Tag Archives: arteries

Ferroelectric switching in the lung, heart, and arteries

A June 23, 2014 University of Washington (state) news release (also on EurekAlert) describes how the human body (and other biological tissue) is capable of generating ferroelectricity,

University of Washington researchers have shown that a favorable electrical property is present in a type of protein found in organs that repeatedly stretch and retract, such as the lungs, heart and arteries. These findings are the first that clearly track this phenomenon, called ferroelectricity, occurring at the molecular level in biological tissues.

The news release gives a brief description of ferroelectricity and describes the research team’s latest work with biological tissues,

Ferroelectricity is a response to an electric field in which a molecule switches from having a positive to a negative charge. This switching process in synthetic materials serves as a way to power computer memory chips, display screens and sensors. This property only recently has been discovered in animal tissues and researchers think it may help build and support healthy connective tissues in mammals.

A research team led by Li first discovered ferroelectric properties in biological tissues in 2012, then in 2013 found that glucose can suppress this property in the body’s connective tissues, wherever the protein elastin is present. But while ferroelectricity is a proven entity in synthetic materials and has long been thought to be important in biological functions, its actual existence in biology hasn’t been firmly established.

This study proves that ferroelectric switching happens in the biological protein elastin. When the researchers looked at the base structures within the protein, they saw similar behavior to the unit cells of solid-state materials, where ferroelectricity is well understood.

“When we looked at the smallest structural unit of the biological tissue and how it was organized into a larger protein fiber, we then were able to see similarities to the classic ferroelectric model found in solids,” Li said.

The researchers wanted to establish a more concrete, precise way of verifying ferroelectricity in biological tissues. They used small samples of elastin taken from a pig’s aorta and poled the tissues using an electric field at high temperatures. They then measured the current with the poling field removed and found that the current switched direction when the poling electric field was switched, a sign of ferroelectricity.

They did the same thing at room temperature using a laser as the heat source, and the current also switched directions.

Then, the researchers tested for this behavior on the smallest-possible unit of elastin, called tropoelastin, and again observed the phenomenon. They concluded that this switching property is “intrinsic” to the molecular make-up of elastin.

The next step is to understand the biological and physiological significance of this property, Li said. One hypothesis is that if ferroelectricity helps elastin stay flexible and functional in the body, a lack of it could directly affect the hardening of arteries.

“We may be able to use this as a very sensitive technique to detect the initiation of the hardening process at a very early stage when no other imaging technique will be able to see it,” Li said.

The team also is looking at whether this property plays a role in normal biological functions, perhaps in regulating the growth of tissue.

Co-authors are Pradeep Sharma at the University of Houston, Yanhang Zhang at Boston University, and collaborators at Nanjing University and the Chinese Academy of Sciences.

Here’s a link to and a citation for the research paper,

Ferroelectric switching of elastin by Yuanming Liu, Hong-Ling Cai, Matthew Zelisko, Yunjie Wang, Jinglan Sun, Fei Yan, Feiyue Ma, Peiqi Wang, Qian Nataly Chen, Hairong Zheng, Xiangjian Meng, Pradeep Sharma, Yanhang Zhang, and Jiangyu Li. Proceedings of the National Academy of Sciences (PNAS) doi: 10.1073/pnas.1402909111

This paper is behind a paywall.

I think this is a new practice. There is a paragraph on the significance of this work (follow the link to the paper),

Ferroelectricity has long been speculated to have important biological functions, although its very existence in biology has never been firmly established. Here, we present, to our knowledge, the first macroscopic observation of ferroelectric switching in a biological system, and we elucidate the origin and mechanism underpinning ferroelectric switching of elastin. It is discovered that the polarization in elastin is intrinsic at the monomer level, analogous to the unit cell level polarization in classical perovskite ferroelectrics. Our findings settle a long-standing question on ferroelectric switching in biology and establish ferroelectricity as an important biophysical property of proteins. We believe this is a critical first step toward resolving its physiological significance and pathological implications.

Using nanoparticles to prevent ruptures (heart attacks and/or strokes) in artery walls

This technique from Temple University (Pennsylania, US)  is a long way from ready for general use but it certainly looks promising. From an Oct. 4, 2013 news item on Azonano,

Omar Z. Fisher, assistant professor of bioengineering in Temple’s College of Engineering, has developed a method for linking polyphenols, which are very strong antioxidants, to polymers that can self-assemble into nanoparticles.

Fisher said the project will focus on using these polymers to encapsulate superparamagnetic iron oxide particles (SPIOs), a nano-scale MRI contrasting agent used by his collaborator, Amber Doiron, assistant professor of bioengineering at Binghamton University.

The Oct. 2, 2013 Temple University news release by Preston Moretz, which originated the news item, describes how the nanoparticles will act in the body,

The antioxidant nanoparticles containing the contrasting agent would travel through the blood vessels until they reach atherosclerotic plaque, enabling doctors to diagnose the severity of plaques before they rupture, said Fisher.

“The worse the plaque is, the more likely it is to rupture and give you a clot,” he said. “Because these polymers are made from antioxidants, they are sensitive to oxidative stress, which is more prevalent in more severe plaques.”

Once the oxidative stress destroys the polymers, the MRI contrast agents will be released inside the plaques.

Fisher said doctors would likely prescribe an MRI when a patient was showing some signs of cardiac distress such as fatigue or chest pains.

“During the MRI, the degree of contrast would be visible and indicate to doctors not only that the plaques were there, but the severity of the plaques and how likely they would be to rupture,” he said.

No mention was made of a published paper in either the news item or the news release.