Understanding the bactericidal mechanism of Cu(OH)₂ nanorods in water through Mg-substitution: high production of toxic hydroxyl radicals by non-soluble particles

Abstract

To date, there is still a lack of definite knowledge regarding the toxicity of Cu(OH)2 nanoparticles towards bacteria. This study was aimed at shedding light on the role played by...

Revisiting Mg solubility in CuO nanorods: limit probed by neutron diffraction and effect on the particle toxicity towards bacteria in water

“…The limited 2 θ range and resolution of NPD patterns of the x = 0.2 sample does not allow the amount of MgO present to be accurately quantified by refinement using the Rietveld method. 29 In our previous study (thanks in particular to thermal analyses), 17 we found that the solubility limit of Mg 2+ ions in Cu(OH) 2 is 10 mol% ( i.e. Cu 0.9 Mg 0.1 (OH) 2 ).…”

“…Prior to decomposition, we checked by EDX analysis that the precursor particles had the expected Mg/Cu atomic ratio. 17 X-ray powder diffraction (XRPD) patterns were recorded after decomposition to determine the phase purity of as-obtained powders. In Fig.…”

“…The single source precursor Cu 1− x Mg x (OH) 2 was prepared at room temperature through a co-precipitation synthesis route extensively described in ref. 17. Hydrogen peroxide (for analysis, 30%), 5,5-dimethyl-1-pyrroline N -oxide (DMPO) and 4-hydroxy-2,2,6,6-tetramethylpiperidine- N -oxyl (TEMPOL) were purchased from Sigma-Aldrich.…”

“…The decomposition temperature was determined by thermogravimetry (TG) and mass spectrometry (MS) of the evolved gas in ref. 17. Once synthesized, raw nanoparticles were stored in an argon-filled glove box with less than 1 ppm in water to avoid the formation of any hydroxide by-products prior to any analysis.…”

“…2c). In the structure of Cu (OH) 2 , 17 the dehydroxylation of the staircase-shaped [Cu (OH) 2 ] ∝ layers stacked along the b axis allows their condensation (oxolation) in order to build the three dimensional network of edge-sharing octahedra found in the structure of CuO. High lattice distortions then appear during this oxolation at the reaction interface between just condensed and still hydroxylated layers due to the local reduction of the packing metal-metal distance.…”