The development of artificial muscles attracts wide interest for industrial and medical applications. Regarding manufacturing, robotic devices with synthetic muscles are able to handle complex-shaped materials more precisely. Moreover, artificial musculatures in medical prostheses can improve the wearing comfort while conveying a rather natural feeling. Currently, muscle-like contractions can be obtained by capacitor systems or by molecular machines incorporating tissue. This project aims to replace the common materials in both branches by biological tissue. While increasing ecological friendliness and the compatibility with human tissue, those fabricated composites can compete with human biological material.

Like a capacitor, the dielectric elastomer actuator (DEA) comprises two lightweight and flexible electrodes separated by an insulating elastomeric layer. In a first set of experiments, the elastomer layers in the capacitor-based muscle need to be replaced by appropriate protein structures. P-Pili with their excellent elastic properties and proteins with high amounts of helical secondary architecture are to be tested for this approach. In a next step, the currently used light weighted graphene or carbon nanotube layers need to be replaced by the Pili to provide conductivity and flexibility comparable to the carbon nanotubes. Both fibril types can be easily expressed in Geobacter sulflurreducens and Escherichia coli in a large scale, which makes the overall system extremely feasible since one organism can provide the whole material.

Another tissue with muscle-like contractions will be fabricated through polymers with integrated molecular machines. Herein, the latter are based on azo dyes capable of having their entire network contracted by light irradiation. The biopolymer matrix is fabricated by Escherichia coli and consists of catcher-tag systems modified with a biotin-accepting anchor. The molecular machines attach to the biopolymer tissue via biotin and biotin acceptor interactions. Due to the crosslinking of the single protein strains the stiffness of the resulting tissue can be adjusted accurately.

In both cases, the achieved tissues are cell-free and can immediately be adapted to the system. Within the scope of the project, the construction of a DEA-prototype is planned, since the realization of electrical stimuli is more feasible than through photo-induced signals.

After iGEM

Read our essay on "The German Bundestag and synthetic biology: legal provisions, problems and future prospects".