Structural characterization of glassy phases in the system Na2O–Ga2O3–P2O5 by MAS-NMR, EXAFS and vibrational spectroscopy. I. Cations coordination

Belkébir, A.; Rocha, João; Esculcas, A.P.; Berthet, P.; Poisson, S.; Gilbert, Bernard; Gabélica, Z.; Llabrès, Gabriel; Wijzen, F.; Rulmont, A.

doi:10.1016/s1386-1425(99)00279-6

Cited by 20 publications

(28 citation statements)

References 15 publications

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“…The FWHM linewidth of this peak is approximately 100 ppm, and for the 5 mol % Ga 2 O 3 sample this width did not appreciably decrease when the field was increased from 14.1 to 18.8 T. A previous 71 Ga MAS NMR study on Ga 2 O 3 -Na 2 O-P 2 O 5 glasses identified a peak at À60 ppm associated with octahedrally coordinated gallium and one at 120 ppm due to tetrahedral gallium. [23] This suggests that the 71 Ga NMR peak observed here arises from octahedrally coordinated gallium. The fact that the linewidth does not appreciably decrease between 14.1 and 18.8 T indicates that chemical shift dispersion is the dominant broadening mechanism at these fields rather than second order quadrupolar broadening.…”

Section: Nmr Analysismentioning

confidence: 62%

“…A one-pulse sequence was used, with a recycle delay of 5 seconds. Certain 23 Na spectra were also recorded at 7.05 T under similar conditions. 31 P MAS NMR experiments were conducted using a 4 mm diameter rotor spinning at 10-12.5 kHz.…”

Section: Methodsmentioning

confidence: 99%

“…Figure 4IV shows the 71 Ga MAS NMR spectra obtained from the 1, 3, and 5 mol % Ga 2 O 3 samples. Figure 4IV(a) is from the 5 mol % Ga 2 O 3 sample at 18.8 T, and Figure 4IV amount of gallium present in the sample, the lower natural abundance of the 71 Ga isotope (39.9 % compared with 100 % for both 23 Na and 31 P), and also the wider lineshape due to second-order quadrupolar broadening. The relatively large linewidth in these spectra meant that the spinning sidebands lay very close to the centre-band, although they are not very clearly visible due to their amplitudes being comparable to that of the noise.…”

Section: Nmr Analysismentioning

confidence: 99%

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Antimicrobial Gallium‐Doped Phosphate‐Based Glasses

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Neel

et al. 2008

Adv Funct Materials

166

130

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Novel quaternary gallium‐doped phosphate‐based glasses (1, 3, and 5 mol % Ga2O3) were synthesized using a conventional melt quenching technique. The bactericidal activities of the glasses were tested against both Gram‐negative (Escherichia coli and Pseudomonas aeruginosa) and Gram‐positive (Staphylococcus aureus, methicillin‐resistant Staphylococcus aureus, and Clostridium difficile) bacteria. Results of the solubility and ion release studies showed that these glass systems are unique for controlled delivery of Ga3+. 71Ga NMR measurements showed that the gallium is mostly octahedrally coordinated by oxygen atoms, whilst FTIR spectroscopy provided evidence for the presence of a small proportion of tetrahedral gallium in the samples with the highest gallium content. FTIR and Raman spectra also afford an insight into the correlation between the structure and the observed dissolution behavior via an understanding of the atomic‐scale network bonding characteristics. The results confirmed that the net bactericidal effect was due to Ga3+, and a concentration as low as 1 mol % Ga2O3 was sufficient to mount a potent antibacterial effect. The dearth of new antibiotics in development makes Ga3+ a potentially promising new therapeutic agent for pathogenic bacteria including MRSA and C. difficile.

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Section: Nmr Analysismentioning

confidence: 62%

Section: Methodsmentioning

confidence: 99%

Section: Nmr Analysismentioning

confidence: 99%

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Antimicrobial Gallium‐Doped Phosphate‐Based Glasses

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Neel

et al. 2008

Adv Funct Materials

166

130

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“…[17] Comparing this result with the few studies of Ga-containing PBG in the literature we find that octahedral coordination with respect to oxygen is typical in glasses with a high P/Ga ratio. [37,38] Hoppe et al [37] studied Ga 2 O 3 -P 2 O 5 melt-quenched glasses with HEXRD and found only GaO 6 octahedra at the metaphosphate composition (P/Ga = 3), whereas at the pyrophosphate composition (P/Ga = 1.5), they found that the majority of Ga 3+ ions occupied tetrahedral sites. Belkébir et al [38] used a combination of Ga K-edge EXAFS and 71 Ga NMR to study Na 2 O-Ga 2 O 3 -P 2 O 5 melt-quenched glasses.…”

