| 1. |
- Qin, Tao, 1984-, et al.
(author)
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A novel method to synthesize low-cost magnesium fluoride spheres from seawater
- 2017
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In: Ceramics International. - : ELSEVIER SCI LTD. - 0272-8842 .- 1873-3956. ; 43:16, s. 14481-14483
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Journal article (peer-reviewed)abstract
- Magnesium fluoride (MgF2) is widely used as optical materials. A novel method for low-cost manufacturing of magnesium fluoride micro spheres from Baltic seawater was studied. The method focuses on a novel strategy of utilizing seawater. This study will facilitate large-scale production of MgF2 micro spheres. This method provides a prototype which can synthesize low-cost inorganic spheres from seawater.
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| 2. |
- Qin, Tao, 1984-, et al.
(author)
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A novel rapid synthesis, characterization and applications of calcium phosphate nanospheres from Baltic seawater
- 2018
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In: Ceramics International. - : ELSEVIER SCI LTD. - 0272-8842 .- 1873-3956. ; 44:8, s. 9076-9079
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Journal article (peer-reviewed)abstract
- Due to the considerable high bio-compatibility, calcium phosphate nanoparticles are widely used in biomedical applications. This study proposes a novel strategy for low-cost manufacturing calcium phosphate nanoporous spheres. The controlled reaction only took less than five minutes, when using Baltic seawater with the dissolved calcium concentration of 2.2 mM as the calcium resources. Porous nanospheres were obtained, with spheres ranging from 50 to 130 nm. The obtained nanospheres possess high drug-loading capacity and exhibit sustained release and pH-dependent properties. In addition, this method provides a general efficient strategy to synthesize other low-cost inorganic nanospheres from seawater.
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| 3. |
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| 4. |
- Qin, Tao, 1984-, et al.
(author)
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A general strategy for template-free and low-cost synthesis of inorganic hollow spheres
- 2017
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In: Powder Technology. - : Elsevier BV. - 0032-5910 .- 1873-328X. ; 319, s. 163-171
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Journal article (peer-reviewed)abstract
- Inorganic hollow spheres have a great potential in many fields, such as calcium phosphate (Ca3(PO4)2) as carriers of active ingredients and local delivery. They are typically synthesized by the methods that reply on template-based strategies. However, the template residue and energy consumption during template removal are drawbacks. Currently developed template-free methods remain challenges such as time, cost and complicated procedures. In this paper, we introduce a general low-cost and template-free precipitation method with simple procedure. A series of inorganic hollow spheres, including calcium phosphate, calcium fluoride, strontium phosphate, strontium fluoride, barium phosphate and barium fluoride via magnesium were successfully synthesized, respectively. Based on these experimental results, a new model is proposed to explain the mechanism of the hollow inorganic spheres formation. This paper provides a general method to synthesize inorganic hollow spheres, which may have an important indication to other systems.
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| 5. |
- Qin, Tao, 1984-, et al.
(author)
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A novel method to synthesize low-cost phosphate-based particles from natural water
- 2017
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In: Materials letters (General ed.). - : Elsevier BV. - 0167-577X .- 1873-4979. ; 206, s. 178-181
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Journal article (peer-reviewed)abstract
- Calcium phosphate (CaP) and magnesium phosphate (MgP) are widely used as biomaterials. A novel method for low-cost manufacturing of calcium phosphate spheres and magnesium phosphate micro particles was studied. The method focuses on novel strategies of utilizing seawater and lake water. In the natural water, the molar ratios of Mg/Ca are constant. The morphologies of the particles are determined by ratio of Ca/P. This simple method provides a prototype to synthesize low-cost inorganic spheres with natural water, which facilitate large-scale production.
