Antimicrobial Nanocomposites Prepared from MontmorilloniteAg+Quaternary Ammonium Nitrate

Abstract EN

Nanocomposites of Ag with organic montmorillonite (Ag-OMMT), Ag with montmorillonite (Ag-MMT), and organic montmorillonite (OMMT) were successfully prepared via a one-step solution-intercalated method.

Sodium MMT, silver nitrate, and dimethyl octadecyl hydroxy ethyl ammonium nitrate were used as precursors.

X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and energy dispersive spectroscopy analyses confirmed that the MMT layers were intercalated, and Ag+ was partly reduced to silver nanoparticles with diameters within 10–20 nm in Ag-OMMT.

The decomposition temperature of the organic cations in OMMT and Ag-OMMT increased to 220°C, as revealed by differential scanning calorimetry-thermogravimetric analysis.

The antimicrobial activity of the nanocomposites was tested by measuring the minimum inhibitory concentration (MIC) and killing rate.

The MICs of Ag-OMMT against Staphylococcus aureus, Escherichia coli, and Candida albicans were 0.313, 2.5, and 0.625 mg/mL, respectively.

Because of the presence of quaternary ammonium nitrate, Ag-OMMT has a better MIC against Gram-positive bacteria compared to Gram-negative bacteria and fungi.

OMMT did not show antimicrobial activity against Escherichia coli and Candida albicans.

In 2 h, 0.0125 mg/mL Ag-OMMT could kill 100% of S.

aureus, E.

coli, and C.

albicans in solution, and Ag-MMT could kill 99.995% of S.

aureus, 90.15% of E.

coli, and 93.68% of C.

albicans.

These antimicrobial functional nanocomposites have the potential for application in the area of surface decoration films.