Rationally designed anisotropic and auxetic hydrogel patches for adaptation to dynamic organs

Current hydrogel or fabric patches for organ repair are generally not designed to conform to the complex mechanics of dynamic organs such as the lung or heart. This work presents a new, biocompatible and bilayered, hydrogel-based patch platform, consisting of a non-fouling top layer and a cell adhesive bottom layer, that caters to the anisotropic and auxetic characteristics of dynamic organs. Integrated computational and experimental studies were used to screen over 116 unique anisotropic-auxetic architectures to establish design rules and tailor the patches to a broad range of target organ dynamics. The patches were then validated in ex vivo and in vivo animal models, where the auxetic patches outperformed non-auxetic patches in conforming to the volumetric dilation-contraction of dynamic organs. To further expand the functionality of the auxetic patch platform, novel hole-filling auxetic patches were developed. These hole-filling patches composited with fibrin robustly reduced pulmonary air leakage in rats with surgically induced lung puncture. This is the first demonstration of a rational patch design framework that features both anisotropic and auxetic properties to cater to a wide range of organ dynamics. These studies will pave the way for future clinical development of biomimetic patches.