Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New equation predicts molecular forces in hydrophobic interactions

12.10.2011
New equation developed by UCSB chemical engineers solves the mystery of forces between water-repelling and water-attracting molecules that are critical to industrial and medical applications

The physical model to describe the hydrophobic interactions of molecules has been a mystery that has challenged scientists and engineers since the 19th century. Hydrophobic interactions are central to explaining why oil and water don't mix, how proteins are structured, and what holds biological membranes together. Chemical engineering researchers at UC Santa Barbara have developed a novel method to study these forces at the atomic level, and have for the first time defined a mathematical equation to measure a substance's hydrophobic character.

"This discovery represents a breakthrough that is a culmination of decades of research," says Professor Jacob Israelachvili. "The equation is intended to be a tool for scientists to begin quantifying and predicting molecular and surface forces between organic substances in water."

Using a light-responsive surfactant – a soap-like molecule related to fats and lipids – the researchers developed an innovative technique to measure or change the forces between layers of the molecule in water by using beams of UV or visible light. The result is a general equation that applies to even more complicated systems, such as cellular membranes or proteins.

"We were fortunate to find the right combination of experimental methods and theory," said Brad Chmelka, UCSB Chemical Engineering professor and co-author of the study. "The keys to our research were using a light-responsive surfactant molecule, a means of measuring these delicate surface forces, and applying knowledge of what to look for."

The highly-sensitive instrument they used to sense these molecular-level hydrophobic forces, called a surface forces apparatus, is a now-standard technique that was originally pioneered by Israelachili and colleagues in the 1970s.

"In basic chemistry, students learn about van der Waal forces – the weak forces that act between all molecules. That theory was developed more than 100 years ago," explains Professor Israelachvili.

"According to the van der Waals theory, however, oil and water shouldn't separate and surfactants shouldn't form membranes, but they do. There has been no proven theory to account for these special hydrophobic interactions. Such behaviors are crucial for life as we know it to exist."

Hydrophobic and hydrophilic interactions are central to the disciplines of chemistry, physics, and biology that have fueled modern developments in industries from detergents to pharmaceuticals and new biotechnologies. The new equation is expected to impact applications in water filtration, membrane separations, biomedical research, gene therapy methods, biofuel production, and food chemistry.

Virus and disease propagation in the human body are directly linked to hydrophobic properties on a cellular level. One of the problems related to chemotherapy treatments for cancer is being able to direct a drug specifically to cancer cells, instead of the entire body. Israelachvili and his colleagues foresee their discovery having an impact in biomedical research that attempts to understand and treat diseases.

"Cell membranes are complex and discriminating structures, allowing the transmission of various signals into cells and mediating specific interactions with bacteria and viruses," said Jean Chin, Ph.D., who oversees membrane structure grants at the National Institute of General Medical Sciences of the National Institutes of Health. "This study, by enhancing our understanding of the role played by hydrophobic forces in membrane dynamics, will expand what we know about membrane structure and function, as well as microbial infection pathways."

"Understanding how water and oil-like substances interact is enormously important for explaining the properties and functions of many biological and engineering materials," says Dr. Robert Wellek, Program Director in the Directorate for Engineering at the National Science Foundation. "The UCSB and USC teams have elegantly combined concepts from synthetic chemistry, photophysics, and chemical engineering to unravel and quantify the elusive hydrophobic interaction. NSF is very pleased that its grantees have been able to contribute important fundamental knowledge in this important area."

Details of the research were published this month in the Proceedings of the National Academy of Sciences. Their research was made possible by support from the National Science Foundation, the National Institutes of Health, and the Procter & Gamble Company.

"We've known for a long time what we were aiming for. It's a bit like climbing a mountain," said Professor Israelachvili. "The whole thing started at the very bottom. I've been searching for the keys to this interaction for thirty years. We are thrilled with the findings, but it took a lot of steps over carefully chosen paths to get there."

Professor Jacob Israelachvili, Professor Bradley Chmelka, and Stephen Donaldson, Ph.D. student, are with the Department of Chemical Engineering at UCSB. Dr. Israelachvili is a Fellow of the Royal Society of London and member of the U.S. National Academy of Science and the U.S. National Academy of Engineering. Dr. Israelachvili received his Ph.D. in Physics from University of Cambridge and joined UCSB in 1986. He was recently named by the American Institute of Chemical Engineers as one of the "100 Chemical Engineers of the Modern Era" for his achievement and leadership in the field.

Melissa Van De Werfhorst | EurekAlert!
Further information:
http://www.ucsb.edu

More articles from Life Sciences:

nachricht Helping to Transport Proteins Inside the Cell
21.11.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht UNH researchers create a more effective hydrogel for healing wounds
21.11.2018 | University of New Hampshire

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First diode for magnetic fields

Innsbruck quantum physicists have constructed a diode for magnetic fields and then tested it in the laboratory. The device, developed by the research groups led by the theorist Oriol Romero-Isart and the experimental physicist Gerhard Kirchmair, could open up a number of new applications.

Electric diodes are essential electronic components that conduct electricity in one direction but prevent conduction in the opposite one. They are found at the...

Im Focus: Nonstop Tranport of Cargo in Nanomachines

Max Planck researchers revel the nano-structure of molecular trains and the reason for smooth transport in cellular antennas.

Moving around, sensing the extracellular environment, and signaling to other cells are important for a cell to function properly. Responsible for those tasks...

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Optical Coherence Tomography: German-Japanese Research Alliance hosted Medical Imaging Conference

19.11.2018 | Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

 
Latest News

Helping to Transport Proteins Inside the Cell

21.11.2018 | Life Sciences

Meta-surface corrects for chromatic aberrations across all kinds of lenses

21.11.2018 | Power and Electrical Engineering

Removing toxic mercury from contaminated water

21.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>