Decoding the Influence of Polyvinyl Alcohol on the Functionalization and Cellular Uptake of Poly(lactic-co-glycolic) Acid Nanoparticles

Poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) are widely investigated drug delivery systems, yet efficient surface functionalization remains challenging. Here, we demonstrate that residual polyvinyl alcohol (PVA), commonly used as a stabilizer during nanoparticle preparation, remains strongly associated with the surface of PLGA NPs and influences their surface properties, functionalization efficiency, and cellular uptake. To investigate this effect, we compared a traditional water-in-oil-in-water (w/o/w) double-emulsion solvent evaporation method with an optimized formulation strategy in which PVA was confined to the internal aqueous phase. The optimized formulation reduced the calculated surface PVA density from 60.68 to 0.83 mg/m2 while requiring only a single purification step. Furthermore, epidermal growth factor (EGF)-functionalized nanoparticles prepared using the optimized method exhibited higher ligand association efficiency and up to 35-fold greater cellular uptake in A549 cells after 24 h compared with nanoparticles prepared using the traditional method. Importantly, both formulations maintained comparable physicochemical stability over 15 days and enabled efficient biomolecule association. Collectively, these findings demonstrate that PVA strongly influences nanoparticle surface characteristics, functionalization efficiency, and cellular interactions, highlighting the importance of surface engineering in the design of functionalized PLGA nanoparticle delivery systems.