Novel carboxylated PEG-coating on magnetite nanoparticles designed for biomedical applications

Fabrication of PEG coating on magnetite nanoparticles (MNPs) is one of the most favoured ways to ensure biocompatibility. Surface modification of magnetite by an own-prepared comb-like PEG-copolymer (PEGA-AA) was compared with two commercially available ones (carboxy-PEG (PEG-C) and phosphate-PEG (PEG-P)). ATR FT-IR data revealed that all polymers form complexes on the surface of MNPs. Electrophoresis and dynamic light scattering (DLS) experiments showed that both the type and quantity of the polymers' anchoring groups influence the aggregation of coated nanomagnets. PEG-C shell does not provide excess negative charges, so magnetite particles became aggregated. However PEG-P and PEGA-AA gradually modify the surface: neutralizing the originally positively charged MNPs below loading 0.5 mmol/g, while above it a polyanionic layer forms on nanomagnets dispersing them in salty media at pH ~6.5. The PEGA-AA comb-like copolymer is more efficient for MNPs PEGylation due to the uniform distribution of carboxylates and PEG chains along the carbon skeleton