So-called hydrogels come across us in everyday life, as i.e. in form of contact lenses or wound healing products. Hydrogels are cross-linked polymer networks, which are highly swollen in solvents like water. If hydrogels have a small, colloidal size, they are called microgels. These are particularly popular in medicine as “drug delivery systems”. Drug delivery systems require two fundamental properties: First the ability to carry the drug and second to release it. If these carriers are sensitive to external stimuli, such as temperature, they are candidates for targeted delivery of drugs. Microgels made from N-Isopropylacrylamide (PNIPAM microgels) undergo a reversible volume phase transition (shrinking and swelling), when they are heated above and cooled below a certain temperature. Combining PNIPAM microgels with adhesive “gluing” properties of maritime systems, such as mussels, is therefore highly interesting in science.
The research team around Prof. Regine v. Klitzing and her PhD candidate Sandra Forg (working group “Soft Matter at Interfaces” at the TU Darmstadt) was able to incorporate a certain component of the mussel’s byssus (DMA) in PNIPAM microgels. A controlled incorporation of DMA is of vital interest for further application. Therefore, reaction kinetics during the microgel synsthesis were investigated. The team could show that a too early injection of DMA stopped the synthesis, while a later injection slowed down the incorporation, but lead to the desired outcome. First adhesion experiments showed that the incorporation of DMA increases the adhesive properties in contrast to conventional PNIPAM microgels.