| 1. |
- Cai, Yixiao, 1986-
(författare)
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Bio-Nano Interactions : Synthesis, Functionalization and Characterization of Biomaterial Interfaces
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Current strategies for designing biomaterials involve creating materials and interfaces that interact with biomolecules, cells and tissues. This thesis aims to investigate several bioactive surfaces, such as nanocrystalline diamond (NCD), hydroxyapatite (HA) and single crystalline titanium dioxide, in terms of material synthesis, surface functionalization and characterization.Although cochlear implants (CIs) have been proven to be clinically successful, the efficiency of these implants still needs to be improved. A CI typically only has 12-20 electrodes while the ear has approximately 3400 inner hair cells. A type of micro-textured NCD surface that consists of micrometre-sized nail-head-shaped pillars was fabricated. Auditory neurons showed a strong affinity for the surface of the NCD pillars, and the technique could be used for neural guidance and to increase the number of stimulation points, leading to CIs with improved performance.Typical transparent ceramics are fabricated using pressure-assisted sintering techniques. However, the development of a simple energy-efficient production method remains a challenge. A simple approach to fabricating translucent nano-ceramics was developed by controlling the morphology of the starting ceramic particles. Translucent nano-ceramics, including HA and strontium substituted HA, could be produced via a simple filtration process followed by pressure-less sintering. Furthermore, the application of such materials as a window material was investigated. The results show that MC3T3 cells could be observed through the translucent HA ceramic for up to 7 days. The living fluorescent staining confirmed that the MC3T3 cells were visible throughout the culture period.Single crystalline rutile possesses in vitro bioactivity, and the crystalline direction affects HA formation. The HA growth on (001), (100) and (110) faces was investigated in a simulated body fluid in the presence of fibronectin (FN) via two different processes. The HA layers on each face were analysed using different characterization techniques, revealing that the interfacial energies could be altered by the pre-adsorbed FN, which influenced HA formation.In summary, micro textured NCD, and translucent HA and FN functionalized single crystalline rutile, and their interactions with cells and biomimetic HA were studied. The results showed that controlled surface properties are important for enhancing a material’s biological performance.
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| 2. |
- 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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| 3. |
- 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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| 4. |
- 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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| 5. |
- Fu, Le, et al.
(författare)
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Biodegradable Si3N4 bioceramic sintered with Sr, Mg and Si for spinal fusion : Surface characterization and biological evaluation
- 2018
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Ingår i: Applied Materials Today. - : Elsevier BV. - 2352-9407. ; 12, s. 260-275
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Tidskriftsartikel (refereegranskat)abstract
- Silicon nitride (Si3N4) is an industrial ceramic used in spinal fusion and maxillofacial reconstructionbecause of its excellent mechanical properties and good biocompatibility. This study compares the sur-face properties, apatite formation ability, bacterial infection, cell-biomaterial interactions, and in vivotoxicity (zebrafish) of newly developed Si3N4 bioceramics (sintered with bioactive sintering additivesSrO, MgO and SiO2) with two standard biomaterials; titanium (Ti) and traditional Si3N4 bioceramics (sin-tered with standard sintering additives Al2O3 and Y2O3). In general, Si3N4 bioceramics (both the newlydeveloped and the traditional) displayed less in vitro bacterial affinity than Ti, which may arise fromdifferences in the surface properties between these two types of material. The newly developed Si3N4bioceramics developed lower biofilm coverage and thinner biofilm, compared to traditional Si3N4 bioce-ramics. The effects of ionic dissolution products (leach) on proliferation and differentiation of MC3T3-E1cell were also investigated. Ionic dissolution products containing moderate amount of Sr, Mg and Siions (approximately 4.72 mg/L, 3.26 mg/L and 3.67 mg/L, respectively) stimulated osteoblast prolifera-tion during the first 2 days in culture. Interestingly, ionic dissolution products from the traditional Si3N4bioceramics that contained small amount of Si and Y ions achieved the greatest stimulatory effect foralkaline phosphatase activity after 7 days culture. The toxicity of ionic dissolution products was investi-gated in a putative developmental biology model: zebrafish (Danio rerio). No toxicity, or developmentalabnormalities, was observed in zebrafish embryos exposed to ionic dissolution products, for up to 144 hpost fertilization. These newly developed Si3N4 bioceramics with bioactive sintering additives show greatpotential as orthopedic implants, for applications such as spinal fusion cages. Future work will focus onevaluation of the newly developed Si3N4 bioceramics using a large animal model.
