The green synthesis of silver nanoparticles represents an important strategy for production of alternative antibacterial agents. Herein, the reduction of silver nanoparticles is provided by the action of leaf extract of Ziziphus joazeiro. The as-synthesized material presented pH-dependent behavior that affects the kinetics of nanoparticles nucleation and the following aggregation. Alkaline and acidic environment favors the increasing polydispersity of nanoparticles providing the production of different distribution of particle size. At neutral condition (pH 7), particles with lower size and reduced aggregation degree are obtained and present antibacterial activity against S. aureus and E. coli. The number of viable cells for both systems (from initial culture containing 10⁴ colonies) reached negligible counting after 5 h of interaction with silver nanoparticles prepared at neutral pH.

中文翻译：

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用Zipiphus joazeiro叶提取物绿色合成银纳米颗粒以生产抗菌剂

银纳米颗粒的绿色合成代表了生产替代抗菌剂的重要策略。在此，银纳米颗粒的还原是​​通过Zipiphus joazeiro的叶提取物的作用提供的。合成后的材料呈现出pH依赖行为，该行为影响纳米颗粒成核和随后的聚集动力学。碱性和酸性环境有利于增加纳米粒子的多分散性，从而提供不同粒度分布的生产。在中性条件下（pH 7），可获得具有较小尺寸和降低的聚集度的颗粒，并且具有对金黄色葡萄球菌和大肠杆菌的抗菌活性。。与在中性pH值下制备的银纳米颗粒相互作用5小时后，两个系统的活细胞数（来自包含10 ^4个菌落的初始培养物）的计数可忽略不计。