<<返回上一页

Coated nanoparticles slip through mucus

发布时间:2019-02-27 06:14:05来源:未知点击:

By Mason Inman Nanoparticles with the right coating can quickly slip through human mucus, a new study shows. The results raise hopes for more efficient delivery of a variety of drugs. Mucus helps protect the lungs, intestines, vaginal tract, and other tissues. The thick mesh of proteins contained in mucus can capture bacteria and dirt, and then flush these invaders out. Previous research also found that mucus acts as a formidable barrier to nanoscopic particles. Nanoparticles about 500 nanometres in diameter show promise for drug delivery, since they are big enough to more easily contain a drug and release it over weeks or months, increasing the effectiveness of many therapies. However, studies have found that such nanoparticles usually become stuck in mucus. While nanoparticles less than 100 nm can often pass through mucus, they also leak drugs more rapidly, lessening the potential advantage. Now researchers have cracked the problem, with a cheap and easy way to make larger nanoparticles slip through mucus. The secret, say Justin Hanes and colleagues at Johns Hopkins University in Maryland, US, is to coat them with the molecule polyethylene glycol (PEG) – a simple, biodegradable polymer. Hanes’s team coated polystyrene nanospheres with PEG and filmed them under a microscope as they moved through mucus collected from a woman’s cervical-vaginal tract. Compared to uncoated nanoparticles, those covered with PEG travelled up to 1000 times more quickly and almost as easily as when diffusing through water. The researchers took inspiration from nature, noting that some viruses of similar size can move through mucus smoothly. They thought of using PEG because, like the viruses’ coatings, it should give particles a neutral charge and make them hydrophilic (attracted to water). These coatings seem to work by preventing the nanoparticles and viruses from sticking to the protein meshwork in the mucus. “Nobody had been suggesting any way to get nanoparticles through mucus,” Hanes told New Scientist. This method of drug delivery “could be used for literally most pharmaceuticals that are swallowed”, Hanes says. The nanoparticles could be encapsulated to survive the trip through the stomach, and then the PEG coating would allow them to slip through the intestine’s mucus layer. PEG-coated nanoparticles could also be used to deliver chemotherapy drugs straight to the cervix or vagina, Hanes says. And, since PEG is already widely used as a coating for pharmaceuticals, it has been proven safe. The findings “will have important implications for drug delivery”, says Robert Langer at MIT in the US. “The results might seem surprising at first,” but they have a good understanding of the mechanism behind it, he says. “A particularly important area might be in cystic fibrosis, where the lung mucus is very thick, and so is especially hard to get drugs through,” Langer adds. Journal reference: Proceedings of the National Academies of Science (DOI: