Time-release curve of 32P-CP particles from 32P-CP-PLGA seeds and ultrastructure changes of 32P-CP-PLGA seeds by SEM in vitro. (a) In vitro releasing experiment was performed by incubating the 32P-CP-PLGA seeds in 6.0 ml of PBS at 37°C for 90 day(s). (b) SEM was performed before day 0 (left: surface; right: cross-section) and 8, 16, 32, and 64 day(s) after intratumoural implantation. 32P-CP particles, indicated with white arrow, encapsulated in the seeds and released with the structure erosion of carrier PLGA polymer. (c) The ultrastructure of 32P-CP particles released from the PLGA in vitro (50 nm).