Optimized Mn-doped iron oxide nanoparticles entrapped in dendrimer for dual contrasting role in MRI.

Magnetic resonance imaging has acquired importance as a major tool for diagnosis and staging of cancers in humans. Injection of certain imaging agents have proved to improve contrast between normal and cancer cells on magnetic resonance imaging (MRI). Using the principles of MR contrast imaging, we have designed a dual mode (T1 and T2) contrast agent based on folic acid functionalized manganese ferrite nanoparticles (MNP) entrapped in 3G polyamidoamide (PAMAM) dendrimers. The ratio of Mn:Fe was tuned to achieve optimal performance. This multifunctional nanocarrier system was developed for targeting cancer cells to produce both T1 and T2 contrast which in turn helps in better diagnosis and staging of cancer. FTIR spectroscopy, X-Ray diffraction, atomic absorption spectroscopy, UV-Visible spectroscopy, and dynamic light scattering measurements were employed to characterize the multifunctional system at different stages of engineering. The ratio of relaxivities r2/r1 is 4.6 at 1.5 T for the MNP prepared with 0.5 molar ratio of Mn/Fe based on MR images obtained from phantom and tumor bearing mouse. The value of r2/r1 shows that the 0.5 molar ratio of Mn/Fe can be used to prepare MNP for the production of dual mode contrast in MR imaging.