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| 6. |
- Hu, Zhekai, et al.
(författare)
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Nano-Structure Designing Promotion Osseointegration of Hydroxyapatite Coated Ti-6Al-4V Alloy Implants in Diabetic Model
- 2019
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Ingår i: Journal of Biomedical Nanotechnology. - : AMER SCIENTIFIC PUBLISHERS. - 1550-7033 .- 1550-7041. ; 15:8, s. 1701-1713
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Tidskriftsartikel (refereegranskat)abstract
- Mammalian diabetes mellitus which contains altered microenvironment always impairs diverse cellular processes such as osteogenesis, angiogenesis and tissue regeneration via different mechanisms. For researches in materials science, modifying the ability of osteogenesis and angiogenesis in dental implants shows its significant importance. Nano-structure designing is considered as a facile strategy to improve the surface bioactivity of the implants. In this study, the nanorod-structured hydroxyapatite (HA) coatings on Ti-6Al-4V implants were facilely designed by the combination of plasma-spraying and hydrothermal treatment via varying reaction media. Intriguingly, hydrothermal treatment eliminated the glassy phase and impurity phases of HA coatings, and nanorod-structured surface was successfully constructed under hydrothermal treatment in Na3PO4 solution. Additionally, the HA coatings with nanorod-structured surface effectively promoted the adhesion and proliferation and further enhanced osteogenic differentiation of DM-rBMSCs in vitro, Moreover, the osseointegration of Ti-6Al-4V implants with nanorod-structured HA coating was also enhanced in diabetes mellitus rabbit model in vivo. Therefore, the nano-structured surface modification of HA coating on Ti-6Al-4V implants could target pathological bone loss via strengthening osteogenesis and angiogenesis and further potentially used as a therapeutic coating to promote diabetic osteointegration.
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| 7. |
- Tang, Xiang-long, et al.
(författare)
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Near-infrared light-activated red-emitting upconverting nanoplatform for T-1-weighted magnetic resonance imaging and photodynamic therapy
- 2018
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Ingår i: Acta Biomaterialia. - : ELSEVIER SCI LTD. - 1742-7061 .- 1878-7568. ; 74, s. 360-373
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Tidskriftsartikel (refereegranskat)abstract
- Photodynamic therapy (PDT) has increasingly become an efficient and attractive cancer treatment modality based on reactive oxygen species (ROS) that can induce tumor death after irradiation with ultraviolet or visible light. Herein, to overcome the limited tissue penetration in traditional PDT, a novel near-infrared (NIR) light-activated NaScF4: 40% Yb, 2% Er@CaF2 upconversion nanoparticle (rUCNP) is successfully designed and synthesized. Chlorin e6, a photosensitizer and a chelating agent for Mn2+, is loaded into human serum albumin (HSA) that further conjugates onto rUCNPs. To increase the ability to target glioma tumor, an acyclic Arg-Gly-Asp peptide (cRGDyK) is linked to rUCNPs@HSA(Ce6-Mn). This nanoplatform enables efficient adsorption and conversion of NIR light (980 nm) into bright red emission (660 nm), which can trigger the photosensitizer Ce6-Mn complex for PDT and T-1-weighted magnetic resonance imaging (T-1-weighted MRI) for glioma diagnosis. Our in vitro and in vivo experiments demonstrate that NIR light-activated and glioma tumor-targeted PDT can generate large amounts of intracellular ROS that induce U87 cell apoptosis and suppress glioma tumor growth owing to the deep tissue penetration of irradiated light and excellent tumor-targeting ability. Thus, this nanoplatform holds potential for applications in T-1-weighted MRI diagnosis and PDT of glioma for antitumor therapy. Statement of Significance A near-infrared (NIR) light-activated nanoplatform for photodynamic therapy (PDT) was designed and synthesized. The Red-to-Green (RIG) ratio of NaScF4: 40% Yb, 2% Er almost reached 9, a value that was much higher than that of a traditional Yb/Er-codoped upconversion nanoparticle (rUCNP). By depositing a CaF2 shell, the red-emission intensities of the rUCNPs were seven times strong as that of NaScF4: 40% Yb, 2% Er. The enhanced red-emitting rUCNPs could be applied in many fields such as bioimaging, controlled release, and real-time diagnosis. The nanoplatform had a strong active glioma-targeting ability, and all results achieved on subcutaneous glioma demonstrated that our NIR light-activated redemitting upconverting nanoplatform was efficient for PDT. By loading Ce6-Mn complex into rUCNPs@HSA-RGD, the nanoplatform could be used as a T-1-weighted magnetic resonance imaging agent for tumor diagnosis.
