Immunotargeting of functional nanoparticles for MRI detection of apoptotic tumor cells

Conjugation of PEGylated superparamagnetic nanoparticles with the 3B9 mAb was reported and the specificity of reactions of these novel molecular hybrid medical resonance imaging (MRI) nanoprobes with apoptotic cells was examined. The PEGylated nanoparticles were activated with EDC/NHS and conjugated either with 3B9 or Sal5, an isotype-matched mAb of irrelevant specificity, to achieve immunotargeting. It is found that solvent-free PRGylation process produces nanoparticle aggregates that average 67 mm in diameter with a narrow polydispersity. Antibody immobilization is confirmed by the observation of frequency and dissipation shifts, which are observed after injection of a 100μg/mL 3B9 mAb solution into the flow cell. The concentration of 3B9-nnaoparticles required to reach half saturation is found to be equivalent to 0.65mM of Fe³⁺, which corresponds to 7.8nM 3B9 mAb.