Quantifying Transport of Polymer-Coated Nanoparticles through Mucus

Mucus coats lung epithelial cells to protect them from foreign particles inhaled during breathing. The mucus, composed of mainly water and mucins, forms a barrier of hydrophobic and hydrophilic domains that limit particles diffusion. While the mucus layer protects the underlying cells from foreign particulates, it also hinders drug transport to those cells to treat diseases such as respiratory infections. We are designing polymer coatings for gold nanoparticles (GNP) that avoid interactions with mucins to traverse through mucus faster than uncoated nanoparticles. To quantify the effect of the polymer coatings GNP diffusion through mucus, the concentration of GNPs that passed through a defined layer of mucus was measured over multiple hours. The diffusion rates between uncoated GNPs and polymer-coated GNPs were compared. Early trials were conducted with Carbopol gels because the gel’s rheological properties are easily tunable to mimic pulmonary mucus. To verify the experimental methods, initial diffusion trials were completed with small dye molecules and fluorescent nanoparticles. Varying the viscosity of the Carbopol gel layer resulted in different transport kinetics with the less viscous gel having faster transport. Slug mucus was then used as a replacement for the Carbopol for a more realistic mucus layer. Initial trials showed rapid diffusion of polymer-coated GNP in the first hour with no diffusion in subsequent hours. Further studies will focus on understanding how the size of the polymer effects GNP diffusion through both slug mucus and synthetic mucin-based hydrogels.