Charge Stabilized Silver Nanoparticles Applied as Antibacterial Agents

Area of Science:

• Materials Science
• Nanotechnology
• Microbiology

Background:

• Silver nanoparticles (AgNPs) are recognized for their antimicrobial properties.
• Conventional synthesis often relies on stabilizing agents, which can influence AgNP behavior.
• Developing AgNPs with controlled surface properties is crucial for enhanced efficacy.

Purpose of the Study:

• To synthesize monodisperse silver nanoparticles in an aqueous environment without stabilizers.
• To investigate the antibacterial activity of these AgNPs against E. coli strains.
• To elucidate the mechanism of AgNP-bacteria interaction and the role of surface chemistry.

Main Methods:

• Chemical reduction using various agents, including gallic acid (GA) and tannin (TA).
• Physicochemical characterization using TEM, SEM, AFM, DLS, and micro-electrophoresis.
• Antibacterial activity assessed via Minimum Bactericidal Concentration (MBC) assays and imaging (TEM, AFM).

Main Results:

• Stable, monodisperse AgNPs were synthesized without polymeric stabilizers or surfactants.
• AgNP sols demonstrated significant bactericidal effects against E. coli K12 (MBC 1-5 mg L⁻¹ for GA and TA sols).
• AgNPs interacted with bacteria, causing surface disintegration and internalization, with surface chemistry playing a key role.

Conclusions:

• Aqueous synthesis of AgNPs is feasible without traditional stabilizers.
• GA and TA are effective agents for producing highly bactericidal AgNPs.
• Surface interactions are critical for AgNP antibacterial mechanisms, offering potential for targeted antimicrobial strategies.