The discovery by a team of researchers co-led by Georges Belfort could lead potentially to artificial aquaporin membranes for desalination systems
Aquaporins are proteins that serve as water channels to regulate the flow of water across biological cell membranes. They also remove excess salt and impurities in the body, and it is this aspect that has led to much interest in recent years in how to mimic the biochemical processes of aquaporins potentially for water desalination systems.
Details of a water wire (central channel) embedded in a self-assembled immidazole channel (blue) in a lipid-bilayer. The summation of the incident visible (green) and IR (red) beams produce a resulting SFG (sum frequency generation) beam that characterizes the hydrogen bonding of the water wire at the molecular level (courtesy of Poul Petersen, Cornell University).
Credit: Rensselaer Polytechnic Institute
An international team of researchers co-led by Georges Belfort has discovered water, in the form of "water wires," contained in another molecule--the imidazole--a nitrogen-based organic compound that could be used as a potential building block for artificial aquaporins. The findings were recently published in Science Advances by the American Association for the Advancement of Science. Belfort is Institute Professor and professor of chemical and biological engineering at Rensselaer Polytechnic Institute.
Belfort's colleague, Mihail Barboiu, a research leader at the European Membranes Institute (EMI) in France, has synthesized and studied the dynamics of a ring structure of the imidazole embedded in a supported lipid bilayer (i.e., in a synthetic model of a biological membrane surrounding a cell). EMI operates under the auspices of several organizations, including France's National Center for Scientific Research (abbreviated CNRS in French).
X-ray studies by Barboiu and dynamic computer simulations by CNRS researcher Marc Baaden show that the imidazole's ring structure makes the molecule an ideal candidate to learn about how artificial aquaporins could be developed. In theory, assembled imidazole molecules act like an aquaporin by allowing water molecules to enter and possibly flow through the center of the ring structure while keeping out other molecules.
Still, there was no direct proof that water existed inside the imidazole water channel. To find out, Barboiu enlisted the help of Belfort and Poul Petersen, assistant professor of chemistry at Cornell University.
Through their experimental studies, Belfort and Petersen have found that not only does water exist in the imidazole water channel, but also that the imidazole ring construct induces the water molecules to self-assemble into a highly oriented linear chain structure--or what the researchers have dubbed "water wires."
"For the first time, we have made a direct observation of this unique water structure inside a synthetic water channel that mimics an aquaporin," Belfort said.
Belfort and his colleagues also discovered that the chirality of the imidazole molecules orients the water molecules and could increase the permeability of water through the water channel compared with achiral (i.e., not chiral) imidazole molecules that they also assembled. Chirality happens when a mirror image of an object is not superimposable--for example, your left and right hand.
In the case of the imidazole molecule, its chirality depends on the way that the groups of atoms in a molecule are organized. As Belfort explained, the chiral imidazole atoms can be seen as spokes on a bicycle wheel that cannot be superimposed on the "spokes" of an imidazole that is achiral.
"If you place several of these rings on top of each other like a pile of pancakes, the center (the 'axel') of the spokes holds the water molecules and enables them to connect with one another in an ordered way to form a water wire," he said. "Our results also showed that the water wire changed its orientation when imidazole chirality changes, further confirming that the chiral shape of the imidazole controls how the water behaves."
In their study, the researchers used artificial water channels that they created from imidazole self-assembled structures inside lipid bilayers, thin membranes that form a continuous barrier around cells. The imidazole building blocks were synthesized by Barboiu and his group in France. Belfort's research group then assembled the lipid bilayers to contain the imidazole structures.
Belfort's team used a quartz crystal microbalance (QCM) to measure the assembly and water content. Researchers use QCM to measure small mass changes on a vibrating quartz crystal. The lipids containing the water wire structures were then carried to Cornell by Mirco Sorci, a research associate in Belfort's lab, to further analyze the presence of the water wire and its orientation, using a special instrument that measures hydrogen bonds between water molecules called a sum frequency generation spectrometer.
About Rensselaer Polytechnic Institute
Rensselaer Polytechnic Institute, founded in 1824, is America's first technological research university. For nearly 200 years, Rensselaer has been defining the scientific and technological advances of our world. Rensselaer faculty and alumni represent 86 members of the National Academy of Engineering, 17 members of the National Academy of Sciences, 25 members of the American Academy of Arts and Sciences, 8 members of the National Academy of Medicine, 8 members of the National Academy of Inventors, and 5 members of the National Inventors Hall of Fame, as well as 6 National Medal of Technology winners, 5 National Medal of Science winners, and a Nobel Prize winner in Physics. With 7,000 students and nearly 100,000 living alumni, Rensselaer is addressing the global challenges facing the 21st century--to change lives, to advance society, and to change the world. To learn more, go to http://www.
Visit the Rensselaer research and discovery blog: http://approach.
Follow us on Twitter: http://www.
News Media | EurekAlert!
Solving the efficiency of Gram-negative bacteria
22.03.2019 | Harvard University
Bacteria bide their time when antibiotics attack
22.03.2019 | Rice University
DESY and MPSD scientists create high-order harmonics from solids with controlled polarization states, taking advantage of both crystal symmetry and attosecond electronic dynamics. The newly demonstrated technique might find intriguing applications in petahertz electronics and for spectroscopic studies of novel quantum materials.
The nonlinear process of high-order harmonic generation (HHG) in gases is one of the cornerstones of attosecond science (an attosecond is a billionth of a...
Nano- and microtechnology are promising candidates not only for medical applications such as drug delivery but also for the creation of little robots or flexible integrated sensors. Scientists from the Max Planck Institute for Polymer Research (MPI-P) have created magnetic microparticles, with a newly developed method, that could pave the way for building micro-motors or guiding drugs in the human body to a target, like a tumor. The preparation of such structures as well as their remote-control can be regulated using magnetic fields and therefore can find application in an array of domains.
The magnetic properties of a material control how this material responds to the presence of a magnetic field. Iron oxide is the main component of rust but also...
Due to the special arrangement of its molecules, a new coating made of corn starch is able to repair small scratches by itself through heat: The cross-linking via ring-shaped molecules makes the material mobile, so that it compensates for the scratches and these disappear again.
Superficial micro-scratches on the car body or on other high-gloss surfaces are harmless, but annoying. Especially in the luxury segment such surfaces are...
The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.
A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...
Researchers at Chalmers University of Technology and the University of Gothenburg, Sweden, have proposed a way to create a completely new source of radiation. Ultra-intense light pulses consist of the motion of a single wave and can be described as a tsunami of light. The strong wave can be used to study interactions between matter and light in a unique way. Their research is now published in the scientific journal Physical Review Letters.
"This source of radiation lets us look at reality through a new angle - it is like twisting a mirror and discovering something completely different," says...
11.03.2019 | Event News
01.03.2019 | Event News
28.02.2019 | Event News
22.03.2019 | Life Sciences
22.03.2019 | Life Sciences
22.03.2019 | Information Technology