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

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

3rd Symposium on Driving Simulation

23.10.2017 | Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

 
Latest News

Introduction of a novel system for in vitro analyses of zebrafish oligodendrocyte progenitor cells

23.10.2017 | Life Sciences

Did you know how many parts of your car require infrared heat?

23.10.2017 | Automotive Engineering

3rd Symposium on Driving Simulation

23.10.2017 | Event News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>