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| 8. |
- Zhu, Wei, et al.
(författare)
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Cemented injectable multi-phased porous bone grafts for the treatment of femoral head necrosis
- 2019
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Ingår i: Journal of materials chemistry. B. - : ROYAL SOC CHEMISTRY. - 2050-750X .- 2050-7518. ; 7:18, s. 2997-3006
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Tidskriftsartikel (refereegranskat)abstract
- Femoral head necrosis (FHN) can induce musculoskeletal disability. It presents a challenge from diagnostic and therapeutic points of view. Open surgery for the treatment of FHN is not an optimal route. To minimize the surgery window, an injectable material with a porous structure and bioactive nature is preferred. The fabrication of an injectable porous bone graft via a simple route was the aim of our study. Therefore, cemented multi-phased calcium phosphate porous granules have been studied with varied phase compositions, pore sizes and porosities, and degradation rates. Granules templated by PEG 100-600 mu m were chosen for cell toxicity and in vitro osteogenic potential testing. Rabbits, making up a femoral head necrosis model, were implanted with granule A. Mature cancellous bone tissue was observed in the femoral head defect after 2 months implantation. The results indicate that the newly formed injectable bioactive porous grafts could be a good candidate for the treatment of femoral head necrosis.
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| 9. |
- 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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| 10. |
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| 11. |
- 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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| 12. |
- Berg, Camilla, et al.
(författare)
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ACP-Mg particles for treatment of dental hypersensitivity : a mode of action study
- 2019
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Introduction/purpose:Dental hypersensitivity is a common clinical condition usually associated with exposed dentinal tubules. Occlusion of those, hindering fluid movement as a response to external stimuli, is one approach to reduce pain.[1] The occluding agent should induce mineralization and have a good filling effect. In this study, particles (200-400 nm) of Amorphous Calcium Phosphate with Mg (ACP-Mg) were used aiming to evaluate the mode of action with in-vitro studies on dentine as well as degradation properties in buffered systems.Methods:Degradation properties and ion-release was monitored by dispersing the particles in Tris-HCl (10 mg/mL) storing the dispersions at 37 °C. In-vitro testing was performed on 1 mm thick dentine discs cut from extracted human molars. Specimens were etched in 35 % phosphoric acid, rinsed with DI-water followed by treatment by applying a gel formulation containing the particles using a soft bristled toothbrush, brushing 1 min on each side and leaving the specimen to rest for 3 min. Treatment was repeated four times during one day and samples were incubated at 37 °C in artificial saliva.Results:In vitro tests and degradation studies showed that ACP-Mg particles induced formation of Hydroxyapatite (HA). ICP-OES, XRD and SEM showed that there was a rapid release of all ions up to 6 hours followed by a re-precipitation of HA at 24 hours with a lower Mg-content. The crystallinity increased with time as the concentration of all ions decreased in the solutions. Morphological evaluation for the in-vitro tests showed that HA-like structures formed already after 24 hours on the dentine surface. Cross-sections revealed that the particles reached as far as 80 µm from the surface and tubules, fully occluded by HA-like structures, was visible at comparable depths after 7 days.Conclusions:ACP-Mg particles can be used to reduce dentine hypersensitivity by effective occlusion of dentine tubules via rapid formation of surface and intra-tubular HA.References:1. Splieth CH, Tachou A. 2013. Epidemiology of dentin hypersensitivity. Clin Oral Investig. 17:3–8.
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| 13. |
- Berg, Camilla, et al.
