Silver nanoparticles deposited layered double hydroxide nanoporous coatings with excellent antimicrobial activities

Simple and facile processes to produce silver nanoparticles deposited layered double hydroxide (Ag-LDH) coatings are reported. High quality nanoporous LDH coatings are obtained under hydrothermal conditions via an improved in situ growth method by immersing the substrates in LDH suspensions after removal of free electrolytes. Different types of substrates including metal, ceramics, and glass with planar and non-planar surfaces can all be coated with the oriented LDH films with strong adhesion. The pore size can be easily tuned by changing the metal:NaOH ratio during the precipiation process of LDH precursors. In the presence of LDH coatings, silver ions can be readily reduced to metallic silver nanoparticles (Ag NPs) in aqueous solutions. The resulting Ag NPs are incorporated evenly on LDH surface. The Ag-LDH coating exhibits excellent and durable antimicrobial activities against both Gram-negative (E. Coli and P. Aeruginosa) and Gram-positive (B. Subtilis and S. Aureus) bacteria. Even at the 4th recycled use, more than 99% of all types of bacteria can be killed. Moreover, the Ag-LDH coating can also effectively inhibit the bacterial growth and prevent the biofilm formation in the nutrient solutions. These newly designed Ag-LDH coatings may offer a promising antimicrobial solution for clinical and environmental applications. A simple method to grow well-oriented nanoporous layered double hydroxide LDH coatings from the homogenous suspension of the LDH precursors is developed. The removal of the free electrolytes is critical in developing high quality LDH coatings. Ag nanoparticles can be readily deposited on the LDH coatings without any reducing agents or toxic organic solvents. The resulting Ag-LDH composite coatings present excellent and durable antimicrobial activities.