Facile synthesis of Mn doped TiO2 rhombic nanocomposites for enhanced T1-Magnetic resonance imaging and photodynamic therapy

Abstract

Multifunctional magnetic photosynthesizer nanocomposites are highly desired to improve the efficacy of the early cancer diagnosis and therapy. However, design a highly biocompatible theranostic system with controlled size and shape at the nanoscale without altering the original properties of the primary materials is a challenging task. Herein, rhombic shaped manganese (Mn) doped titanium dioxide (TiO2) nanocomposites are designed to enhance the generation of reactive oxygen species (ROS) by photocatalytic property and spin relaxation for MRI. Transmission electron microscopy (TEM) results revealed the average size of the synthesized Mn-TiO2 rhombic nanocomposites (RNCs) was about 20–30 nm with homogeneous shape and dispersion. EDS and XPS analyses proved the incorporation of Mn ions into the anatase TiO2 lattice. After Pluronic® F-68 surface modification, Mn-TiO2-PF-68 RNCs demonstrated negligible toxicity and physiological stability. Prepared fluorescein isothiocyanate (FITC) labeled RNCs are encapsulated by the plasma membrane and surrounded the nucleus of 4T1 mice breast cancer cells which improve the efficiency of prepared RNCs. In addition, the Mn3+ ions remarkably enhanced the positive contrast (T1) for magnetic resonance imaging (MRI) and presented significant r1 relaxivity and low r2/r1 relaxivity ratio. Finally, Mn3+ doped with photosensitizers (TiO2) also exhibited a great synergistic effect of photo-killing in vitro by developing hydroxyl radicals. Therefore, the as-prepared Mn–TiO2 RNCs are promising candidate as a new kind of multifunctional agent for both MRI and PDT applications.