The Role of Structural Dispersity of Polymer Brushes in Determining the Colloidal Stability of Core-Shell Nanoparticles and Their Interaction with Anti-PEG Antibodies.

The structural dispersity of poly-[oligo-(ethylene glycol) methacrylate] (POEGMA) brushes critically influences the stabilization of Au nanoparticles (NPs) and their interactions with anti-PEG antibodies (APAs). Commercial oligo-(ethylene glycol) methacrylate (OEG _p MA) macromonomers are intrinsically polydisperse, featuring a distribution of ethylene glycol (EG) units spanning from n = 2 to n = 15. Flash chromatography was applied to isolate OEG ₈ MA with discrete length (n = 8)the most abundant species in commercial mixtures. Controlled radical polymerization of polydisperse and discrete monomer sources was subsequently applied to generate POEG _p MA and POEG ₈ MA, which feature heterogeneous and homogeneous structures, respectively, while displaying an overall identical composition. When used to form shells on Au NPs, uniform POEG ₈ MA brushes provided enhanced colloidal stability across a wide temperature range compared to their polydisperse counterparts. While serum protein corona formation was largely determined by polymer composition, APA binding was promoted by longer OEG segments present in polydisperse POEG _p MA shells, which acted as epitopes for antibody recognition. These findings highlight how controlling polymer architecture and dispersity in the design of PEG-based shells for NPs could give access to nonimmunogenic formulations. More broadly, polymer dispersity emerges as an additional tool for modulating the behavior of nanomaterials within biological systems.