Bionic artificial penile Tunica albuginea

The mammalian tunica albuginea (TA) is characterized by a double-layer orthogonal structure composed of stacked parallel wavy collagen fibers. During an erection, these fibers undergo sequential straightening and stretching to mediate the soft-to-firm transition. Inspired by the delicate strain-adaptive structure of natural TA, we propose an artificial TA (ATA) composed of a strain-stiffening hydrogel consisting of aligned yet crimped fibers. This delicate structure is produced via the stretching of an isotropic polyvinyl alcohol gel followed by covalent cross-linking. ATA possesses several key mechanical features of natural TA, including rapid strain stiffening over small intervals of deformation, excellent fatigue resistance to sustain cyclic bursts, and high toughness to withstand pointwise acupuncture during suturing. Furthermore, ATA displays the capability to repair injuries and restore normal erectile function of the TA-damaged penile tissue in a pig model. Our study demonstrates that ATA has great promise for penile injury repair.