Influence of Size, Flexibility, Hydrophobicity, Surface Charge, and Surface Chemistry on the Biodistribution of Orally Administered Polymer Nanoparticles

The optimal pharmacokinetics (PK) of orally administered nanoparticles (NPs) varies depending on their application (e.g., drug delivery, adsorbent, and adjuvant). Therefore, engineering NPs to achieve optimal PK is essential for the development of drug designs. Some studies have demonstrated that individual NP factors change the intestinal absorption of NPs; however, no technology has been established to control the biodistribution of orally administered NPs. In this study, a database about the influence of NP characteristics on biodistribution after oral administration was provided. A library of N-isopropylacrylamide polymer NPs with various characteristics that could influence the biodistribution after oral administration, such as size, flexibility, hydrophobicity, surface charges, and surface chemistries, were prepared. NPs with various sizes were synthesized by tuning the surfactant concentration only during synthesis, whereas NPs with different flexibility, hydrophobicity, surface charge, and surface chemistry were synthesized by feeding the corresponding functional monomer. The total amount of NPs accumulated in the organs decreased with increasing NP size, rigidity, hydrophobicity, electric potential (whether positive or negative), and polyethylene glycol modification. The results indicated that the absorption of orally administered NPs can be controlled by optimizing the characteristics of NP such as size, flexibility, hydrophobicity, surface charge, and surface chemistry. The results of this study will provide useful information to design NP formulations.