Tips for biomolecular engineering can be found in early Earth

Research outlines potential mechanisms for how life emerged ‘before biology’

Leah Shaffer 09.29.2025

Early earth was a desolate landscape that could not support life. Researchers at Washington University in St. Louis are uncovering potential mechanisms for how early forms of oxygen and energy made their way to the molecular starter packs of life. (Image: Shutterstock).

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Scientists know some of the broad strokes for how life emerged from primordial earth but digging into the processes that allowed for the emergence of an oxygenated atmosphere, processes like photosynthesis, development of single cell and multi-cell organisms, still need to be sorted.

Organisms capable of ‘breathing’ or using oxygen may have arisen as early as 3.1 billion years ago. However, the Great Oxidation Event, when free oxygen in the atmosphere suddenly increased, did not occur until around 2.4 billion years ago. Then, how did oxygenation happen in an age long before plants existed?

Yifan Dai, assistant professor of biomedical engineering in the McKelvey School of Engineering at Washington University in St. Louis, is tackling that question with a recent study published in Proceedings of the National Academy of Sciences.

Dai and colleagues outline how largely overlooked noncovalent interaction forces, anion-pi, can drive “molecular assemblies”— the starting block for what will become a protocell that can generate oxygen, enabling the utilization of light to energy.

In primordial earth — imagine a rocky surface with a hazy sky — the formation of anion-π-cation triads, assemblies of negative and positively charged ions mediated by a pi-based peptide, propel loosely gathered molecules to become “micron-sized assemblies.”

This sets the stage for the type of electrochemical reactions that prime oxygen evolution from water molecules.

The study demonstrates a plausible pathway for how protocell chemistry provides an electrochemical energy source, eventually increasing the chemical complexity of carbon-based life, said Dai.

And, as biomedical engineers like Dai understand more about how evolution “made” the molecules of today, they can use similar methods to design bespoke compounds that benefit human health and industry.

Ren X, Song X, Lyu L, Chen MW, Zare RN, Dai Y. Anion–π interaction–induced phase separation as a prebiotic pathway to oxygenation. PNAS. Sept. 26. DOI: https://www.pnas.org/doi/10.1073/pnas.2508804122.

Funding supported by the Air Force Office of Scientific Research (FA9550-21-1-0170 to R.N.Z.).

The McKelvey School of Engineering at Washington University in St. Louis promotes independent inquiry and education with an emphasis on scientific excellence, innovation and collaboration without boundaries. McKelvey Engineering has top-ranked research and graduate programs across departments, particularly in biomedical engineering, environmental engineering and computing, and has one of the most selective undergraduate programs in the country. With 165 full-time faculty, 1,524 undergraduate students, 1,554 graduate students and 22,000 living alumni, we are working to solve some of society’s greatest challenges; to prepare students to become leaders and innovate throughout their careers; and to be a catalyst of economic development for the St. Louis region and beyond.