Labeling of islet cells with iron oxide nanoparticles through DNA hybridization for highly sensitive detection by MRI

DNA hybridization is proposed for monitoring of transplanted islets by magnetic resonance imaging (MRI). The surfaces of SPIOs were modified with oligo-(deoxyadenylic acid) ((dA)20). The SPIOs were immobilized on islet cells which had been pretreated with oligo-(thymidylic acid)-poly(ethylene glycol)-phospholipid conjugates ((dT)20-PEG-DPPE) through DNA hybridization. Transmission electron microscopy observations revealed that SPIOs were initially anchored on the islet cell surfaces and subsequently transferred to endosomes with time. The SPIO-labeled islet cells could be clearly detected as dark spots by T2-weighted MR image.