Microceramic stars make skin layers permeable for active ingredients

Researchers at the Swiss Federal Laboratories for Materials Science and Technology Empa have developed nanoceramic microstars that enable the transport of active ingredients into the skin via micro-bursts. In an interview with MEDICA-tradefair.com, Dr. Michael Stuer describes the new development, which is to be used by an industrial partner for the treatment of skin diseases.

Dr. Stuer, how does the technology work?

Dr. Michael Stuer: This project offers an alternative to microneedle patches. These generate small skin lesions as a passageway for active medical ingredients that cannot overcome the skin barrier. The patches do not work well in hard-to-reach areas or on highly curved skin surfaces.

Our microceramic stars are distributed in a gel that can be applied anywhere. The aim is to allow larger areas to be treated ergonomically and to make everyday use easier than with patches.

The stars cause small injuries through friction and thus enable new therapies that use "small interfering RNA (siRNA)". The injuries are only large enough to allow the therapeutically active molecules of the drugs to reach their target and they are closed again within a few hours. No blood vessels are injured in the process. The feeling could be described as that of a very strong peeling. However, people are of course individually sensitive to pain.

Our industrial partner uses this medical device to treat skin diseases such as atopic dermatitis, white spot disease or psoriasis with new therapeutic approaches.

How does the manufacturing process work, what material do you use?

Stuer: The process is a modified slip casting. A powder is worked into a suspension. The particles are not agglomerated and the flow properties allow very small molds to be completely filled thanks to the addition of various additives.

A critical point is the drying process, because these green bodies must be very cohesive so that they can be removed undamaged. The stars are then debinded and fired in the kiln. The basis for the production of the three-armed sharp-edged stars is a high-purity aluminum oxide. The stars are biocompatible, their diameter is around 0.8 millimeters, the passage in the skin is less than 0.1 millimeters. To ensure that no mineral substances are left behind, these small stars must have very high mechanical properties. We have developed polymer casting molds for their production, which allow large production quantities to be manufactured much more quickly and easily than with the laser process.

What other applications is the procedure suitable for?

Stuer: The focus is on the treatment of skin diseases. But I think we have found a new approach that can be used in many different ways. Medical products are becoming increasingly complex. In order to avoid undesirable effects, more and more active ingredients are being introduced in a targeted manner so that the entire body is not affected.

What developments are you aiming for?

Stuer: This new process enables us to exploit the advantages of ceramics with further precision parts in the nano and micro range. We are working on current problems, but we also want to try to tackle the issues ahead of time.

One requirement was that the process should be cost-efficient and scalable, for example to enable rapid increases in production. With the laser cutting process, scaling only works by purchasing a large number of laser devices, which is complicated and cost-intensive.

Our process only incurs high costs in the production of the master for the polymer molds. The production of the molds and the replication of the micro-ceramic stars are very inexpensive. The decisive factor is the know-how. We were able to turn the problems of the manufacturing process into an advantage by optimizing the mold stars and increasing the efficiency compared to stars produced with laser cutters. It was also important for us to develop an environmentally friendly process in which, for example, the molds can be reused.