Silver nanoparticles stabilized by ramnolipids: Effect of pH

Area of Science:

• Nanotechnology
• Materials Science
• Biotechnology

Background:

• Rhamnolipids, glycolipid biosurfactants, exhibit self-assembly properties suitable for nanobiotechnology.
• Silver nanoparticles (AgNPs) possess valuable catalytic and antimicrobial properties.
• Stabilizing AgNPs with biosurfactants offers a sustainable approach for nanomaterial synthesis.

Purpose of the Study:

• To investigate the effect of pH on rhamnolipid-stabilized silver nanoparticle synthesis.
• To evaluate the influence of pH on AgNP size, morphology, and stability.
• To explore the potential of rhamnolipids as stabilizers for silver nanoparticles.

Main Methods:

• Synthesis of silver nanoparticles using rhamnolipids derived from glycerol.
• Characterization of nanoparticles using dynamic light scattering (DLS) for size analysis.
• Assessment of nanoparticle stability via zeta potential measurements.
• Morphological analysis using field emission gun scanning electron microscopy (FEG-SEM).

Main Results:

• Particle size varied significantly with pH: larger at pH 5 (78-190 nm) and smaller at pH 7 (6.5-43 nm) and pH 9 (5.6-28.1 nm).
• Nanoparticle stability, indicated by zeta potential, increased with pH, ranging from -29.86 mV at pH 5 to -40.33 mV at pH 9.
• FEG-SEM confirmed the spherical morphology of the synthesized silver nanoparticles.
• Localized surface plasmon resonance (LSPR) spectra remained consistent across different pH values.

Conclusions:

• Synthesis pH is a critical factor influencing the size and stability of rhamnolipid-stabilized silver nanoparticles.
• Optimal stability is achieved at higher pH values (7 and 9).
• Rhamnolipids are effective stabilizers for silver nanoparticles, with pH control offering a method to tune nanoparticle properties.