Potent and durable antibacterial activity of ZnO-dotted nanohybrids hydrothermally derived from ZnAl-layered double hydroxides.

• ZnO-dotted nanohybrids using LDHs as precursor (ZnO/LDHs) were synthesized via facile hydrothermal method. • Transformation of LDHs to ZnO and ZnAl 2 O 4 crystallites on zinc hydroxide nitrate layers was found. • ZnO/LDHs showed a potent and 4 days' antimicrobial activity toward E. coli and S. aureus at 100–300 μg/mL. The search for effective alternatives to traditional antibiotics to avoid antibiotic resistant bacteria is growing worldwide. ZnO nanoparticles are found to effectively inhibit growth and proliferation of bacteria, and ZnO-based layered double hydroxides (ZnO-based LDHs) have been intensively investigated for this purpose. However, the nanocomposites are made in a multi-step preparation process with severe agglomeration and limited bactericidal ability. In this research, ZnO-dotted nanohybrids using Zn 3 Al-LDHs as precursors (ZnO-dotted LDHs or ZnO/LDHs) were synthesized under facile hydrothermal conditions. An understanding of the transformation of the LDH precursors to the ZnO/LDHs was conducted with TEM/HRTEM/XRD/FTIR. ZnO/LDHs can be transformed from ZnAl-LDHs, with more ZnO nanodots generated upon heating at 150 and 200 °C for 2 h (Zn 3 Al-150, Zn 3 Al-200). Zn 3 Al-200 nanohybrids showed potent antibacterial activity towards Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) at 100–300 μg/mL for 4 days. Antibacterial activity of Zn 3 Al-200 may be attributed to the synergistic effects (ROS, leached Zn2+ and physical interaction). This research thus suggests a potential economic approach to prepare ZnO/LDH nanocomposites for avoiding the antibiotic resistant bacteria in environmental engineering or clinic fields. [ABSTRACT FROM AUTHOR]