Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International



Home > Press > Antioxidants get small: Molecular compounds mimic effective graphene agents, show potential for therapies

The crystal structure of PEG-PDI is achieved using cobaltocene as a reducing agent and omitting solvents and hydrogen atoms for clarity. Carbon atoms are gray, nitrogens are blue, oxygens red and cobalts purple. The molecules created by scientists at Rice University, the McGovern Medical School at the University of Texas Health Science Center at Houston and Baylor College of Medicine are efficient antioxidants and help scientists understand how larger nanoparticles quench damaging reactive oxygen species in the body.
CREDIT
Tour Group/Rice University
The crystal structure of PEG-PDI is achieved using cobaltocene as a reducing agent and omitting solvents and hydrogen atoms for clarity. Carbon atoms are gray, nitrogens are blue, oxygens red and cobalts purple. The molecules created by scientists at Rice University, the McGovern Medical School at the University of Texas Health Science Center at Houston and Baylor College of Medicine are efficient antioxidants and help scientists understand how larger nanoparticles quench damaging reactive oxygen species in the body. CREDIT Tour Group/Rice University

Abstract:
Treated particles of graphene derived from carbon nanotubes have demonstrated remarkable potential as life-saving antioxidants, but as small as they are, something even smaller had to be created to figure out why they work so well.

Antioxidants get small: Molecular compounds mimic effective graphene agents, show potential for therapies

Houston, TX | Posted on January 27th, 2017

Researchers at Rice University, the McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth) and Baylor College of Medicine created single-molecule compounds that also quench damaging reactive oxygen species (ROS) but are far easier to analyze using standard scientific tools. The molecules may become the basis for new antioxidant therapies in their own right.

The research appears in the American Chemical Society journal ACS Nano.

The original compounds are hydrophilic carbon clusters functionalized with polyethylene glycol, known as PEG-HCCs and created by Rice and Baylor scientists five years ago. The particles help neutralize ROS molecules overexpressed by the body's cells in response to an injury before they damage cells or cause mutations.

PEG-HCCs show promise for treating cancer, rebooting blood flow in the brain after traumatic injury and controlling chronic diseases.

The new particles, called PEG-PDI, consist of polyethylene glycol and perylene diimide, a compound used as a dye, the color in red car paint and in solar cells for its light-absorbing properties. Their ability to accept electrons from other molecules makes them functionally similar to PEG-HCCs. They're close enough to serve as an analog for experiments, according to Rice chemist James Tour, who led the study with University of Texas biochemist Ah-Lim Tsai.

The researchers wrote that the molecule is not only the first example of a small molecular analogue of PEG-HCCs, but also represents the first successful isolation of a PDI radical anion as a single crystal, which allows its structure to be captured with X-ray crystallography.

"This allows us to see the structure of these active particles," Tour said. "We can get a view of every atom and the distances between them, and get a lot of information about how these molecules quench destructive oxidants in biological tissue.

"Lots of people get crystal structures for stable compounds, but this is a transient intermediate during a catalytic reaction," he said. "To be able to crystallize a reactive intermediate like that is amazing."

PEG-HCCs are about 3 nanometers wide and 30 to 40 nanometers long. By comparison, much simpler PEG-PDI molecules are less than a nanometer in width and length.

PEG-PDI molecules are true mimics of superoxide dismutase enzymes, protective antioxidants that break down toxic superoxide radicals into harmless molecular oxygen and hydrogen peroxide. The molecules pull electrons from unstable ROS and catalyze their transformation into less-reactive species.

Testing the PEG-PDI molecules can be as simple as putting them in a solution that contains reactive oxygen species molecules like potassium superoxide and watching the solution change color. Further characterization with electron paramagnetic resonance spectroscopy was more complicated, but the fact that it's even possible makes them powerful tools in resolving mechanistic details, the researchers said.

Tour said adding polyethylene glycol makes the molecules soluble and also increases the amount of time they remain in the bloodstream. "Without PEG, they just go right out of the system through the kidneys," he said. When the PEG groups are added, the molecules circulate longer and continue to catalyze reactions.

