Poly-L-lactic acid (PLLA) lacks osteogenic activity, which limits its application in bone repair. Zinc (Zn) is widely applied to strengthen the biological properties of polymers due to its excellent osteogenic activity. In the present study, Zn-doped mesoporous silica (Zn-MS) particles were synthesized by one-pot hydrothermal method. Then, the particles were induced into PLLA scaffolds prepared by selective laser sintering technique, aiming to improve their osteogenic activity. Our results showed that the synthesized particles possessed rosette-like morphology and uniform mesoporous structure, and the composite scaffold displayed the sustained release of Zn ion in a low concentration range, which was attributed to the shield effect of the PLLA matrix and the strong bonding interaction of Si-O-Zn. The scaffold could evidently promote osteogenesisdifferentiation of mouse bone marrow mesenchymal stem cells by upregulating their osteogenesis-related gene expression. Besides, Zn-MS particles could significantly increase the compressive strength of the PLLA scaffold because of their rosettelike morphology and mesoporous structure, which can form micromechanical interlocking with the PLLA matrix. The Zn-MS particles possess great potential to improve various polymer scaffold properties due to their advantageous morphology andphysicochemical properties.

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Bacterial infection with high morbidity (>30%) seriously affects the defect’s healing after bone transplantation. To this end, chemotherapy and photothermal therapy have been utilized for antibacterial treatment owing to their high selectivity and minimal toxicity. However, they also face several dilemmas. For example, bacterial biofilms prevented the penetration of antibacterial agents and local temperatures (over 70 °C) caused by the photothermal therapy damaged normal tissue. Herein, a co-dispersion nanosystem with chemo-photothermal function was constructed via the in situ growth of zeolitic imidazolate framework-8 (ZIF-8) on graphene oxide (GO) nanosheets. In this nanosystem, GO generates a local temperature (∼50 °C) to increase the permeability of a bacterial biofilm under near-infrared laser irradiation. Then, Zn ions released by ZIF-8 seized this chance to react with the bacterial membrane and inactivate it, thus realizing efficient sterilization in a low-temperature environment. This antibacterial system was incorporated into a poly-l-lactic acid scaffold for bone repair. Results showed that the scaffold showed a high antibacterial rate of 85% against both Escherichia coli and Staphylococcus aureus. In vitro cell tests showed that the scaffold promoted cell proliferation.

Magnetite (Fe3O4) nanoparticles as drug carriers can achieve precise drug target due to their magnetic property. However, they are easy to aggregate in the physiological environment, which obviously limits their application in drug delivery. The development of the Fe-MIL-88B-derived method to construct the Fe3O4-loaded mesoporous carbon (Fe3O4/carbon) system is a feasible strategy to solve the issue. First, iron atoms evenly distribute in the organic links through coordination bonds in Fe-MIL-88B. After the carbonization of Fe-MIL-88B, mesoporous carbon acts as a barrier to prevent the aggregation of Fe3O4 nanoparticles. Herein, Fe-MIL-88B particles were fabricated by the hydrothermal method and then pyrolyzed to construct Fe3O4/carbon systems. Results showed that Fe3O4 nanoparticles uniformly in situ grew on mesoporous carbon generated by the carbonization of organic components. More encouragingly, the Fe3O4/carbon system loaded with DOX demonstrated pH-responsive DOX release, efficient delivery of DOX into cancer cells, and significant cancer cell killing ability. Therefore, the Fe3O4/carbon systems prepared by the Fe-MIL-88B-derived method might open up a way for targeted and controlled drug delivery.