High Entropy Oxide Nanoparticles: Studies on the Interaction with Murine Macrophages

In the last few years, high entropy nanomaterials have gained significant interest in the scientific community due to their tunable elemental compositional flexibility and unique physicochemical properties. Specifically, high entropy oxide (HEO) nanoparticles (NPs) are being investigated for various energy storage, catalytic and biomedical applications. In the present study, we have evaluated the interaction between J774a.1 murine macrophages and HEO NPs with a novel composition comprised of five immiscible elements in the form of (Mn, Fe, Ni, Cu, Zn)3O4. Macrophages are innate immune cells playing key roles in the host defense and are known to be involved in cancer and inflammatory tissue damage. Herein, we synthesized HEO NPs by flame spray pyrolysis route, and used aberration corrected scanning transmission electron microscopy technique to evaluate their elemental composition and crystal structure. The results indicate that the synthesized NPs possess a single-phase solid solution spinel crystal structure confirming their high mixing entropy by energy dispersive X-ray spectroscopy. MTT assay was performed for evaluating the macrophage cells viability in the presence of HEO NPs. The results from the MTT assay indicate a significant decrease in macrophage cell viability after 24 hours of exposure to various concentrations of HEO NPs. Complementary DAPI and ActinRed fluorescent staining images showed a decrease in signal intensity with increasing concentration of HEO NPs. Furthermore, the fluorescent staining demonstrates morphological changes in J774a.1 macrophage cells which confirms a strong cytotoxic effect of the synthesized HEO NPs. This study is the pioneering work for the development of biocompatible HEO NPs in order to promote their candidacy for biomedical applications.