The Petri Dish – Engineered or evolved? The world of synthetic biology

Pure scientific curiosity mixed with mounting pressures on environmental resources has given birth to the world of synthetic biology. Indeed, a general acknowledgment in the scientific world is that we must now start looking for alternatives to the destructive technologies of the industrial age that impact our planet’s ecosystems.

Synthetic biology uses the principles of engineering and biology to design and create new biological parts, devices, and systems, or to redesign existing natural ones to perform useful functions. I believe this field might hold the key to unlocking the future of biology: not only does synthetic biology have applications in medicine and agriculture, but in infrastructure and computing too.

I have carefully combed through some pretty jargon heavy (and at times completely incomprehensible) bioengineering journals, selecting areas I believe have the most potential for real-world change in the rapidly evolving world of synthetic biology. Therefore, this article will detail all of my weird and wacky findings: from cyborg plants to mini robots made of heart cells, and even self-healing concrete!

Biohybrid robots

Biohybrid robots are engineered to integrate organic and inorganic components into a machine composed of living and non-living matter. These ‘soft robots’ have potential advantages of both artificial and biological systems: we can “create robots with capabilities beyond traditional machines,” said Shoji Takeuchi, a researcher from the University of Tokyo, who develops biohybrid robots.

An important principle used in the field of biohybrid robotics is the mimicry of natural processes to drive artificial ones. For example, many cells in the body are used as actuators, which are units that convert signal energy into physical motion. Such examples include cardiomyocytes (heart cells), which turn electrical signals from the brain into a physical contraction to make a heartbeat.

Combining heart cells with tiny inorganic devices could have potential in monitoring disease in the body, or even drug testing

This capability has been mirrored by myocyte-driven robots (i.e. heart cell driven robots). They are composed of biomaterials which – in the same way that biotic substances can regenerate – have self-assembling and self-healing abilities, making them uniquely biocompatible. Scientists have fabricated many forms of these cardiac robots, namely swimmers and walkers (which act as their respective names suggest!).

In swimmers, the natural movement of some aquatic organisms, like jellyfish, has been mimicked. Scientists have fabricated a simple ‘swimmer-like’ robot that, by contracting in the same way as a heart, propels itself forward.

In walkers, the crawling locomotion of snakes and caterpillars was replicated. Researchers created a myocyte-driven robot with layers of inorganic graphene tubes mixed with heart cell tissue, alongside asymmetric claws, which enabled it to mirror the crawling ability of caterpillars during contraction.

The applications of these hybrid robots are vast – most notably in organ-on-a-chip systems. Combining heart cells with tiny inorganic devices could have potential in monitoring disease in the body, or even drug testing. This works via the biohybrid robots measuring the frequency of heartbeats, which can change in response to different drug concentrations, giving an indicator into the behaviour of a novel drug.

Engineered living materials (ELMs)

Like biohybrid robots, engineered living materials (ELMs) are a class of materials that contain elements of living cells and non-living matrices. In being alive, they can self-organise, respond to environmental cues, and even self-repair: this occurs via the living (or cellular) components of ELMs extracting energy from the environment, which then helps them self-assemble. With these features, they have the potential to help improve many fields, from healthcare to engineering.

Applications of ELMs have important implications for infrastructure. Their self-healing abilities can be integrated into concrete using Bacillus spores (dormant cells formed by different strands of bacteria) which produce limestone to fill cracks if they form. The basic mechanism is that if these cracks occur, water will penetrate deeper into the rock: spores produced by Bacillus will then become ‘activated’ and produce limestone by hydrolysing (i.e. breaking down) compounds like calcium, forming an aggregate that fills the crack over time. This has clear applications in construction: indeed, this process has been commercialised by Basilisk Self-Healing Concrete!

Nanobionic plants: Strano’s lab

“The goal of plant nanobionics is to introduce nanoparticles into the plant to give it non-native functions,” says Michael Strano, a professor of Chemical Engineering at MIT. By hybridising plant and mechanical elements, researchers on Strano’s team have been among the first to implement electronic systems into plants. When they’re not making plants glow like desk lamps, they are pioneering a new field of synthetic biology they have called ‘plant nanobionics’.

[The] electrical circuit, like the ones that help turn your lights on and off at home, tells researchers when pores on the leaf open and close to let water in or out of the plant

Giving plants the ability to detect explosives was one of their first endeavours. The way this works involves putting carbon nanotubes (similar to the ones in biohybrid robots) into spinach plants to wirelessly relay information to a device. The plants were designed to sniff out nitroaromatics, substances commonly used in explosives. When these chemicals are found in groundwater, the plant triggers a fluorescent response via the nanotubes. This is then detected with an infrared camera, warning the user of the presence of these compounds and the explosives.

Following these experiments, the MIT engineers were able to create a sensor that can be integrated into a plant’s leaves. For example, under conditions of water stress, such as drought, the sensor can notify the user. Uniquely, this process is reliant on electrical circuits. Using the same electrically conductive carbon nanotubes, which are dissolved in a solvent and then printed onto a leaf, to create a circuit.

This electrical circuit, like the ones that help turn your lights on and off at home, tells researchers when pores on the leaf open and close to let water in or out of the plant. The opening and closing behaviour of these pores is indicative of how much water the plant has access to. On a larger scale, this technology could be useful in detecting agricultural droughts.

It’s clear that synthetic biology sits at the intersection – and forefront – of biological and engineering innovation. As the field grows, so too does its potential to make our infrastructure smarter, our materials more sustainable, and our relationship with nature more collaborative rather than competitive.