Record-size molecular threads boost nerve cell growth in the lab
Northwestern University researchers build molecular threads weighing billions of daltons with precisely placed charged segments. Nerve cells formed more branches and synapses with them.
Photo: ZEISS Microscopy from Germany / Wikimedia Commons, CC BY 2.0 (cropped and resized)
Video: YouTube · Northwestern University · youtube.com
A team led by materials scientist Samuel Stupp at Northwestern University (USA) has presented a new type of supramolecular polymer in the journal Science (DOI 10.1126/science.aeg5583, 1 October). The threads assemble themselves from small building blocks, grow longer than a cell's diameter and reach a mass of billions of daltons – about a hundred times more than very large conventional polymers or the largest known proteins.
The trick: when the building blocks run out, flexible segments at the thread ends fold over and stop the growth. Adding new molecules lets the thread keep growing. This makes it possible to place segments with different electrical charges one after another. A short positively charged segment anchors the thread to the negatively charged surface of nerve cells.
In cell cultures, treated nerve cells showed, when stimulated, about four times more calcium activity than untreated ones after seven days and formed more synapses after 14 days – without added biological signalling molecules. The researchers see this as an approach for bioactive materials in regenerative medicine. The results so far come from lab experiments.