(författare)
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Amorphous Calcium Magnesium Phosphate Particles for Treatment of Dentin Hypersensitivity : A Mode of Action Study
- 2020
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Ingår i: ACS Biomaterials Science & Engineering. - : AMER CHEMICAL SOC. - 2373-9878. ; 6:6, s. 3599-3607
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Tidskriftsartikel (refereegranskat)abstract
- Occlusion of exposed dentin tubules may eliminate or reduce dentin hypersensitivity by hindering fluid movements within the tubules. In this study, the mode of action of spherical particles of amorphous calcium magnesium phosphate (180-440 nm in diameter) was studied. A degradation study of the particles in Tris-HCl buffer showed that the particles continuously released Ca2+, Mg2+, and phosphate, and XRD analysis revealed the formation of hydroxyapatite (HA) after 1 week. The occluding effect and efficacy of the spherical particles as an occluding agent were evaluated in an in vitro study. The ACMP particles were incorporated in a gel intended for at-home use and tested on extracted human molars. Application of the particles followed by incubation in artificial saliva resulted in occlusion of exposed tubules, and examination with SEM showed that the particles could penetrate the tubules down to 100 mu m from the dentin surface. Transformation of the particles into nanocrystalline HA-structures (nanoHA) was initiated at the dentin surface within 12 h of application, and tubule penetration of the particles, accompanied by further ion release and diffusion of ions, resulted in deep intratubular occlusion in the majority of the tubules within 3 days from application. NanoHA was tightly adhered to the tubule walls, filling the entire tubule volume after 7 days. The results of this study demonstrate the mode of action of the amorphous calcium magnesium phosphate particles in occluding exposed dentin tubules. Interaction with saliva and transformation of the particles within the tubules inducing further mineralization indicate that the particles may be used as an effective treatment to reduce dentin hypersensitivity.
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| 14. |
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| 15. |
- 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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| 16. |
- Berg, Camilla, et al.
(författare)
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Electron microscopy evaluation of mineralization on peritubular dentin with amorphous calcium magnesium phosphate microspheres
- 2020
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Ingår i: Ceramics International. - : Elsevier BV. - 0272-8842 .- 1873-3956. ; 46:11, s. 19469-19475
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Tidskriftsartikel (refereegranskat)abstract
- Dentin hypersensitivity can be reduced by the use of a remineralization agent to hinder movement of fluids within the dentin tubules. Penetration of particles into the tubules and a continuous release of Ca2+ and phosphate ions can induce the mineralization of a material mimicking the mineral component of dentin, sealing the tubules. In this work, we have used complementary electron microscopy techniques to investigate the ultrastructure of dentin and crystallization and occlusion effects when using amorphous calcium magnesium phosphate (ACMP) microspheres on extracted human molars. Application of the particles in a gel intended for athome use resulted in intra-tubular mineralization of a carbonate substituted hydroxyapatite (HA). Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) showed that crystallization was initiated on the peritubular dentin (PTD) with undirected crystal growth leading to the formation of a porous material. We additionally investigated the effects from using a fluoride toothpaste to potentially improve the remineralization and anti-cariogenic properties of the ACMP microspheres. Energy dispersive x-ray spectroscopy (EDX) using TEM in scanning mode (STEM) showed that fluoride incorporation resulted in an increase in aspect ratio of the crystals, crystal growth directed towards the center of the tubule lumen and densification of the mineralized material. Thus, ACMP microspheres are promising alternatives as occluding agents and the efficacy of the particles could be further improved with the complementary use of a fluoride toothpaste.
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| 17. |
- Berg, Camilla, et al.
(författare)
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Ion substitution induced formation of spherical ceramic particles
- 2019
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Ingår i: Ceramics International. - : ELSEVIER SCI LTD. - 0272-8842 .- 1873-3956. ; 45:8, s. 10385-10393
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Tidskriftsartikel (refereegranskat)abstract
- How to precipitate ceramic nano- and microspheres in water based solutions only using inorganic ions is a challenge. In this study, spherical particles of alkaline earth phosphates and fluorides were synthesized using a precipitation reaction. Substituting ions, through inhibition of crystal growth, was used to induce sphere formation and to alter the morphology, size and composition of the spheres. The difference in ionic radius between the substituting ion (Mg, Ca and Sr) and the main cation (Sr and Ba) influenced the critical concentration to allow for sphere formation as well as the crystallinity. The larger difference, the lower was the concentration needed to form spheres. Low concentrations of Mg was enough to generate amorphous spheres of Sr- and Ba- phosphates whereas higher concentrations were needed if the radius difference were smaller. An increasing degree of substitution leads to a decrease in crystallinity of precipitated particles. The degree of substitution was determined to 16-55% where a low degree of ion substitution in the phosphates resulted in the formation of spheres (500-800 nm) with rough surfaces composed of apatite like phases. A higher degree of substitution resulted in amorphous spheres (500 nm- (1) mu m) with smooth surfaces.
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| 18. |
- Berg, Camilla, et al.
