Conjugating folate on superparamagnetic Fe3O4@Au nanoparticles using click chemistry

•Azidoundecanethiol was coated on the superparamagnetic Fe3O4@Au nanoparticles by forming self-assembled monolayers.•Alkyne-terminated folate was synthesized from a reaction between the amine and the carboxylic acid.•Conjugation of Fe3O4@Au nanoparticles with folate was made by copper-catalyzed azide-alkyne cycloaddition click chemistry.

Gold-coated magnetic core@shell nanoparticles, which exhibit magneto-optical properties, not only enhance the chemical stability of core and biocompatibility of surface, but also provide a combination of multimodal imaging and therapeutics. The conjugation of these tiny nanoparticles with specific biomolecules allows researchers to target the desired location. In this paper, superparamagnetic Fe3O4@Au nanoparticles were synthesized and functionalized with the azide group on the surface by formation of self-assembled monolayers. Folate (FA) molecules, non-immunogenic target ligands for cancer cells, are conjugated with alkyne and then immobilized on the azide-terminated Fe3O4@Au nanoparticles through copper(I)-catalyzed azide-alkyne cycloaddition (click reaction). Myelogenous leukemia K562 cells were used as a folate receptor (FR) model, which can be targeted and extracted by magnetic field after interaction with the Fe3O4@Au–FA nanoparticles.

Graphical abstractSelf-assembled azide-terminated group on superparamagnetic Fe3O4@Au nanoparticles followed by click reaction with alkyne-functionalized folate, allowing the nanoparticles target folate receptor of cancer cells.Figure optionsDownload full-size imageDownload as PowerPoint slide