Mucus Magic: TUM Researchers Develop Mucin-Based Coatings for Medical Applications
The natural lubricant made of mucous molecules – mucins – found in our bodies is more than just a mechanical protective layer, it also wards off bacteria and viruses. Oliver Lieleg, Professor of Biopolymer Materials at TUM, and his team develop mucin-based materials for medical applications. Here is a look at some of their selected projects.
Mucus for dry eyes
The team developed a coating for contact lenses that improves the interaction of the lenses with water. It reduces friction between the lens and the eye, thus helping to prevent damage to the cornea. Andreas Heddergott / TUM
The team developed a coating for contact lenses that improves the interaction of the lenses with water. It reduces friction between the lens and the eye, thus helping to prevent damage to the cornea.
What it’s about: The team developed a coating for contact lenses that reduces friction between the lens and the eye, thus helping to prevent damage to the cornea.
Why it’s important: There are approximately four million contact lens wearers in Germany. However, for patients with dry eyes suffering from an insufficient natural protective lubricant film between the eye and the lens, wearing contact lenses can be uncomfortable and may even result in corneal damage. Lieleg’s team responded by developing a coating from mucins which is only a few micrometers thick, transparent, and protects the eye from damage.
How it works: The team used specially purified mucins to coat both hard and soft contact lenses. The researchers tested the coated lenses in the lab on pig eyes. The coating improved the interaction of the lenses with water; and the researchers were able to show under the microscope that the porcine cornea remained intact even after stress tests with rubbing. The lenses stayed transparent and the mucin layer even made them resistant to the fat deposits that occur naturally in the tear fluid – otherwise, such deposits can result in clouding of the contact lenses after extended periods of use.
Publications: https://pubmed.ncbi.nlm.nih.gov/36521413/; https://pubs.acs.org/doi/10.1021/acsami.0c06847
Preventing respiratory tract damage
The researchers are developing coatings for intubation tubes to prevent tissue damage. Here they are testing the coating in the laboratory.Andreas Heddergott / TUM
The researchers are developing coatings for intubation tubes to prevent tissue damage. Here they are testing the coating in the laboratory.
What it’s about: The researchers have developed a mucin coating for endotracheal tubes to prevent tissue damage during in- and extubation.
Why it’s important: Artificial respiration can save lives, but endotracheal tubes can also cause complications resulting from tissue damage or infection. An appropriate coating could reduce the risks involved in intubation.
How it works: The team used the same method to generate four different coatings on endotracheal tubes and compared the results. All the options tested (based on mucin, hyaluronic acid, polyethylene glycol, and lysine-dextran) reduced friction on tracheal tissue and prevented tissue damage. However, the mucin-based coating was much more efficient in preventing deposits of cells, bacteria, or fats
Investigating the body’s mucus layers
Researchers examine mucin interfaces with microfluidic chips. In this setup, green fluorescent nanoparticles are penetrating the mucin gel.
What it’s about: The researchers use a model system to investigate what happens in the body’s mucus layers when they come into contact with nano- or microparticles. For example, they tested if respirable dust has a negative impact on the protective effect of the mucus layer. They are also developing inhalable microparticle systems that release miniscule drug carriers specifically onto the mucus layer of the respiratory tract.
Why it’s important: When we inhale tiny dust particles, pathogens or pollutants, the mucus layer in our respiratory tracts captures some of them. Thus, it is important for prevention, diagnosis, and medical applications to understand how harmful particles interact with the mucus layer. Moreover, the researchers are utilizing the moist properties of the mucus layer to package medications in such a way that they are released precisely at the mucus layer.
How it works: The researchers work with microfluidic chips, i.e., a model system in which they can study a gel made of mucins. This allows them to investigate the interfaces between the mucus layer and fluids, as in the intestines, and between the mucus layer and the air, as in the bronchia.
They used the model system to investigate what happens when the mucus layer is contaminated by respirable dust. “When the mucin layer contains respirable dust particles, its barrier effect is impaired. The tiny particles occupy molecular binding sites in the mucin gel which are intended to capture other molecules,” says Oliver Lieleg.
In their latest project, the TUM researchers have been working together with scientists from LMU to develop tiny packagings for pharmaceuticals, which can be inhaled. Here they have designed small spheres (microparticles) which they can use to encapsulate even smaller drug carriers (nanoparticles). The charge and the structure of the microparticles determines their docking and decomposition process upon contact with the moist mucus. Among the various materials tested, the most successful one was the lysine packaging, since this positively charged amino acid performed best in binding to the negatively charged mucus.