External magnet-guided targeted delivery and tissue distribution analysis of anti-cluster of differentiation 3 conjugated magnetic nanoparticles of Fe₃O₄ using in vivo imaging system

Drug distribution is a vital parameter for depicting the pharmacokinetic properties of therapeutic agents. Magnetic nanoparticles (MNPs) conjugated with anti-cluster of differentiation 3 (anti-CD3) monoclonal antibody (MNPs-Ab) is a promising immunotherapeutic agent. Magnet-guided targeted delivery of MNPs has been studied exclusively in oncology. The distribution of MNPs is routinely analyzed by measuring Fe levels using inductively coupled mass spectrometry (ICP-MS). However, the ICP-based methods measure the total iron content, including endogenous iron. We used an efficient approach that measured MNPs-Ab distribution after intravenous administration using an in vivo imaging system. The fluorescent-labeled anti-CD3s are conjugated with dextran-coated magnetic nanoparticles (50 nm diameter) by the glutaraldehyde conjugation method. MNPs-Ab was intravenously administered to BALB/c mice. The fluorescence intensity in live animal and organs were analyzed after 0, 1, and 24 h. The conjugation of fluorescently labeled antibodies with MNPs was validated. The attachment of a permanent magnet on the dorsal skin area successfully guided the intravenously injected Ab-MNPs within 24 h. However, after 1 h, no observable fluorescence was seen at the target site. The in vitro organ distribution study confirms nanoparticles' predominant distribution in the liver and kidneys-the intensities of the fluorescence increase after 24 h than 1 h. Our in vivo imaging studies confirmed the external magnet-driven targeted distribution of the antibody-conjugated nanoparticle. Besides, the in vivo imaging system enables rapidly identifying the distributed nanoparticles.