Morphology-dependent toxicity and MRI contrasting properties of Mn₃O₄ nanostructures: A comparative study

In the past decade, numerous fields have been revolutionized by nanotechnology, with nanostructures being particularly important for advances in medicine. Manganese-based nanostructures (Mn-NS) with a range of morphologies (cuboids, spheres, rice-grain, and plates) were synthesized, and their potential for theragnostic uses was assessed in this research work.

For efficient cancer diagnosis and treatment, Mn₃O₄ nanostructures exhibit unique MRI contrast enhancement, biocompatibility, and the ability to scavenge reactive oxygen species (ROS). To ascertain the impact of shape on biological interactions, a thorough characterization was conducted, encompassing physicochemical characteristics, MRI contrasting ability, and toxicity profiles.

The findings demonstrated that spherical Mn-NS had the highest toxicity, largely due to ROS-induced apoptosis and cellular damage, whereas other shapes showed moderate to low cytotoxicity. Spermidine was also investigated as a potential defense against Mn-NS-induced cytotoxicity, and it was found to significantly reduce ROS and apoptosis in neuroblastoma cells. Plate-shaped Mn-NS showed excellent T₁-T₂ dual-mode contrast in MRI experiments, confirming their potential as MRI agents.

This study contributes to the development of safer nanomaterials for biomedical applications by shedding light on the safety profile and possible therapeutic benefit of Mn₃O₄ nanostructures.