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Islam MT, Macri-Pellizzeri L, Hossain KMZ, Sottile V, Ahmed I. Effect of varying the Mg with Ca content in highly porous phosphate-based glass microspheres. Mater Sci Eng C Mater Biol Appl 2021; 120:111668. [PMID: 33545833 DOI: 10.1016/j.msec.2020.111668] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 10/07/2020] [Accepted: 10/20/2020] [Indexed: 12/22/2022]
Abstract
This paper reports on the role of phosphate-based glass (PBG) microspheres and their physicochemical properties including in vitro biological response to human mesenchymal stem cells (hMSCs). Solid and porous microspheres were prepared via a flame spheroidisation process. The Mg content in the PBG formulations explored was reduced from 24 to 2 mol% with a subsequent increase in Ca content. A small quantity of TiO2 (1 mol%) was added to the lower Mg-content glass (2 mol%) to avoid crystallisation. Morphological and physical characterisation of porous microspheres revealed interconnected porosity (up to 76 ± 5 %), average external pore sizes of 55 ± 5 μm with surface areas ranging from 0.38 to 0.43 m2 g-1. Degradation and ion release studies conducted compared the solid (non-porous) and porous microspheres and revealed 1.5 to 2.5 times higher degradation rate for porous microspheres. Also, in vitro bioactivity studies using simulated body fluid (SBF) revealed Ca/P ratios for porous microspheres of all three glass formulations were between 0.75 and 0.92 which were within the range suggested for precipitated amorphous calcium phosphate. Direct cell seeding and indirect cell culture studies (via incubation with microsphere degradation products) revealed hMSCs were able to grow and undergo osteogenic differentiation in vitro, confirming cytocompatibility of the formulations tested. However, the higher Mg content (24 mol%) porous microsphere showed the most potent osteogenic response and is therefore considered as a promising candidate for bone repair applications.
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Ojha N, Szczodra A, Boetti NG, Massera J, Petit L. Nucleation and growth behavior of Er 3+ doped oxyfluorophosphate glasses. RSC Adv 2020; 10:25703-25716. [PMID: 35518613 PMCID: PMC9055356 DOI: 10.1039/d0ra04681g] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 07/01/2020] [Indexed: 11/21/2022] Open
Abstract
The nucleation and growth behavior of glasses with the composition (75 NaPO3-25 CaF2)100-x -(TiO2/ZnO/MgO) x , with x = 0 and x = 1.5 (in mol%) is investigated. The glasses possess similar activation energy for crystallization and Johnson-Mehl-Avrami exponent, with value 2 confirming bulk crystallization of crystals with needle like shape. The Ti and Mg glasses exhibit broader nucleation curve and higher T n max than the x = 0 and Zn glasses due to their stronger field strength. The crystal growth rates were determined and validated using SEM. Finally, we showed that the nucleation and growth of glasses can be controlled due to the large difference between onset of crystallization and maximum nucleation temperature which is crucial when preparing novel transparent glass-ceramics.
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Affiliation(s)
- N Ojha
- Photonics Laboratory, Tampere University Korkeakoulunkatu 3 FI-33720 Tampere Finland
| | - A Szczodra
- Photonics Laboratory, Tampere University Korkeakoulunkatu 3 FI-33720 Tampere Finland
| | - N G Boetti
- Fondazione LINKS - Leading Innovation & Knowledge for Society Via P. C. Boggio 61 10138 Torino Italy
| | - J Massera
- Faculty of Medicine and Health Technology, Tampere University Korkeakoulunkatu 3 FI-33720 Tampere Finland
| | - L Petit
- Photonics Laboratory, Tampere University Korkeakoulunkatu 3 FI-33720 Tampere Finland
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Ren K, Xu X, Yao Z, Chen X, Hu T, Li P, Fan X, Du J, Qiao X, Qian G. Temperature dependent molecular fluorescence of [Ag m] n+ quantum clusters stabilized by phosphate glass networks. Phys Chem Chem Phys 2020; 22:21307-21316. [PMID: 32935686 DOI: 10.1039/d0cp03828h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Molecule like silver quantum clusters ([Agm]n+ QCs) exhibit an ultrasmall size confinement resulting in efficient broadband fluorescence. However, free [Agm]n+ QCs are also chemically active, so their stabilization is required for practical applications. We report in this work a phosphate oxyfluoride glass network enabled stabilization strategy of [Agm]n+ QCs. A series of silver-doped P2O5-ZnF2-xAg glasses were prepared by a conventional melt-and-quench method. The NMR and XPS results reveal that two types of [P(O,F)4] tetrahedrons (Q1, Q2) form chain structures and Zn(iv) connects [P(O,F)4] chains into a 3-dimension network in the glasses. The frameworks with limited void spaces were designed to restrict the polymerization degree, m, of [Agm]n+ QCs; the negatively charged tetrahedrons were designed to restrict the charge, n, of [Agm]n+ QCs. Through optical and mass spectroscopy studies, silver quantum clusters, [Ag2]2+ and [Ag4]2+, were identified to be charge compensated by [ZnO4] tetrahedrons and surrounded with [P(O,F)4] complex anions. The fluorescence thus gives high quantum efficiencies of 55.2% and 83.4%, for P2O5-ZnF2-xAg glass stabilized [Ag2]2+ and [Ag4]2+ QCs, respectively. This further reveals that the peak fixed fluorescence of [Ag2]2+ and [Ag4]2+ can be described by molecular fluorescence mechanisms. These are parity-allowed singlet-singlet transitions (S1 → S0), parity-forbidden triplet-singlet transitions (T1 → S0) and intersystem crossings between singlets (S1) and triplets (T1). The phonon coupled intersystem crossing between singlets (S1) and triplets (T1) determines the phosphate stabilized [Ag4]2+ QCs to exhibit a series of temperature dependent fluorescence behaviors. These include fluorescence intensity (at 50-200 K), intensity ratio (FIR) (at 50-200 K), peak shift (at 100-300 K) and lifetime (at 300-450 K) with maximum sensitivities of 1.27% K-1, 0.94% K-1, 0.29% K-1 and 0.41% K-1, respectively. Therefore, phosphate stabilized [Ag4]2+ QCs can be applied as temperature sensing probes, especially at low temperatures (10-300 K) and for color-based visualized temperature sensors.
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Affiliation(s)
- Kai Ren
- State Key Laboratory of Silicon Materials & School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China.
| | - Xiuxia Xu
- State Key Laboratory of Silicon Materials & School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China.
| | - Zeyu Yao
- State Key Laboratory of Silicon Materials & School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China.
| | - Xiaotong Chen
- State Key Laboratory of Silicon Materials & School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China.
| | - Tian Hu
- State Key Laboratory of Silicon Materials & School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China.
| | - Pengcheng Li
- State Key Laboratory of Silicon Materials & School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China.
| | - Xianping Fan
- State Key Laboratory of Silicon Materials & School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China.
| | - Jincheng Du
- Department of Materials Science and Engineering, University of North Texas, Denton, Texas 76203-5017, USA
| | - Xvsheng Qiao
- State Key Laboratory of Silicon Materials & School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China.
| | - Guodong Qian
- State Key Laboratory of Silicon Materials & School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China.
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