Glass formation and chemical durability of dysprosium lithium borate glasses intended for in vivo radiation synovectomy

Abstract

The glass formation and structure/property relationships for Dy2O3-Li2O-B2O3 glasses were investigated. Such glasses are currently being considered for in vivo radiation delivery vehicles. Chemical dissolution tests were conducted in simulated synovial fluid (pH 7.4, at 37 °C, for 11 d) to evaluate the release of dysprosium from selected glasses. The chemical durability, Tg, nD and density increased as either the Li2O or Dy2O3 content in a glass was increased. Such property trends are attributed to increased cross-linking within the glass structure as BO3 triangles are converted to BO4 tetrahedra. Αproposed structural model assumes dysprosium is incorporated into the glass with a coordination number of eight and is surrounded by four BO4 tetrahedra. Glasses containing ≥ 1.0 mol% Dy2O3 released less than 0.1 % of their initial dysprosium content after being immersed in simulated synovial fluid for 11 d at 37 °C. These glasses are considered safe for in vivo radiation delivery from the standpoint of radiation release, since dysprosium will be the only radioisotope in the glass during treatment.