Preparation and characterization of copper and zinc adsorbed cetylpyridinium and N-lauroylsarcosinate intercalated montmorillonites and their antibacterial activity

The main objective of the present study was the preparation and characterization of new cationic/anionic surfactants and Cu2+/Zn2+ modified montmorillonites and the evaluation of their potential applicability as antibacterial agents for topical applications. To evaluate the antibacterial activity of Cu2+ and Zn2+ by synergistic effect, as well as to reduce the well-known toxicity of these metal cations; cetylpyridinium (CP) and N-lauroylsarcosinate (SR) intercalated montmorillonite (Mt-CP-SR) was used as the host material. In addition to their role to capture the metal cations and inhibit their release in any contact medium, these surfactants also increase the efficacy of the material due to their antibacterial properties. The effect of surfactant loading on the adsorption behavior of the metal cations onto the Mt-CP was investigated using SR in two different concentrations, namely 0.7 and 1.0 CEC of sodium montmorillonite (Mt-Na). The samples prepared were characterized using SEM, ATR-FTIR, zeta potential, and XRD analyses and they were subjected to antibacterial tests using the Standard Method Under Dynamic Contact Conditions on the Gram positive S. aureus, and Gram negative E. coli. As confirmed with desorption and characterization studies, the addition of Cu2+/Zn2+ onto the Mt-CP-SR yielded double adsorbed amounts compared to that of the Mt-CP, which indicated that Cu2+/Zn2+ bound to SR- interacted with the Mt surface. In contrary of Zn2+ caused no considerable change in the antibacterial effect of the host, Cu2+ addition enhanced the antibacterial activity. The produced antibacterial agents have the potential use in dyes, polymer composites, personal care products, and topical medicinal applications.