Mechanical Adaptability of the MMP-Responsive Film Improves the Functionality of Endothelial Cell Monolayer.

Extracellular matrix and cells are inherent in coordinating and adapting to each other during all physiological and pathological processes. Synthetic materials, however, show rarely reciprocal and spatiotemporal responses to cells, and lacking self-adapting properties as well. Here, a mechanical adaptability based on the matrix metalloproteinase (MMPs) sensitive polyelectrolyte film is reported. Poly-lysine (PLL) and methacrylated hyaluronic acid (HA-MA) nanolayers are employed to build the thin film through the layer-by-layer assembly, and it is further crosslinked using MMP sensitive peptides, which endows the films with changeable mechanical properties in response to MMPs. It is demonstrated that stiffness of the (PLL/HA-MA) films increases with the crosslinking, and then decreases in response to a treatment of enzyme. Consequently, the crosslinked (PLL/HA-MA) films reveal effective growth of endothelial cells (ECs), leading to fast formation of EC monolayer. Importantly, significantly improved endothelial function of the EC monolayer, which is characterized by integrity, biomolecules release, expression of function related gene, and antithrombotic properties, is achieved along with the decrosslinking of the film because of EC-secreted MMPs. These results suggest that mechanical adaptability of substrate in Young's modulus plays a significant role in endothelial progression, which shows great application potential in tissue engineering, regenerative medicine, and organ-on-a-chip.

Self-Healing Spongy Coating for Drug "Cocktail" Delivery.

Optimized ratio in the codelivery of therapeutics is of crucial importance to promote the synergism rather than the antagonistic effects. In this study, a self-healing spongy coating was described to facilitate the surface-mediated delivery of drug "cocktails" proportionally. The formation of spongy structures within the coating was achieved by acidic treatment and freeze-drying. Various drug combinations can be readily integrated through wicking method and subsequent micropore self-healing. The ratio of drug loading can be precisely regulated by the composition of loading solution and the embedded drugs were released in proportion according to the initial ratio of drug combination.