Loaded Layer-by-Layer Capsules

Layer-by-Layer Structured Capsules

The walls of polyelectrolyte capsules are in general semi-permeable i.e. for molecules with a molecular weight less than 10 kDa they are permeable, while for higher molecular weight molecules they are impermeable.

A number of techniques have been developed which allow the loading of polyelectrolyte LbL capsules with proteins, enzymes or DNA/RNA. In addition to loading, the capsules can also be equipped with fluorescent dyes, magnetic charge and various surface functionalities.

Image: Capsules (Ø 8-10 µm) which are filled with a solution of the glycoprotein Concanavalin A-Cy5. The walls of the capsule are impermeable to 100 kDa-sized protein molecules. (Image size 40 µm x 40 µm.)

Some Applications

Macromolecules inside the polyelectrolyte capsule are well protected against any attack by bacteria or enzymes, however, small molecules for reactions or scavenging can still pass through the wall and be immobilised within. Vice versa, the release of molecules from within the capsule is also possible by manipulating the surrounding medium (pH, salt concentration, polarity).