Tumor accumulation of ε-poly-lysines-based polyamines conjugated with boron clusters.

Boron Neutron Capture Therapy (BNCT) is one of the potent cancer radiotherapies using nuclear reaction between (10)B atoms and the neutron. Whether BNCT will succeed or not depends on tumor selective delivery of (10)B compounds. ε-Poly-L-lysine is a naturally occurring polyamine characterized by the peptide linkages between the carboxyl and ε-amino groups of L-lysine. Because of high safety ε-PLL is applied practically as a food additive due to its strong antimicrobial activity. In this study, we focus on a development of a novel polymeric delivery system for BNCT using biodegradable ε-PLL conjugated with (10)B-containing clusters (BSH). This polymeric boron carrier will be expected to deliver safely and efficiently into tumor tissues based on Enhanced Permeability and Retention (EPR) effect.