Antibody conjugated onto surface modified magnetic nanoparticles for separation of HER2+breast cancer cells

Breast cancer is one of the leading causes of death among women worldwide, therefore early diagnosis and monitoring the status of cancer are essential. In the present study we developed antibody-conjugated iron oxide magnetic nanoparticles (MNPs) with highly efficient potential to detect HER2-expressing cancer cells in blood, a compartment where tumor cells are very rare. The MNPs were first coated with (3-aminopropyl) trimethoxysilane. Effective coating was checked by VSM, XRD, FT-IR, TGA, EDX, and SEM. Anti-HER2 antibody (Herceptin) was conjugated on the surface of silane-coated MNPs (MNP-Si). The affinity of antibody-conjugated MNPs (Ab/MNP-Si) for HER2-expressing cells was evaluated in the SK-BR-3 cell line as a breast cancer cell model. Different concentrations of SK-BR-3 cells were mixed with peripheral blood mononuclear cells and subjected to isolation with Ab/MNP-Si in a magnetic field. Separation efficiency, as determined by flow cyto-metry, was 77-98%. Further evaluation with fluorescence microscopy also confirmed the ability of Ab/MNP-Si to detect low numbers of SK-BR-3 cells in whole blood. Our results suggest that Ab/MNP-Si is a potentially useful tool to isolate circulating tumor cells by targeting tumor-specific surface receptors under a magnetic field, and may improve breast cancer diagnosis and monitoring.