BERLIN – A team of researchers at Johannes Gutenberg University Mainz (JGU), the Max Planck Institute for Polymer Research, and the University of Texas at Austin have made a groundbreaking discovery regarding molecular motion within DNA polymers. Contrary to the expectation that “guest molecules” would diffuse randomly within droplets of DNA polymers, the team observed that these molecules propagate in a distinct, organized manner, forming a “clearly-defined frontal wave” [2].

According to Weixiang Chen of the Department of Chemistry at JGU, “This is an effect we did not expect at all.” The findings, published in Nature Nanotechnology, offer new insights into how cells regulate signals and could pave the way for advancements in clever biomaterials, innovative membranes, programmable drug carriers, and synthetic cell systems that mimic the complexity of living organisms.

Traditionally, molecules in liquids disperse through simple diffusion, creating gradual color gradients, like dye in water. However, the behavior of guest molecules in DNA droplets defies this model. Professor Andreas Walther from JGU’s Department of chemistry, who led the research, explained, “The molecules move in a structured and controlled manner that is contrary to the customary models, and this takes the form of what appears to be a wave of molecules or a mobile boundary.”

The research team utilized droplets composed of thousands of DNA strands, known as biomolecular condensates. The properties of these droplets can be precisely controlled using DNA structures and parameters like salt concentration. These synthetic droplets mirror condensates found in biological cells, wich cells use to organise biochemical processes without membranes. Chen emphasizes, “Our synthetic droplets thus represent an excellent model system with which we can simulate natural processes and come to better understand them.”

The researchers introduced specially designed ‘guest’ DNA strands into the droplets,which specifically recognized and bound to the inner structure of the droplets.The observed motion is attributed to the interaction between the added DNA and the DNA within the droplets, based on the “key-and-lock principle.” This interaction leads to a less dense and more dynamic surrounding material. Chen further explains, “the well-defined, highly concentrated front continues to move forward in a linear fashion over time, driven by chemical binding, material conversion and programmable DNA interactions. Something that is fully new when it comes to soft matter.”

“The molecules move in a structured and controlled manner that is contrary to the traditional models.”

Implications for Cellular Processes and Disease Treatment

The discovery has significant implications for understanding the physics of soft matter and the chemical processes within cells. Walther suggests, “This might be one of the missing pieces of the puzzle that, once assembled, will reveal to us how cells regulate signals and organize processes on the molecular level.”

This understanding could also impact the treatment of neurodegenerative disorders, where proteins migrate from cell nuclei into the cytoplasm, forming condensates that transform into problematic fibrils. Walther concludes,”It is indeed quite conceivable that we might potentially be able to find a way of influencing these aging processes with the aid of our new insights,so that,over the long term,an entirely new approach to the treatment of neurodegenerative diseases could emerge.”