The present invention relates to a device for the treatment of blood comprising a solid phase on which a polypeptide is immobilized which is suitable for the inactivation of free nucleic acids. Suitable polypeptides are, for example, deoxyribonucleases, ribonucleases, DNA methyltransferases or cytosine deaminases. The invention further comprises the use of such devices for the treatment of patients suffering from chronic kidney failure, cancer or lupus erythematosus, as well as methods and systems for the treatment of blood, wherein free nucleic acids are inactivated outside the body.
