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<p>The growing resistance of the pathogenic bacteria to traditional antibiotics has provoked a strong demand of the new antimicrobial materials. Silver nanoparticles (AgNPs) have emerged as potent candidates due to their broad-spectrum antibacterial activity and tunable physicochemical properties. This study presents a systematic research on how the reaction parameters affect the formation, structure and antibacterial behavior of silver nanoparticles (AgNPs) prepared through a straightforward chemical reduction method. Five AgNP formulations (S1–S5) were prepared by varying reaction temperature and time, using sodium dodecyl sulfate (SDS) as a stabilizer and hydrazine hydrate as a reducing agent. UV–visible spectroscopy and XRD analyses were performed for all synthesized samples to examine the effect of synthesis conditions on the optical and structural evolution of AgNPs. The optimized sample (S4, 70 °C, 60 min) was subjected to comprehensive microstructural and surface characterization through SEM, TEM, EDS, and FTIR analyses to establish a clear structure–property relationship. The UV–Vis spectra exhibited distinct surface plasmon resonance (SPR) bands in the range of 395–420 nm, red-shifting systematically with increasing reaction temperature and time, confirming particle growth and enhanced crystallinity. XRD analysis revealed the formation of highly crystalline face-centered cubic (FCC) silver with increasing phase purity under optimized conditions. SEM and TEM imaging of the optimized sample revealed spherical nanoparticles in the range of 60–75 nm, while EDS confirmed compositional purity and uniform spatial distribution of silver. Antibacterial evaluation against <i>Escherichia coli</i> and <i>Staphylococcus aureus</i> revealed that AgNPs prepared at 70 °C for 60 min exhibited the highest efficiency, with minimum inhibitory concentrations (MICs) of 25 µg/mL and 50 µg/mL, respectively. A weak DPPH radical scavenging activity was also observed, reflecting moderate antioxidant potential. The findings demonstrate that the increased crystallinity and homogeneous microstructure of the AgNPs are the direct factors determining their antibacterial effectiveness. This enhanced performance is attributed to improved Ag⁺ ion release and stronger interaction of well-crystallized, uniformly shaped nanoparticles with bacterial cell walls, resulting in more effective disruption of cellular integrity. Overall, this study establishes a direct correlation between synthesis parameters, structural evolution, and biological performance, providing a reliable framework for the rational design of functional AgNPs.</p> Graphical Abstract <p></p>

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Facile chemical reduction synthesis of silver nanoparticles: influence of reaction parameters on structure and antibacterial properties

  • 期刊论文

  • 发表日期：

    2026年2月5日

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  • Kamran Heydaryan

摘要

The growing resistance of the pathogenic bacteria to traditional antibiotics has provoked a strong demand of the new antimicrobial materials. Silver nanoparticles (AgNPs) have emerged as potent candidates due to their broad-spectrum antibacterial activity and tunable physicochemical properties. This study presents a systematic research on how the reaction parameters affect the formation, structure and antibacterial behavior of silver nanoparticles (AgNPs) prepared through a straightforward chemical reduction method. Five AgNP formulations (S1–S5) were prepared by varying reaction temperature and time, using sodium dodecyl sulfate (SDS) as a stabilizer and hydrazine hydrate as a reducing agent. UV–visible spectroscopy and XRD analyses were performed for all synthesized samples to examine the effect of synthesis conditions on the optical and structural evolution of AgNPs. The optimized sample (S4, 70 °C, 60 min) was subjected to comprehensive microstructural and surface characterization through SEM, TEM, EDS, and FTIR analyses to establish a clear structure–property relationship. The UV–Vis spectra exhibited distinct surface plasmon resonance (SPR) bands in the range of 395–420 nm, red-shifting systematically with increasing reaction temperature and time, confirming particle growth and enhanced crystallinity. XRD analysis revealed the formation of highly crystalline face-centered cubic (FCC) silver with increasing phase purity under optimized conditions. SEM and TEM imaging of the optimized sample revealed spherical nanoparticles in the range of 60–75 nm, while EDS confirmed compositional purity and uniform spatial distribution of silver. Antibacterial evaluation against Escherichia coli and Staphylococcus aureus revealed that AgNPs prepared at 70 °C for 60 min exhibited the highest efficiency, with minimum inhibitory concentrations (MICs) of 25 µg/mL and 50 µg/mL, respectively. A weak DPPH radical scavenging activity was also observed, reflecting moderate antioxidant potential. The findings demonstrate that the increased crystallinity and homogeneous microstructure of the AgNPs are the direct factors determining their antibacterial effectiveness. This enhanced performance is attributed to improved Ag⁺ ion release and stronger interaction of well-crystallized, uniformly shaped nanoparticles with bacterial cell walls, resulting in more effective disruption of cellular integrity. Overall, this study establishes a direct correlation between synthesis parameters, structural evolution, and biological performance, providing a reliable framework for the rational design of functional AgNPs.

Graphical Abstract