(författare)
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Synthesis of Ion Substituted Ceramic Core-Shell Particles for Dental Applications
- 2018
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Konferensbidrag (refereegranskat)abstract
- Calcium phosphate spheres are interesting alternatives for dental applications due to their chemical similarity to teeth and biocompatibility. A spherical shape with a hollow cores allows for loading of therapeutic agents for drug delivery which potentially could be combined with other applications such as tooth remineralization and treatment of hypersensitivity.Precipitation reactions are one of the techniques used for synthesizing spherical particles, but little is known about the mechanism behind the sphere formation, which makes tuning of the material properties challenging. Previously, it has been shown that substituting ions can influence the crystallization process, which can enable greater control during the synthesis.In this study, several different substituting ions has been used in the synthesis of alkaline earth phosphates, to further investigate their role in sphere formation and to develop a robust synthesis technique.Particles of alkaline earth phosphates (Ca, Sr and Ba) were synthesized with a precipitation reaction. Solutions with constituent anions and cations were mixed at room temperature, and substituting ions (Mg, Ca or Sr) were added before heating at 60-100 °C. Reaction times varied between 10 minutes to 24 hours. Characterization of precipitates was performed with SEM, DLS and FIB to analyze morphology, size and cross-sections of the spheres. Crystal structure and atomic composition was analyzed with XRD and ICP-OES.Without substituting ions, precipitates had no specific shape and crystallized in an apatitic structure or as a hydrogenated phosphate. Substituting ions stabilized the initial amorphous phase during the reaction, hindering rapid crystal growth which allowed for self-assembly into hollow, spherical particles with a diameter between 300-700 nm. The phase composition and degree of ion substitution in the precipitates depended on the size and concentration of the substituting ions. The amount of substitution was determined in the range between 5-30 %, where precipitates with a low degree of substitution crystallized in a structure similar to β-tricalcium phosphate, whereas materials with a higher degree of substitution had an amorphous structure.In this study it was shown that it was possible to obtain hollow, spherical particles of calcium-, strontium- and barium phosphate, by using substituting ions during a precipitation reaction. This indicates that the approach can be used to tailor the properties of spherical particles intended for dental applications.
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| 19. |
- Cai, Bing, 1986-
(författare)
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Ceramic Materials for Administration of Potent Drugs
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis aimed to investigate and document the potential of applying ceramics in two specific drug delivery applications: tamper-resistant opioid formulations and transdermal enhancement protrusions.Geopolymers were developed into the matrix for a tamper-resistant formulation, aiming to protect drug substances from non-medical abuse. The synthesis conditions and excipients composition of the geopolymer-based formulation were modified in this work to facilitate a stable and extended drug delivery. Results showed that 37ºC 100% humidity for 48 hours were applicable conditions to obtain geopolymer with suitable mechanical strength and porosity. Moreover, it was found that the integration of poly(methyl acrylate) into the geopolymer-based formulation could reduce the drug release at low pH and, meanwhile, maintain the mechanical strength. Therefore, the geopolymer-based drug formulations concluded from these studies were applied in oral and transdermal delivery systems. Evidence of the tamper-resistance of geopolymer-based oral and transdermal formulations was documented and compared to the corresponding commercial opioid formulations. The results provided experimental support for the positive effects of geopolymers as drug carriers for the tamper-resistance of oral and transdermal delivery systems.Self-setting bioceramics, calcium phosphate and calcium sulfate were fabricated into transdermal enhancement protrusions in this work for the first time. Results showed that, under mild conditions, both bioceramics could form pyramid-shaped needles in the micron size. The drug release from these needles could be controlled by the bulk surface area, porosity and degradation of the bioceramics. An in vitro insertion test showed that the bioceramic microneedles had enough mechanical strength to insert into skin. Further optimization on the geometry of needles and the substrate material was also performed. The higher aspect-ratio needles with a flexible and self-swellable substrate could release most of the drug content within 4 hours and could penetrate through the stratum corneum by manual insertion. This study explored the potential application of bioceramics in transdermal enhancement protrusions and showed promising indication of their future developments.
