Facile synthesis of Cu-LDH with different Cu/Al molar ratios: application as antibacterial inhibitors

Abstract

A range of Cu-LDHs has been synthesized by co-precipitation using metal nitrate precursors and sodium carbonate under varying molar ratios Cu/Al (Cu 0.05 -Al 0.15 , Cu 0.10 -Al 0.10 , Cu 0.14 -Al 0.06 , and Cu 0.15 -Al 0.05 ). The uncalcined and calcined Cu-LDHs were characterized by powder X-ray diffraction and N 2 adsorption-desorption. The uncalcined solids showed clear hydrotalcite-like crystalline phases having a particle measurement between 5 and 16 nm. The best structure is attributed to the sample Cu 0.05 -Al 0.15 -LDHs. The particular surface areas are ranging between 40 and 92 m 2 /g, while the calcined samples showed the formation of Cu and Mg oxides. The antibacterial activity of Cu-LDHs with various molar ratios Cu/Al and their calcined phases were estimated towards multiple types of bacteria (Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis, Staphylococcus aureus, and Bacillus Subtilis). The Cu 0.10 -Al 0.10 -LDHs sample shows high activity against all types of bacteria either for calcined or uncalcined materials. The obtained results of the application of Cu-LDHs antibacterial inhibitors seem to be quite promising material in the antibacterial fields.

Direct contact, dissolution and generation of reactive oxygen species: How to optimize the antibacterial effects of layered double hydroxides

“…Despite the fact the aforementioned studies suggested the contribution of ROS to the antibacterial mechanism of pristine and NPs-loaded LDHs [38,47,48,53,77,78,81,133], these investigations lack real measurements of ROS and the evaluation of their role in the achieved antibacterial effect was not evident. ROS generation could be evaluated using different methods including fluorescence spectroscopy using fluorescent dye probes, ESR and chromatography methods [136].…”

“…Tabti et al synthesized a range of Cu-LDHs having different molar ratios of Cu:Al (Cu0.05-Al0.15, Cu0.10-Al0.10, Cu0.14-Al0.06, and Cu0.15-Al0.05) [48]. The antibacterial activity of the synthesized samples was estimated toward several bacterial strains, e.g.…”

“…2 illustrates the three different suggested mechanisms explaining the antimicrobial activity of these different types of antibacterial LDHs. The first is the direct surface interactions between pristine and NPs-loaded LDHs with the bacteria thus leading to their growth inhibition or death [41,44,46,48,50]. The second comprise the dissolution antibacterial molecules present in the LDH interlaminar region of antibacterial molecules-loaded LDH composites [45,51].…”

“…antibacterial molecules and NPs-loaded LDHs, have developed several control experiments to prove that the pristine LDH matrices do not contribute to the antibacterial activity imposed by the LDH-composites [42][43][44][45]. On the other hand, recent studies had shown that some pristine LDHs, more precisely Zn and Cu-based pristine LDHs, could also induce an efficient antibacterial without any further modification [22,[46][47][48][49].…”

“…Zn 2+ , Cu 2+ , Ag + [12,46,49,52], by which these released soluble cations could contribute to the antibacterial activity. Finally, the third LDH antibacterial mechanism is the generation of reactive oxygen species (ROS) by pristine and NPsloaded LDHs to yield an efficient antibacterial effect [16,38,[46][47][48]53]. .…”