In this disclosure, we describe a method for the treatment of tumor(s) or tumor cell(s) or cancer(s) in a subject in need by the generation of heat. The latter is produced by chains of magnetosomes extracted from whole magnetotactic bacteria and subjected to an alternative magnetic field. These chains of magnetosomes yield efficient antitumoral activity whereas magnetosomes unbound from the chains or kept within the whole bacteria produce poor or no antitumoral activity. The introduction of various chemicals such as chelating agents and/or transition metals within the growth medium of the bacteria improves the heating properties of the chains of magnetosomes. Moreover, the insertion of the chains of magnetosomes within a lipid vesicle is also suggested in order to favor their rotation in vivo and hence to improve their heating capacity. The vesicle can contain an antitumoral agent together with the chains of magnetosomes. In this case, the agent is released within the tumors by heating the vesicle.
