The researchers have developed more than 10 kinds of nanocapsules (inner diameter of 5 to 40 nm) that can stably contain middle molecules and macromolecules such as peptides and proteins.

Structure of nanocapsules with different inner diameter sizes (left) and transmission electron microscope images (right) The black parts on the right show the space inside the capsules.

Nanocapsules can easily be synthesized from just amino acids, sugars, and fatty acids, and their inner diameter size can be controlled by the size of the outer amino acids. The nanocapsules can be mass produced with far fewer steps than conventional nanocapsule manufacturing methods. In addition, it is possible to change the charge in the inner space by changing the pH of the aqueous solution to control the encapsulation and release of compounds. Aggregation and association of a compound are suppressed by encapsulating the compound in nanocapsules with an inner diameter size suitable for the size of the compound, so the structure and function of the compound can be stabilized.

There is demand for technology to stably protect, store, and deliver the active ingredients of medicines and functional cosmetics, such as by encapsulating them in capsules. However, while nanocapsules such as liposomes that have been put to practical use show excellent storage and delivery functionality for low-molecular-weight molecules, it proved difficult to efficiently encapsulate middle molecules and macromolecules in the nanocapsules, as the molecules were adsorbed to the surface of the nanocapsules.

The researchers will collaborate with companies to continue verification of encapsulation and stabilization of industrial enzymes and antibody pharmaceuticals.