Amine- and hydroxyl-functionalization of iron nanoparticles for tailoring the properties of Fmoc-FF-based magnetic hydrogels: interfacial design toward biocompatible materials

Abstract

In this work, we propose a surface functionalization of magnetic nanoparticles (MNPs) with hydroxyl and/or amino groups by the use of poly(ethylene glycol) (PEG) and its mixture with other functionalization agents, bearing amine groups, namely, amine-terminated PEG (NH₂-PEG) and aminopropyltriethoxysilane (APTES). The proposed functionalization method enabled the preparation of MNPs that were nontoxic to human skin cells and could accelerate or delay human blood coagulation, which may be useful for designing materials with controlled hemostatic properties. Subsequently, these nanoparticles were used to obtain supramolecular magnetic hydrogels with the use of a short peptide hydrogelator: fluorenylmethoxycarbonyl-diphenylalanine (Fmoc-FF). The hydrogel matrices were obtained which, along with MNPs themselves, were thoroughly studied using a wide range of physicochemical, mechanical, and biological methods. It was demonstrated that surface functionalizations of the obtained MNPs remarkably affected the mechanical properties of the final magnetic hydrogels, despite the relatively low content of these nanoparticles within the total hydrogel mass. This ability to fine-tune the mechanical properties of the hydrogels, combined with their biocompatibility and the versatile potential for functionalizing such nanoparticles, makes them excellent candidates as biomaterials for a wide range of biomedical applications.