More than 700 000 cochlea implants (CIs) were registered in 2019 all over the world. Despite these successes, an explantation or exchange may still become neces-sary. Possible reasons for this can be persisting infections, a defective device or an available more advanced technology. However, since after implantation often con-nective tissue is formed on the silicone surface, removal of the implant often involves tissue damage for the patient, which can even lead to trauma. This makes the inte-gration of the new implant more difficult.

For this project, different core-shell nanoparticles (CSNP) have been developed. Su-perparamagnetic nanoparticles in the size range of 10-20 nm (magnetite) build the core. A biostable shell around these, makes them accessible for modifications and stable in body fluids. Therefore, a dense silica-shell around the magnetite core is de-posed and within a further reaction step an additional organosilica shell is formed. As other suitable shell materials zeosiles or titanium dioxide are possible. Through sub-sequent modification reactions with silanes the interactions with tissue or polymer can be adjusted.

The developed CSNP with superparamagnetic properties will be used for two differ-ent material concepts aiming the stimulus-inducible modification of the composite’s rheological properties. In the first concept, two surfaces of hydrogels or even soft tissue like e. g. liver can be glued together by placing the CSNP in-between. Super-paramagnetic CNSP, brought into an alternating magnetic field, can develop thermal energy to weaken the attractive forces. Therefore, an easier separation of the hy-drogels is made accessible.

The second concept uses the CSNP as crosslinkers in a polymer. In this way, the CSNPs are covalently and thermoreversibly attached to the polymer. By applying an alternating magnetic field, the CNSP heat up, whereby the bond between the poly-mer and the CSNP can break as a result of the retro-Diels-Alder reaction, which then softens the polymer.