A comparative evaluation of green colloidal silver variants for enhanced stability and bioactivity

Area of Science:

• Materials Science
• Nanotechnology
• Green Chemistry

Background:

• Colloidal silver (CS) enhances consumer products but faces challenges with conventional synthesis (toxicity, cost, stability).
• Green synthesis using plant extracts presents a sustainable alternative for CS production.

Purpose of the Study:

• To compare the stability, composition, and efficacy of CS synthesized via a patented plant-based method (CS_BX3), lemon juice (CS_LJ), and green tea (CS_GT) against a commercial reference (CS_Ref).
• To evaluate the antioxidant and antimicrobial properties of the green-synthesized CS formulations.

Main Methods:

• Characterization techniques included UV-Vis, Dynamic Light Scattering (DLS), Scanning Electron Microscopy (SEM), Zeta Potential, and Energy Dispersive X-ray Spectroscopy (EDS).
• Stability was assessed under long-term storage (60 days), varying temperatures (4-37°C), pH (3-11), and phosphate-buffered saline (PBS).
• Antioxidant activity and minimum inhibitory concentration (MIC) against E. coli and Listeria were determined.

Main Results:

• CS_BX3 and CS_LJ demonstrated superior colloidal stability under various stress conditions, including low temperatures and PBS.
• CS_BX3 maintained particle dispersion and uniformity across a wide pH range (neutral to alkaline).
• CS_GT and CS_BX3 exhibited the most potent antioxidant and antimicrobial activities, with CS_GT showing 20% higher antioxidant capacity and over 90% bacterial eradication within 24 hours.

Conclusions:

• Green synthesis methods, particularly CS_BX3 and CS_LJ, yield highly stable colloidal silver formulations.
• CS_BX3 and CS_GT show significant potential for applications in food, biomedical, and personal care industries due to their enhanced properties.