Accelerated Conversion of Silicate Bioactive Glass (13-93) to Hydroxyapatite in Aqueous Phosphate Solution Containing Polyanions


The influence of alginic acid, an anionic polysaccharide, on the conversion of 13-93 bioactive glass to hydroxyapatite (HA) in aqueous phosphate solution was investigated. Disks of 13-93 glass were immersed in phosphate-buffered saline (PBS) containing 0-1 weight percent (wt%) alginic acid. HA was detected on the glass surface by scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy after 2 weeks in PBS containing 0.5 wt% alginic acid, compared with 6 weeks in PBS without alginic acid. In the presence of alginic acid (0.5 wt%), the growth of the HA layer on the glass increased almost linearly with time, at a rate that was approximately six times faster than that for the system without alginic acid. The thickness of the HA layer increased with the concentration of alginic acid (0-1 wt%). Chelation of the electron-donating moieties of alginic acid polymer, such as carboxyls and hydroxyls, to the leached cations from the bioactive glass, in particular calcium ions, is suggested as a mechanism for the enhanced corrosion of the glass and, hence, the enhanced conversion to HA. The use of natural or synthetic polyelectrolytes could provide a method for manipulating the conversion rate of bioactive glass to HA.


Materials Science and Engineering

Keywords and Phrases

Bioactive Glass; Biological Materials; Acids; Apatite; Calcium; Fourier transform infared spectroscopy; Hydroxyapatite; Hydroxylation; Leaching; Scanning electron microscopy; Silicates

International Standard Serial Number (ISSN)

0002-7820; 1551-2916

Document Type

Article - Journal

Document Version


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© 2009 American Ceramic Society, All rights reserved.

Publication Date

01 Dec 2009