Biodegradable nanoparticles penetrate mucosal surfaces

Mucus secretions play an important role in the immune system by immobilizing foreign particles and neutralizing invading pathogens. The protective effect of these slippery linings that coat the eyes, airways, and other organs, however, prevents the effective delivery of therapeutics. Benjamin Tang et al. developed a biodegradable nanoparticle that may be able to penetrate thick mucus layers, including sputum from cystic fibrosis patients. The authors composed nanoparticles from copolymers of hydrophobic poly(sebacic acid) (PSA) and low molecular weight poly(ethylene glycol) (PEG), both of which are routinely used in patients. In human cervicovaginal mucus, PSA-PEG nanoparticles diffused at an average speed 12 lower than the same particles in pure water, whereas similarly sized nanoparticles composed exclusively of PSA diffused at least 3,300 slower than in water. The nanoparticles showed similar movement in sputum expectorated by cystic fibrosis patients. Hydrophilic PEG partitioned to the nanoparticles’ surfaces, reducing particle aggregation and allowing rapid transport in mucus. Encapsulation of drugs and genes in these copolymer particles may allow for the sustained release of therapeutics at these organ barriers, potentially improving treatment options for cervicovaginal disorders, cystic fibrosis, and other diseases, according to the authors. — F.A.