Amazing stuff!
"... Researchers have long sought to make chemical computers where molecules, rather than transistors, do the work. The appeal lies not in speed, but in setting computation loose in fluid environments—and potentially even within living cells.
For years, the research involved wiring reactions together one by one so that one enzyme’s product became the next enzyme’s fuel, like tiny chemical circuits. “Until recently, most molecular computing relied on painstaking design—every reaction mapped in advance like lines of code,” ...
The approach worked for small systems but faltered as networks grew more tangled and unpredictable. The harder chemists tried to control every pathway, the faster disorder crept in. ...
The team built a simple network of enzymes—proteins that speed up chemical reactions—competing for their fuel in the form of tiny protein fragments called peptides. When an enzyme consumes some of that shared fuel or releases its products, it subtly alters the mixture’s acidity and composition, conditions that determine how fast other enzymes work. Those shifts, in turn, ripple back to influence the first reaction. No enzyme directs the process, yet together their competing actions form a coordinated pattern. ...
The team then prepared the enzyme mixture at different starting conditions: variations in acidity, temperature, and exposures to pulses of blue LED light. Each test was run until the reactions in the mixture reached equilibrium. Using mass spectrometry—a tool that identifies molecules by their weight—the researchers read the chemical fingerprints in the final steady state. Those measurements showed that each set of external conditions provoked a distinct, repeatable pattern of reactions: the network’s way of sensing what was happening outside the vial.
Next, Huck’s team trained a simple computer model to read the final reaction patterns. It could tell which changes in acidity, temperature, or light had produced the patterns—proof that the chemistry had captured and encoded information about its surroundings. That the reaction mixture managed to classify these changes “was the most surprising” to Huck, as it meant “the system can sense the environment.” ..."
From the abstract:
"Living cells understand their environment by combining, integrating and interpreting chemical and physical stimuli. Despite considerable advances in the design of enzymatic reaction networks that mimic hallmarks of living systems, these approaches lack the complexity to fully capture biological information processing.
Here we introduce a scalable approach to design complex enzymatic reaction networks capable of reservoir computation based on recursive competition of substrates. This protease-based network can perform a broad range of classification tasks based on peptide and physicochemical inputs and can simultaneously perform an extensive set of discrete and continuous information processing tasks.
The enzymatic reservoir can act as a temperature sensor from 25 °C to 55 °C with 1.3 °C accuracy, and performs decision-making, activation and tuning tasks common to neurological systems.
We show a possible route to temporal information processing and a direct interface with optical systems by demonstrating the extension of the network to incorporate sensitivity to light pulses. Our results show a class of competition-based molecular systems capable of increasingly powerful information-processing tasks."
A recursive enzymatic competition network capable of multitask molecular information processing (open access)
Fig. 1: Design of a recursive enzymatic competition network.
Fig. 2: Chemical and physicochemical non-linear classification tasks.
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