Characterization and evaluation of the therapeutic benefits of pure and lanthanides mono- and co-doped zinc oxide nanoparticles

Exploring the cytotoxic and antioxidant properties of lanthanide-doped ZnO nanoparticles: a study with machine learning interpretation

BACKGROUND

Lanthanide-based nanomaterials offer a promising alternative for cancer therapy because of their selectivity and effectiveness, which can be modified and predicted by leveraging the improved accuracy and enhanced decision-making of machine learning (ML) modeling.

METHODS

In this study, erbium (Er3+) and ytterbium (Yb3+) were used to dope zinc oxide (ZnO) nanoparticles (NPs). Various characterization techniques and biological assays were employed to investigate the physicochemical and optical properties of the (Er, Yb)-doped ZnO NPs, revealing the influence of the lanthanide elements.

RESULTS

The (Er, Yb)-doped ZnO NPs exhibited laminar-type morphologies, negative surface charges, and optical bandgaps that vary with the presence of Er3+ and Yb3+. The incorporation of lanthanide ions reduced the cytotoxicity activity of ZnO against HEPG-2, CACO-2, and U87 cell lines. Conversely, doping with Er3+ and Yb3+ enhanced the antioxidant activity of the ZnO against DPPH, ABTS, and H2O2 radicals. The extra tree (ET) and random forest (RF) models predicted the relevance of the characterization results vis-à-vis the cytotoxic properties of the synthesized NPs.

CONCLUSION

This study demonstrates, for the first time, the synthesis of ZnO NPs doped with Er and Yb via a solution polymerization route. According to characterization results, it was unveiled that the effect of optical bandgap variations influenced the cytotoxic performance of the developed lanthanide-doped ZnO NPs, being the undoped ZnO NPs the most cytotoxic ones. The presence alone or in combination of Er and Yb enhanced their scavenging capacity. ML models such as ET and RF efficiently demonstrated that the concentration and cell line type are key parameters that influence the cytotoxicity of (Er, Yb)-doped ZnO NPs achieving high accuracy rates of 98.96% and 98.67%, respectively. This study expands the knowledge of lanthanides as dopants of nanomaterials for biological and medical applications and supports their potential in cancer therapy by integrating robust ML approaches.

Ecotoxicity of doped zinc oxide nanoparticles: Perspectives on environmental safety

Studies on the ecotoxicity of doped zinc oxide nanoparticles (ZnO NPs) are recent, with the first publications starting in 2010. In this sense, this is the first study that comprehensively reviews the ecotoxicological effects of ZnO NPs doped with lanthanide elements to fill this literature gap. This research explores a multifaceted question at the intersection of nanotechnology, toxicology, and environmental science. Different types of dopants commonly used for ZnO doping were investigated in this review, focusing on the ecotoxicological effects of lanthanides as dopants. Bacteria were the main class of organisms used in ecotoxicological studies, since antimicrobial activity of these nanomaterials is extensively explored to combat the imminent problem of resistant bacteria, in addition to enabling the safe use of these nanomaterials for biomedical applications. Doping appears to exhibit greater efficacy when compared to undoped ZnO NPs in terms of antimicrobial effects; however, it cannot be said that it has no impact on non-target organisms. An extensive examination of the literature also establishes the importance and need to evaluate the effects of doped ZnO NPs on organisms from different environmental compartments in order to identify their potential impacts. We underscore the dearth of research information regarding the environmental toxicity/ecotoxicity of doped ZnO nanoparticles across various ecological levels, thereby limiting the extrapolation of findings to humans or other complex models. Therefore, we emphasize the urgency of a multi-parameter assessment for the development of sanitary and environmentally safe nanotechnologies.

Enhancing antioxidant properties of CeO2 nanoparticles with Nd3+ doping: structural, biological, and machine learning insights

The antioxidant capabilities of nanoparticles are contingent upon various factors, including their shape, size, and chemical composition. Herein, novel Nd-doped CeO2 nanoparticles were synthesized and the neodymium content was varied to investigate the synergistic impact on the antioxidant properties of CeO2 nanoparticles. Incorporating Nd3+ induced changes in lattice parameters and significantly altered the morphology from nanoparticles to nanorods. The biological activity of Nd-doped CeO2 was examined against pathogenic bacterial strains, breast cancer cell lines, and antioxidant models. The antibacterial and anticancer activities of nanoparticles were not observed, which could be associated with the Ce3+/Ce4+ ratio. Notably, the incorporation of neodymium improved the antioxidant capacity of CeO2. Machine learning techniques were employed to forecast the antioxidant activity to enhance understanding and predictive capabilities. Among these models, the random forest model exhibited the highest accuracy at 96.35%, establishing it as a robust computational tool for elucidating the biological behavior of Nd-doped CeO2 nanoparticles. This study presents the first exploration of the influence of Nd3+ on the structural, optical, and biological attributes of CeO2, contributing valuable insights and extending the application of machine learning in predicting the therapeutic efficacy of inorganic nanomaterials.

Green-route synthesis and ab-initio studies of a highly efficient nano photocatalyst:Ce/zinc-oxide nanopetals

In the present work, Zinc-oxide nanostructures and Ce/Zinc-oxide nanopetals were synthesized by a new environmentally friendly green synthesis method using the Withania coagulans plant. Cerium nitrate Ce(NO3)3 and zinc nitrate Zn(NO3)2 were used as precursors. The prepared nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet spectroscopy (UV-vis). Crystal planes (100), (002), (101), (102), (110), (103), (200), (112) and (201) at 2θ 31.75°, 34.35°, 36.2°, 47.55°, 56.6°, 62.75°, 66.3°, 67.9°, and 69.09° respectively confirmed the hexagonal wurtzite crystal structure of Zinc-oxide. Angular shifts for Ce1% doped Zinc-oxide and Ce3% doped Zinc-oxide nanopetal nanostructures were observed in the (100) and (101) planes of the crystal. More specifically, using Scherrer's equation, the crystallite sizes of Zinc-oxide, Ce1% doped Zinc-oxide nanopetals, Ce3% doped Zinc-oxide nanopetals, and Ce5% doped Zinc-oxide nanopetals were 16.48 ± 02 nm, 17.8 ± 2 nm, 18.8 ± 2 nm, and 18.87 ± 2 nm, respectively. The pure Zinc-oxide grain had the appearance of a nanoflower. On the other hand, the nanopetal structure of Ce5% doped Zinc-oxide nanopetals had oval-shaped nanopetal morphology. The absorption peaks were observed at 373, 376.4, 377, and 378 nm for Zinc-oxide, Ce1% doped Zinc-oxide nanopetals, Ce3% doped Zinc-oxide nanopetals, and Ce5% doped Zinc-oxide nanopetals, respectively, which results in a progressive redshift. The gap energies of Zinc-oxide, Ce1% doped Zinc-oxide nanopetals, Ce3% doped Zinc-oxide nanopetals, and Ce5% doped Zinc-oxide nanopetals were 2.796, 2.645, 2.534, and 2.448 eV, respectively. Photodegradation under visible light (>400 nm) indicates the high efficiency of the photocatalyst based on Ce5% doped Zinc-oxide nanopetals. DFT calculations, structural changes, charge analysis, and electronic band structures were carried out to confirm the experiment.