Development of a thermosensitive hydrogel system for local delivery of 188Re colloid drugs

A novel internal radiation therapy (IRT) mode intended for controlled local delivery of 188Re-Tin colloid was developed by using chitosan-based thermosensitive hydrogel. Chitosan (C) and β-glycerophosphate (β-GP) were used to prepare the thermosensitive hydrogel (C/GP). The prepared C/GP hydrogel featured a rapid sol-gel transition within 5 min after it was brought into an environment of 37 deg. C. 188Re-Tin colloid was prepared with labeling efficiency of 93.9±0.6%, and could be increased to more than 98% following centrifugation. The average particle size of 188Re-Tin colloid was 12.1±1.2 μm, with only 7.2±1.5% less than 1 μm. Scintigraphic study showed that 188Re-Tin colloid contained in the C/GP hydrogel was localized (>91%) around the injection site for up to 48 h post injection, verifying the intended function of the IRT design. The developed novel form of IRT in this study could be an effective treatment mode for regional radiotherapy.