Nav: Home

Microcapsules gain a new power -- scavenging reactive oxygen species

January 30, 2018

BIRMINGHAM, Ala. - Stable, biocompatible microcapsules from the lab of Eugenia Kharlampieva, Ph.D., have gained a new power -- the ability to scavenge reactive oxygen species.

This may aid microcapsule survival in the body as the tiny polymer capsules carry a drug or other biomolecules, says Kharlampieva, associate professor of chemistry in the University of Alabama at Birmingham College of Arts and Sciences. The microcapsules may also find use in antioxidant therapy or in industrial applications where scavenging of free radicals is needed.

Reactive oxygen species play a Janus-like role in the body -- they can be a weapon against pathogens when produced by the immune system; but excess production of reactive oxygen species during biological stress can damage human cells in diseases like diabetes, atherosclerosis, Alzheimer's disease, kidney disease and cancer.

Current natural and synthetic antioxidants lack biocompatibility and bioavailability, and they are chemically unstable. This means they have a limited capability to scavenge reactive oxygen species. The new microcapsules do not show these limitations, and they may provide a way to locally modulate oxidative stress.

Kharlampieva and colleagues describe the construction and properties of these new microcapsules in the paper "Manganoporphyrin-polyphenol multilayer capsules as radical and ROS scavengers," published in Chemistry of Materials, a publication of the American Chemical Society. Graduate student Aaron Alford and research associate Veronika Kozlovskaya, Ph.D., are co-first authors, and Hubert Tse, Ph.D., associate professor of microbiology in the UAB School of Medicine, is co-corresponding author with Kharlampieva.

The UAB researchers have previous experience making and testing biocompatible microcapsules with alternating layers of tannic acid and poly(N-vinylpyrrolidone), or TA/PVPON. The layers are formed around a sacrificial core, such as solid silica, that is dissolved after the layers are complete.

Tannic acid is a natural antioxidant, and the TA/PVPON microcapsules have some reactive oxygen species-scavenging ability. However, they lose that ability and begin to degrade with prolonged exposure to the oxygen radicals.

So, the Kharlampieva team explored adding a metalloporphyrin to the PVPON layer of the TA/PVPON microcapsules.

Specifically, they devised a synthesis to covalently attach a manganoporphyrin to the PVPON. The addition of this pendant catalyst created an MnP-PVPON/TA capsule with the following characteristics: 1) the microcapsules synergistically remove reactive oxygen species, including superoxide and hydrogen peroxide, at dramatically increased rates compared to unmodified TA/PVPON microcapsules; 2) the microcapsule does not degrade with long exposure to reactive oxygen species; and 3) the microcapsules are nontoxic to mouse splenocytes.

Furthermore, the manganoporphyrin was stably contained within the microcapsule without release, and researchers showed that both manganoporphyrin and tannic acid were required for the synergistic scavenging of reactive oxygen species.

The presence of the manganoporphyrin did not interfere with the alternate-layer construction of the microcapsules, and the MnP-PVPON/TA capsules had increased wettability compared to the PVPON/TA capsule, which may aid microcapsule maintenance in the blood. The microcapsules had five or five and a half bilayers placed around a 4-micrometer silica particle.

Biological experiments with the MnP-PVPON/TA capsules are underway.
-end-
Besides Alford, Kozlovskaya, Tse and Kharlampieva, co-authors are Bing Xue, Nirzari Gupta and William Higgins, UAB Department of Chemistry; Dana Pham-Hua, UAB Department of Microbiology; and Lilin He and Volker S. Urban, Oak Ridge National Laboratory, Oak Ridge, Tennessee.

Support for this work came from National Science Foundation grant DMR 1608728, National Institutes of Health grant DK099550, American Diabetes Association Career Development Award 7-12-CD-11 and Juvenile Diabetes Research Foundation Award 1-SRA-2015-42-AN.

University of Alabama at Birmingham

Related Free Radicals Articles:

Research measures potentially damaging free radicals in cigarette smoke
Smoking cigarettes can lead to illness and death. Free radicals, which are atoms or groups of atoms with unpaired electrons, in inhaled smoke are thought to be partly responsible for making smokers sick.
How to measure potentially damaging free radicals in cigarette smoke
Smoking cigarettes can lead to illness and death. Free radicals, which are atoms or groups of atoms with unpaired electrons, in inhaled smoke are thought to be partly responsible for making smokers sick.
Where belief in free will is linked to happiness
Free will describes the ability to make independent choices, where the outcome of the choice is not influenced by past events.
Should gluten-free foods be available on prescription?
In The BMJ this week, experts debate whether gluten-free prescriptions for people with coeliac disease should be removed.
Semiconductor-free microelectronics are now possible, thanks to metamaterials
Engineers at the University of California San Diego have fabricated the first semiconductor-free, optically-controlled microelectronic device.
Future therapeutics: Drugs that stop free radicals at their source
Researchers at the Buck Institute have stopped free radicals from being produced at their source.
Low-cost and defect-free graphene
Graphene is one of the most promising new materials. However, researchers across the globe are still looking for a way to produce defect-free graphene at low costs.
New movie screen allows for glasses-free 3-D
In a new paper, a team from MIT's Computer Science and Artificial Intelligence Lab and Israel's Weizmann Institute of Science have demonstrated a display that lets you watch 3-D films in a movie theater without extra eyewear.
What free will looks like in the brain
Johns Hopkins University researchers are the first to glimpse the human brain making a purely voluntary decision to act.
How to get moral 'free-riders' to cooperate
What motivates people to contribute to trustful moral judgment, which is a public good yet tends to be costly?

Related Free Radicals Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Bias And Perception
How does bias distort our thinking, our listening, our beliefs... and even our search results? How can we fight it? This hour, TED speakers explore ideas about the unconscious biases that shape us. Guests include writer and broadcaster Yassmin Abdel-Magied, climatologist J. Marshall Shepherd, journalist Andreas Ekström, and experimental psychologist Tony Salvador.
Now Playing: Science for the People

#513 Dinosaur Tails
This week: dinosaurs! We're discussing dinosaur tails, bipedalism, paleontology public outreach, dinosaur MOOCs, and other neat dinosaur related things with Dr. Scott Persons from the University of Alberta, who is also the author of the book "Dinosaurs of the Alberta Badlands".