Herein, a new molecular nanoparticle based on iron(III)-tannic complexes (Fe–TA NPs) is presented. The Fe–TA NPs were simply obtained by mixing the precursors in a buffered solution at room temperature, and they exhibited good physicochemical properties with capability of inducing autophagy in both hepatocellular carcinoma cells (HepG2.2.15) and normal rat hepatocytes (AML12). The Fe–TA NPs were found to induce HepG2.2.15 cell death via autophagic cell death but have no effect on cell viability in AML12 cells. This is possibly due to the much higher uptake of the Fe–TA NPs by the HepG2.2.15 cells via the receptor-mediated endocytosis pathway. As a consequence, enhancement of the T1 MRI contrast was clearly observed in the HepG2.2.15 cells. The results demonstrate that the Fe–TA NPs could provide a new strategy combining diagnostic and therapeutic functions for hepatocellular carcinoma. Additionally, because of their autophagy-inducing properties, they can be applied as autophagy enhancers for prevention and treatment of other diseases.

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Herein, a new magnetic resonance imaging (MRI) agent based on molecular nanoparticles of iron(III)-tannic complexes (Fe-TA NPs) is reported. The paramagnetic and molecularlike Fe-TA NPs were successfully synthesized at room temperature within a few minutes without the use of any toxic agents or expensive equipment. The coordination states of the Fe-TA NPs were pH-dependent. The r relaxivity values of the bis-dominated and tris-dominated structures of the Fe-TA NPs were determined to be 6.31 and 5.24 mMs, respectively, by using a Philips Achieva 1.5T MRI scanner. The Fe-TA NPs were 177 ± 12 nm in diameter (hydrodynamic size) with a zeta potential value of -28 ± 0.9 mV, dispersing very well in aqueous solution and were highly stable in phosphate buffered saline buffer (pH 7.4) containing competitive ligands and metals. From in vitro studies, it was evident that the Fe-TA NPs exhibited good biocompatibility, with high cellular uptake in HepG2 cells. Clearly, the Fe-TA NPs were found to induce signal enhancement in the T-weighted image of the HepG2 cells. As a result, it can be stated that the Fe-TA NPs may have the potential for being developed as low-cost and clinically translatable magnetic resonance imaging agents in the near future.

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The autophagic stress induced by Fe–TA NPs is capable of reducing liver cancer cell migration and invasion. This would be a new tactic to treat liver cancer.