Drug Encapsulation with >2,000-Fold Concentration —Inorganic Nanoparticle Capsules as a New Drug Delivery Carrier —

A joint research team led by Prof. Hideyuki Mitomo and Prof. Kuniharu Ijiro at Research Institute of Electronic Science (RIES), Hokkaido University with Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University (Dr. Takehiro Yachi) and RIKEN Synchrotron Radiation Research Center (Group Director Koji Yonekura, also serving as Professor at IMRAM, Tohoku University) have developed a new technique for fabricating nano-sized hollow capsule structures composed of functional inorganic nanoparticles.

In this study, hollow capsules with a diameter of 100 nm were constructed via liquid-liquid phase separation between a water-miscible organic solvent and a citric acid aqueous solution, accompanied by the accumulation of inorganic nanoparticles at the interface. Functional nanoparticles, such as light-responsive gold nanoparticles and magnetic field-responsive iron oxide nanoparticles, were used as building blocks, enabling precise control of drug release in response to external stimuli. The research team also discovered a remarkable phenomenon: the encapsulated substances were concentrated more than 2,000-fold during the capsule formation process. These findings may open new avenues for the development of inorganic nanocapsule-based drug delivery systems capable of targeted, stimulus-responsive drug release, contributing to safer and more effective medical treatments with minimized side effects.

The research has been published in Small on May 7, 2025. It has also been selected for the Inside Cover of the published issue.