Synthesis and characterization of phosphate glass microspheres for radiotherapy applications

Abstract

Glass microspheres containing radioisotopes 90Y or 32P can be used for cancer radiotherapy. 90Y and 32P emit β - particles with short penetration range of about 2.5 mm in living tissue with the half-life of respectively 2.7 days and 14.3 days. Glass microspheres containing such radioisotopes with suitable activity can be easily introduced in specific human organs as liver, stomach, pancreas, and uterus to kill cancer cells, reducing significantly damages to other health tissues allowing a major therapeutic effect. The use of Y2O3-Al2O3-SiO2 glass microspheres for cancer therapy is an efficient alternative compared to conventional chemotherapy treatments. However, the activity of the glass microspheres with 90Y is relatively low, due to the limitation of content of Y2O3 to only 17 mol %, and short half-life, in a way that 90Y may decay substantially even before the treatment. A potential alternative is to produce microspheres with high content of 31P that could be transmuted to 32P with higher activity and longer half-life than 90Y. In the present work phosphate glass microspheres were produced with different compositions and particle size distribution in the range of 20 µm to 30 µm by using two different thermal processes to spherodize glass particles originally with irregular shapes. Samples were characterized by Differential Thermal Analysis, X-rays diffraction, and Energy Dispersive X-rays Fluorescence Spectroscopy. The glass dissolution rate in water was determined at 90 oC, and in Simulated Body Fluid (SBF) at 37oC. Glasses with dissolution rates close to 10-5 g/(cm2 .d) were obtained, which make them suitable for the present application. Scanning Electron Microscopy was used to evaluate the shape of the microspheres before and after the dissolution tests. The cytotoxicity tests showed that these microspheres can be used for biological applications.