Ultrasound-Triggered Mg²⁺ Blasting Release Hydrogel Microspheres for Promoting Bone Reconstruction

Mg²⁺ (Magnesium ion) can affect bone tissue metabolism by regulating related signaling pathways in bone metabolism. However, how to realize precise controlled release of Mg²⁺ in bone regeneration treatment still presents a challenge. Herein, for the first time, the GelMA-BP (Gelatin Methacryloyl-Bisphosphonate) and the composite nano-bubble system are fused to construct the Mg²⁺ blasting controlled-release hydrogel microspheres, the stability of the nano-bubbles in the microspheres is enhanced through metal coordination complexation, and the burst of the nano-bubbles is controlled by using ultrasonic cavitation to achieve the precise controlled release of Mg²⁺, ultimately effectively promoting bone reconstruction. First, GelMA-BP composite is prepared by Schiff base reaction. Second, the nanobubble BP (Bisphosphonate) system is constructed, and Mg²⁺ is combined with the ligand coordination to prepare the composite nanobubble system. Thirdly, through Mg²⁺ co-coordination, the ultrasound-triggered Mg²⁺ blasting controlled release microspheres were prepared to achieve bone repair. Overall, this innovative strategy effectively solves the problem of accurate controlled release of Mg²⁺, and finally effectively activates in situ bone tissue regeneration.