Green Synthesis of Zeolite/Fe2O3 Nanocomposites: Toxicity & Cell Proliferation Assays and Application as a Smart Iron Nanofertilizer

Abstract

Purpose: The aim of this study was to prepare zeolite/iron (III) oxide nanocomposites (zeolite/Fe₂O₃-NCs) as a smart fertilizer to improve crop yield and soil productivity.

Methods: Zeolite/Fe₂O₃-NCs were successfully produced by loading of Fe₂O₃-NPs onto the zeolite surface using a quick green precipitation method. The production of zeolite/Fe₂O₃ nanocomposites was performed under a mild condition using environmentally friendly raw materials as a new green chemistry method. The product was characterized using several techniques such as near and far Fourier-transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

Results: The results confirmed the formation of Fe₂O₃-NPs with mean particle sizes of 1.45, 2.19, and 2.20 nm on the surface of the zeolite per amount of 4, 7 and 12 wt% Fe₂O₃-NPs, respectively. Such results indicated that the size of the Fe₂O₃-NPs did not significantly change when Fe amounts increased from 7 to 12 wt% for the zeolite/Fe₂O₃-NCs. In terms of medical applications, in vitro cell studies demonstrated that zeolites and zeolite/Fe₂O₃-NCs were generally non-toxic to human fibroblast cells and significantly pernicious to human malignant melanoma cells. From MTS cytotoxicity assays, the concentration of Fe₂O₃ within the zeolite/Fe₂O₃-NCs that was effective at inhibiting the growth of malignant melanoma cells by 50% (the IC50 value) was ~14.9 wt%. The three types of nanocomposites were further tested as an iron smart nanofertilizer for the slow-release of iron ions.

Conclusion: Advantages of this project include the production of non-toxic nanocomposites as a smart fertilizer to develop crops while the reaction involves the use of commercial and natural materials as low-cost raw materials with low energy usage due to a mild reaction condition, as well as the use of an environmentally friendly solvent (water) with no toxic residues.

Keywords: cell proliferation assays; green chemistry; iron (III) oxide nanoparticles; melanoma; smart nanofertilizer; zeolite; zeolite/iron (III) oxide nanocomposites.