Abstract: A method for isolating exosomes from blood platelets using superparamagnetic nanoparticles of iron oxide (Fe3O4), by means of a charge attraction mechanism based on the predetermined Zeta potential of the exosomes. The method involves the use of iron oxide nanoparticles that are previously synthesised with a predetermined positive charge, and that bond to the negatively charged exosomes contained in the biological sample. During incubation, the cationic magnetic nanoparticles are absorbed by the surface of the membrane of the exosomes owing to electrostatic interaction. Exposure of the material to a magnetic field makes it possible to separate the exosomes bonded to the nanoparticles. The success of this technique has been confirmed by characterisation of the exosomes by flow citometry. The method has been shown to be suitable for this purpose, since it allows exosomes to be isolated and purified, without undergoing alterations of their original morphological and structural characteristics.