He said PEG-PDI is just as effective as PEG-HCCs if measured by weight. "Because they have so much more surface area, PEG-HCC particles probably catalyze more parallel reactions per particle," Tour said. "But if you compare them with PEG-PDI by weight, they are quite similar in total catalytic activity."

Understanding the structure of PEG-PDI should allow researchers to customize the molecule for applications. "We should have a tremendous ability to modify the molecule's structure," he said. "We can add anything we want, exactly where we want, for specific therapies."

The researchers said PEG-PDI may also be efficient metal- and protein-free catalysts for oxygen reduction reactions used in industry and essential to fuel cells. They are intrinsically more stable than enzymes and can function in much a wider pH range, Tsai said.

Co-author Thomas Kent, a professor of neurology at Baylor who has worked on the project from the start, noted small molecules have a better chance to get on the fast track to approval for therapy by the Food and Drug Administration than nanotube-based agents. "A small molecule that is not derived from larger nanomaterial may have a better chance of approval to use in humans, assuming it is safe and effective," he said.

Tour said PEG-PDI serves as a precise model for other graphene derivatives like graphene oxide and permits a more detailed study of graphene-based nanomaterials. "Making nanomaterials smaller, from well-defined molecules, permits 150 years of synthetic chemistry methods to address the mechanistic questions within nanotechnology," he said.

###

Almaz Jalilov, a Rice alumnus and now a professor at King Fahd University of Petroleum and Minerals, Saudi Arabia, is lead author of the study. Co-authors are graduate students Lizanne Nilewski and Chenhao Zhang of Rice; senior research scientist Vladimir Berka and instructor Wu Gang of the McGovern Medical School at UTHealth; and assistant chemist Andrey Yakovenko of Argonne National Laboratory. Tour is the T.T. and W.F. Chao Chair in Chemistry as well as a professor of computer science and of materials science and nanoengineering at Rice. Tsai is a professor at UTHealth.

The National Institutes of Health and the Dunn Foundation supported the research.

####

About Rice University
Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,910 undergraduates and 2,809 graduate students, Rice's undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for happiest students and for lots of race/class interaction by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to http://tinyurl.com/RiceUniversityoverview .

Follow Rice News and Media Relations via Twitter @RiceUNews

For more information, please click here

Contacts:
David Ruth

713-348-6327

Copyright © Rice University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

Read the abstract at:

"Nano-antioxidants prove their potential":

The Tour Group:

Ah-Lim Tsai bio:

Rice Department of Chemistry:

Wiess School of Natural Sciences:

Related News Press

News and information

Hanging by a thread: Imaging and probing chains of single atoms: Scientists develop a method to visualize monoatomic chains and measure the strength and conductance of single-atom bonds May 14th, 2021

Nanophotonics enhanced coverslip for phase imaging in biology May 14th, 2021

New technology enables rapid sequencing of entire genomes of plant pathogens May 14th, 2021

Harvesting light like nature does:Synthesizing a new class of bio-inspired, light-capturing nanomaterials May 14th, 2021

Graphene/ Graphite

Graphene key for novel hardware security May 10th, 2021

Oregon scientists create mechanism to precisely control soundwaves in metamaterials: Theoretical modeling shows that designer materials incorporating drum-like membranes allow precise stoppage and reversal of sound pulses April 16th, 2021

Better metric for thermoelectric materials means better design strategies: New quantity helps experimentally classify dimensionality of thermoelectric materials April 15th, 2021

Better metric for thermoelectric materials means better design strategies: New quantity helps experimentally classify dimensionality of thermoelectric materials April 15th, 2021

Govt.-Legislation/Regulation/Funding/Policy

Hanging by a thread: Imaging and probing chains of single atoms: Scientists develop a method to visualize monoatomic chains and measure the strength and conductance of single-atom bonds May 14th, 2021

Nanophotonics enhanced coverslip for phase imaging in biology May 14th, 2021

New technology enables rapid sequencing of entire genomes of plant pathogens May 14th, 2021

