Engineering homeostasis into living materials

Engineered Living Materials (ELMs) are dynamically emerging at the intersection of synthetic biology and materials sciences and are providing solutions in a rapidly growing number of application fields. Current areas of application comprise, for example, biomedicine, textiles, sensors, soft robotics, electronics, or construction materials. From a conceptual point of view, ELMs provide the opportunity of endowing materials with properties and functions long sought for in materials sciences, such as adaptivity and interactivity, evolvability, hierarchical design, self-reproduction, energy harvesting from the environment, synthesis from renewable resources, as well as biodegradability. Despite intensive research, however, a key defining property of life is largely missing in ELMs, that is homeostasis. Homeostasis is the ability of a system to maintain an inner steady state despite external fluctuations that impact this state. For example, mammals maintain a constant body temperature despite varying external temperatures. In STEADY, we will develop and test the concept of engineering homeostasis into living materials. To this aim, we will develop three genetically encoded modules, (i) a sensor to sense the actual state of a specific mechanical property of the material, (ii) a controller to process the sensor signal, and (iii) an actuator, that, based on the controllers output, steers the material towards the setpoint. The design of the homeostatic system will be highly modular, so that the sensor and actuator can be adapted in order to maintain homeostasis for other properties or functions of the material. The tools developed here are not restricted to ELMs but may also be used to confer homeostasis to polymer-based soft materials with regard to maintaining a desired feature. Thus, STEADY will open novel opportunities for engineering materials to be robust and resilient to changing environmental conditions.