At the core of complex systems and of those which allowed the emergence of life on Earth, there is an autocatalytic aggregation process of the constituents, such as atoms and molecules. In everyday language, autocatalysis can be described as “the more of it there is, the faster it yields” mechanism. In chemistry, biophysics, and materials science autocatalysis is the process by which molecules produced by a chemical reaction act as true catalysts for the very same reaction, thus making it faster. For example, autocatalysis occurs in the polymerization reaction of amines and epoxides that leads to the formation of complex, highly adhesive materials typically employed in the automotive and aerospace industries. It is also believed that the prebiotic synthesis of molecular building blocks needed on Earth for the design of life, and the successive emergence of biological systems, which are able to self-replicate and evolve, were based on autocatalytic reactions. 

A novel study, conducted by Cristiano De Michele and Francesco Sciortino of the Department of Physics of “Sapienza” University of Rome and by Silvia Corezzi of the Department of Physics and Geology of University of Perugia, opens up new scenarios for a full comprehension of the autocatalytic process, by evidencing the unexpected role played by a physical mechanism which accelerates the reaction of the constituent particles independently from their chemical properties. The results have been published in Nature Communications. 

In the approach used by the team of scientists, a reacting molecule is modelled as a patchy particle, which is quite common in soft matter physics. Such a particle comprises a repulsive hard core, whose shape and volume are similar to those of the real molecule, complemented with a set of attractive sites on the surface (also called patches) which can interact with similar sites present on other particles, thus forming reversible or irreversible bonds.

“We started – says Silvia Corezzi – from a minimalist model, directly inspired by Nature, which has long been used to study aggregating systems but was completely lacking autocatalysis. Our study highlights the key ingredients which are sufficient to realize, in silico as well as in the laboratory, autocatalytic patchy particles”.

This is the beginning of a new era in the use of patchy particles. These particles will allow us to better exploit the autocatalytic aggregation processes of molecules and synthetic DNA constructs, for the creation of novel materials, whose structure is modulated by the time over which their constituent building blocks are formed. “If on the one hand - says Cristiano De Michele – these experiments will allow us to confirm our predictions, on the other hand they will provide a better understanding of the mechanisms that led to the emergence of life on Earth starting from simpler molecules which - through autocatalytic reactions  - organized themselves into the fascinating complexity of actual biological systems.”

References:

Exploiting Limited Valence Patchy Particles to Understand Autocatalytic Kinetics - Silvia Corezzi, Francesco Sciortino & Cristiano De Michele - Nature Communications volume 9, Article number: 2647 (2018) DOI: 10.1038/s41467-018-04977-0

For further information

Cristiano De Michele
Department of Physics, Sapienza University 
cristiano.demichele@roma1.infn.it