Magnetic nanoparticles modified with DTPA-AMC-rare earth for fluorescent and magnetic resonance dual mode imaging

In the present study, we report new water-soluble cell fluorescence imaging and contrast agents that are based on DTPA-AMC(7-amino-4-methyl coumarin)-Eu3+ and DTPA-AMC(7-amino-4-methyl coumarin)-Gd3+ compounds conjugated to Fe3O4 NPs via a PEG-NH2 linker. The novel Fe3O4 NP-conjugates present two main advantages for cell fluorescence labelling: water solubility and targeting ability. The in vitro experiments demonstrate that water-soluble Fe3O4 NPs-DBI-PEG-NH-DTPA-AMC(7-amino-4-methyl coumarin)-Eu3+ has excellent cell permeating activity. Moreover, the relaxation rate test of Fe3O4 NPs-DBI-PEG-NH-DTPA-AMC(7-amino-4-methyl coumarin)-Gd3+ shows a higher T1 relaxation effect than traditional DTPA-Gd3+ MRI agents. According to in vivo liver MRI experiments, better contrast of the liver was achieved after addition of Fe3O4 NPs-DBI-PEG-NH-DTPA-AMC(7-amino-4-methyl coumarin)-Gd3+. The results will provide a significant guide for researchers exploring the biomedical applications of superparamagnetic Fe3O4 NPs.