Solvent molecular descriptors on poly(d, l-lactide-co-glycolide) particle size in emulsification–diffusion process

The size of poly(d, l-lactide-co-glycolide) (PLGA) nanoparticle was influenced by the thermodynamic parameters (after [Sung-Wook Choi, Hye-Young Kwon, Woo-Sik Kim, Jung-Hyun Kim, Colloids Surf. A Physicochem. Eng. Aspects 201 (2002) 283–289.]) such as mutual diffusion coefficients (exchange ratio, R) and solvent–polymer interaction parameters (χ). However, this study introduces the concept of solvent molecular descriptors for elucidating the effect of solvent on the PLGA nanoparticle size in the emulsification–diffusion method. The most pronounced effects on the nanoparticle sizes have the empirical hydrophilicity index Hy, and the molecular descriptors such as the Randic shape descriptor. More rigor results that various molecular descriptors have on the PLGA nanoparticle size are obtained by the molecular descriptors that correspond to the 3D structure of molecules (3D MoRSE descriptors, directional WHIM indicies and the GETAWAY [Geometry, Topology and Atom-Weights Assembly] molecular descriptors). The derived experimental data correlated well with information available from other procedures, confirming that this new approach provides complementary insight into the thermodynamics and the molecular nature of the polymer nanoparticle formation in the solvent type of chemical environments.