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| 6. |
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| 7. |
- Qin, Tao, 1984-
(author)
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Submicron Calcium Phosphate Spheres for Biomedical Applications : Synthesis and Use
- 2016
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Doctoral thesis (other academic/artistic)abstract
- Calcium phosphate spheres as biomaterials have been attracting attention in recent years. Calcium phosphate occurs naturally in bone, and a hollow structure could be advantageous for drug loading and release. The combination of a calcium phosphate chemistry and a spherical-hollow structure could be an optimal strategy for specific biomaterial applications, e.g., certain dental and drug-delivery applications.The focus of this thesis is on the synthesis, formation mechanism and applications of hollow, spherical calcium phosphate particles. First, the thesis describes two methods for the synthesis of calcium phosphate (CaP) spherical particles. The first method involves synthesis of hollow calcium phosphate spherical particles via a supersaturated buffer solution based on a previous study. It was utilised to prepare spheres for applications in drug delivery and dentistry. The second method was developed to explain the mechanism of formation of hollow calcium phosphate spheres. It aimed at revealing the particular function of magnesium in the formation of spherical particles. With the use of this modified method, it could be concluded that the only ions active in the formation of CaP spherical particles are calcium ions, phosphate ions and magnesium ions. Compared with the thermodynamics of micellisation, a new model, called three ions virtual micelle effect, was developed to explain the mechanism of the Mg function. Following this mechanism, a series of spherical particles of other compositions were explored. These spherical particles included strontium phosphate, barium phosphate, calcium fluoride, strontium fluoride and barium fluoride.In this thesis, CaP spheres were studied for the controlled delivery of active ingredients and as active agent for tooth remineralisation. The first investigated application was to control the release of vancomycin from Poly(methyl methacrylate) (PMMA) cement via strontium-doped CaP spheres (SCPS). The results showed that incorporation of CaP spheres into PMMA could enhance antibiotic release while maintaining the mechanical strength. The second application was to control hydrogen peroxide (HP) release from two bleaching gel, in which CP-loaded CaP spheres were the active ingredient. One gel with low HP concentration was developed as an at-home bleaching gel, and one with high HP concentration was developed as an in-office bleaching gel. The results showed that CaP spheres would give a controlled release of peroxide and thus have a potential to increase the efficacy of the bleaching. The third application was to investigate the potential for an anti-sensitivity effect of the spheres, as active agents in toothpaste. We studied the tooth tubules occlusion and the remineralisation effect of CaP spheres. After 7 days of application, the open dentin tubules and surface were fully covered by a newly formed apatite layer, demonstrating the remineralisation potential of the spheres.
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| 8. |
- Qin, Tao, 1984-, et al.
(author)
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Template-free synthesis of phosphate-based spheres via modified supersaturated phosphate buffer solutions
- 2017
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In: Journal of materials science. Materials in medicine. - : SPRINGER. - 0957-4530 .- 1573-4838. ; 28:7
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Journal article (peer-reviewed)abstract
- Modified supersaturated phosphate buffer solutions were used to synthesize phosphate-based spheres, including calcium phosphate (CaP), strontium phosphate (SrP) and barium phosphate (BaP). A series of ions concentrations in the modified phosphate buffer solutions were investigated in order to study their effects in precipitates morphologies. During synthesis, it was found that magnesium was the key factor in sphere formation. The morphologies of calcium phosphate, strontium phosphate and barium phosphate precipitates varied as the concentration of magnesium ions varied. When sufficient magnesium was provided, the precipitates appeared spherical, and the diameter was in range of 0.5-2 mu m. The morphologies, compositions and structure of spheres were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N-2 adsorption analysis. Moreover, the application of magnesium substituted calcium phosphate spheres in dentin tubules occlusion was investigated.
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| 9. |
- Qin, Tao, 1984-, et al.
(author)
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The formation of calcium fluoride microspheres via solubility equilibrium
- 2017
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In: Ceramics International. - : ELSEVIER SCI LTD. - 0272-8842 .- 1873-3956. ; 43:16, s. 14521-14524
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Journal article (peer-reviewed)abstract
- The focus of this study is on synthesis and mechanism of calcium fluoride (CaF2) spheres. Magnesium is the decisive factor in the formation of the spheres. The solubility product constant of Mg1-xCaxF2 is higher than those of CaF2 and MgF2. The structure of particles evolved to being spherical due to solubility equilibrium. The calcium fluoride spheres have great potential as dental materials in bleaching products.
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