Section: Structural Characterisationmentioning

confidence: 99%

“…[37,38] Hoppe et al [37] studied Ga 2 O 3 -P 2 O 5 melt-quenched glasses with HEXRD and found only GaO 6 octahedra at the metaphosphate composition (P/Ga = 3), whereas at the pyrophosphate composition (P/Ga = 1.5), they found that the majority of Ga 3+ ions occupied tetrahedral sites. Belkébir et al [38] used a combination of Ga K-edge EXAFS and 71 Ga NMR to study Na 2 O-Ga 2 O 3 -P 2 O 5 melt-quenched glasses. Their results suggest that, in the ternary system, once the P/Ga gets to 5 or above all the Ga 3+ ions adopt octahedral coordination.…”

Section: Structural Characterisationmentioning

confidence: 99%

Preparation, structural characterisation and antibacterial properties of Ga-doped sol–gel phosphate-based glass

et al. 2009

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A sol-gel preparation of Ga-doped phosphate-based glass with potential application in antimicrobial devices has been developed. Samples of composition (CaO) 0.30 (Na 2 O) 0.20-x (Ga 2 O 3 ) x (P 2 O 5 ) 0.50 where x = 0 and 0.03 were prepared, and the structure and properties of the gallium-doped sample compared with those of the sample containing no gallium. Analysis of the 31 P MAS NMR data demonstrated that addition of gallium to the sol-gel reaction increases the connectivity of the phosphate network at the expense of hydroxyl groups. This premise is supported by the results of the elemental analysis which showed that the gallium-free sample contains significantly more hydrogen and by FTIR spectroscopy, which revealed a higher concentration of OH groups in that sample. Ga K-edge EXAFS and XANES data revealed that the gallium ions are coordinated by six oxygen atoms. In agreement with the X-ray absorption data, the high-energy XRD results also suggest that the Ga 3+ ions are octahedrally coordinated with respect to oxygen. Antimicrobial studies demonstrated that the sample containing Ga 3+ ions had significant activity againstStaphylococcus aureus compared to the control.

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Gallium‐ and Cerium‐Doped Phosphate Glasses with Antibacterial Properties for Medical Applications

et al. 2020

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Novel cerium‐ (Ce) and gallium (Ga)‐doped phosphate glasses (PGs) are successfully obtained by the peroxidation method. The new glasses are characterized using Fourier‐transform infrared spectroscopy (FTIR), Raman spectroscopy, X‐ray diffraction, inductively coupled plasma‐optical emission spectroscopy (ICP‐OES), and pH measurements. A strong correlation between glass properties and their composition is found. The incorporation of Ga/Ce in the glass structure is confirmed by peak shifts in Raman and FTIR spectra. Degradation tests conducted in water confirm the soluble character of the PGs and reveal the influence of Ga and Ce on the degradation rate. Ga‐doped glasses are found to be less soluble than Ce‐doped ones (43%, 33%, 21%, and 16% of dry mass remained after 7 weeks for 7Ga, 5Ga, 5Ce, and 7Ce, respectively). Biological evaluation using ST‐2 cells shows adequate cell response with a cell viability of 80% measured using the indirect contact method depending on the composition. The cell viability decreases with an increase in Ga content and increases with Ce content. The antibacterial character of Ga/Ce‐doped PGs is confirmed by turbidity measurements against Escherichia coli and Staphylococcus carnosus. The novel Ce/Ga‐doped PGs exhibiting antibacterial properties and biocompatibility reported here are interesting for tissue engineering and wound healing applications.

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Structural characterization of glassy phases in the system Na2O–Ga2O3–P2O5 by MAS-NMR, EXAFS and vibrational spectroscopy. I. Cations coordination

Cited by 20 publications

References 15 publications

Antimicrobial Gallium‐Doped Phosphate‐Based Glasses

Antimicrobial Gallium‐Doped Phosphate‐Based Glasses

Preparation, structural characterisation and antibacterial properties of Ga-doped sol–gel phosphate-based glass

Gallium‐ and Cerium‐Doped Phosphate Glasses with Antibacterial Properties for Medical Applications

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