| 1. |
- Ji, Zhenbing, et al.
(författare)
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Effects of surface morphology and composition of titanium implants on osteogenesis and inflammatory responses : a review
- 2023
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Ingår i: Biomedical Materials. - : IOP Publishing. - 1748-6041 .- 1748-605X. ; 18:4
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Forskningsöversikt (refereegranskat)abstract
- Titanium and its alloys have been widely used in bone tissue defect treatment owing to their excellent comprehensive properties. However, because of the biological inertness of the surface, it is difficult to achieve satisfactory osseointegration with the surrounding bone tissue when implanted into the body. Meanwhile, an inflammatory response is inevitable, which leads to implantation failure. Therefore, solving these two problems has become a new research hotspot. In current studies, various surface modification methods were proposed to meet the clinical needs. Yet, these methods have not been classified as a system to guide the follow-up research. These methods are demanded to be summarized, analyzed, and compared. In this manuscript, the effect of physical signal regulation (multi-scale composite structure) and chemical signal regulation (bioactive substance) generated by surface modification in promoting osteogenesis and reducing inflammatory responses was generalized and discussed. Finally, from the perspective of material preparation and biocompatibility experiments, the development trend of surface modification in promoting titanium implant surface osteogenesis and anti-inflammatory research was proposed.
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| 2. |
- Wan, Yi, et al.
(författare)
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Osteogenic and antibacterial ability of micro-nano structures coated with ZnO on Ti-6Al-4V implant fabricated by two-step laser processing
- 2022
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Ingår i: Journal of Materials Science & Technology. - : Elsevier BV. - 1005-0302. ; 131, s. 240-252
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Tidskriftsartikel (refereegranskat)abstract
- The biological performance of Ti-6Al-4V implant is primarily determined by their surface properties. However, traditional surface modification methods, such as acid etching, hardly make improvement in their osseointegration ability and antibacterial capacity. In this study, we prepared a multi-scale composite structure coated with zinc oxide (ZnO) on Ti-6Al-4V implant by an innovative technology of two-step laser processing combined with solution-assistant. Compared with the acid etching method, the physicochemical properties of surface significantly improved. The in vitro results showed that the particular dimension of micro-nano structure and the multifaceted nature of ZnO synergistically affected MC3T3-E1 osteogenesis and bacterial activities: (1) The surface morphology showed a 'contact guidance' effect on cell arrangement, which was conducive to the adhesion of filopodia and cell spreading, and the osteogenesis level of MC3T3-E1 was enhanced due to the release of zinc ions (Zn2+); (2) the characterization of bacterial response revealed that periodic nanostructures and Zn2+ released could cause damage to the cell wall of E. coli and reduce the adhesion and aggregation of S. aureus. In conclusion, the modified surface showed a synergistic effect of physical topography and chemical composition, making this a promising method and providing new insight into bone defect repairment.
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| 3. |
- Zhang, Shuangshuang, et al.
(författare)
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Discovery of carbon-based strongest and hardest amorphous material
- 2022
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Ingår i: National Science Review. - : Oxford University Press. - 2095-5138 .- 2053-714X. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Carbon is one of the most fascinating elements due to its structurally diverse allotropic forms stemming from its bonding varieties (sp, sp2, and sp3). Exploring new forms of carbon has always been the eternal theme of scientific research. Herein, we report the amorphous (AM) carbon materials with high fraction of sp3 bonding recovered from compression of fullerene C60 under high pressure and high temperature previously unexplored. Analysis of photoluminescence and absorption spectra demonstrates that they are semiconducting with a bandgap range of 1.5–2.2 eV, comparable to that of widely used amorphous silicon. Comprehensive mechanical tests demonstrate that the synthesized AM-III carbon is the hardest and strongest amorphous material known so far, which can scratch diamond crystal and approach its strength. The produced AM carbon materials combine outstanding mechanical and electronic properties, and may potentially be used in photovoltaic applications that require ultrahigh strength and wear resistance.
