Improving stability of cerium oxide nanoparticles by microbial polysaccharides coating

Abstract

Cerium oxide (CeO 2) nanoparticles (CONPs) are interesting biomaterials with various applications in biomedicine, cosmetics and the pharmaceutical industry, but with limited practical application because of their low stability in aqueous media. The aim of this study was to obtain CONPs with increased stability by coating the particles. Microbial exopolysaccharides (levan, pullulan) and glucose were used to prepare CONPs under different synthesis conditions. Coating was attempted by adding the carbohydrates during (direct coating) or after (subsequent coating) the synthesis of CONPs. The obtained nanoparticles were characterized by X-Ray diffraction analysis, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The suspension stability of the uncoated and coated CONPs in aqueous media was evaluated by measuring the hydrodynamic size, zeta potential and turbidity. The FT-IR spectra revealed the differences between coated CONPs and showed the success of subsequent coating with carbohydrates. Coating with carbohydrates improved the stability the CONP suspension by decreasing the size of aggregated particles. The suspensions of levan-and glucose-coated CONPs had the best stability. In this study, CONPs were prepared using non-toxic materials, which were completely environmentally friendly. The obtained results open new horizons for CONP synthesis, improving their biological applications.

Interaction of Carbohydrate Coated Cerium-Oxide Nanoparticles with Wheat and Pea: Stress Induction Potential and Effect on Development

“…Uncoated nCeO 2 (Figure 1A) and coated, G-, L-, and P-CeO 2 , were analyzed by HRTEM (Figure 1B–D). The results of Z-average particle size, the intensity distribution of particle size, zeta potential, Fourier-transform infrared (FTIR) spectra, and turbidity for these nanoparticles were previously analyzed [9].…”

“…The high Ce concentration in wheat shoots after Gro treatment differs from the literary results [28] (Supplementary Table S1) and could be attributed to the longer exposure time to nCeO 2 in our experiments. Although G-CeO 2 is one of the most stable nCeO 2 [9], their concentration in plants was the lowest after Ger treatments. This indicates that nanoparticles’ suspension stability does not necessarily affect Ce concentration in plants.…”

“…Cerium-oxide nanoparticles were synthesized using the self-propagating room temperature (SPRT) method according to Milenković et al (2018) [9]. In brief, starting materials (Ce(NO 3 ) 3 ∙6H 2 0 and NaOH) were hand-mixed in a mortar with a pestle for about 5–10 min.…”

“…The mass ratio of carbohydrates to nCeO 2 was 1:7, or 2.523 g of carbohydrates and 0.360 g of nCeO 2 . The obtained nanoparticles CeO 2 , G-, L- and P-CeO 2 had an average hydrodynamic size of 385 nm, 235 nm, 216 nm, and 314 nm, and zeta potential values of 32.2, 31.3, 20.8, and 19.8, respectively [9]. The dry weights of the prepared nanocomposites were 2.379 g, 2.389 g, and 2.381g for G-, L-, and P-CeO 2 , respectively.…”

“…Thus, the nanoparticles can be found in the environment, and analysis of their ecotoxicity is needed. To improve their solubility, the coating of nCeO 2 with different polymers has been performed by many researchers [8,9]. The studies reported on positive and negative effects on different plants of uncoated nCeO 2 and nCeO 2 coated with various organic compounds are presented in Supplementary Table S1.…”