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Synergistic therapeutic strategies for bacterial infection have attracted extensive attentions owing to their enhanced therapeutic effects and less adverse effects compared with monotherapy. Herein, we report a novel synergistic antibacterial platform that integrates the nanocatalytic antibacterial therapy and photothermal therapy (PTT) by hemoglobin-functionalized copper ferrite nanoparticles (Hb-CFNPs). In the presence of a low concentration of hydrogen peroxide (H2O2), the excellent Fenton and Fenton-like reaction activity of Hb-CFNPs can effectively catalyze the decomposition of H2O2 to produce hydroxyl radicals (·OH), rendering an increase in the permeability of the bacterial cell membrane and the sensitivity to heat. With the assistance of NIR irradiation, hyperthermia generated by Hb-CFNPs can induce the death of the damaged bacteria. Additionally, owing to the outstanding magnetic property of Hb-CFNPs, it can improve the photothermal efficiency by about 20 times via magnetic enrichment, which facilitates to realize excellent bactericidal efficacy at a very low experimental dose (20 μg/mL). In vitro antibacterial experiment shows that this synergistic antibacterial strategy has a broad-spectrum antibacterial property against Gram-negative Escherichia coli (E. coli, 100%) and Gram-positive Staphylococcus aureus (S. aureus, 96.4%). More importantly, in vivo S. aureus-infected abscess treatment studies indicate that Hb-CFNPs can serve as an antibacterial candidate with negligible toxicity to realize synergistic treatment of bacterial infections through catalytic and photothermal effects. Accordingly, this study proposes a novel, high-efficiency, and multifunctional therapeutic system for the treatment of bacterial infection, which will open up a new avenue for the design of synergistic antibacterial systems in the future.

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We report a Mg alloy Mg-2.2Nd-0.1Zn-0.4Zr (wt.%, denoted as JDBM-2) showing great potential in clinical vascular stent application by integrating the advantages of traditional medical stainless steel and polymer. This alloy exhibits high yield strength and elongation of 276 ± 6 MPa and 34.3 ± 3.4% respectively. The JDBM-2 with a stable degradation surface results in a highly homogeneous degradation mechanism and long-term structural and mechanical durability. In vitro cytotoxicity test of the Mg extract via human vascular endothelial cells (HUVECs) indicates that the corrosion products are well tolerated by the tested cells and potentially negligible toxic effect on arterial vessel walls. This alloy also exhibits compromised foreign body response (FBR) determined by human peripheral blood derived macrophage adhesion, foreign body giant cell (FBGC) formation and inflammatory cytokine and chemokine secretion. Finally, vascular stents manufactured from the JDBM-2 were implanted into rabbits for long-term evaluation. The results confirm excellent tissue compatibility and up to 6-month structural and mechanical integrity of the stent in vivo. Thus, the JDBM-2 stent with up to 6-month structural and mechanical integrity and excellent tissue compatibility represents a major breakthrough in this field and a promising alternative to traditional medical stainless steel and polymer for the clinical application.

To diminish incongruity between bone regeneration and biodegradation of implant magnesium alloy applied for mandibular bone repair, a brushite coating was deposited on a matrix of a Mg-Nd-Zn-Zr (hereafter, denoted as JDBM) alloy to control the degradation rate of the implant and enhance osteogenesis of the mandible bone. Both in vitro and in vivo evaluations were carried out in the present work. Viability and adhesion assays of rabbit bone marrow mesenchyal stem cells (rBM-MSCs) were applied to determine the biocompatibility of a brushite-coated JDBM alloy. Osteogenic gene expression was characterized by quantitative real-time polymerase chain reaction (RT-PCR). Brushite-coated JDBM screws were implanted into mandible bones of rabbits for 1, 4, and 7 months, respectively, using 316L stainless steel screws as a control group. In vivo biodegradation rate was determined by synchrotron radiation X-ray microtomography, and osteogenesis was observed and evaluated using Van Gieson's picric acid-fuchsin. Both the naked JDBM and brushite-coated JDBM samples revealed adequate biosafety and biocompatibility as bone repair substitutes. In vitro results showed that brushite-coated JDBM considerably induced osteogenic differentiation of rBM-MSCs. And in vivo experiments indicated that brushite-coated JDBM screws presented advantages in osteoconductivity and osteogenesis of mandible bone of rabbits. Degradation rate was suppressed at a lower level at the initial stage of implantation when new bone tissue formed. Brushite, which can enhance oeteogenesis and partly control the degradation rate of an implant, is an appropriate coating for JDBM alloys used for mandibular repair. The Mg-Nd-Zn-Zr alloy with brushite coating possesses great potential for clinical applications for mandibular repair.

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