[Development of Synthetic Polymer-based Nanomachine for Cancer Diagnosis and Therapy]

This paper introduces the research of nanomachines utilizing boron chemistry. Boron neutron capture therapy (BNCT) has beeing attracting increasing attention as a minimally invasive cancer treatment, and p-boronophenylalanine (BPA) has been approved as a potent BNCT drug. However, intratumoral retention of BPA remains to be improved. Recently, we have developed a BPA delivery system [poly vinyl alcohol (PVA)-BPA] utilizing PVA. PVA-BPA altered the uptake pathway of BPA by cancer cells and significantly improved the intracellular retention in cancer cells. in the in vivo experiments, PVA-BPA showed improved tumor accumulation and a remarkable tumor growth inhibition upon thermal neutron irradiation. On the other hand, a useful delivery system of bioactive proteins has been strongly demanded. In this study, we have developed the ternary complex micelles for the protein delivery utilizing tannic acid (TA) and block copolymer containing a boronic acid group. The ternary micelles improved the blood retention and tumor accumulation of the loaded proteins, and realized a tumor tissue-selective enzymatic reaction in the enzyme delivery.