The Antimicrobial Activity of Silver Nanoparticles in Ag/Ag2O Composites Synthesized by Oxygen Plasma Treatment of Silver Thin Films

Abstract

In this work, Ag/Ag2O composites were synthesized by treating silver thin films manufactured by thermal evaporation method with oxygen plasma afterglow. In order to verify the antibacterial behavior of these composites, inhibition zone tests were realized for Staphylococcus aureus. The results showed that individual silver nanoparticles at concentrations that can be controlled by the stoichiometric ratios of the Ag/Ag2O composites, were the main factor in the inhibition of bacteria. In addition, we found that the degree of degradation of individual silver nanoparticles absorption peaks represented a suitable criterion for determining the bacterial inhibition activity of the prepared silver oxide films. The results also showed that the sample treated at 1000 watts gave the highest rate of bacterial inhibition. This research includes an attempt to correlate the bacterial inhibition activity of silver oxide thin films with the structural and spectroscopic properties of these films.

Ag2O Nanoparticles as a Candidate for Antimicrobial Compounds of the New Generation

“…The electrochemical synthesis (anode oxidation of metal silver) [102], precipitation upon ultrasound treatment [63], boiling [67,78], treatment with microwave radiation [22,78], evaporation of metal silver under the action of plasma [81] and laser ablation in water [52,53] can be assigned to physical methods.…”

Biosynthesis of Silver Nanoparticles Functionalized with Histidine and Phenylalanine Amino Acids for Potential Antioxidant and Antibacterial Activities

“…Besides, the peak near 32.85° (110) implied the possible existence of Ag 2 O. , Ag ions (salt) were converted to silver(I) oxide, whereas by significantly increasing the pH of the medium during the biosynthesis of silver nanoparticles, Ag + can be converted to silver(I) oxide due to NaOH (aq) used for the pH adjustment. The use of NaOH to produce a solid Ag 2 O phase was previously reported , that silver ions in the presence of OH ions form AgOH (aq), which quickly decompose when heated and precipitate to form the desired Ag 2 O, as shown in the following chemical reaction eq . Conversely, the use of amino acids (phenylalanine and histidine) as reducing and capping agents has significantly supported the Ag + to Ag° reduction (Figure A,B) 2 Ag false( aq false) + + 2 OH false( aq false) − → Ag 2 normalO ( s ) + normalH 2 normalO ( l ) The average crystal size of the nanoparticles was computed from selected major peaks using the Debye–Scherrer’s formula ( D = ( k λ/β cos θ)), where D represents the crystalline size (nm), λ indicates the wavelength of X-rays (0.1541 nm), β specifies the angular line full width at half-maximum (FWHM) of the peak (in radians), and θ displays the Braggs angle (in degrees) .…”

“…64,65 Ag ions (salt) were converted to silver(I) oxide, whereas by significantly increasing the pH of the medium during the biosynthesis of silver nanoparticles, Ag + can be converted to silver(I) oxide due to NaOH (aq) used for the pH adjustment. The use of NaOH to produce a solid Ag 2 O phase was previously reported 66,67 that silver ions in the presence of OH ions form AgOH (aq), which quickly decompose when heated and precipitate to form the desired Ag 2 O, 68 as shown in the following chemical reaction eq 2. Conversely, the use of amino acids (phenylalanine and (2)…”