EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Core-shell nanoparticles (NPs) smaller than 100 nm are in demand for biomedical applications, e.g., as imaging contrast agents, for hyperthermia and in drug delivery, as well as for biotechnological applications such as separation and purification. For all biomedical and biotechnological uses, the NP's functional core must be protected from the environment and targeted to specific disease markers or other biomolecules.
The first and most critical step to achieve this is to design a biocompatible polymer shell around the nanoparticle core that repels biomolecules, e.g., proteins, and enables dispersing the nanoparticles in biofluids. If serum proteins, especially opsonins, adsorb on the nanoparticles to form a protein corona, they will lose their function and be cleared from the blood by the immune system.
We will describe the state-of-the-art synthesis, design, and physico-chemical characterization of polymer-brush-grafted NPs to avoid forming a protein corona using superparamagnetic iron oxide nanoparticles as an example. We focus on how the nanoscale geometry imposed by the core influences the properties of molecules grafted to its surface, placing higher demands on the brush density and homogeneity and how polymer topology is a tool to further improve this design.
Our approach to characterizing the colloidal and biological interactions of core-shell nanoparticles also highlights the need to apply a complementary set of the most sensitive methods available to predict their properties in biological systems. Common pitfalls are insufficient recognition of the polymer shell's chemical instabilities and the formation of partial soft coronas also on colloidally stable stealth nanoparticles. Additionally, we show the importance of taking the core's long-range colloidal interactions into account when assessing protein interactions with the shell and with functional ligands attached to targeted nanoparticles.