As some compounds are effective for the treatment only when they are in cancer cells, delivering the bioactive compounds to cancer cells efficiently in vivo is an important step for the treatment. The cancer cells can be eradicated by the secondary killing irradiations which are generated by boron neutron capture therapy (BNCT), a therapeutic method using thermal neutron irradiation to react with 10B-compounds that exist in cancer cells. The effective length of the secondary killing irradiations could be the same as the cellular diameter, and cellular uptake of 10B-compounds is required for the efficient tumor BNCT.
However, the therapeutic efficacy of 10B-compound of sodium borocaptate (BSH) which is clinically approved is limited due to the low cellular uptake by cancer cells. Therefore, researchers self-assembled the BSH-conjugated block copolymers and developed the multifunctional polymeric micelles with endosome escape and redox-responsive functions for enhanced delivery of BSH into cancer cells.
The hydrodynamic diameter of the BSH-loaded polymeric micelles (BSH/micelle) is around 50nm, with monodispersed size distribution. The BSH/micelles are stable in normal physiological environment, and BSH can be released when responding to high level of redox potential in cancer cells. In addition, BSH/micelles are capable of promoting the intracellular BSH delivery by the endosome escape function of micelles to further improve the tumor treatment efficacy by BNCT.