Ji Tan,Zixiao Liu,Donghui Wang,Xianming Zhang,Shi Qian,Xuanyong Liu
Multifarious strategies have been proposed to enhance the antibacterial ability of implant surfaces for preventing bacterial infection, however, developing facile and universal modification methods still remains extremely elusive. Herein, inspired by the fact that the electron transfer respiratory chain of bacteria is embedded in the membrane, we proposed a novel strategy of local alkalinity disturbing bacterial respiration to endow implant materials with antibacterial ability. As a demonstration, MgO was deposited on biomedical titanium via magnetron sputtering to regulate surface alkalinity. With the thickness of MgO films increasing, they exhibited an excellent antibacterial rate against both Gram-negative and positive bacteria. The antibacterial mechanism confirmed that the alkaline surface can disturb the bacterial respiration action via weakening the transmembrane proton concentration gradient, resulting in the blockage of energy metabolism and the increase of oxidative stress of bacteria. Cell experiments indicated that MgO films not only have no obvious cytotoxicity to osteoblast cells, but can also selectively kill bacteria and promote cell proliferation in the presence of both bacteria and cells. More importantly, the by-product of MgO was only the biocompatible Mg2+, reducing any concerns about potential toxic effects. Furthermore, sputtering alkaline MgO films was confirmed to work well on polyetheretherketone polymer and zirconia ceramic implants, which indicates that this strategy has broad prospects of clinical application for preventing implant-associated bacterial infection.
Herein, the chelated precursor solution (Mg/BzAc) was synthesized using magnesium acetate as raw material and benzoylacetone as chemical modifier. The prepared solution was coated on (00 l )-oriented LaAlO 3 (LAO) single crystal substrate to fabricate the MgO/BzAc gel films. First, ultraviolet absorption spectroscopy was employed to analyze the ultraviolet photosensitivity of the MgO/BzAc gel films and the characteristic absorption peak corresponding to π-π* transition in Mg/BzAc chelate rings was detected at the wavelength of 329 nm. It is found that the intensity of this peak decreased gradually with increase in UV irradiation time, which indicates that the MgO/BzAc gel films exhibit good ultraviolet photosensitive properties. Then, MgO crystalline films with biaxial texture were prepared by heat-treating MgO/BzAc gel films at 850 °C in air for 60 min. Finally, micro-patterned MgO films with biaxial textures were prepared on the LAO substrate using photosensitive sol-gel lithography in combination with the above heat-treatment process.
A nano-MgO film supported on 3D nickel mesh was prepared via an electrodeposition–thermolysis process. The film possessed high catalytic activity for the ozonation of toluene, but suffered from deactivation. Interestingly, after fluorination, its breakthrough time was 20 times longer (i.e., from 30 to 600 min) under 50% relative humidity. This significant enhancement was attributed to the formation of a fluorinated MgO film, Mg(OH)F, as confirmed using XRD, XPS, SEM, etc. Mg(OH)F possessed two typical acidic sites (Brønsted and Lewis sites), and they could co-catalyze O3 to generate more highly active ˙OH and O radicals. In particular, its Brønsted acidity could considerably decrease the accumulation of acidic intermediates on the film, suppressing its deactivation. Fluorinated MgO, Mg(OH)F, could be applied as a multifunctional ozonation catalyst for the degradation of other refractory pollutants.
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