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Detailed Program
Paper Number : BI-O06
Time Frame : 15:25~15:37
Presentation Date : Thurse day, 27, November
Session Name : Biomaterials
Session Chair 1# : H. S. Yoon
Session Chair 2# : K. Uetsuki
Effect of Ag2O substitution on solubility and structure of CaO-P2O5-Nb2O5 glasses
Sungho LEE
Nagoya Institute of Technology
Infrequently biomaterial-centered infection occurred and some of case led to revision surgery. Antibiotics are one of method for prophylaxis of infection, but they show low efficacy to adherent bacteria on biomaterials. To increase efficacy of infection prophylaxis around biomaterial surface, antibacterial biomaterials is important. Silver ion is representative antibacterial species and shows antibacterial activity in low concentration. Niobium-containing phosphate invert glasses were developed in our group. They compose Nb-O-P bonds in glass network; it indicates excellent chemical durability and glassification. ALP activity and calcification enhanced due to Nb5+ ion dissolved from the glasses [1]. Purpose in this work is to evaluate effect of Ag2O substitution on solubility and structure of niobium-containing phosphate invert glasses. Silver/Niobium-containing glasses expect to enhance bone-forming ability and antibacterial activity due to dissolved ions.
Niobium-containing phosphate invert glasses substituted with silver oxide or sodium oxide were prepared by melt-quenching method (1500 oC, 30 min, composition: 60CaO•30P2O5•(10-x)Nb2O5•xAg2O (mol%, x = 0 ~ 5, denoted by xAg), 60CaO•30P2O5•5Nb2O5•5Na2O (mol%, denoted by 5Na)). The samples structures were evaluated by FT-IR and 31P MAS-NMR and solubility were evaluated by ICP-AES (Tris buffer solution (37 oC), 1 ~ 7 days).
FT-IR spectra of the 5Ag and 5Na glasses show no significant differences. This means silver in the glass acts as a network modifier like a sodium. From the 31P MAS-NMR spectra, orthophosphate (Q0) ratio increased (43% to 46%) and pyrophosphate (Q1) ratio decreased (57% to 54%) linearly with increasing Ag2O substitution (1 to 5 mol%). Q0/Q1 ratio of 5Ag and 5Na shows no significant difference (0.85 and 0.88). This means silver in the glasses break the phosphate chains, which is a similar role as sodium. M. Bellantone et al. reported 1 ~ 10 mM of Ag+ ion shows antibacterial activity [2]. Silver ion dissolution amounts of 1Ag indicate 3 ~ 11 mM, which expected to show antibacterial activity.
Ag2O substituted niobium-containing phosphate invert glasses were successfully prepared. Silver in glasses acts as a network modifier, which break the phosphate chains as similar as sodium. 1Ag glass is expected to show antibacterial activity.


References:

[1] A. Obata, Y. Takahashi, T. Miyajima, K. Ueda, T. Narushima, T. Kasuga, ACS Appl. Mater. Interfaces 4 (2012) 5684.
[2] M. Bellantone, H.D. Williams, L.L. Hench, Antimicrob. Agents Chemother. 46 (2002) 1940.
Acknowledgements :