The increasing concern about antibiotic-resistance has led to the search for alternative antimicrobial agents. In this effort, different metal oxide nanomaterials are currently under investigation, in order to assess their effectiveness, safety and mode of action. This study focused on CuO nanoparticles (CuO NPs) and was aimed at evaluating how the properties and the antimicrobial activity of these nanomaterials may be affected by the interaction with ligands present in biological and environmental media. Ligands can attach to the surface of particles and/or contribute to their dissolution through ligand-assisted ion release and the formation of complexes with copper ions. Eight natural amino acids (L-Arg, L-Asp, L-Glu, L-Cys, L-Val, L-Leu, L-Phe, L-Tyr) were chosen as model molecules to investigate these interactions and the toxicity of the obtained materials against the Gram-positive bacterium Staphylococcus epidermidis ATCC 35984. A different behavior from pristine CuO NPs was observed, depending on the aminoacidic side chain. These results were supported by physico-chemical and colloidal characterization carried out by means of Fourier-Transform Infrared spectroscopy (FTIR), Differential Scanning Calorimetry (DSC) and Thermo-Gravimetric Analysis (TGA), Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and light scattering techniques (Dynamic Light Scattering (DLS), Electrophoretic Light Scattering (ELS) and Centrifugal Separation Analysis (CSA).

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Efficient, environmentally and economically sustainable, and nontoxic antibacterial products are of global relevance in the fight against microorganism contamination. In this work, an easy and straightforward method for the synthesis of bis‐morpholino triazine quaternary ammonium salts (bis‐mTQAS) is reported, starting from 2,4,6‐trichloro‐1,3,5‐triazine or 2,4‐dichloro‐6‐methoxy‐1,3,5‐triazine and various N‐alkylmorpholines. Bis‐mTQAS were tested as antimicrobials against Gram‐negative and Gram‐positive bacterial strains. The best‐performing bis‐mTQAS were found to achieve total disinfection against Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922 at 50 and 400 μg/mL, respectively. Distinctively, bis‐mTQAS with the highest antimicrobial efficiency had lowest cytotoxicity.

The first examples of highly efficient antimicrobial triazine-derived bis imidazolium quaternary ammonium salts (TQAS) are reported.