A new laboratory method permits researchers to develop compartments within a liquid that, like drops of oil in water, are separate but have no physical barrier between them. The method may help researchers understand how human cells use similar “membraneless compartments” to segregate and concentrate components for essential cellular processes, chemical reactions, or other organic functions.
Researchers at Penn State developed and used the method to create complex multi-sectioned compartments and chambers within chambers, all without any membranes. Their results are featured in a paper published online in the journal Biomacromolecules.
Membraneless compartments within cells emerge from the separation of molecules like proteins and RNA into different liquid phases. To create membrane-less compartments in the lab, the researchers mixed simplified charged polymers of repeating amino acids or nucleic acids in water. The polymers had been fluorescently tagged, which allowed the researchers to observe the resulting interactions.
As the charged polymers interacted, with reverse charges attracting, separate chambers developed in the liquid with no physical dividers. Integrating four polymers allowed the researchers to produce droplets with two compartments in addition to compartments-within-compartments. Incorporating six polymers generated droplets with three compartments.
To understand how molecules might gather within compartments, the researchers added macromolecule probes. They discovered that the probes tended to amass within compartments that included polymers having the strongest charge-based frictions with the probes.