en 23407330 Conjugation of monoclonal antibodies to super paramagnetic nanoparticles is an effective method for cancer diagnosis and treatment. In this study the humanized anti her2/neu monoclonal antibody- Herceptin- was conjugated to super paramagnetic iron oxide (SPIO) nanoparticles using EDC method. The concentration of the conjugated antibodies was measured by Bradford assay. The antibody-nanoparticle conjugates were incubated with SKBR-3 and T47D human breast carcinoma cell lines and the presence of the conjugates on cell surface was confirmed by Prussian blue iron staining method. Conjugation of Herceptin to SPIO resulted in a precipitate-free conjugate containing 20µg antibody/mg SPIO. Prussian blue iron-staining of cells showed successful binding of the conjugates to the cell surfaces. Conjugation of monoclonal antibodies to SPIO may be a useful method for detection of tumor cells, especially by MRI techniques. Breast cancer, Conjugation, Herceptin, Nanomagnetic particles 27 31 https://www.ajmb.org/En/Article.aspx?id=4 https://www.ajmb.org/PDF/En/FullText/4.pdf FereshtehShamsipourMonoclonal Antibody Research Center, Avicenna Research Institute, ACECR , Tehran, Iran6Amir-HassanZarnaniDepartment of Immunology, Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR , Tehran, Iran7RoyaGhodsMonoclonal Antibody Research Center, Avicenna Research Institute, ACECR , Tehran, Iran8MahmoodChamankhahNanobiotechnology Research Center, Avicenna Research Institute, ACECR , Tehran, Iran9FloraForouzeshNanobiotechnology Research Center, Avicenna Research Institute, ACECR , Tehran, Iran10SedighehVafaeiMonoclonal Antibody Research Center, Avicenna Research Institute, ACECR , Tehran, Iran11Ali AhmadBayatMonoclonal Antibody Research Center, Avicenna Research Institute, ACECR , Tehran, Iran12Mohammad MehdiAkhondiDepartment of Immunology, Reproductive Biotechnology Research Center, Avicenna Research Institute, ACECR , Tehran, Iran13Mohammad AliOghabianResearch Centre for Science and Technology in Medicine, Tehran University of Medical Sciences , Tehran, Iran14MahmoodJeddi-TehraniMonoclonal Antibody Research Center, Avicenna Research Institute, ACECR , Tehran, Iran15