At the time of 2019, 730.000 cochlear implants (CI) have been registered showing that the electrical stimulation electrode is the most important prosthesis to give deaf people a new sense of hearing. The biocompatibility and biointegrability of CI are steadily improved, nevertheless, cases where the implant has to be removed, cannot be canceled out. Reasons for removal can be an untreatable infection, a defective device, or even the improvement of technology. When removing the implant, the ongrown tissue represents a problem, by not only causing trauma for the patient but also making reimplantation more difficult. Further, the possibility of remaining electrodes in the cochlea makes a reimplanted CI less efficient. For that reason, we are developing a new material concept that employs light-degradable periodic mesoporous organosilica (ld-PMOs) as filler particles in silicone.
Within this concept, the silicone of the cochlea implant is strengthened by nanoporous filler nanoparticles. When implant removal becomes a treatment option, the ld-PMO or ld-MOFs are irradiated with UV to induce the degradation of the particles. Thus, the strengthening effects disappear. To achieve the light-degradable properties, both materials are constructed with respective linker molecules containing a 2-nitrobenzyl group which is cleaved upon irradiation with UV light.