Mg 2+ (Magnesium ion) can affect bone tissue metabolism by regulating related signaling pathways in bone metabolism. However, how to realize precise controlled release of Mg 2+ 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 Mg 2+ 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 Mg 2+ , ultimately effectively promoting bone reconstruction. First, GelMA-BP composite is prepared by Schiff base reaction. Second, the nanobubble BP (Bisphosphonate) system is constructed, and Mg 2+ is combined with the ligand coordination to prepare the composite nanobubble system. Thirdly, through Mg 2+ co-coordination, the ultrasound-triggered Mg 2+ blasting controlled release microspheres were prepared to achieve bone repair. Overall, this innovative strategy effectively solves the problem of accurate controlled release of Mg 2+ , and finally effectively activates in situ bone tissue regeneration.
Double-network (DN) hydrogels consisting of noncovalent interacting networks are highly desired due to their well-controlled compositions and environmental friendliness, but the low water resistance always impairs their mechanical strength. Here, an anti-swelling hydrogel possessing the core/shell architecture through rational regulation of multiple weak noncovalent interactions is prepared. A composite hydrogel consists of chitosan (CS) and poly( N -acryloyl 2-glycine) (PACG), readily forming the shell-structured DN hydrogel after soaking in a FeCl 3 solution because of in situ formation of chain entanglements, hydrogen bonds, and ionic coordination. The produced DN hydrogels exhibit excellent anti-swelling behaviors and mechanical durability for over half a year, even in some strict situations. Taking the merits of noncovalent bonds in adjustability and reversibility, the swelling property of these hydrogels can be easily customized through control of the ion species and concentrations. A dynamically reversible transition from super-swelling to anti-swelling is realized by breaking up and rebuilding the metal-coordination complexes. This facile but efficient strategy of turning the noncovalent interactions and consequently the mechanics and anti-swelling properties is imperative to achieve the rational design of high-performance hydrogels with specific usage requirements and expand their applicability to a higher stage.
Postoperative infection and poor osteogenesis will cause the failure of dental implant surgery. Thus, the antibacterial and osteogenic activities are the core requirements for the surface modification of dental implants. Inspired by the strong chelating ability of naturally occurring phytic acid (PA), an in situ deposition method on the surface of titanium implants was developed based on the metal–phosphate coordination networks. Biologically relevant metal cations (i.e. ferric ions and divalent copper ions) were selected as metal constituents for the construction of organic–inorganic coordination network films. The stability of PA–metal coordination bonds is rationally explained by the chemical nature of transition metal elements. This PA–metal coordination complex coating exhibited an excellent antibacterial activity against Porphyromonas gingivalis, reducing the bacterial implant colonization by > 3.92 log10. The abundant phosphate groups greatly increased the surface hydrophilicity, promoted the early adhesion of proteins, improved the proliferation of bone marrow mesenchymal stem cells, and finally achieved an enhanced osteogenic activity. In addition, the phosphate groups of PA also facilitated the deposition of hydroxyapatite by providing reaction sites to chelate with calcium ions. These findings evaluate the anti-bacterial and osteogenic potentials of PA–metal coordination complexes, and clarify the feasibility for surface modification of dental implants.
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