The high-strength and toughness Janus bionic periosteum matching bone development and growth in children

Pediatric periosteum requires suitable strength to stabilize bone injury and match the rapid growth of children's bone, as well as strong osteogenic and angiogenic capacity to promote bone repair. Here, a Janus membrane was constructed based on the natural gradient network of bacterial nano-cellulose (BNC), the molecular chain assembly of fish collagen (Col I) was achieved through the formation of amide bond from the amino group on the collagen and carboxyl group on the BNC surface after selective oxidization by using TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical). In situ synthesis of nano-hydroxyapatite (nHA) was conducted in the looser network of BNC by adjusting pH after addition in sequence of Ca(NO3)2·4H2O and Na3PO4 solution. The Janus membrane possessed Young's modulus and tensile capacity within the ligament range (0.113 GPa and 29.63 MPa, respectively), which allow material-bone fixation and integration. In vitro biomolecular experiments showed that the Janus periosteum promoted the proliferation of bone marrow mesenchymal stem cells and the expression of angiogenic and osteogenic factors. The promotions in angiogenesis and osteogenesis were further verified in vivo. Overall, the Janus biomimetic periosteum met the requirements of growth and development in children, indicating its regenerative potential for the treatment of periosteum-associated diseases in children.