Аннотация:The isolation of small extracellular vesicles (sEVs), including those secreted by pathological cells with high efficiency and purity is highly demanded for research studies and practical applications. Conventional sEVs isolation methods suffer from low yield, presence of contaminants, long-term operation and high costs. Bead-assisted platforms are considered to be effective for trapping sEVs with high recovery yield and sufficient purity for further molecular profiling. In this study, magnetically responsive beads made of calcium carbonate (CaCO3) particles impregnated with iron oxide (Fe3O4) nanoparticles are fabricated using freezing-induced loading (FIL) method. The developed magnetic beads demonstrate sufficient magnetization and can be collected by the permanent magnet, ensuring their rapid and gentle capture from an aqueous solution. The tannic acid on the surface of magnetic beads is formed by layer-by-layer (LbL) method and is used to induce coupling of sEVs with the surface of magnetic beads. These tannic acid coated magnetic beads (TAMB) were applied to investigate a capture efficiency of sEVs derived from MCF7 cell line. Quantitative data derived from analysis of nanopartciles tracking ananlysis (NTA) measurements revealed the capture efficiency of ~ 87%, while high resolution transmission electron microscopy (HRTEM) imaging of sEVs on the surface of TAMB indicated their structural integrity. These results demonstrated that TAMB could be applied for trapping sEVs and would be of interest for separation of sEVs from complex biological samples like blood plasma.