Frontispiece: Designed Boron-Rich Polymeric Nanoparticles Based on Nano-ion Pairing for Boron Delivery Keywords: boron neutron capture therapy; boron cluster compounds; nano-ions; polymer nanoparticles; self-assembly EN boron neutron capture therapy boron cluster compounds nano-ions polymer nanoparticles self-assembly 1 1 1 11/16/20 20201111 NES 201111 B Boron-rich nanoparticles b (boron content ca. 15-20 wt%) of designed size and shape were prepared and studied as promising boron-delivery agents in nanomedicine. Boron neutron capture therapy, boron cluster compounds, nano-ions, polymer nanoparticles, self-assembly.