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| 4. |
- Zhang, Shuangshuang, et al.
(författare)
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Narrow-gap, semiconducting, superhard amorphous carbon with high toughness, derived from C60 fullerene
- 2021
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Ingår i: Cell Reports Physical Science. - : Elsevier. - 2666-3864. ; 2:9
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Tidskriftsartikel (refereegranskat)abstract
- New carbon forms that exhibit extraordinary physicochemical properties can be generated from nanostructured precursors under extreme pressure. Nevertheless, synthesis of such fascinating materials is often not well understood. That is the case of the C60 precursor, with irreproducible results that impede further progress in the materials design. Here, the semiconducting amorphous carbon, having band gaps of 0.1–0.3 eV and the advantages of isotropic superhardness and superior toughness over single-crystal diamond and inorganic glasses, is produced from fullerene at high pressure and moderate temperatures. A systematic investigation of the structure and bonding evolution is carried out with complementary characterization methods, which helps to build a model of the transformation that can be used in further high-pressure/high-temperature (high p,T) synthesis of novel nano-carbon systems for advanced applications. The amorphous carbon materials produced have the potential of accomplishing the demanding optoelectronic applications that diamond and graphene cannot achieve.
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| 5. |
- Zhao, Yijin, et al.
(författare)
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Production of β-carotene in Saccharomyces cerevisiae through altering yeast lipid metabolism
- 2021
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Ingår i: Biotechnology and Bioengineering. - : Wiley. - 0006-3592 .- 1097-0290. ; 118:5, s. 2043-2052
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Tidskriftsartikel (refereegranskat)abstract
- Saccharomyces cerevisiae is a widely used cell factory for the production of fuels and chemicals. However, as a non-oleaginous yeast, S. cerevisiae has a limited production capacity for lipophilic compounds, such as β-carotene. To increase its accumulation of β-carotene, we engineered different lipid metabolic pathways in a β-carotene producing strain and investigated the relationship between lipid components and the accumulation of β-carotene. We found that overexpression of sterol ester synthesis genes ARE1 and ARE2 increased β-carotene yield by 1.5-fold. Deletion of phosphatidate phosphatase (PAP) genes (PAH1, DPP1, and LPP1) also increased β-carotene yield by twofold. Combining these two strategies resulted in a 2.4-fold improvement in β-carotene production compared with the starting strain. These results demonstrated that regulating lipid metabolism pathways is important for β-carotene accumulation in S. cerevisiae, and may also shed insights to the accumulation of other lipophilic compounds in yeast.
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| 6. |
- Zhao, Yijin, et al.
(författare)
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Protein engineering of invertase for enhancing yeast dough fermentation under high-sucrose conditions
- 2023
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Ingår i: Folia Microbiologica. - : Springer Science and Business Media LLC. - 0015-5632 .- 1874-9356. ; 68:2, s. 207-217
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Tidskriftsartikel (refereegranskat)abstract
- During yeast dough fermentation, such as the high-sucrose bread-making process, the yeast cells are subjected to considerable osmotic stress, resulting in poor outcomes. Invertase is important for catalyzing the irreversible hydrolysis of sucrose to free glucose and fructose, and decreasing the catalytic activity of the invertase may reduce the glucose osmotic stress on the yeast. In this study, we performed structural design and site-directed mutagenesis (SDM) on the Saccharomyces cerevisiae invertase (ScInV) in an Escherichia coli expression system to study the catalytic activity of ScInV mutants in vitro. In addition, we generated the same mutation sites in the yeast endogenous genome and tested their invertase activity in yeast and dough fermentation ability. Our results indicated that appropriately reduced invertase activity of yeast ScInV can enhance dough fermentation activity under high-sucrose conditions by 52%. Our systems have greatly accelerated the engineering of yeast endogenous enzymes both in vitro and in yeast, and shed light on future metabolic engineering of yeast.
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