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Drawing inspiration from how the cells in our eyes react differently to different wavelengths of light, researchers have succeeded in using visible light to control – by amplifying or stopping – chemical reactions inside nanometre-sized vesicles. These findings could open up new approaches for engineering synthetic cells and building biomimetic systems that can regulate their own processes and be used in industry to support the production of biological compounds.

Feedback loop: a mechanism that regulates many biological processes

Thermostats are valuable devices in our homes. They keep the temperature close to the desired level and help us reduce our bills by not using more energy than necessary for heating. Too cold? The heating system switches on. Too hot? It switches off. The temperature produced determines whether or not the system should continue to heat. This regulatory mechanism is a feedback loop; it also occurs in biological processes at all levels of life, from single cells to ecosystems. They regulate, for example, our day-night cycle and our perception of colours. At the cellular level, these loops help cells maintain the stability of their internal state, adapt to their environment and communicate with other cells.

There are two main types of feedback loops: in a positive feedback loop, the output of a reaction serves as input to amplify that same reaction, much like a snowball effect. In a negative feedback loop, the output attenuates or stops that reaction.

Researchers are taking a close interest in the replication of these feedback loops at the nanometre scale, both for fundamental reasons and for developing applications. Recently, scientists from the United Kingdom, Switzerland and Australia managed to trigger positive and negative feedback loops in synthetic nanocontainers, thereby controlling their chemical reaction, using visible light as the sole stimulus. Their findings were published in Nature Communications in July 2026.

A team specialising in the design of polymersomes with controlled chemical activity

“Like many groups in the field of synthetic cells, we ask ourselves the following question: when does chemistry become biology? How can life arise from inanimate matter?”, said Omar Rifaie Graham, an assistant professor at Queen Mary University of London in the UK, whose team led this study.

His group specialises in designing polymersomes – nanocontainers with polymer membranes – capable of controlling their own activity. For this study, Omar’s team and their collaborators drew inspiration from human corneal cells, which respond differently to yellow and blue wavelengths. Using light, they induced positive and negative feedback loops, which controlled the chemical activity of polymersomes.

A single setup, light as the only variable, and two contrasting outcomes

The researchers prepared polymersomes containing an enzyme capable of catalysing the production of an acid. These “nanoreactors” were equipped with a photoswitch that made the vesicle membrane permeable when exposed to light, thereby allowing facilitated transport (diffusion) of molecules through the membrane. They then placed these nanoreactors in a basic pH solution, containing acetate ester and a pH-sensitive dye which, under basic conditions, absorbs yellow light.

In a first experiment, they exposed the solution to yellow light and generated a positive feedback loop. Initially, the dye absorbed most of the light and the polymersomes very little; consequently, a very small amount of ester entered the vesicles and was converted into acid. As a result, only a small quantity of acids was produced and released into the medium. However, over time, the solution became more acidic, which reduced the dye’s ability to absorb yellow light; the polymersomes thus received more and more light and produced more and more acid.

In a second experiment, using the same initial conditions, they applied blue light and generated a negative feedback loop. Initially, the polymersomes faced no competition, as the dye was not sensitive to blue light. This resulted in the production of large quantities of acids. However, as the solution became more acidic, the dye became increasingly sensitive to blue light and absorbed more and more light, slowing down and eventually halting acid production.

The researchers also alternated between blue and yellow light, which allowed the acid production to reach levels that would not have been possible without this alternation.

Outlook: Synthetic cells, a future in biomanufacturing??

For Omar, synthetic cell research offers opportunities to develop technologies at the interface between living and non-living matter. One of his ambitions is to be able to offer an alternative to the bioproduction of compounds by genetically modified micro-organisms. “Too many genetic modifications pose a problem of metabolic burden and, consequently, a problem in scaling up production using this method. I want to create communities of synthetic cells and microorganisms, in which synthetic nanoreactors do the heavy chemistry and supplement living microorganisms.”

To make the system they have designed ready for technological implementation, the team would like to encapsulate their polymersomes, treating them as synthetic organelles, within a synthetic membrane, with the pH-sensitive dye inside. However, this project is not yet on the agenda. “We are currently exploring other types of photoswitches to achieve active transport of compounds, which, from a technological perspective, is interesting as it would enable these polymersomes to harvest energy from the environment, carry specific molecules against the concentration gradient and do complex reactions that microorganisms cannot do.”  

Scientific publication

Wavelength-dependent feedback behavior in light-gated polymersome nanoreactors
Uthaya Lathan, Beyzanur Kaya, Farzina Matubbar, Mohamed Chami, Jonathan Yeow and Omar Rifaie-Graham
Nature Communications 17, 8742 (2026).