Grafting copolymers with controllable degradation rates has potential value in biomaterial applications, such as tissue engineering scaffolds, drug delivery, and prevention of postsurgical adhesion. Chaorong Peng et al. on page 704 focus on controlling the degradation and biocompatibility of N-vinyl pyrrolidone (PLA-g-PVP) induced by gamma ray irradiation. The cover shows a microscopic image of the polylactic acid grafting PLA-g-PVP copolymer induced by gamma ray irradiation during an in vivo implant experiment. The copolymer films infiltrate the tissue for absorption, exhibiting excellent cell adhesion. Grafting hydrophilic PLA-g-PVP improves both the degradation rate and biocompatibility, which could broaden the medical applications of this material.