Harvesting light like nature does:Synthesizing a new class of bio-inspired, light-capturing nanomaterials May 14th, 2021

Possible Futures

Emergence of a new heteronanostructure library May 14th, 2021

New technology enables rapid sequencing of entire genomes of plant pathogens May 14th, 2021

Harvesting light like nature does:Synthesizing a new class of bio-inspired, light-capturing nanomaterials May 14th, 2021

You're so vein: Scientists discover faster way to manufacture vascular materials May 14th, 2021

Nanomedicine

Implantable 'living pharmacy' could control body's sleep/wake cycles: Project receives DARPA contract worth up to $33 million over 4 1/2 years May 13th, 2021

Tiny, Wireless, Injectable Chips Use Ultrasound to Monitor Body Processes May 12th, 2021

World's first fiber-optic ultrasonic imaging probe for future nanoscale disease diagnostics April 30th, 2021

Arrowhead Announces Improvement in Fibrosis after ARO-AAT Treatment in Patients with Alpha-1 Liver Disease April 28th, 2021

Discoveries

Emergence of a new heteronanostructure library May 14th, 2021

Hanging by a thread: Imaging and probing chains of single atoms: Scientists develop a method to visualize monoatomic chains and measure the strength and conductance of single-atom bonds May 14th, 2021

Nanophotonics enhanced coverslip for phase imaging in biology May 14th, 2021

You're so vein: Scientists discover faster way to manufacture vascular materials May 14th, 2021

Announcements

Emergence of a new heteronanostructure library May 14th, 2021

Nanophotonics enhanced coverslip for phase imaging in biology May 14th, 2021

New technology enables rapid sequencing of entire genomes of plant pathogens May 14th, 2021

Harvesting light like nature does:Synthesizing a new class of bio-inspired, light-capturing nanomaterials May 14th, 2021

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers/Posters

Hanging by a thread: Imaging and probing chains of single atoms: Scientists develop a method to visualize monoatomic chains and measure the strength and conductance of single-atom bonds May 14th, 2021

Nanophotonics enhanced coverslip for phase imaging in biology May 14th, 2021

New technology enables rapid sequencing of entire genomes of plant pathogens May 14th, 2021

Harvesting light like nature does:Synthesizing a new class of bio-inspired, light-capturing nanomaterials May 14th, 2021

Grants/Sponsored Research/Awards/Scholarships/Gifts/Contests/Honors/Records

Hanging by a thread: Imaging and probing chains of single atoms: Scientists develop a method to visualize monoatomic chains and measure the strength and conductance of single-atom bonds May 14th, 2021

Nanophotonics enhanced coverslip for phase imaging in biology May 14th, 2021

New brain-like computing device simulates human learning: Researchers conditioned device to learn by association, like Pavlov's dog April 30th, 2021

Silver ions hurry up, then wait as they disperse: Rice chemists show ions’ staged release from gold-silver nanoparticles could be useful property April 23rd, 2021

Nanobiotechnology

Implantable 'living pharmacy' could control body's sleep/wake cycles: Project receives DARPA contract worth up to $33 million over 4 1/2 years May 13th, 2021

Tiny, Wireless, Injectable Chips Use Ultrasound to Monitor Body Processes May 12th, 2021

Arrowhead Announces Improvement in Fibrosis after ARO-AAT Treatment in Patients with Alpha-1 Liver Disease April 28th, 2021

Synthetic gelatin-like material mimics lobster underbelly’s stretch and strength: The membrane’s structure could provide a blueprint for robust artificial tissues April 23rd, 2021

Research partnerships

Nanophotonics enhanced coverslip for phase imaging in biology May 14th, 2021

Implantable 'living pharmacy' could control body's sleep/wake cycles: Project receives DARPA contract worth up to $33 million over 4 1/2 years May 13th, 2021

Graphene key for novel hardware security May 10th, 2021

Silver ions hurry up, then wait as they disperse: Rice chemists show ions’ staged release from gold-silver nanoparticles could be useful property April 23rd, 2021

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project