Intelligent implants: when the material is the key to the solution

Today we use implants to stabilize or compensate for injuries inside the body and to aid in the healing process. Implants cannot act autonomously and treat the patient if they deem it necessary. However, it is just a matter of time before this happens because research on intelligent implant materials that respond to stimuli is on the cusp of a breakthrough.

In this MEDICA-tradefair.com interview, Prof. Christine Selhuber-Unkel explains the technology behind intelligent implants, describes the role of responsive materials in this setting and reveals possible applications.

Prof. Selhuber-Unkel, what are "intelligent implants" in the context of your work?

Prof. Christine Selhuber-Unkel: For me, they are autonomous implants with integrated intelligence. More explicitly, these implants incorporate sensing and actuation components to detect and intelligently respond to changes in the environment.

What are the possible applications for these types of implants?

Selhuber-Unkel: There are many diseases that demand an acute response. One possible application is the use of these types of implants in epileptic patients. If a patient suffers an acute epileptic seizure, the "intelligent" implant would register and react to the seizure by releasing the corresponding anti-epileptic medication.

Another option would be to use the implant in tissue engineering. This would not be an implant in the traditional sense since the goal of tissue engineering is to restore and recreate tissue to mimic natural systems as best as possible. This is an area where materials could control the formation of new viable tissue.

What specific ideas and goals do you pursue at the newly founded Institute for Molecular Systems Engineering (IMSE)?

Selhuber-Unkel: We partnered up in a collaborative project with colleagues of the Research Training Group "Materials for Brain", which -among other things - studies intelligent implants. We pursue projects that focus on responsive material-controlled drug release. Other projects emphasize the control of cell growth via materials. This type of control mechanism is essential for implant applications to achieve the best possible results in terms of functionality.

What makes these materials responsive, and what sensor and actuation technologies does this entail?

Selhuber-Unkel: Certain materials will respond to the changes in the pH of the surrounding medium. It changes if there is inflammation in the body, for example. This type of material would fight inflammation by releasing an anti-inflammatory drug.

Responsive materials often need external stimuli – such as light – as a control component. That is why we still have a long way to go before we will have a fully autonomous material.

What advances in material development does this still require?

Selhuber-Unkel: We are not concerned with developing new alloys or polymers. Our goal is to lead molecules to certain functions and combine them into systems, making the nano and micro levels very important. To accomplish this, we collaborate with material scientists, but also work closely with chemists, physicists, and biologists. It would be exciting to have brand-new, autonomously reacting molecules, since many of the currently available responsive materials are well-known and well-tried, including light-activated azobenzenes.

We still must solve several engineering issues when it comes to autonomously responding implants. For example, if the implant is meant to release drugs inside the body, we must find a way to store them safely for a longer period of time. Design has to address this issue and manage to refill the implant.

Your institute was founded in November 2020. What is the importance of Molecular Systems Engineering?

Selhuber-Unkel: Molecular engineering is an emerging field of study, with Centers in Basel, Chicago, and Boston. What makes this so exciting is the fact that molecular systems engineering is an important element of many disciplines, including the life sciences since biological molecules also require design. The point is to control larger systems via the nanoscale and microscale. I consider this a very exciting field of research, which will allow us to achieve many breakthroughs in multiple areas, ranging from DNA origami to biohybrid robots.

What are your next steps?

Selhuber-Unkel: As far as the institute itself is concerned, we continue to set up the different laboratories and fill vacancies in professorships.

I recently received an ERC Consolidator Grant for tissue engineering. My working group aims to regulate cell functions in three dimensions through photoswitchable molecules that exert external physical forces on cells. This will enable us to study whether it is possible to control stem cell differentiation. The long-term perspective would be to control the formation of organoids or small organs mechanically versus purely biologically.