Boron‐Based Hybrid Nanostructures: Novel Applications of Modern Materials

Abstract

This chapter reviews some of the recent developments in the use of nanoparticles as adjuncts to boron containing compounds in boron neutron capture therapy (BNCT) or, in the cases of boron nanotubes (BNTs) and boron nitride nanotubes (BNNTs), the boron agent itself. BNCT is a bimodal therapy in which boron-10 is preferentially localized in a cancer cell and then irradiated with low energy (thermal) neutrons. The B absorbs the neutron giving an excited B, which immediately undergoes a fission reaction yielding a high energy alpha (a) particle and recoil Li particle, plus a low energy gamma (g) ray. The therapeutic advantage of this method is that the two charged particles deposit their energy through a distance of 9mm, which is of the order of a cell dimension. Therefore, damage will be confined to the cell in which fission reaction occurs, sparing neighboring cell that are free of boron. The chemical challenge in BNCT is constructing molecules or delivery agents that preferentially target neoplastic cells. Although this requirement is common to all chemotherapy, the required amount of B needed for effective BNCT (10–35 mg/g tumor cell) is much higher than that required in other forms of chemotherapy. A number of macromolecular entities and new delivery methods used in BNCTare discussed. They include liposomes, dendrimers, carbon nanotubes (CNTs), BNTs and BNNTs, and magnetic nanoparticles. References are given to some of the latest applications.