4D Printed Self-bending Sodium Alginate Composite Scaffold lad-en with Nano-spherical Mineralized Collagen for Bone repair

Although traditional 3D-printed scaffolds have static personalized structures, which usually face complex structures and undergo physicochemical stimuli in vivo. For repairing irregular bone defects, the response to morphological characteristics and multi-stage in bone healing can be required. SAGMA (modification of sodium al-ginate with glycidyl methacrylate) composite hydrogel can achieve adjustable self-bending through three-step crosslinking with gradient UV, calcium ions as well as chitosan in vitro. Accordingly, this study fabricated a thermoresponsive SAG-MA/PF127 bilayer hydrogel scaffold and adopted a 4D printed strategy to endow it with tunable self bending behavior in vivo. The top layer (bionic cambium layer of periosteum) was composed of SAGMA3/PF20 hydrogel loaded with nano-spherical mineralized collagen, whereas the bottom layer (bionic fibrous layer of periosteum) consisted of SAGMA6/PF15 hydrogel incorporated with magnesium ions. Upon tem-perature elevation, mismatched interlayer strain originating from the different con-tents of SAGMA and PF127 in the two layers triggers the oriented bending of scaf-fold, realizing the requirements of programmable deformation. In vitro cell experi-ments were conducted to evaluate cytocompatibility and osteogenic differentiation, while in vivo animal studies were performed to investigate the efficacy of scaffold in repairing cranial defects. This work provides a novel material design strategy for per-sonalized biomimetic periosteum capable of tunable self-bending behavior for the treatment of irregular bone defects.

Dr. Xiaojie Lian is currently an Associate Professor at Taiyuan University of Technology. She is awarded the Sanjin Talent of Shanxi province. She graduated from Beijing institute of technology in 2009, with a Ph.D. degree in Applied Chemistry. She was a postdoctoral researcher in School of Materials Science and Engineering at Tsinghua University from 2009 to 2012. She has joined the Taiyuan University of Technology in 2012. She worked as an academic visitor in the department of bioengineering at Rice University from 2019 to 2020.

Her major research interest focuses on biomedical materials and 3D printing for tissue repair. She published articles in journals including Carbohydrate Polymers, International Journal of Biological Macromolecules, Regenerative Biomaterials, Materials & Design, Colloids and Surfaces B: Biointerfaces, and so on. She also had 7 Chinese patents authorized. Her research was funded by the programs including National Natural Science Foundation of China, the Key Research and Development Program of Shanxi Province (International Cooperation), Natural Science Foundation of Shanxi Province and so on.