Tumor-specific hyperthermia with aptamer-tagged superparamagnetic nanoparticles

Targeted therapy is a method owing to its limited side effect profile, particularly in cancer treatment. Magnetic hyperthermia, which is induced by nanoparticles (NPs) conjugated with targeting agents, can be useful in combination with chemo- or radiotherapy. In this paper, we constructed dextran-coated ferric oxide NPs conjugated with specific anti-human epidermal growth factor receptor (HER2) aptamer and used them to induce magnetic hyperthermia in cultured cells. The specificity of the tagged NPs was determined by studying their effect relative to that of non-tagged NPs against two cell lines: human adenocarcinoma SK-BR3, overexpressing the HER2 receptor; and U-87 MG, a human glioblastoma epithelial cell line, not expressing HER2. In order to confirm the interaction of the tagged NPs with the cells we used, fluorescence microscopy and fluorescence-activated cell sorting analysis were performed. All of these experiments showed that the aptamer-tagged NPs were highly specific toward the HER2-expressing cells. In addition, a ninetyfold lower dose of the tagged NPs relative to that of the non-tagged NPs was needed to achieve ~50% cell killing by hyperthermia of the SK-BR3 cell line, while for the U-87 MG cells the viability level was close to 100%. These results show that targeted NPs can be applied at substantially lower doses than non-targeted ones to achieve similar effects of hyperthermia, which should greatly limit the side effects of treatment.