Cell Rescue by Nanosequestration: Reduced Cytotoxicity of An Environmental Remediation Residue, Mg(OH)₂ Nanoflake/Cr(VI) Adduct

Abstract

Some nanomaterials, such as Mg(OH)2 nanoflakes, are heavily used in pollutant adsorption and removal. Residues from these environmental remediations are potential hazardous materials. Safety evaluations of these materials are needed for environmental protection and human health. Although nanotoxicity has been widely investigated in recent years, research on the toxicity of nanoparticle/pollutant adducts has been rather inadequate. Here, we report the cellular perturbations and cytotoxicity of nano-Mg(OH)2/Cr(VI) adducts as a case study to elucidate how nanoparticle/pollutant adducts impact human cells. We found that Mg(OH)2 nanoflakes barely enter cells, while desorbed Cr(VI) anions enter cells, generate ROS, induce cell apoptosis, and cause cytotoxicity. This cytotoxicity is only a fraction of the cytotoxicity of free Cr(VI) because nano-Mg(OH)2 particles are able to retain more than half of their Cr(VI) anions.

Isolation and engineering of plant growth promoting rhizobacteria <i>Pseudomonas aeruginosa</i> for enhanced cadmium bioremediation

“…Expression of MTs have been employed as biological chelators to increase the immobilization of Cd by bacterial cells (He et al, 2012;Valls et al, 2000) and it was found to bind four Cd 2+ ions (Winge and Miklossy, 1982). Compared with intracellular accumulation, adsorption of heavy metal ions on the cell surface has greater merits; for example, metal ions bound on the cell surface could be desorbed and recovered with mild chemical treatment without damage to the cells (Kuroda and Ueda, 2006;Zhang et al, 2014). We have shown that a hybrid fusion protein inaK-N/MT is efficiently expressed and firmly anchored in the outer membrance of Pseudomonas aeruginosa cells, providing a 3-fold increase in their metal-coordinating capacity and conferring a more protective effect upon Pisum sativum L. growth in polluted soils.…”

Crossing Biological Barriers by Engineered Nanoparticles

“…For BPB crossing by ZnO NPs, the order was 13 nm > 57 nm . Besides, nonspherical ENPs such as Mg­(OH) 2 nanoflakes rarely cross the intestinal barrier probably because they can hardly be taken up by cells . Even though positively charged (surface modified with cysteamine, NH 3 + ) gold NPs have a much lower crossing efficiency across the intestinal barrier and secondary distribution in most internal organs, compared to the negatively charged NPs (surface modified with thioglycolic acid, COO – ), they have a higher accumulation in the brains .…”

“…13 Besides, nonspherical ENPs such as Mg(OH) 2 nanoflakes rarely cross the intestinal barrier 47 probably because they can hardly be taken up by cells. 48 Even though positively charged (surface modified with cysteamine, NH 3 + ) gold NPs have a much lower crossing efficiency across the intestinal barrier and secondary distribution in most internal organs, compared to the negatively charged NPs (surface modified with thioglycolic acid, COO − ), they have a higher accumulation in the brains. 49 Meanwhile, crossing efficiency for the BPB is reduced for negatively charged iron oxide NPs (ζ-potential: −52 mV) 24 and gold NPs (ζ-potential: −17 mV) 26 compared with positively (ζ-potential: 51 mV) or neutrally charged (ζpotential: −6 mV or −1.6 mV) ones.…”

The adsorption features between insecticidal crystal protein and nano-Mg(OH) 2

“…Nano-Mg(OH) 2 is an environmentally friendly material; it is widely used as an adsorbent in wastewater removal [ 18 – 20 ] with low biological toxicity [ 21 , 22 ]. Our previous studies indicated that Cry11Aa protein had high activity against disease vector mosquitoes, and the Cry11Aa protein loaded onto nano-Mg(OH) 2 had even stronger toxicity toward mosquitoes [ 23 ].…”