Enhanced bactericidal activity of brucite through partial copper substitution

• Published in: Journal of materials chemistry. B, Materials for biology and medicine Materials for biology and medicine, 2020-01, Vol.8 (1), p.1-113
• Main Authors: Clavier, Batiste, Baptiste, To, Massuyeau, Florian, Jouanneaux, Alain, Guiet, Amandine, Boucher, Fabien, Fernandez, Vincent, Roques, Christine, Corbel, Gwenal
• Format: Article
• Language: English
• Subjects: Anti-Bacterial Agents - chemical synthesis; Anti-Bacterial Agents - pharmacology; Bactericidal activity; Brucite; Chemical Sciences; Copper; Copper - chemistry; Copper - pharmacology; Copper oxides; Cristallography; Cupric ions; Dehydration; E coli; Escherichia coli - drug effects; Galleries; Hydroxides; Hydroxyl ions; Infrared spectroscopy; Inorganic chemistry; Ions; Magnesium hydroxide; Magnesium Hydroxide - chemical synthesis; Magnesium Hydroxide - pharmacology; Material chemistry; Metal Nanoparticles - chemistry; Moisture content; Organic chemistry; Oxides; Photoelectron spectroscopy; Photoelectrons; Platelets; Reaction kinetics; Room temperature; Sodium carbonate; Sodium hydroxide; Spectrometry; Spectrum analysis; Stacking; Staphylococcus aureus - drug effects; Substitutes; Viability; Water chemistry; Water content; X ray photoelectron spectroscopy
• ISSN: 2050-750X; 2050-7518
• DOI: 10.1039/c9tb01927h

Brucite Mg(OH) 2 belongs to a family of two-dimensional compounds with a CdI 2 -type structure built up from layers of edge-sharing octahedra delineating 2D galleries. In the current study, nanometer-sized platelets of copper substituted Mg(OH) 2 were prepared by co-precipitation at room temperature in mixed alkaline (NaOH/Na 2 CO 3 ) medium. Very weak substitution of a few hydroxyl ions by carbonate groups was highlighted at first by infrared spectroscopy and then quantified by thermogravimetric (TG) and mass spectrometric (MS) evolved gas analyses. The presence in a very low amount of water molecules in the galleries induces disorder in the stacking of layers of edge-sharing octahedra along the c -axis. The dehydration of the hydroxides taking place below 225 C preserves the brucite-type structure of the samples while suppressing the stacking disorder. Copper substitution greatly enhances the bactericidal activity of nanometer-sized platelets of brucite against two bacteria frequently involved in healthcare-associated-infections. 10 mol% of cupric ions in Mg(OH) 2 (a copper loading of 0.102 mg mL 1 in the suspension) were sufficient to induce, after 3 h in contact, 100% and 99.3% reductions in viability of Gram-negative E. coli and Gram-positive S. aureus , respectively (reductions as low as 23% and 48% are reported for the parent compound Mg(OH) 2 in the same conditions). A good compromise between fast bactericidal kinetics and a high reduction in viability is reached by the 15 mol% copper-substituted Mg(OH) 2 hydroxide. Its use gives the opportunity to five-fold reduce the copper loading of the bactericidal agent while being at least equally or even more efficient compared to the conventional CuO (a Cu loading of 0.799 mg mL 1 and 0.154 mg mL 1 in the suspension of CuO and 15 mol% copper substituted Mg(OH) 2 particles, respectively). Copper substituted Mg(OH) 2 nanoplatelets exhibit high bactericidal activity towards S. aureus and E. coli with fast kinetics.