Navigation Links
Triple threat polymer captures and releases

A chemist at Washington University in St. Louis has developed a remarkable nanostructured material that can repel pests , sweeten the air, and some day might even be used as a timed drug delivery system –as a nasal spray, for instance.

Karen L. Wooley, Ph.D., Washington University James S. McDonnell Distinguished University Professor in Arts & Sciences, has taken the same materials that she developed more than four years ago as marine "antifouling" coatings that inhibit marine organisms such as barnacles from attaching to the hull of ships to now capture fragrance molecules and release them at room temperature.

Wooley mixes two normally incompatible polymers -- a hyperbranched fluoropolymer and a linear polyethylene glycol -- and lets them phase-separate into distinct domains, one interspersed in the other. A chemical process called crosslinking then solidifies the mixture, thus creating a heterogeneous coating that, upon close examination, reveals treacherous nanometer-sized terrain composed of mountains and valleys, ranging from hard to soft, hydrophilic to hydrophobic. The complex surface that is created makes it difficult for marine organisms to establish a toehold. Her laboratory has produced these novel materials and they are being used around the world

Wooley and her collaborators were intrigued by the surface of these nanostructured materials and began to wonder what was beneath the surface. They found that their materials made a perfect host to serve guest molecules.

"We looked at the roughness and complexity of the surface and thought that the surface might provide interesting entrance and exit ports for small molecule guests," Wooley explained."So , our material would be a host that would act like a sponge, because we have this complex subsurface morphology, and we thought of it as being domains that might be like holes in sponges and other domains that might be like sponge material."

Be my guest

The subsurface composition and properties might thereby allow the guests to partition off into one domain and then another guest partition into another domain.

"We have these channels to serve as capillaries to take in guest molecules and hold them inside the material,," said Wooley, a member of Washington University's Center for Materials Innovation, (CMI) which enables collaborators from across the Washington University campus to make basic and applied advances in materials research, touching many aspects of daily life..

She and her group received a research grant from Imperial Chemical Industries/National Starch to continue their study, with a goal of taking the guest molecules in and holding them. Using the technology of thermogravimetric analysis (TGA), Gerald O. Brown, Ph.D., a postdoctoral research associate in Wooley's group, began analyzing the release of these guests ?fragrance molecules ?as gaseous small molecules from the polymer across the network of the host material.

"We found that the temperatures at which the guests left the material were dependent on the composition of the host, and when the release of the small guest molecules was monitored from just an empty TGA pan, there was a slight difference versus those guests in the presence of either the hyperbranched fluoropolymer or the polyethylene glycol," she said. "There is a slight depression of temperature at which the small molecule fragrance volatilizes and becomes a gas."

However ,when they looked at the complex materials ?the ones designed to be anti-fouling materials -- they found a progression of decreasing temperature as they went with different amounts of poly(ethylene glycol) relative to hyperbranched fluoropolymer in the composite material.

"What's amazing is that there is a 55 degree temperature reduction at which this small molecule leaves the host material versus it leaving an empty pan,, she said. "Then we thought th at this material could be very useful as something to promote the release of a volatile agent ?maybe for some kind of nasal inhalation-based delivery of drugs. Or maybe something as simple as a room temperature release of a fragrance.."

Sponge analogy

Wooley said that they don't know where the guest molecules are residing in the host material, and her group is now inserting stable isotopes into the host and guest molecules and with the help of her colleague Jacob Schaefer, Ph.D., Washington University Charles Allen Thomas Professor of Chemistry, will measure the difference between those stable isotopes to help find where the guests are located relative to the host..

"We want to know where they reside because that should tell us why this material is providing a favorable environment at room temperature but at elevated temperature for some reason everything is being expelled rapidly,," she said. "We don't know if there is some reorganization of the morphology of the material or whether the guests partition to different domains at different temperatures."

Wooley says that the results of her research with the polymers ?the promoted release, the anti-fouling application ?are "strange, if not weird, but there is so much going on here, we want to explore it all.."

That weirdness suggests equally weird mechanical properties. Wooley and her post doctoral researcher Jinqi Xu, Ph.D., are exploring those properties and one essential irony ?the material, similar to a hydrogel because it takes in water, oddly becomes stronger when water absorbs into it. Think of a soggy diaper as a hydrogel. If you liken Wooley' s materials to a diaper, that wet one becomes nearly petrified. That's known as an increased modulus value ?a measure of stress versus strain.

"When you pull on a sponge, the water comes back out," she said. "But in our case, because our sponge and the channels within it are essentially nanosco pic, the water cannot get out, at least not fast enough to allow for a reorganization of the material, and therefore it just rigidifies the material."


Source:Washington University in St. Louis

Related biology news :

1. Triple threat: World fin trade may harvest up to 73 million sharks per year
2. Triplex assay used to assay duplex genomic DNA
3. Scientists decipher genome of fungus that can cause life-threatening infections
4. Essential mangrove forest threatened by cryptic ecological degradation
5. Simple drug has the potential to save many lives threatened by malaria
6. Alien woodwasp, threat to US pine trees, found in N.Y.
7. Poaching, logging, and outbreaks of Ebola threaten central African gorillas and chimpanzees
8. Acid water in East Java threatens biodiversity and local welfare
9. Hurricane aftermath: Infectious disease threats from common, not exotic, diseases
10. Does manganese inhaled from the shower represent a public health threat?
11. Logging doubles threat to the Amazon, rivaling clear-cutting, study suggests
Post Your Comments:

(Date:11/19/2015)... YORK , Nov. 19, 2015  Although some ... market is dominated by a few companies, according to ... companies own 51% of the market share of the ... The World Market for Molecular Diagnostic s ... "The market is still controlled by one company ...
(Date:11/17/2015)... PARIS , November 17, 2015 ... 17 au 19 novembre  2015.  --> Paris ... 2015.  --> DERMALOG, le leader de l,innovation ... à la fois passeports et empreintes sur la même ... pour les passeports et l,autre pour les empreintes digitales. ...
(Date:11/12/2015)...  A golden retriever that stayed healthy despite having ... provided a new lead for treating this muscle-wasting disorder, ... of MIT and Harvard and the University of São ... Cell, pinpoints a protective gene that boosts ... The Boston Children,s lab of Lou Kunkel , ...
Breaking Biology News(10 mins):
(Date:11/24/2015)... ... , ... InSphero AG, the leading supplier of easy-to-use solutions for production, culture, ... serve as Chief Operating Officer. , Having joined InSphero in November 2013 ... was promoted to Head of InSphero Diagnostics in 2014. There she has built ...
(Date:11/24/2015)... - ProMetic Life Sciences Inc. (TSX: PLI) (OTCQX: PFSCF) ("ProMetic" ... , President and Chief Executive Officer of ProMetic, will be ... th Annual Healthcare Conference to be held at the ... st , at 8.50am (ET) and ProMetic,s management team ... presentation will be available live via a webcast accessible at ...
(Date:11/24/2015)... 2015 HemoShear Therapeutics, LLC, a privately ... metabolic disorders, announced today the appointment of ... Directors (BOD). Mr. Watkins is the former president ... (HGS), and also served as the chairman of ... , Chairman and CEO of HemoShear Therapeutics. "The ...
(Date:11/24/2015)... YORK , November 24, 2015 ... in a European healthcare ... which the companies will work closely together in identifying European ... unmet medical need. The collaboration is underpinned by a significant ... fund. This is the first investment by Bristol-Myers Squibb in ...
Breaking Biology Technology: