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Author: Admin | 2025-04-28
Scaffold and are used as hyperthermia agents in cancer therapy [239]. MgO NPs exhibited effective bactericidal potential against both gram-positive (S. aureus) and gram-negative (E. coli) bacteria [240] and even against fungi such as Aspergillus niger and Penicillium oxalicum [241]. MgO NPs demonstrated better inhibition for rod-shaped bacteria (E. coli) in contrast to spherical-shaped bacteria [242]. Portions of MgO NPs possibly react with water to form Mg(OH)2 which could lose OH− ion into the solutionand increase the pH. It was previously demonstrated that the peptide linkage in the cell membrane of Pseudomonas aeruginosa and E. coli was destroyed by the generated superoxide ions on the surface of MgO NPs [243]. O2− was more stable in the alkaline environment that contributed to the higher antibacterial effect of MgO NPs [244]. The mean zeta-potential of MgO NPs exhibits a positive charge in pH range from 4 to 8 [245] favoring the electrostatic interaction of NPs with bacteria cells. These MgO NPs could completely kill phytopathogen bacteria R. solanacearum at a comparatively higher concentration, 250 μg mL−1. Similarly to the other MONPs, MgO NPs destroyed and disintegrated the cell wall of the phytopathogen bacteria leading to leakage of the intercellular content and cell death. The same authors discovered that except for retained biofilm formation, MgO NPs improved the bacterial susceptibility to antibiotics. In contrast to nisin (antibiotic) addition, MgO and ZrO mixing did not enhance MgO activity against pathogens [246]. MgO NPs possess also the advantage of not being cytotoxic to human cells at lower concentrations (0.3 mg mL−1) [247]. However, the bactericidal activity of MgO NPs increases with raising the concentration of NPs. 3.8.6. Calcium Oxide NanoparticlesSimilarly to MgO NPs, the formation of ROS in the presence of CaO NPs was influenced by the higher pH that helped in antibacterial activity [248]. For both MgO and CaO, the contact between NPs and bacteria is an important factor for the bactericidal activity [249]. The active superoxides ions reacted with the carbonyl group in the peptide linkages of the cell wall of bacteria and disrupted them [250]. High-concentrated CaO and MgO NPs slurries in physiological saline were even able to kill spores of B. subtilis that are more robust with their thick proteinous wall than the vegetative cells. In contrast to the little affinity of ZnO NPs to fungal cells, the alkali MONPs – CaO and MgO, showed stronger affinity to postharvest fungal cells
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