Tag Archives: Colorado State University

‘Superhemophobic’ medical implants

Counterintuitively, repelling blood is the concept behind a new type of medical implant according to a Jan. 18, 2017 news item on ScienceDaily,

Medical implants like stents, catheters and tubing introduce risk for blood clotting and infection — a perpetual problem for many patients.

Colorado State University engineers offer a potential solution: A specially grown, “superhemophobic” titanium surface that’s extremely repellent to blood. The material could form the basis for surgical implants with lower risk of rejection by the body.

Blood, plasma and water droplets beading on a superomniphobic surface. CSU researchers have created a superhemophobic titanium surface, repellent to blood, that has potential applications for biocompatible medical devices. Courtesy: Colorado State University

A Jan. 18, 2017 Colorado State University news release by Anne Ju Manning, which originated the news item, explains more,

t’s an outside-the-box innovation achieved at the intersection of two disciplines: biomedical engineering and materials science. The work, recently published in Advanced Healthcare Materials, is a collaboration between the labs of Arun Kota, assistant professor of mechanical engineering and biomedical engineering; and Ketul Popat, associate professor in the same departments.

Kota, an expert in novel, “superomniphobic” materials that repel virtually any liquid, joined forces with Popat, an innovator in tissue engineering and bio-compatible materials. Starting with sheets of titanium, commonly used for medical devices, their labs grew chemically altered surfaces that act as perfect barriers between the titanium and blood. Their teams conducted experiments showing very low levels of platelet adhesion, a biological process that leads to blood clotting and eventual rejection of a foreign material.

Chemical compatibility

A material “phobic” (repellent) to blood might seem counterintuitive, the researchers say, as often biomedical scientists use materials “philic” (with affinity) to blood to make them biologically compatible. “What we are doing is the exact opposite,” Kota said. “We are taking a material that blood hates to come in contact with, in order to make it compatible with blood.” The key innovation is that the surface is so repellent, that blood is tricked into believing there’s virtually no foreign material there at all.

The undesirable interaction of blood with foreign materials is an ongoing problem in medical research, Popat said. Over time, stents can form clots, obstructions, and lead to heart attacks or embolisms. Often patients need blood-thinning medications for the rest of their lives – and the drugs aren’t foolproof.

“The reason blood clots is because it finds cells in the blood to go to and attach,” Popat said. “Normally, blood flows in vessels. If we can design materials where blood barely contacts the surface, there is virtually no chance of clotting, which is a coordinated set of events. Here, we’re targeting the prevention of the first set of events.”

nanotubes

Fluorinated nanotubes provided the best superhemophobic surface in the researchers’ experiments.

The researchers analyzed variations of titanium surfaces, including different textures and chemistries, and they compared the extent of platelet adhesion and activation. Fluorinated nanotubes offered the best protection against clotting, and they plan to conduct follow-up experiments.

Growing a surface and testing it in the lab is only the beginning, the researchers say. They want to continue examining other clotting factors, and eventually, to test real medical devices.

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

Hemocompatibility of Superhemophobic Titania Surfaces by Sanli Movafaghi, Victoria Leszczak, Wei Wang, Jonathan A. Sorkin, Lakshmi P. Dasi, Ketul C. Popat, and Arun K. Kota. Advanced Healthcare Materials DOI: 10.1002/adhm.201600717 Version of Record online: 21 DEC 2016

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Repelling liquid with superomniphobic tape

The Kota lab at Colorado State University has created a superomniphobic tape that adheres to any surface and imparts liquid-repellant properties. Credit: Kota lab/Colorado State University

The Kota lab at Colorado State University has created a superomniphobic tape that adheres to any surface and imparts liquid-repellant properties. Credit: Kota lab/Colorado State University

An Oct. 20, 2016 news item on ScienceDaily celebrates the creation of a liquid-repelling superomniphobic tape,

Arun Kota, assistant professor of mechanical engineering at Colorado State University, has made a superomniphobic tape that, when adhered to any surface, gives the surface liquid-repelling properties. This recent breakthrough has been published by the American Chemical Society.

An Oct. 20, 2016 Colorado State University news release on EurekAlert, which originated the news item, provides more description,

Superomniphobic surfaces are extremely repellent to all liquids, made possible by an air cushion that lies between a liquid and a solid surface. With more than 10 years of research in this area, Kota has made many breakthroughs in super-repellent coatings. This latest product is similar in flexibility to Scotch Tape, but has the additional functionality of being extremely liquid-repellant.

