P-12 The influence of test conditions on zinc release from the 45S5 bioactive glass

Topic: Biomaterials

A. Švančárková^1,2*, D. Galusková¹, H. Kaňková¹, and D. Galusek¹

¹ FunGlass, Alexander Dubček University of Trenčín, Študentská 2, 911 50 Trenčín, Slovakia

² Faculty of chemical and food technology STU, Radlinského 9, 812 37 Bratislava

^* E-mail: anna.svancarkova@tnuni.sk

Keywords: bioactive glass, dissolution, test condition, 45S5+Zn, simulated body fluid

Abstract: The 45S5 Bioglass (BG) (Hench, 1971) is a bioactive material that stimulates bone repair. In an aqueous environment, this material undergoes a series of reactions to create a surface layer of hydroxyapatite (HA) and hydroxy-carbonate apatite (Filgueiras, 1993). The incorporation of ions in BG can enhance the therapeutic effects of the material. Zinc is a co-factor for over 400 enzymes, a key mediator of bone matrix mineralization and plays a significant role in bone formation (Lakhkar N.J., 2013). Additionally, zinc is well known for its antibacterial effects. In vitro bioactivity experiments are normally conducted under static conditions, which could lead to local ion saturation and increased pH values (Zhang, 2008). Dynamic dissolution configuration is a convenient alternative to analyze the leaching behavior of bioactive glasses under a continuous flow of a suitable solution simulating conditions in a human body. In this study, the effect of different test conditions on the leaching behavior of 45S5 BG doped with zinc (4 wt%) was investigated. The static and dynamic regimens of bioactivity testing were compared. In vitro tests were also carried out under static and dynamic conditions in the simulated body fluid (pH 7.4) (SBF) and deionized water (pH 6.5, conductivity 0.14µS/cm). During all tests, the temperature was maintained at 37°C. For static dissolution studies, 35 mg of glass particles were added in 25 mL of SBF. Dynamic dissolution studies were performed with a continuous flow-through cell set-up. The sample cell was filled with 550 mg of glass and SBF solution was flowing through glass particles with a rate of 0.66 ±0.5 ml/min. The solutions were periodically collected for ICP-OES analyses. The release of zinc as a potential antibacterial inhibitor was meeting the limit of quantification in SBF solution during static bioactivity testing. The test revealed a faster dissolution of the material during the dynamic test as well as a detectable amount of zinc released from the glass. The dynamic tests are more suitable to study ion release in an aqueous environment with high ionic strength, where precipitation reactions occur rapidly due to the fast dissolution of a material.

 References

Filgueiras, M. T. (1993). Solution effects on the surface reactions of a bioactive glass. J.Biomed. Mater. Res., 445-453.

Hench, L. S. (1971). Bonding mechanisms at the interface of ceramic prosthetic materials. J.Biomed. Mater. Res.(5), 117-141.

Lakhkar N.J., L. I. (2013). Adv. Drug Delivery Rev., 405-420.

Zhang, D. (2008). In situ pH within particle beds of bioactive glasses. Acta Biomater., 1498-1505.

Acknowledgments

This work is a part of the dissemination activities of project FunGlass. This project has received funding from the European Union´s Horizon 2020 research and innovation programme under grant agreement No 739566. Financial support of this work by the grant VEGA 1/0191/20 is gratefully acknowledged. This presentation was also created in the frame of the project Centre for Functional and Surface Functionalized Glass (CEGLASS), ITMS code is 313011R453, operational program Research and innovation, co-funded from European Regional Development Fund.