<p>Green Synthesis of Zeolite/Fe<sub>2</sub>O<sub>3</sub> Nanocomposites: Toxicity & Cell Proliferation Assays and Application as a Smart Iron Nanofertilizer</p>

Abstract

Purpose: The aim of this study was to prepare zeolite/iron (III) oxide nanocomposites (zeolite/Fe 2 O 3 –NCs) as a smart fertilizer to improve crop yield and soil productivity. Methods: Zeolite/Fe 2 O 3 –NCs were successfully produced by loading of Fe 2 O 3 -NPs onto the zeolite surface using a quick green precipitation method. The production of zeolite/Fe 2 O 3 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 Fe 2 O 3 -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% Fe 2 O 3 –NPs, respectively. Such results indicated that the size of the Fe 2 O 3 -NPs did not significantly change when Fe amounts increased from 7 to 12 wt% for the zeolite/Fe 2 O 3 –NCs. In terms of medical applications, in vitro cell studies demonstrated that zeolites and zeolite/Fe 2 O 3 –NCs were generally non-toxic to human fibroblast cells and significantly pernicious to human malignant melanoma cells. From MTS cytotoxicity assays, the concentration of Fe 2 O 3 within the zeolite/Fe 2 O 3 –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: green chemistry, iron (III) oxide nanoparticles, zeolite, zeolite/iron (III) oxide nanocomposites, smart nanofertilizer, melanoma, cell proliferation assays