Hydration and bactericidal activity of nanometer- and micrometer-sized particles of rock salt-type Mg1-xCuxO oxides

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

“…We have observed a similar behaviour during the thermal decomposition of Mg 1− x Cu x (OH) 2 into Mg 1− x Cu x O. 16…”

“…We have observed a similar behaviour during the thermal decomposition of Mg 1−x Cu x (OH) 2 into Mg 1−x Cu x O. 16 Since the limit of the solid solution Cu 1−x Mg x O is x = 0.1, the next sections focus on the three single-phase samples CuO, Cu 0.95 Mg 0.05 O and Cu 0.9 Mg 0.1 O only. Before evaluating the bactericidal activity of these three compositions, the morphology and the size of their nanoparticles were determined by transmission electron microscopy (TEM).…”

“…The beneficial effect of magnesium is nevertheless limited in time as the reductions in cell viability after 180 min for Cu 0.9 Mg 0.1 O do not exceed that for CuO. In order to elucidate this point, In our previous study, 16 we showed that the bactericidal activity of 10-20 nmsized particles of Mg 1−x Cu x O in the water suspension depends on the speed at which they dissolve and the nanoparticles of Mg 1−x Cu x (OH) 2 precipitate. These results incited us to also probe the dissolution of CuO and Cu 0.9 Mg 0.1 O nanorods after 180 min of immersion in water, according to the protocol described in the Experimental section 2.6.…”

“…Our recent study reveals that 10–20 nm-sized MgO particles completely dissolve in water over a 3 h period. 16 As the Mg substitution in CuO should thereby favour a partial dissolution of the nanoparticles in water, atomic emission spectroscopy (AES), X-ray powder diffraction (XRPD) and infrared (IR) spectroscopy are used to quantify the amount of free cupric and magnesium ions in the supernatant and to detect any trace of hydroxides formed. Against all expectations, the mass concentration of free cupric ions in the water suspension of Cu 0.9 Mg 0.1 O, although slightly higher than that for CuO, also remains below the MIC.…”

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

“…5,5-dimethyl-1-pyrroline N -oxide, DMPO) to form a more stable radical-adduct detectable by EPR. In a previous study, 52 we showed that MgO and Mg 0.9 Cu 0.1 O nanoparticles immersed in water can generate free HO˙ and O 2 ˙ − radicals by detecting the corresponding DMPO-adducts by EPR. Hydroxyl radical HO˙ is the most active among all ROS because it can initiate a free radical chain reaction leading to extensive lipid and organic peroxide formation in aerobically living organisms (oxidative stress).…”