| 1. |
- Wei, Zhu, et al.
(författare)
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Injectable and assembled 3D solid structure for free-to-fixed shape in bone reconstruction
- 2020
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Ingår i: Applied Materials Today. - : Elsevier BV. - 2352-9407. ; 21
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Tidskriftsartikel (refereegranskat)abstract
- There is a gap between injectable and scaffold-like bioceramics. Injectable bioactive materials, such as bone cement and hydrogel, are good for minimized surgery, but the extremely low porosity and small pore size limited enhanced bone repair and regeneration. Macroporous bioceramic scaffolds are used because of the controlled pore size and porosity, but not injectable. It's a challenge of preparation of an injectable macroporous ceramic scaffold for minimized bone reconstruction. By using the reversible setting reaction of calcium sulfate and combining a dual setting system with magnesium silicate hydrate, the injectable and assembled 3D porous bioceramic scaffold has been successfully developed. The content of amorphous magnesium silicate hydrate in the dual setting system affected the mechanical strength and degradation. The porous structure could be controlled by the size of granules. The granules can also be used for the fabrication of porous materials with varied shapes and customized structures by using a simple injection process. The biological testing showed good biocompatibility and in vitro osteogenesis. By using the femoral lateral condyle defect model, we can see the granules could be injected into the defect and formed a rigid porous structure in situ, and further presented better new bone formation compared with autologous bone chips. Briefly, we demonstrated the first injectable 3D solid porous ceramic structure for minimized bone repair and free-form shaping.
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| 2. |
- Berg, Camilla
(författare)
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Ceramic Core–Shell Particles : Synthesis and Use within Dentistry
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dentin hypersensitivity is one of the most prevalent conditions related to oral health, affecting a large share of the adult population. Shortcomings with the available treatment options are related to non-ideal particle sizes and degradation properties. An improved clinical outcome could possibly be obtained using a bioactive occluding agent that can offer a high, continuous release of ions, as well as having a particle size that allows for penetration into the dentin tubules. The work in this thesis focused on the development and investigation of a synthesis approach for calcium phosphate core–shell particles and the use of those in the treatment of dentin hypersensitivity. The overall aim was to increase the knowledge about the synthesis and to evaluate the in vitro performance of amorphous calcium magnesium phosphate (ACMP) particles when used as an occluding agent. The synthesis of the core-shell particles was based on precipitation reactions in aqueous solutions and the synthesized materials were studied in terms of morphological, structural, and compositional aspects. Resulting particles had diameters ranging from 400 nm–1. 5 µm (depending on reaction conditions), with morphologies and structures that were shown to correlate with the ionic radius and the concentration of the substituting ion. This insight resulted in the possibility to control the outcome of the reaction and to extend the synthesis to other alkaline earth phosphates. The mechanism of formation was suggested to be the simultaneous precipitation of primary nanoparticles (NPs) and the formation of gas bubbles that could function as soft templates.A study of the degradation properties together with a series of in vitro studies, using a dentin-disc model, indicated that the ACMP particles may be a promising candidate for clinical use. The material was shown to offer a rapid and continuous release of Ca2+, Mg2+, and phosphate, aiding surface, as well as intratubular occlusion and mineralization. Additional use of a fluoride toothpaste resulted in incorporation of F– in the mineralized material. This could enhance the in vivo performance due to the known benefits of including F– in dental tissues, e.g. decreased solubility. The ACMP particles were, furthermore, shown to be more efficient in terms of degree of occlusion when compared to other similar products available on the market. The intratubular mineralization was additionally mitigating the effect of an acid attack, which is of importance for a long-lasting effect in clinical use.
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| 3. |
- Cheng, Kaiyuan, et al.
(författare)
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Injectable tricalcium phosphate/calcium sulfate granule enhances bone repair by reversible setting reaction
- 2021
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier. - 0006-291X .- 1090-2104. ; 557, s. 151-158
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Tidskriftsartikel (refereegranskat)abstract
- Towards repairing bone defects, calcium sulfate and calcium phosphate cement have been recognized as promising bone grafts. However, the current bone cements are generally lack of proper porosity for cell migration and new tissue formation. On the other hand, porous scaffold cannot be delivered by injection, which limits its use its clinical use. Herein, we develop a novel tricalcium phosphate/calcium sulfate granule to overcome the limitations of injectable cements and traditional scaffolds. The biocompatible granule underwent in situ self-setting to form scaffold with porous structure after injection. It con-tributes to calcium deposition and upregulation of osteogenic genes of mesenchymal stem cells in a time-dependent manner. Within three months, cavitary bone defects of distal rabbit femurs implanted the granules exhibited better bone formation than those with those implanted with autologous bone.
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| 4. |
- Bai, Xuan, et al.
