Excitation Wavelength Independent Carbon-Decorated Ferrite Nanodots for Multimodal Diagnosis and Stimuli Responsive Therapy

The combination of superparamagnetism and excitation independency have been packed into carbon-decorated ferrite nanodots (CDs@MNFs) for the introduction of a cost-effective and less-toxic multimodal contrast agent in fluorescence/MR imaging to replace conventional heavy metal containing Gd-DOTA. The label-free surface engineered ferrite nanodots are capable of generating twin T1 (longitudinal) and T2 (transverse) weighted magnetic resonance (MR) along with fluorescence emission. The calculated molar relaxivities and molar radiant efficiency obtained from in vitro and in vivo studies are the indication of its multimodal efficacy in medical imaging compared to the conventional contrast agents. The cellular internalization of nanodots was established by confocal microscopy and flow cytometric assay, whereas the hemolysis and cell viability assays support their appreciable toxicity. Furthermore, the surface chemistry due to the presence of -COOH was utilized to attach the anticancer agent, doxorubicin (-NH₂) making it an external stimuli responsive drug delivery vehicle for the treatment of cancer. Given the ease of fabrication, negligible toxicity, and significant contrast enhancement with stimuli responsive drug release kinetics CDs@MNFs prove to be a potential, cost-effective multimodal imaging agent which could be used for theragnosis.