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 Superconductivity research reveals potential new state of matter
17.08.2017 | DOE/Los Alamos National Laboratory

nachricht Spray-on electric rainbows: Making safer electrochromic inks
17.08.2017 | Georgia Institute of Technology

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Gold shines through properties of nano biosensors

17.08.2017 | Physics and Astronomy

Greenland ice flow likely to speed up: New data assert glaciers move over sediment, which gets more slippery as it gets wetter

17.08.2017 | Earth Sciences

Mars 2020 mission to use smart methods to seek signs of past life

17.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>