Partial aggregation of silver nanoparticles induced by capping and reducing agents competition.

Area of Science:

• Materials Science
• Nanotechnology
• Chemistry

Background:

• Nanomaterial properties depend critically on size, shape, and morphology.
• Silver nanoparticles (AgNPs) possess versatile properties beneficial for biomedical and technological uses.
• Nanoparticle aggregation can diminish desirable properties due to altered size and morphology.

Purpose of the Study:

• To investigate the aggregation of silver nanoparticles (AgNPs) during synthesis.
• To understand how varying reducing agent concentration affects AgNP formation and aggregation.
• To correlate aggregation states with physicochemical parameters and structural characteristics.

Main Methods:

• Synthesis of AgNPs via chemical reduction of silver nitrate using sodium borohydride and sodium citrate.
• Controlled variation of reducing agent concentration to obtain unaggregated and aggregated AgNPs.
• Characterization using UV-vis spectroscopy, zeta potential measurements, Small-Angle X-ray Scattering (SAXS), and pH monitoring.

Main Results:

• Increasing sodium borohydride concentration led to larger average AgNP size and induced aggregation.
• Zeta potential and pH were found to significantly influence AgNP formation and aggregation.
• SAXS analysis revealed that the aggregates formed were elongated-like particles.

Conclusions:

• The concentration of the reducing agent is a critical factor controlling AgNP aggregation.
• Physicochemical parameters like pH and zeta potential play a crucial role in AgNP stability and aggregation.
• The study successfully identified and characterized AgNP aggregation states using a combination of techniques, revealing elongated aggregate morphology.