapsulated inside. Overall, the importance of this approach is the fabrication of tubular constructs with a patterned interior that can support the proliferation and alignment of muscle cells for muscle tissue regeneration.

This paper reports an approach for the fabrication of highly aligned soft elastic fibrous scaffolds using touch spinning of thermoplastic polycaprolactone− polyurethane elastomers and demonstrates their potential for the engineering of muscle tissue. A family of polyester−polyurethane soft copolymers based on polycaprolactone with different molecular weights and three different chain extenders such as 1,4-butanediol and polyethylene glycols with different molecular weight was synthesized. By varying the molar ratio and molecular weights between the segments of the copolymer, different physicochemical and mechanical properties were obtained. The polymers possess elastic modulus in the range of a few megapascals and good reversibility of deformation after stretching. The combination of the selected materials and fabrication methods allows several essential advantages such as biocompatibility, biodegradability, suitable mechanical properties (elasticity and softness of the fibers), high recovery ratio, and high resilience mimicking properties of the extracellular matrix of muscle tissue. Myoblasts demonstrate high viability in contact with aligned fibrous scaffolds, where they align along the fibers, allowing efficient cell patterning on top of the structures. Altogether, the importance of this approach is the fabrication of highly oriented fiber constructs that can support the proliferation and alignment of muscle cells for muscle tissue engineering applications.

Stimuli-responsive polymers are a subject of numerous studies in recent decades due to its variety of possible applications ranging from nanomedicine, drug delivery systems, biosensing, to smart textile development and aerospace engineering. The current demand of reliable and easy-programmable polymericactuating components underlines the necessity to understand the mechanism that governs the actuation of materials. This work sheds new light on the understanding of the two-way shape memory effect (2W-SME) of cross-linked semicrystalline polymers. We investigated and compared melting/crystallization of cross-linked polycaprolactone under constant stress and constraint strain conditions. We observed three regions of behavior upon cooling: rubbery, semicrystalline, and an intermediate one associated with entropic softening of the network prior to crystallization. Based on obtained observations, we proposed possible mechanisms for the processes occurring in cross-linked polymers upon their crystallization/melting and quantitatively investigated the effects of applied stress, elongation, and cross-linking density to allow programmable design of reversible actuators.