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Background The reinforcement effect of fiber-reinforced polymer composites is usually limited because of the poor interfacial interaction between fiber and polymer, though fiber reinforcement is regarded as an effective method to enhance the mechanical properties of polymer. Methods In this study, nano-SiO2 particles grafted by 3-Glycidoxypropyltrimethoxysilane (KH560) were introduced onto the surface of 3-Aminopropyltriethoxysilane (KH550) modified carbon fiber (CF) by a self-assembly strategy to improve the interfacial bonding between CF and biopolymer poly (lactic acid) (PLLA). Results The results indicated that PLLA chains preferred to anchor at the surface of nano-SiO2 particles and then formed high order crystalline structures. Subsequently, PLLA spherulites could epitaxially grow on the surface of functionalized CF, forming a transcrystalline structure at the CF/PLLA interface. Meanwhile, the nano-SiO2 particles were fixed in the transcrystalline structure, which induced a stronger mechanical locking effect between CF and PLLA matrix. The results of tensile experiments indicated that the PLLA/CF-SiO2 scaffold with a ratio of CF to SiO2 of 9:3 possessed the optimal strength and modulus of 10.11 MPa and 1.18 GPa, respectively. In addition, in vitro tests including cell adhesion and fluorescence indicated that the scaffold had no toxicity and could provide a suitable microenvironment for the growth and proliferation of cell. Conclusion In short, the PLLA/CF-SiO2 scaffold with good mechanical properties and cytocompatibility had great potential in the application of bone tissue engineering.

Strontium ion (Sr 2+ ) enabled us to endow polymer bone scaffolds with bioactivity owing to its excellent osteoinductive capacity. Nevertheless, the burst release of Sr 2+ hindered its further application. Herein, strontium substituted hydroxyapatite (SrHA) was constructed to achieve a sustained release system. Specifically, Sr 2+ could substitute Ca 2+ in a HA lattice framework through ion exchange due to their similar ion radius. The ionic bond formed by Sr 2+ and surrounding ions could prevent the rapid escape of Sr 2+ and thereby achieve the sustained release of Sr 2+ . Subsequently, SrHA was introduced into the poly-L-lactic (PLLA) scaffold fabricated by selective laser sintering. Results demonstrated that PLLA/SrHA scaffolds presented a sustained Sr 2+ release with a cumulative concentration of 5.6 mg/L over 28 days. The released Sr 2+ significantly promoted the cell proliferation and differentiation. Furthermore, the tensile and compressive strengths of PLLA/ SrHA scaffolds were also greatly enhanced in comparison with that of PLLA scaffolds. These positive findings demonstrated that PLLA/SrHA scaffolds had considerable potential for bone repair.

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.