Antibacterial Activity of New Shigaite-like Ni/Co-Al and Ni/Cu-Al Layered Double Hydroxides Intercalated with Sulfate and Sodium Cations: Preliminary Studies.

Solid solutions of bimetallic and trimetallic layered double hydroxides (LDHs) containing aluminum and cobalt or aluminum and copper, with the chemical compositions [Ni6- x M x 2+Al3(OH)18]-[(SO4)2Na]·yH2O (M2+ = Co or Cu and x varied from 0 to 6), were synthesized by coprecipitation with increasing pH at room temperature, hydrothermally treated at 90 °C for 120 h and dried at 60 °C for 48 h. The compounds were analyzed by X-ray diffraction (XRD), whereby all systems presented basal distances close to 11 Å, typical of sulfate intercalation in double-layer arrangements in the presence of hydrated alkali metal cations. FTIR spectra indicated the presence of typical bands attributed to sulfate, water molecules and metal-oxygen vibrations (M-O). Scanning electron microscopy (SEM)/energy-dispersive spectroscopy (EDS) and ICP/OES also corroborated the successful synthesis of all LDH solid-state solutions. The preliminary potential antibacterial activity of the LDHs was evaluated using the agar well diffusion method against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), while the bimetallic CuAl-LDHs had the most effective antibacterial activity.