Radiolabeled nanoporous hydroxyapatite microspheres: An advanced material for potential use in radiation synovectomy

Abstract

The design and fabrication of porous and biocompatible inorganic materials having high adsorption capacity for therapeutic radioisotopes can trigger development of ‘next-generation’ radiopharmaceuticals for use in clinical nuclear medicine. In this study, nanoporous hydroxyapaptite (HA) microspheres of 1–10 μm diameter were synthesized by sol-gel technique followed by spray drying. The synthesized microparticles exhibited remarkably high sorption capacity for 90Y (141 ± 5 mg Y/mg) and 166Ho (262 ± 3 mg Ho/mg), which enabled the use of low specific activity radioisotopes produced in medium flux research reactors. Sorption of 90Y and 166Ho in nanoporous HA followed Langmuir-Freundlich adsorption isotherm and pseudo second order kinetics, indicating that the process was chemisorption. A chelator-free radiolabeling technique was developed for loading clinically relevant doses of radioisotopes such as 90Y and 166Ho in the HA matrix for use in treatment of arthritis. As a proof of concept, 90Y labeled formulation was administered in a patient with painful arthritis of knee joint. Selective localization of the radiolabeled agent in the synovial cavity was demonstrated by SPECT/CT imaging which demonstrated its potential for use in radiation synovectomy.