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| 20. |
- Chen, Song
(författare)
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Glass Ionomer Cements with Improved Bioactive and Antibacterial Properties
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dental restorative cements are placed in a harsh oral environment where they are subjected to thermal shock, chemical degradation, and repeating masticatory force. The ideal restorative dental cements should have superior mechanical properties, chemical stability, aesthetic, good handling properties, biocompatibility, antibacterial properties, and preferably bioactivity. This thesis presents research on dental restorative cements with enhanced properties. The overall aim was to increase the bioactivity and antibacterial properties of dental restorative cements without affecting their other properties.The effect from adding calcium silicate to glass ionomer cement (GIC) was investigated. The results showed that calcium silicate could increase the bioactivity and reduce the cytotoxicity of conventional glass ionomer cement without compromising its setting and mechanical properties.Hydroxyapatite (HA) with a high aspect ratio and thin nacreous-layered monetite sheets were also synthesized. Nano HA particles with an aspect ratio of 50 can be synthesized by both precipitation and hydrothermal methods. The aspect ratio was controlled via the pH of reaction medium. Thin nacreous-layered monetite sheets were synthesized through a self-assembly process in the presence of an amine based cationic quaternary surfactant. Temperature, pH, and presence of surfactant played essential roles in forming the nacreous-layered monetite sheets. Then the effect from adding silver doped HA and monetite particles was investigated. The results showed that the antibacterial properties of GIC could be increased by incorporating silver doped HA and monetite particles. Further examination showed that the pH change, F- ion release, and concentration of released Ag+ ions were not responsible for the improved antibacterial properties.The quasi-static strengths and compressive fatigue limits of four types of the most commonly used dental restorations were evaluated. In our study, resin modified GIC and resin-based composite showed superior static compressive strength and fatigue limits compared to conventional GIC. The static compressive strength of dental cements increased with the aging time. However, aging had no effect on the compressive fatigue limit of resin modified GIC and resin-based composite. The compressive fatigue limit of conventional GIC even showed a drastic decrease after aging.
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| 21. |
- 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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| 22. |
- 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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| 23. |
- 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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| 24. |
- Fu, Le, et al.
(författare)
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Fabrication of mechanically robust nanoporous ZrSiO4 ceramics at low temperature with a low doping level of Mn dopant
- 2024
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Ingår i: International Journal of Applied Ceramic Technology. - : John Wiley & Sons. - 1546-542X .- 1744-7402. ; 21:3, s. 1954-1964
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Tidskriftsartikel (refereegranskat)abstract
- Zircon (ZrSiO4) ceramics have been widely used in many fields due to their excellent physical and chemical properties. However, ZrSiO4 ceramics typically possess moderately low mechanical properties, which hinders their wider application. Meanwhile, elevated temperatures (similar to 1500 degrees C) are required to obtain high-purity synthetic ZrSiO4 ceramics, which is time- and energy-consuming. In the present study, we prepared mechanically robust ZrSiO4 ceramics at low temperature (similar to 1170 degrees C) with a low doping level of Mn dopant (<2 mol%). The ZrSiO4 ceramic processed by hot isostatic pressing with .5 mol% Mn dopant achieved the highest flexural strength (512 MPa), elastic modulus (341 GPa), and nanohardness (20.8 GPa). These values are significantly higher than conventional ZrSiO4 ceramics. The strengthening mechanisms of the prepared ZrSiO4 ceramics were attributed to the formation of homogeneously-distributed nanopores due to incomplete densification and submicron ZrSiO4 grains (similar to 300 nm). The nanopores avoided stress concentration and deflected microcracks during loading, and the submicron ZrSiO4 grains endowed the ZrSiO4 ceramics with grain refinement strengthening. The results reported in this study would offer guidance to fabricate mechanically robust ZrSiO4 ceramics at low temperatures with a low doping level of dopant.
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| 25. |
- Fu, Le, et al.
(författare)
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Far from equilibrium ultrafast high-temperature sintering of ZrO2-SiO2 nanocrystalline glass-ceramics
- 2023
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Ingår i: Journal of The American Ceramic Society. - : John Wiley & Sons. - 0002-7820 .- 1551-2916. ; 106:7, s. 4005-4012
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Tidskriftsartikel (refereegranskat)abstract
- Ultrafast high-temperature sintering (UHS) is a novel sintering technique with ultrashort firing cycles (e.g., a few tens of seconds). The feasibility of UHS has been validated on several ceramics and metals; however, its potential in consolidating glass-ceramics has not yet been demonstrated. In this work, an optimized carbon-free UHS was utilized to prepare ZrO2-SiO2 nanocrystalline glass-ceramics (NCGCs). The phase composition, grain size, densification behavior, and microstructures of NCGCs prepared by UHS were investigated and compared with those of samples sintered by pressureless sintering. Results showed that NCGCs with a high relative density (similar to 95%) can be obtained within similar to 50 s discharge time by UHS. The UHS processing not only hindered the formation of ZrSiO4 and cristobalite but also enhanced the stabilization of t-ZrO2. Meanwhile, owing to the ultrashort firing cycles, the UHS technology allowed the NCGCs to be consolidated in a far from equilibrium state. The NCGCs showed a microstructure of spherical monocrystalline ZrO2 nanocrystallites embedded in an amorphous SiO2 matrix.
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