Synthesis and antibacterial activity of colloidal silver prepared by electrochemical method

Abstract

Study was conducted on the electrochemical method of preparing colloidal silver at low DC voltage. A natural stabilizer was used as a carob bean gum from the carob bean. Using a UV-Vis spectrophotometer and a transmission electron microscope (TEM), colloidal silver (silver nanoparticles) was characterized. It is possible to produce colloidal silver of satisfactory quality by means of this electrochemical method. Silver nanoparticles have exhibited surface plasmon resonance as determined by UV-vis analysis. Based on the TEM analysis, the silver nanoparticles appear to be spherical except in sample E1, where they appear rod-shaped and micrometer-sized. Other three samples had particle sizes ranging from 23–52 nm. In a qualitative analysis of colloidal silver solutions, two types of antibacterial activity were observed. At all dilutions, some colloidal solutions showed better antibacterial activity against gram-positive bacteria (S. aureus, S. pyogenes, E. faecalis) while others displayed better antibacterial activity against gram-negative bacteria (S. enteridis, P. aeruginosa, E. coli).

Keywords

• Colloidal silver
• UV-Vis spectrophotometry
• TEM
• surface plasmon resonance
• carob bean gum
• antimicrobial activity