Uncoated negatively charged silver nanoparticles: speeding up the electrochemical synthesis and microbiological applications

L. Scotti
University of Chieti,
Italy

Keywords: silver nanoparticles, electrochemical synthesis, colloids, bacterial activity

Summary:

A new electronic device has been assembled and employed to obtain a stable solution of spherical silver nanoparticles (SNPs) in 10 min. Time of current inversion phase, number of electrodes and purification procedure have been optimized; different techniques as UV-vis spectroscopy, Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FE-SEM), Dynamic Laser Light Scattering (DLS) have been carried out to characterize the SNPs in size and shape and morphology. The stability of the SNPs solution has been tested by zeta potential measurements. The results presented herein show that the obtained nanoparticles kept in the dark at 5°C under inert atmosphere remain stable for at least 6 months. The DLS analysis show the presence of three different population (Polidispersity index 0.33 ± 0.01; Particle range 1.4-3.7 nm)) confirmed by TEM analysis. The SNPs solution at pH 7.8 is characterized by a good stability (Z-Potential value -51.5 ± 2.5 mV) and the final concentration of nSNPs is 6.3x10-4 M. Fast synthesis (10 min vs 100 min compared with electrochemical methods) and high stability are the main advantages of our method. The rise of multidrug-resistant bacteria and the difficulty of treating chronic biofilm-mediated infections have prompted renewed the need for novel antimicrobial agents. In recent years, several studies have reported metallic nanomaterials as a promising alternative to antibiotics because of their relevant bactericidal effects, thus suggesting high potential in medical devices, burn dressings, water treatment and food preservation.