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 design improves performance of flexible wearable electronics
23.06.2017 | North Carolina State University

nachricht Plant inspiration could lead to flexible electronics
22.06.2017 | American Chemical Society

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Supersensitive through quantum entanglement

28.06.2017 | Physics and Astronomy

X-ray photoelectron spectroscopy under real ambient pressure conditions

28.06.2017 | Physics and Astronomy

Mice provide insight into genetics of autism spectrum disorders

28.06.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>