Manipulation of Liquid Crystals Could Help Control Drug-Delivery Process
News Sep 14, 2016
Liquid crystals are strange substances—they can flow like a liquid, but have the orderly molecular structure of a crystalline solid. And that internal structure can be changed by small cues from outside.
A group of scientists at the University of Chicago’s Institute for Molecular Engineering has found a way to exploit this property to turn liquid crystals into a tool to manipulate the shape of synthetic cell membranes. The technique has potential for use in biology, medicine, and advanced materials development.
“What we’ve done is reproduced the beginnings of cell division in a synthetic system,” said Juan de Pablo, the Liew Family Professor in Molecular Engineering, who headed the group. When a cell divides, the spherical cell membrane stretches into an elliptical form, develops a waist in the middle, and then splits into two spherical cells. The scientists built sophisticated models that produced this behavior on the computer and then reproduced it in the real world, testing the model’s predictions.
“It’s the first time that this has been done,” said de Pablo. “It’s a system that has been engineered at the molecular level using computer models.”
Standing in for cells in the experiments were capsules, or “vesicles,” a few microns in diameter (a fraction the width of a human hair) made of some of the same phospholipids that make up real cell membranes. These were immersed in a bath of liquid crystal oil whose molecules are slightly elongated rather than round. At temperatures above 97 degrees Fahrenheit, the oil behaves like any other oil. But when the temperature is lowered slightly, the molecules of the oil pack tightly against one another like cigarettes and align along a single direction.
“When that happens, the liquid crystal presses on the vesicle more in one direction than in the other, so the vesicle becomes elongated,” de Pablo said. “If you squash it more and more, it becomes an ellipsoid, and the two ends become pointier and pointier. There is a point when the molecules around those points separate from one another and create a little gap in the membrane through which things could be squeezed out.”
Lipid vesicles are in current use for drug delivery. De Pablo envisions using the liquid crystal technique as a cunning way to control that process.
“What we find intriguing is that we have a mechanism that will allow us to take vesicles loaded with something interesting, and by changing the temperature a little bit, we could deform the vesicle and have it squeeze out whatever it has inside without our ever touching the vesicle. And then as we restore the temperature to the original value, the vesicle becomes spherical again.”
Calculations indicate that squeezing more or less would alter the size of the gap, allowing for the release of contents of varying sizes. “But that’s something that we still have to demonstrate,” said de Pablo.
Researchers Democratize Neuroscience by Making it Easier to Share Brain Imaging DataNews
Researchers have developed a set of tools to make one critical area of big data research — that of our central nervous system — easier to share.READ MORE
New Chemical Synthesis Process: Synergy of Two Catalysts in One FlaskNews
Researchers report the one-step synthesis of a ketone from an aldehyde by the combination of thiazolium N-heterocyclic carbene and palladium/bisphosphine catalysts in one flask. The two catalysts function in a synergistic manner. This study is expected to lead to new synthesis processes of precursor compounds for medications.READ MORE
'Body-on-a-Chip' Could Advance Drug EvaluationNews
MIT engineers have developed new technology that could be used to evaluate new drugs and detect possible side effects before the drugs are tested in humans. Using a microfluidic platform that connects engineered tissues from up to 10 organs, the researchers can accurately replicate human organ interactions for weeks at a time.READ MORE