Highly Condensed Boron Cage Cluster Anions in 2D Carrier and Its Enhanced Antitumor Efficiency for Boron Neutron Capture Therapy

An attempt is made to apply layered double hydroxide (LDH) as a boron delivery carrier for boron neutron capture therapy (BNCT), which needs a sufficient amount of boron in tumor cells for its successful administration. To meet this requirement, a nanohybrid (BSH‐LDH), mercaptoundecahydro‐closo‐dodecaborate (BSH) anionic molecules in LDH, is developed as a boron delivery system. The cellular boron content upon permeation of BSH‐LDH nanoparticles (42.4 µg 10B 10−6 cells) in U87 glioblastoma cell line is found to be ≈2000 times larger than the minimum boron requirement (≈0.02 µg 10B 10−6 cells) for BNCT and also orders of magnitude higher than the previous results (0.2–1.5 µg 10B 10−6 cells) by those applied with other targeting strategies, and eventually results in excellent neutron capture efficiency even under such low dose (30 µg 10B mL−1) and weak irradiation (1 × 1012 n cm−2 corresponding to 20 min) condition. According to the biodistribution studies in xenograft mice model, the tumor‐to‐blood ratio of BSH in the BSH‐LDH‐treated‐group is found to be 4.4‐fold higher than that in the intact BSH treated one in 2 h after drug treatment. The present BNCT combined with boron delivery system provides a promising integrative therapeutic platform for cancer treatment. Developing a novel boron neutron capture therapy‐drug delivery system based on the mercaptoundecahydro‐closo‐dodecaborate‐layered double hydroxide nanohybrid system is quite successful, which greatly enhance the boron delivery to cancer cells, and thereby resulting in effective cell destruction even after irradiation of such a low neutron flux (1 × 1012 n cm−2). This result can eventually be very helpful in the radiation administration for cancer patients.