Kota, doctoral student Hamed Vahabi, and postdoctoral fellow Wei Wang, developed the unusual tape. Though simple at first glance, the technology’s potential impact is extraordinary, the researchers say.

The concept of superomniphobic surfaces isn’t new. Researchers have been studying superomniphobic coatings since about 2007, and currently superomniphobic coatings can be sprayed, deposited or etched onto any surface for a similar effect; however, it requires costly equipment, complex techniques, and must be done by an experienced professional.

By contrast, the Kota group’s superomniphobic tape can be used by anyone, making it a practical solution in a variety of civilian, commercial, and military applications including corrosion resistance, self cleaning, drag reduction, liquid waste minimization, and more.

The researchers feel that future challenges in this field are exciting ­- yet puzzling. While many applications of superomniphobic coatings have already been outlined, coming up with a superomniphobic coating that is mechanically durable remains a major challenge.

Kota has filed a patent and sees tape and adhesive manufacturers as well as the packing industry having a strong interest in the product. He and his group will continue to research the mechanical durability of their product.

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

Free-Standing, Flexible, Superomniphobic Films by Hamed Vahabi, Wei Wang, Sanli Movafaghi, and Arun K. Kota. ACS Appl. Mater. Interfaces, 2016, 8 (34), pp 21962–21967 DOI: 10.1021/acsami.6b06333 Publication Date (Web): August 19, 2016

Copyright © 2016 American Chemical Society

This paper is behind a paywall.

D-PLACE: an open access database of places, language, culture, and enviroment

In an attempt to be a bit more broad in my interpretation of the ‘society’ part of my commentary I’m including this July 8, 2016 news item on ScienceDaily (Note: A link has been removed),

An international team of researchers has developed a website at d-place.org to help answer long-standing questions about the forces that shaped human cultural diversity.

D-PLACE — the Database of Places, Language, Culture and Environment — is an expandable, open access database that brings together a dispersed body of information on the language, geography, culture and environment of more than 1,400 human societies. It comprises information mainly on pre-industrial societies that were described by ethnographers in the 19th and early 20th centuries.

A July 8, 2016 University of Toronto news release (also on EurekAlert), which originated the news item, expands on the theme,

“Human cultural diversity is expressed in numerous ways: from the foods we eat and the houses we build, to our religious practices and political organisation, to who we marry and the types of games we teach our children,” said Kathryn Kirby, a postdoctoral fellow in the Departments of Ecology & Evolutionary Biology and Geography at the University of Toronto and lead author of the study. “Cultural practices vary across space and time, but the factors and processes that drive cultural change and shape patterns of diversity remain largely unknown.

“D-PLACE will enable a whole new generation of scholars to answer these long-standing questions about the forces that have shaped human cultural diversity.”

Co-author Fiona Jordan, senior lecturer in anthropology at the University of Bristol and one of the project leads said, “Comparative research is critical for understanding the processes behind cultural diversity. Over a century of anthropological research around the globe has given us a rich resource for understanding the diversity of humanity – but bringing different resources and datasets together has been a huge challenge in the past.

“We’ve drawn on the emerging big data sets from ecology, and combined these with cultural and linguistic data so researchers can visualise diversity at a glance, and download data to analyse in their own projects.”

D-PLACE allows users to search by cultural practice (e.g., monogamy vs. polygamy), environmental variable (e.g. elevation, mean annual temperature), language family (e.g. Indo-European, Austronesian), or region (e.g. Siberia). The search results can be displayed on a map, a language tree or in a table, and can also be downloaded for further analysis.

It aims to enable researchers to investigate the extent to which patterns in cultural diversity are shaped by different forces, including shared history, demographics, migration/diffusion, cultural innovations, and environmental and ecological conditions.

D-PLACE was developed by an international team of scientists interested in cross-cultural research. It includes researchers from Max Planck Institute for the Science of Human history in Jena Germany, University of Auckland, Colorado State University, University of Toronto, University of Bristol, Yale, Human Relations Area Files, Washington University in Saint Louis, University of Michigan, American Museum of Natural History, and City University of New York.

The diverse team included: linguists; anthropologists; biogeographers; data scientists; ethnobiologists; and evolutionary ecologists, who employ a variety of research methods including field-based primary data collection; compilation of cross-cultural data sources; and analyses of existing cross-cultural datasets.

“The team’s diversity is reflected in D-PLACE, which is designed to appeal to a broad user base,” said Kirby. “Envisioned users range from members of the public world-wide interested in comparing their cultural practices with those of other groups, to cross-cultural researchers interested in pushing the boundaries of existing research into the drivers of cultural change.”