(författare)
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Sequential macrophage transition facilitates endogenous bone regeneration induced by Zn-doped porous microcrystalline bioactive glass
- 2021
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Ingår i: Journal of materials chemistry. B. - : Royal Society of Chemistry. - 2050-750X .- 2050-7518. ; 9:12, s. 2885-2898
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Tidskriftsartikel (refereegranskat)abstract
- Macrophages play an important role in the immune microenvironment during bone healing, and sequential macrophage phenotypic transition could achieve superior osteogenic outcomes. Microcrystalline bioactive glasses (MCBGs) with osteoimmunomodulatory effects show potential in bone tissue regeneration. Zinc (Zn) has been approved to coordinate innate and adaptive immunity. Therefore, in this study, different amounts of ZnO were incorporated into microcrystalline bioactive glass to improve its immunomodulatory ability. The effect of Zn-MCBG ionic extracts on macrophage transition was studied, and the 5Zn-MCBG extracts could orchestrate sequential M1-to-M2 macrophage transition and promote the expression of proinflammatory and anti-inflammatory genes and cytokine expression to induce human bone marrow stromal cells (hBMSCs) osteogenic differentiation in vitro. Macroporous Zn-MCBG scaffolds containing mesopores were fabricated and showed good cell adhesion and feasible apatite formation when immersed in SBF in vitro. Furthermore, a rat calvarial defect model was used to confirm that the Zn-MCBG scaffold could modulate macrophage phenotypic transition and create a desirable osteogenic microenvironment to promote osteogenesis in vivo.
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| 5. |
- Bang, Le T., et al.
(författare)
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Synthesis and assessment of metallic ion migration through a novel calcium carbonate coating for biomedical implants
- 2020
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Ingår i: Journal of Biomedical Materials Research. Part B - Applied biomaterials. - : Wiley. - 1552-4973 .- 1552-4981. ; 108:2, s. 429-438
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Tidskriftsartikel (refereegranskat)abstract
- Titanium (Ti) implants are commonly regarded as well accepted by the body. However, metal ion release is still a cause for concern. A small decrease in pH, which can be caused by inflammation, may produce a large increase in the corrosion rate of Ti implants. Coating the alloy with a buffer layer could have a significant protective effect. In this study, a calcium carbonate coating was developed on commercially pure Ti and a Ti-6Al-4V alloy through a hydrothermal treatment of previously NaOH-treated surfaces in calcium-citric acid chelate complexes. The results showed that a superstructured calcite coating layer formed on the Ti substrate after treatment at 170 degrees C for 3 hr. The coating was approx. 1 mu m thick and covered the substrate surface uniformly. When prolonging the hydrothermal treatment from 5 hr to 24 hr, the rhombohedral structure of calcite was observed in addition to the superstructure of calcite. Dissolution test results showed no significant differences in solution pH between the coated- and un-coated samples. However, the CaCO3 coating reduced by approx. 2-5 times the Ti and V ion release from the substrate as compared to the uncoated material, at pH 4. CaCO3 and hydroxyapatite (HA) coatings gave nonsignificant effects at neutral pH although the HA coating showed a trend for better results at the longer time points. The reduction in metal ion release from the substrate and the buffering ability of the CaCO3 coating encourage further studies on this coating for clinical applications.
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| 6. |
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| 7. |
- Berg, Camilla, et al.
(författare)
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Comparative study of technologies for tubule occlusion and treatment of dentin hypersensitivity
- 2021
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Ingår i: Journal of Functional Biomaterials. - : MDPI. - 2079-4983. ; 12:2
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to evaluate the occluding/remineralization performance and resistance to acid attacks of the mineralization layer formed by a tooth-desensitizing gel containing amorphous calcium magnesium phosphate (ACMP) particles and compare it to six other desensitizing products available on the market. Similar comprehensive studies are few and there is especially a lack of studies that are up to date. A dentin-disc model was used for in vitro evaluation of the desensitizing toothpastes/gels. Application of the products was performed twice daily for seven days. One set of specimens were evaluated using scanning electron microscopy (SEM) directly after the final treatment and another set was evaluated after an acid challenge, exposing specimens to 2 wt% citric acid. The ACMP desensitizing gel was the only product resulting in complete occlusion by the formation of mineralized material on the dentin surface and inside the tubules. Particle deposition was dominant after treatment with the other desensitizing products, with little or no mineralization, resulting in partial occlusion only. Sensodyne Repair & Protect and Oral-B Pro-Expert showed the highest resistance toward acid attacks. Material inside the tubules remained relatively unaffected by acid attacks in all specimens. The results in this study indicated a great variability among the occluding agents in terms of occlusion and acid resistance of the mineralization layer. The high degree of occlusion and intra-tubular mineralization that could mitigate the effect of acid solubilization indicate that the ACMP desensitizing gel may be a superior option for the treatment of dentin hypersensitivity.
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| 8. |
- F. Abdel-Magied, Ahmed, et al.
