Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Creating polymers that act like biomolecules

01.04.2004


Ames Laboratory researchers studying self-assembling polymers



A group of bioinspired polymers are being studied by researchers at the Department of Energy’s Ames Laboratory to understand how they are able to form and react to stimuli similar to the way proteins, lipids and DNA react in nature. Unlocking how these soluble block polymers are able to self-assemble could potentially lead to a variety of uses such as controlled release systems for sustained and modulated delivery of drugs or gene therapies.

Ames Laboratory materials chemist Surya Mallapragada and her research team are focusing on pentablock polymers - polymers that form in strings of five chains. Each string is comprised of two cationic (positively charged) blocks, two hydrophilic (water loving) blocks, and one hydrophobic block. Because the hydrophobic block tries to avoid water, it forms the center of the string, with the hydrophilic next and the cationic blocks on the outside. In solution, these strings form in small clusters called micelles, again with the hydrophobic blocks at the center.


"The interesting thing about these polymers is that they respond to changes in temperature and pH," Mallapragada says. "As the temperature goes up, the micelles cluster together more, forming a polymer gel. A similar reaction takes place as pH rises - the hydrophobicity of the cationic blocks increases which also helps in gel formation."

As temperature and/or pH drops, the process reverses itself and the gels dissolve back into micelles and polymer strands. Using cryotransmission electron microscopy, Mallapragada’s group is working to understand just how these micelles look and how fast the polymers respond to changes in temperature and pH.

"Samples are plunged into liquid ethane which freezes them so quickly that ice doesn’t form and disrupt the crystal structure," she says. "We’re able to then view the gel formation at various stages (temperature and pH) under very controlled conditions." She adds that this work will be complemented by conducting x-ray scattering studies at the Advanced Photon Source facility at the DOE’s Argonne National Laboratory.

The structure appears to be the key in how the polymers react to stimuli similar to the way biomolecules react in nature. These substances carry out a wide variety of tasks, responding to subtle changes in body chemistry regulating those changes. The problem in working with proteins and similar biomolecules, according to Mallapragada, is that it is difficult to isolate the materials without damaging them.

"Biomolecules often exist in extremely small quantities," she says, "and are not very robust. In separating them from a source, they become denatured or damaged. The polymers we are studying are much more stable, readily available and therefore easier to study."

Because they are easier to work with, the polymers could potentially be modified and used as a way to deliver drugs or gene therapies. For example, incorporating the glucose oxidase enzyme in the polymer would make it sensitive to changes in glucose levels in the body. Soluble at room temperature, the polymer could be injected under the skin where it would form in a gel due to the higher temperature of the body. When the gluconic acid level falls, the resulting drop in pH would cause the polymer to swell and release insulin.

The injectable gels would be much less invasive than surgically implanting automatic insulin delivery systems and the gels would dissolve on their own after about a week.

For potential gene therapies, the positively charged (cationic blocks) polymers can complex with DNA (negatively charged). The polymers could be used to deliver so-called suicide genes and chemotherapy drugs directly and selectively to tumors, since normal cells would be less likely to react with the polymer and express the incorporated gene.

A preliminary invivo study in rats is now underway in conjunction with the John Stoddard Cancer Center at Iowa Methodist Medical Center in Des Moines. The basic research on polymer synthesis and characterization is funded by the DOE’s Office of Basic Energy Sciences. The gene therapy and bioapplication work is funded by a Bailey Career Development Grant.


###
Ames Laboratory is operated for the DOE by Iowa State University. The Lab conducts research into various areas of national concern, including energy resources, high-speed computer design, environmental cleanup and restoration, and the synthesis and study of new materials. More information about the Ames Laboratory can be found at http://www.ameslab.gov.

Contacts:
Surya Mallapragada, 515-294-7407, suryakm@iastate.edu
Kerry Gibson, Public Affairs, 515-294-1405, kgibson@ameslab.gov

Surya Mallapragada | EurekAlert!
Further information:
http://www.external.ameslab.gov/

More articles from Materials Sciences:

nachricht New concept for structural colors
18.05.2018 | Technische Universität Hamburg-Harburg

nachricht Saarbrücken mathematicians study the cooling of heavy plate from Dillingen
17.05.2018 | Universität des Saarlandes

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

Im Focus: Entangled atoms shine in unison

A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.

The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Designer cells: artificial enzyme can activate a gene switch

22.05.2018 | Life Sciences

PR of MCC: Carbon removal from atmosphere unavoidable for 1.5 degree target

22.05.2018 | Earth Sciences

Achema 2018: New camera system monitors distillation and helps save energy

22.05.2018 | Trade Fair News

VideoLinks
Science & Research
Overview of more VideoLinks >>>