A Polymeric Bowl for Multi-Agent Delivery

This paper describes a simple system for multi-agent delivery. The system consists of a biodegradable polymer particle with a hollow interior, together with a hole on its surface that can be completely or partially sealed via thermal annealing. A hydrophobic dye, Nile-red, entrapped within the shell of hollow particles presents a sustained release behavior while methylene blue, a hydrophilic model agent, encapsulated in the hollow interior shows a fast release manner. The release profiles of the probes can be further independently controlled by encapsulating methylene blue-loaded polymer nanoparticles, instead of free dye, in the hollow particle with a small hole on its surface. A simple dual-agent delivery system, consisting of a hollow particle entrapping Nile-red in its shell and methylene blue-loaded nanoparticles, can deliver the agents in a temporally distinct manner. A small-sized hole on the surface of the hollow particle prevents the undesired escape of the encapsulated nanoparticles from the hollow interiors, thereby keeping the independent release of methylene blue.