Multifunctional mucus and polydopamine spheres enable targeted, adjustable drug delivery

Researchers from the Munich Technical University (TUM) have developed hollow mucus and polydopamine microspheres using a simple and scalable production method. These tiny spheres are intended to serve as packaging for therapeutic substances, for example in the joints or on the oral mucosa. Their properties and mode of action can be adjusted by the choice of materials and are also influenced by the surrounding biological environment.

Oliver Lieleg, professor of biopolymer equipment, and his team exploit the various properties of mucine – the key components of natural liners such as those found in the oral mucosa or the stomach – to create technological solutions in biomedicine.

Their latest development is a multifunctional microsphere in mucin and polydopamine. The microsphere is designed to allow a delayed release of molecular cargoes on the sites of the body where the adhesion of these drug carriers is otherwise difficult, as on the oral mucosa or on cartilage.

The work is published in the journal Little.

This good grip has been tested on animal tissues and is caused by the strong adhesive properties of polydopamine. At the same time, mucin adds precious characteristics: it makes the spheres more adjustable concerning their size of pores and allows them to act as a natural lubricant.

“In the joints, for example, this could help prevent damage created by joint movements. It can also provide a protective coating on wounded tissues in the mouth, another advantage in addition to the function of microspheres as an agents of medication administration,” said Di Fan, the first author of the study.

Hollow spheres are easy to produce, load and seal

The production of new hollow spheres begins with an established process: a nucleus is first coated with desired materials and then removed, leaving behind a hollow structure. With other materials, the spheres sometimes shrink or even collapse when the nucleus is dissolved.

On the other hand, microspheres made from polydopamine and mucin remain structurally stable. Their surface is porous. This allows you to add the cargo after the production of microspheres and to enter the spheres by diffusion, as indicated with model cargo molecules in the study.

The next step is new and crucial: the researchers apply an additional component to the surface, which partially seals the shells of the spheres. This helps keep more cargo inside the sphere after loading while ensuring that it is gradually released over time. A range of materials can be used for this locking stage, but the approach has proven to be particularly effective with silver ions – silver atoms loaded with space.

Protect or destroy: how material selection and the biological framework determine the effect

The choice of equipment for sealing is also crucial for the effects of microspheres. “If silver ions are used, microspheres help kill cells. This could be particularly useful in the treatment of tumors,” said Di Fan, which has demonstrated different effects in cell cultures.

On the other hand, without silver ions, the anti-inflammatory properties of polydopamine take effect and rather protect the cells of chemical stress. This is particularly useful in tissues with inflammation, with potential applications in cases such as osteoarthritis or chronic wounds. The type of sealing agent used and the biological framework influence the speed with which the cargo is released.

“With the hollow microsphere system, we have created an easy -to -produce, scalable and adaptable versatile system for the release of versatile drugs,” explains the Lieleg project manager.

“Our chosen combination of mucin and polydopamine brings together many advantages offered by biomolecules which go beyond the typical tasks of a system of liberation of conventional drugs; for example, it can protect or eliminate cells – relax on the envisaged application.”