Injectable sodium alginate-black phosphorus composite microspheres for cell delivery and enhanced bone regeneration

Bone tissue regeneration engineering aims to construct scaffolds with natural bone biological characteristics. Traditional autologous/allogeneic bone transplantation has limited donor sources and carries immunological risks. Stem cell injection, due to its minimally invasive nature and bone repair-promoting effects, has emerged as an alternative strategy. However, direct injection faces challenges such as cell migration and low survival rates. To address this, researchers have employed hydrogels and microspheres as delivery carriers. Among these, sodium alginate (ALG) microspheres, with their excellent biocompatibility and injectability, are widely used for cell encapsulation. Combining the osteogenic-promoting properties of black phosphorus (BP), this study utilized electrospray injection to prepare ALG-BP composite microspheres encapsulating MC3T3-E1 cells (ALG-BP@MC3T3-E1). The results showed that ALG-BP microspheres had no effect on the activity of MC3T3-E1 cells, while ALG-BP@MC3T3-E1 microspheres exhibited excellent bone healing promotion and osteoporosis inhibition capabilities, significantly reducing bone healing time. This hydrogel microsphere achieves a dual effect of stimulating endogenous cell secretion and providing exogenous cells, representing a cell tissue engineering strategy with promising application prospects.