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

D-PLACE: A Global Database of Cultural, Linguistic and Environmental Diversity by Kathryn R. Kirby, Russell D. Gray, Simon J. Greenhill, Fiona M. Jordan, Stephanie Gomes-Ng, Hans-Jörg Bibiko, Damián E. Blasi, Carlos A. Botero, Claire Bowern, Carol R. Ember, Dan Leehr, Bobbi S. Low, Joe McCarter, William Divale, Michael C. Gavin.  PLOS ONE, 2016; 11 (7): e0158391 DOI: 10.1371/journal.pone.0158391 Published July 8, 2016.

This paper is open access.

You can find D-PLACE here.

While it might not seem like that there would be a close link between anthropology and physics in the 19th and early 20th centuries, that information can be mined for more contemporary applications. For example, someone who wants to make a case for a more diverse scientific community may want to develop a social science approach to the discussion. The situation in my June 16, 2016 post titled: Science literacy, science advice, the US Supreme Court, and Britain’s House of Commons, could  be extended into a discussion and educational process using data from D-Place and other sources to make the point,

Science literacy may not be just for the public, it would seem that US Supreme Court judges may not have a basic understanding of how science works. David Bruggeman’s March 24, 2016 posting (on his Pasco Phronesis blog) describes a then current case before the Supreme Court (Justice Antonin Scalia has since died), Note: Links have been removed,

It’s a case concerning aspects of the University of Texas admissions process for undergraduates and the case is seen as a possible means of restricting race-based considerations for admission.  While I think the arguments in the case will likely revolve around factors far removed from science and or technology, there were comments raised by two Justices that struck a nerve with many scientists and engineers.

Both Justice Antonin Scalia and Chief Justice John Roberts raised questions about the validity of having diversity where science and scientists are concerned [emphasis mine].  Justice Scalia seemed to imply that diversity wasn’t esential for the University of Texas as most African-American scientists didn’t come from schools at the level of the University of Texas (considered the best university in Texas).  Chief Justice Roberts was a bit more plain about not understanding the benefits of diversity.  He stated, “What unique perspective does a black student bring to a class in physics?”

To that end, Dr. S. James Gates, theoretical physicist at the University of Maryland, and member of the President’s Council of Advisers on Science and Technology (and commercial actor) has an editorial in the March 25 [2016] issue of Science explaining that the value of having diversity in science does not accrue *just* to those who are underrepresented.

Dr. Gates relates his personal experience as a researcher and teacher of how people’s background inform their practice of science, and that two different people may use the same scientific method, but think about the problem differently.

I’m guessing that both Scalia and Roberts and possibly others believe that science is the discovery and accumulation of facts. In this worldview science facts such as gravity are waiting for discovery and formulation into a ‘law’. They do not recognize that most science is a collection of beliefs and may be influenced by personal beliefs. For example, we believe we’ve proved the existence of the Higgs boson but no one associated with the research has ever stated unequivocally that it exists.

More generally, with D-PLACE and the recently announced Trans-Atlantic Platform (see my July 15, 2016 post about it), it seems Canada’s humanities and social sciences communities are taking strides toward greater international collaboration and a more profound investment in digital scholarship.

Gold-144 is a polymorph

Au-144 (also known as Gold-144) is an iconic gold nanocluster according to a June 14, 2016 news item announcing its polymorphic nature on ScienceDaily,

Chemically the same, graphite and diamonds are as physically distinct as two minerals can be, one opaque and soft, the other translucent and hard. What makes them unique is their differing arrangement of carbon atoms.

Polymorphs, or materials with the same composition but different structures, are common in bulk materials, and now a new study in Nature Communications confirms they exist in nanomaterials, too. Researchers describe two unique structures for the iconic gold nanocluster Au144(SR)60, better known as Gold-144, including a version never seen before. Their discovery gives engineers a new material to explore, along with the possibility of finding other polymorphic nanoparticles.

A June 14, 2016 Columbia University news release (also on EurekAlert), which originated the news item, provides more insight into the work,

“This took four years to unravel,” said Simon Billinge, a physics professor at Columbia Engineering and a member of the Data Science Institute. “We weren’t expecting the clusters to take on more than one atomic arrangement. But this discovery gives us more handles to turn when trying to design clusters with new and useful properties.”