(författare)
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Magnetic metal-organic frameworks for efficient removal of cadmium(II), and lead(II) from aqueous solution
- 2022
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Ingår i: Journal of Environmental Chemical Engineering. - : Elsevier BV. - 2213-2929 .- 2213-3437. ; 10:3
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Tidskriftsartikel (refereegranskat)abstract
- Efficient and convenient methods for the removal of toxic heavy metal ions especially Cd(II) and Pb(II) from aqueous solutions is of great importance due to their serious threat to public health and the ecological system. In this study, two magnetic metal-organic frameworks (namely: Fe3O4@ZIF-8, and Fe3O4@UiO-66–NH2) were synthesized, fully characterized, and applied for the adsorption of Cd(II) and Pb(II) from aqueous solutions. The adsorption efficiencies for the prepared nanocomposites are strongly dependent on the pH of the aqueous solution. The maximum adsorption capacities of Fe3O4@UiO-66–NH2, and Fe3O4@ZIF-8 at pH 6.0 were calculated to be 714.3 mg·g−, and 370 mg·g−1 for Cd(II), respectively, and 833.3 mg·g−1, and 666.7 mg·g−1 for Pb(II), respectively. The adsorption process follows a pseudo-second-order model and fit the Langmuir isotherm model. Moreover, the thermodynamic studies revealed that the adsorption process is endothermic, and spontaneous in nature. A plausible adsorption mechanism was discussed in detail. The magnetic adsorbents: Fe3O4@ZIF-8, and Fe3O4@UiO-66–NH2 showed excellent reusability, maintaining the same efficiency for at least four consecutive cycles. These results reveal the potential use of magnetic Fe3O4@ZIF-8, and Fe3O4@UiO-66–NH2 as efficient adsorbents in removing Cd(II) and Pb(II) from aqueous solutions.
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| 9. |
- Fu, Le, et al.
(författare)
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Doping of tantalum, niobium, and hafnium in a translucent ZrO2-SiO2 nanocrystalline glass-ceramic
- 2022
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Ingår i: Journal of the European Ceramic Society. - : Elsevier. - 0955-2219 .- 1873-619X. ; 42:4, s. 1731-1742
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Tidskriftsartikel (refereegranskat)abstract
- The addition of dopant(s) is an effective strategy to regulate the microstructure and properties of ZrO2-based ceramics. In this study, we investigated the effects of ternary element alloying, namely tantalum (Ta), niobium (Nb), and hafnium (Hf) elements, on the microstructure and transformability of ZrO2 nanocrystallites in a ZrO2SiO2 nanocrystalline glass-ceramic (NCGC) during sintering and thermal treatments. The ternary dopants enhanced the transformability of tetragonal ZrO2 (t-ZrO2) nanocrystallites during sintering, i.e., the dopants acted as t-ZrO2 destabilizer. The Ta, Nb and Hf elements dissolved in ZrO2 nanocrystallites, forming ZrO2 solid solution. Meanwhile, lamella nanotwins were formed within many ZrO2 nanocrystallites. No obvious segregation of dopants was detected at ZrO2 grain boundaries. t-ZrO2 and monoclinic (m) ZrO2 nanocrystallites were metastable in thermal treatments process, with "t" to "m" and the reverse "m" to "t" polymorphic transformation occurred simultaneously. Meanwhile, t-ZrO2 and m-ZrO2 nanocrystallites had a great tendency to grow larger during thermal treatments.
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| 10. |
- Fu, Le, et al.
(författare)
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Enhanced Bacteriostatic Properties of Ti Alloys by Surface Nitriding
- 2023
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Ingår i: Biomedical Materials & Devices. - : Springer Nature. - 2731-4812 .- 2731-4820. ; 1, s. 760-771
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Tidskriftsartikel (refereegranskat)abstract
- Surface nitriding has been widely used to improve the surface physicochemical properties of Ti alloys. However, the currently utilized surface nitriding methods, such as laser nitriding, typically require expensive and complicated instruments, which makes surface nitriding a less cost-effective process. Meanwhile, the antibacterial properties of surface-nitrided Ti alloy implants have not been evaluated. Thereafter, in this study, we were aiming to develop an effective, simple, and cost-effective surface nitriding strategy to enhance the antimicrobial properties of Ti alloy implants. The surface nitriding strategy was realized by wet-chemical etching and thermal treatment at controlled conditions. Results showed that the above surface modification treatments exerted significant effects on the phase composition and morphology of the newly formed phases on the surface of Ti samples. Crystalline TiN and TiO2 formed after treatments. Meanwhile, amorphous nitrides and oxynitride were also presented on the sample surfaces. The surface-modified Ti samples showed a bacterial inhibition effect compared with the non-treated Ti ones, and the bacterial inhibition effect was attributed to the released ammonia species from the surface of Ti samples. The surface modification strategy shows promise to improve the bacteriostatic property of Ti implants in dental and orthopedic fields.
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