Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Coated nanoparticles solve sticky drug-delivery problem

26.01.2007
Researchers take cues from viruses to get treatment through body's protective

The layers of mucus that protect sensitive tissue throughout the body have an undesirable side effect: they can also keep helpful medications away. To overcome this hurdle, Johns Hopkins researchers have found a way to coat nanoparticles with a chemical that helps them slip through this sticky barrier.

During experiments with these coated particles, the researchers also discovered that mucus layers have much larger pores than previously thought, providing a doorway that should allow larger and longer-acting doses of medicine to reach the protected tissue.

The team's findings were reported this week in the Early Online Edition of Proceedings of the National Academy of Sciences.

... more about:
»Hanes »coat »mucus »nanometers »nanoparticle
The discoveries are important because mucus layers, which trap and help remove pathogens and other foreign materials, can block the localized delivery of drugs to many parts of the body, including the lungs, eyes, digestive tract and female reproductive system. Because of these barriers, doctors often must prescribe pills or injections that send drugs through the entire body, an approach that can lead to unwanted side effects or doses that are too weak to provide effective treatment.

"Mucus barriers evolved to serve a helpful purpose: to keep things out," said Justin Hanes, an associate professor of chemical and biomolecular engineering who supervised the research. "But if you want to deliver medicine in a microscopic particle, they can also keep the drugs from getting through. We've found a way to keep helpful nanoparticles from sticking to mucus, and we learned that the openings in the mucus 'mesh' are much larger than most people expected. These findings set the stage for a new generation of nanomedicines that can be delivered directly to the affected areas."

To get its particles past the mucus, Hanes' team studied an unlikely model: viruses. Earlier research led by Richard Cone, a professor in the Department of Biophysics at Johns Hopkins, had established that some viruses are able to make their way through the human mucus barrier. Hanes and his colleagues decided to look for a chemical coating that might mimic the characteristics of a virus.

"We found that the viruses that got through had surfaces that were attracted to water, and they had a net neutral electrical charge," said Samuel K. Lai, a Johns Hopkins chemical and biomolecular engineering doctoral student from Canada and Hong Kong who was lead author of the journal article. "We thought that if we could coat a drug-delivery nanoparticle with a chemical that had these characteristics, it might not get stuck in the mucus barrier."

To make their nanoparticles behave like viruses, the researchers coated them with polyethylene glycol, PEG, a non-toxic material commonly used in pharmaceuticals. PEG dissolves in water and is excreted harmlessly by the kidneys.

The researchers also considered the size of their nanoparticles. Previous studies indicated that even if nanoparticles did not stick to the mucus, they might have to be smaller than 55 nanometers wide to pass through the tiny openings in the human mucus mesh. (A human hair is roughly 80,000 nanometers wide.) Using high-resolution video microscopy and computer software, the researchers discovered that their PEG-coated 200-nanometer particles could slip through a barrier of human mucus.

They then conducted further tests to see how large their microscopic drug carriers could be before they got trapped in the mesh. Larger nanoparticles are more desirable because they can release greater amounts of medicine over a longer period of time. "We wanted to make the particles as large as possible," said Hanes, who also serves as director of therapeutics for the Institute for NanoBioTechnology at Johns Hopkins. "The shocking thing was how fast the particles that were 500 nanometers wide moved through the mucus mesh. The work suggests that the openings in the mucus barrier are much larger than originally expected by most. And we were also surprised to find that the larger nanoparticles (200 and 500 nanometers wide) actually moved through the mucus layer more quickly than the smaller ones (100 nanometers wide)."

This has important implications, Hanes said, because a 500-nanometer particle can be used to deliver medicine to a targeted area, released over periods of days to weeks. Larger particles also allow a wider array of drug molecules to be efficiently encapsulated. He and his colleagues believe this system has great potential in the delivery of chemotherapy, antibiotics, nucleic acids and other treatment directly to the lungs, gastrointestinal tract and cervicovaginal tract.

Phil Sneiderman | EurekAlert!
Further information:
http://www.jhu.edu/chbe/
http://www.jhu.edu/~cheme/hanes/

Further reports about: Hanes coat mucus nanometers nanoparticle

More articles from Life Sciences:

nachricht A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht On the way to developing a new active ingredient against chronic infections
18.08.2017 | Deutsches Zentrum für Infektionsforschung

All articles from Life 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

A Map of the Cell’s Power Station

18.08.2017 | Life Sciences

Engineering team images tiny quasicrystals as they form

18.08.2017 | Physics and Astronomy

Researchers printed graphene-like materials with inkjet

18.08.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>