Polymer Topology Determines the Formation of Protein Corona on Core-Shell Nanoparticles.

Martina Schroffenegger,Edmondo M Benetti,Max Willinger,Erik Reimhult,Nikolaus S Leitner,Shivaprakash N Ramakrishna,Giulia Morgese

doi:10.1021/acsnano.0c02358

Martina Schroffenegger, Edmondo M Benetti + Show 5 more

Open Access

https://doi.org/10.1021/acsnano.0c02358

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Abstract

Linear and cyclic poly(2-ethyl-2-oxazoline) (PEOXA) adsorbates provide excellent colloidal stability to superparamagnetic iron oxide nanoparticles (FexOy NPs) within protein-rich media. However, dense shells of linear PEOXA brushes cannot prevent weak but significant attractive interactions with human serum albumin. In contrast, their cyclic PEOXA counterparts quantitatively hinder protein adsorption, as demonstrated by a combination of dynamic light scattering and isothermal titration calorimetry. The cyclic PEOXA brushes generate NP shells that are denser and more compact than their linear counterparts, entirely preventing the formation of a protein corona as well as aggregation, even when the lower critical solution temperature of PEOXA in a physiological buffer is reached.

Highlights

Linear and cyclic poly(2-ethyl-2-oxazoline) (PEOXA) adsorbates provide excellent colloidal stability to superparamagnetic iron oxide nanoparticles (FexOy NPs) within protein-rich media
CPEOXA were obtained from α-alkyne-ω-azide PEOXA linear precursors using a ring-closure strategy through CuI-catalyzed Huisgen cycloaddition.[30,31]
A schematic of the polymer synthesis and functionalization is provided in Scheme S1, with 1H NMR, Fourier transform infrared (FTIR), and size exclusion chromatography (SEC) data of the products presented in the Supporting Information (Figures S1−S6)

Summary

Introduction

Linear and cyclic poly(2-ethyl-2-oxazoline) (PEOXA) adsorbates provide excellent colloidal stability to superparamagnetic iron oxide nanoparticles (FexOy NPs) within protein-rich media. Particles, their interactions are convoluted with those of the core, and their architecture can influence protein adsorption and vice versa.[16] It was early shown using isothermal titration calorimetry (ITC) that the density of the polymer chains on the nanoparticle surface influences the affinity of serum proteins such as albumin to the surface, which in these studies was related to the overall hydrophilicity of the particle.[17] In other words, the grafting stability and grafting density (σ) of the polymer brush shell determine the reduction of nonspecific protein adsorption, which strongly correlates with the suppression of receptor-mediated endocytosis by cells as well as recognition by phagocytes.[14,18,19]. ∼1 chain nm−2 as the threshold to prevent phagocytosis of NPs with diameters

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