Concanavalin A-activated magnetic nanoparticles as an affine material for urinary exosome isolation

Exosomes are a type of membrane vesicle secreted into the extracellular medium by most cell types. They have a great potential for clinical practice as noninvasive biomarkers for diagnosis of various diseases, prognosis, and monitoring of therapy, which stimulates the development of simple methods for isolating exosomes from biological fluids. A novel affine material based on aminosilanized superparamagnetic core‒shell nanoparticles for fast isolation of urinary exosomes is reported. Iron oxide nanoparticles coated with amino organosilane have been synthesized. The structural and magnetic characteristics of the resulting nanoparticles have been studied by transmission electron microscopy and ferromagnetic resonance. The surface of the synthesized nanoparticles has been chemically functionalized with lectin (concanavalin A), and the efficiency of the obtained material as a sorbent for affine exosome isolation from human urine has been demonstrated. A highly purified fraction of exosomes 90–200 nm in size has been obtained. The exosomal nature of the isolated vesicles has been confirmed by bioluminescent solid-phase microassay of tetrasporine receptor markers. The presence of exosomal miR-21 in the isolated human urine exosome samples has been established.