Information processing materials system. Credit: Wilfried Weber.
Information processing materials system. Credit: Wilfried Weber.

All living systems from single cells to entire organisms respond to external stimuli in a variety of different ways. Inspired by the way synthetic biology uses simple building blocks to create complex responsive systems, researchers from the University of Freiberg have designed ‘smart’ materials systems made from protein and polymer components that can perceive and process information [Wagner et al., Materials Today (2018),].

“We used principles and building blocks from synthetic biology to endow polymer materials with new functions,” explains first author of the study, Hanna J. Wagner.

The team led by Wilfried Weber assembled biohybrid materials able to process information and perform tasks such as detecting enzymes or small molecules. The construction of the system starts with specially designed protein building blocks with sensing, switching, transmitting, or output functions, which are engineered to couple with polymer materials. Then these material units are interconnected to create a signal detector and amplification – or positive feedback – system that responds to external stimuli.

“One material can, for example, sense an input and react by sending another signal to a second material,” explains Wagner. “The second material can again sense and react – depending on the design of the biomaterial. Based on this strategy, materials systems can be ‘programmed’ to process information.”

The team’s initial system is based on a tobacco etch virus protease construct immobilized in an agarose polymer network that can detect an external ‘input’ and transmit a signal to a second material, which further activates the first in a positive feedback loop. The second material releases a molecule – a red fluorescent protein, mCherry – that serves as the system’s output. The positive feedback loop boosts the output signal and makes the system sensitive to very low concentrations. From a user’s perspective, the system fluoresces red when it detects enzymes or small molecules such as antibiotics.

“A great thing about these synthetic biology-inspired materials systems is their versatility,” says Wagner. “In principle, we can use the whole collection of synthetic biological parts to incorporate new functions into materials, including therapeutics for biomedical purposes.”

The modular approach allows materials to be put together in different ways to sense various physical, chemical, or biological signals and respond with a useful function, such as amplifying a signal, storing information, or releasing a drug or active molecule.

“It is a versatile approach that offers the possibility of endowing polymer materials with a complete, new set of functions and engineering materials systems with different, customized computational functionalities,” Wagner told Materials Today.

The circuit function, biological components (receptors, transmitters, and output), and appropriate polymer can all be chosen depending on the goal of the system.