Magnesium-based layered double hydroxide nanosheets: a new bone repair material with unprecedented osteogenic differentiation performance

Osteonecrosis of femoral head (ONFH) has been one of the most common diseases, and thus the development of novel biomaterials with superior osteogenic ability is the key issue. In this work, Yb-containing MgAl-layered double hydroxide (LDH) monolayer nanosheets (MgAlYb-LDHs) were designed and synthesized and were used as a new biomaterial with outstanding osteogenic differentiation ability. The LDH monolayer nanosheets gave a high loading content (LC) of 197% for alendronate (AL) with an encapsulation efficiency (EE) of 98.6%. Notably, outstanding in vitro osteogenic differentiation performance of MgAlYb-LDHs was demonstrated in the transcriptional level of Collagen I, with a 3000-fold enhancement compared with the blank control. For in vivo tests with rabbits, the total volume of bone regeneration after treatment with the LDH group was 2.77 and 1.41 times larger than that with the negative control group and positive control group (autologous bone graft, clinical gold standard) at 8 weeks postoperatively. In addition, with the degradation of AL/LDHs, the bone mass density (BMD) of the femoral head increased by 1.52 times compared with that for the positive control group at 8 weeks postoperatively. Therefore, this work provides a new perspective for the design and preparation of 2D monolayer MgAlYb-LDHs and their drug formulation (AL/LDHs), which show great promise in ONFH accompanied by osteoporosis.