Molecular characterization of silver-stearate nanoparticles (AgStNPs): A hydrophobic and antimicrobial material...

In this study, silver-stearate nanoparticles (AgStNPs) have been produced from silver nitrate solutions by replacing the nitrate by stearate ions and then reducing by thermal treatment. AgStNPs were characterized by particle size, zeta-potential, ATR-FTIR, contact angle and SEM (scanning electron microscopy) analyses. The mean particle size and zeta potential of AgStNPs were determined to be 69.22±7.30nm and +8.02±0.88mV. ATR-FTIR analysis showed characteristic IR bands of stearate, revealing the two strong peaks at 2848 and 2915cm^-1 associated to symmetric (ν_s(CH₂)) and asymmetric (ν_as(CH₂)) stretching vibrations of methylene groups, respectively. On the other hand, the scissoring and rocking modes of methylene group were observed at 1470 and 718cm^-1, respectively. Nanomorphological characterization by SEM revealed a layered morphology of AgStNPs. Contact angle measurements demonstrated that a contact angle of water drop on glass coated with AgStNPs was found to be 108.76°, which proved the strong hydrophobic properties of AgStNPs. AgStNPs seemed to be very effective in inhibiting foodborne pathogens (Salmonella Typhimurium, Escherichia coli O157:H7, Staphylococcus aureus, Listeria monocytogenes and Candida albicans). The results suggest the use of AgStNPs as a coating material to reduce biofilm or biofouling formation in terms of achieving appropriate food contact surfaces and higher hygiene/easier sanitation due to their strong hydrophobic and antimicrobial properties.