Gold has been used in coins and jewelry for thousands of years for its durability, but shrink it to a size 10,000 times smaller than a human hair [at one time one billionth of a meter or a nanometer was said to be 1/50,000, 1/60,000 or 1/100,000 of the diameter of a human hair], and it becomes wildly unstable and unpredictable. At the nanoscale, gold likes to split apart other particles and molecules, making it a useful material for purifying water, imaging and killing tumors, and making solar panels more efficient, among other applications.

Though a variety of nanogold particles and molecules have been made in the lab, very few have had their secret atomic arrangement revealed. But recently, new technologies are bringing these miniscule structures into focus.

Under one approach, high-energy x-ray beams are fired at a sample of nanoparticles. Advanced data analytics are used to interpret the x-ray scattering data and infer the sample’s structure, which is key to understanding how strong, reactive or durable the particles might be.

Billinge and his lab have pioneered a method, the atomic Pair Distribution Function (PDF) analysis, for interpreting this scattering data. To test the PDF method, Billinge asked chemists at the Colorado State University to make tiny samples of Gold-144, a molecule-sized nanogold cluster first isolated in 1995. Its structure had been theoretically predicted in 2009, and though never confirmed, Gold-144 has found numerous applications, including in tissue-imaging.

Hoping the test would confirm Gold-144’s structure, they analyzed the clusters at the European Synchrotron Radiation Source in Grenoble, and used the PDF method to infer their structure. To their surprise, they found an angular core, and not the sphere-like icosahedral core predicted. When they made a new sample and tried the experiment again, this time using synchrotrons at Brookhaven and Argonne national laboratories, the structure came back spherical.

“We didn’t understand what was going on, but digging deeper, we realized we had a polymorph,” said study coauthor Kirsten Jensen, formerly a postdoctoral researcher at Columbia, now a chemistry professor at the University of Copenhagen.

Further experiments confirmed the cluster had two versions, sometimes found together, each with a unique structure indicating they behave differently. The researchers are still unsure if Gold-144 can switch from one version to the other or, what exactly, differentiates the two forms.

To make their discovery, the researchers solved what physicists call the nanostructure inverse problem. How can the structure of a tiny nanoparticle in a sample be inferred from an x-ray signal that has been averaged over millions of particles, each with different orientations?

“The signal is noisy and highly degraded,” said Billinge. “It’s the equivalent of trying to recognize if the bird in the tree is a robin or a cardinal, but the image in your binoculars is too blurry and distorted to tell.”

“Our results demonstrate the power of PDF analysis to reveal the structure of very tiny particles,” added study coauthor Christopher Ackerson, a chemistry professor at Colorado State. “I’ve been trying, off and on, for more than 10 years to get the single-crystal x-ray structure of Gold-144. The presence of polymorphs helps to explain why this molecule has been so resistant to traditional methods.”

The PDF approach is one of several rival methods being developed to bring nanoparticle structure into focus. Now that it has proven itself, it could help speed up the work of describing other nanostructures.

The eventual goal is to design nanoparticles by their desired properties, rather than through trial and error, by understanding how form and function relate. Databases of known and predicted structures could make it possible to design new materials with a few clicks of a mouse.

The study is a first step.

“We’ve had a structure model for this iconic gold molecule for years and then this study comes along and says the structure is basically right but it’s got a doppelgänger,” said Robert Whetten, a professor of chemical physics at the University of Texas, San Antonio, who led the team that first isolated Gold-144. “It seemed preposterous, to have two distinct structures that underlie its ubiquity, but this is a beautiful paper that will persuade a lot of people.”

Here’s an image illustrating the two shapes,

Setting out to confirm the predicted structure of Gold-144, researchers discovered an entirely unexpected atomic arrangement (right). The two structures, described in detail for the first time, each have 144 gold atoms, but are uniquely shaped, suggesting they also behave differently. (Courtesy of Kirsten Ørnsbjerg Jensen)

Setting out to confirm the predicted structure of Gold-144, researchers discovered an entirely unexpected atomic arrangement (right). The two structures, described in detail for the first time, each have 144 gold atoms, but are uniquely shaped, suggesting they also behave differently. (Courtesy of Kirsten Ørnsbjerg Jensen)

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

Polymorphism in magic-sized Au144(SR)60 clusters by Kirsten M.Ø. Jensen, Pavol Juhas, Marcus A. Tofanelli, Christine L. Heinecke, Gavin Vaughan, Christopher J. Ackerson, & Simon J. L. Billinge.  Nature Communications 7, Article number: 11859  doi:10.1038/ncomms11859 Published 14 June 2016

This is an open access paper.