Nanoparticle Delivery Vehicle Penetrates Mucus Layer

Nanoparticle Delivery Vehicle Penetrates Mucus Layer
Opens doors for local delivery of drugs

Nanoparticles coated with polyethylene glycol (PEG) easily penetrated human mucus in research performed at Johns Hopkins University. Researchers there suggested that drugs protected by a PEG coating could pass through the protective mucus barrier in order to deliver localized therapies more effectively.
We have improved the coatings considerably to allow faster penetration for a wider array of particle sizes.—Samuel K. Lai, PhD, Johns Hopkins University

Synthetic nanoparticles coated with low molecular weight PEG were able to move through undiluted human mucus at sizes of up to 500 microns, according to Samuel K. Lai, PhD, who presented the data at the American Chemical Society meeting in August. (Lai SK, Wang Y-Y, Hanes J. Engineering mucus penetrating particles for transmucosal delivery. Paper presented at: American Chemical Society National Meeting and Exposition; August 20, 2008; Philadelphia.)
“We studied the properties of disease-causing viruses that evolved to infect mucosal surfaces to engineer a coating that enables our drug delivery particles to penetrate mucus layers in minutes. In our new work, we have improved the coatings considerably to allow faster penetration for a wider array of particle sizes,” Dr. Lai said in a news release.
The human mucus barrier was, until recently, thought to be impenetrable to polymer particles as small as 59 nm, according to the abstract of Dr. Lai’s presentation. Because of this perceived barrier, research into long-lasting controlled-release delivery strategies for mucosal sites such as the lungs and the female reproductive tract has lagged, the abstract states.
While the low molecular weight PEG-coated nanoparticles moved easily through mucus, the researchers found that high molecular weight particles moved even more slowly than uncoated nanoparticles. The density of the PEG was “especially critical” with smaller-sized particles, the researchers said.
Drug delivery with this technology could potentially improve localized treatments in areas protected by mucosa, the researchers said. “For example, cervical cancer patients could locally apply chemo drugs inside mucus-penetrating particles, which would then deliver the drug locally in the female reproductive tract at efficient concentrations over prolonged periods of time, instead of delivering it everywhere else in the body,” Dr. Lai said in a news release. “That could drastically reduce the side effects as well as prolong the presence of drugs at the target site.”