An Encapsulation-Free and Hierarchical Porous Triboelectric Scaffold with Dynamic Hydrophilicity for Efficient Cartilage Regeneration.

Tissue engineering and electrotherapy are two promising methods to promote tissue repair. However, their integration remains an underexplored area, because their requirements on devices are usually distinct. Triboelectric nanogenerators (TENGs) have shown great potential to develop self-powered devices. However, due to their susceptibility to moisture, TENGs have to be encapsulated in vivo. Therefore, existing TENGs cannot be employed as tissue engineering scaffolds, which require direct interaction with surrounding cells. Here, the concept of triboelectric scaffolds (TESs) is proposed. Poly(glycerol sebacate), a biodegradable and relatively hydrophobic elastomer, is selected as the matrix of TESs. Each hydrophobic micropore in multi-hierarchical porous TESs efficiently serves as a moisture-resistant working unit of TENGs. Integration of tons of micropores ensures the electrotherapy ability of TESs in vivo without encapsulation. Originally hydrophobic TESs are degraded by surface erosion and transformed into hydrophilic surfaces, facilitating their role as tissue engineering scaffolds. Notably, TESs seeded with chondrocytes obtain dense and large matured cartilages after subcutaneous implantation in nude mice. Importantly, rabbits with osteochondral defects receiving TES implantation show favorable hyaline cartilage regeneration and complete cartilage healing. This work provides a promising electronic biomedical device and will inspire a series of new in vivo applications.