Aptamer modified nanoprobe for multimodal fluorescence/magnetic resonance imaging of human ovarian cancer cells

A multifunctional-aptamer (APT) nanoprobe, TOV6 APT-superparamagnetic iron oxide nanoparticle-carbon dots (APT-SPION-CDs), for fluorescence and magnetic resonance targeted imaging (FI/MRI) of human ovarian cancer cells (OVCAR-3) is introduced. The SPION-CDs were synthesized and conjugated with TOV6 APT recognizing the stress-induced phosphoprotein 1 (STIP1) overexpressed on OVCAR-3 cells. The capability of the nanoprobe as a contrast agent for MRI and simultaneously as a fluorescent probe for fluorescence microscopy was studied. TOV6 APTs were adsorbed on SPION-CDs and were confirmed with Fourier transform infrared spectrometer. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed higher cytotoxic effects for APT-SPION-CDs compared to SPION-CDs on STIP1-negative HeLa cells. But on OVCAR-3, as STIP1-positive cells, the cytotoxic effect was negligible. The fluorescence microscopic images confirmed that APT-SPION-CDs specifically targeted ovarian cancer cells due to the tumor-targeting effect of TOV6 APT. High spin-spin relaxivity value (r(2)=308.5 mM(-1) s(-1)) and the signal enhancement in T-2-weighted MRIs confirmed the capability of the nanoprobe as a T-2-based contrast agent. In vitro cellular uptake and signal enhancement of this multimodal FI/MRI nanoprobe demonstrated the potential application of APT-SPION-CDs as a contrast agent for MRI and as a fluorescent probe for fluorescence microscopic imaging.