The present study reports the optimization of various parameters for green synthesis of silver nanoparticles using aqueous leaf extract of Ocimum gratissimum. The effects of various parameters such as concentration of AgNO₃, ratio of AgNO₃ to extract, pH and incubation time were studied in order to optimize the synthesis process. 5 mM AgNO₃, 1:0.06 ratio of AgNO₃ to O. gratissimum leaf extract, pH 9.0 and incubation of reaction mixtures for 24 h were found to be the optimum parameters for synthesis of silver nanoparticles (AgNPs). The synthesized AgNPs were characterized by UV–visible absorption spectroscopy, scanning electron microscopy and transmission electron microscopy. The nature of the reducing and capping agents in the leaf extract was determined using Fourier transform infrared spectrometer analysis. Furthermore, AgNPs showed higher antimicrobial activity against the Gram negative (Escherichia coli, Klebsiella pneumoniae) in comparison to the Gram positive bacteria (Staphylococcus aureus, Bacillus subtilis and Micrococcus luteus). In addition to this, AgNP containing solution was subjected to toxicity analysis using seeds of Moong Bean (Vigna radiata). It was found that seeds treated with AgNP solutions showed better rates of germination and oxidative stress enzyme activity was at par with the control levels. This study demonstrates that O. gratissimum leaf extract can be used for production of AgNPs with potential antibacterial activity. Future research is warranted on the investigation of detailed mechanism of their antimicrobial activity, uptake and translocation in plants.

中文翻译：

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用免费赠送的Ocimum gratissimum叶提取物绿色合成银纳米颗粒：表征，抗菌活性和毒性分析

本研究报告了利用桔梗含水提取物优化绿色合成银纳米粒子的各种参数。各种参数，如硝酸银的浓度的影响₃，硝酸银的比₃至提取物，pH和孵育时间以优化的合成过程进行了研究。5 mM AgNO ₃，AgNO ₃与O. gratissimum的比例为1：0.06发现叶提取物，pH 9.0和反应混合物孵育24小时是合成银纳米颗粒（AgNPs）的最佳参数。通过紫外可见吸收光谱，扫描电子显微镜和透射电子显微镜对合成的AgNPs进行表征。使用傅里叶变换红外光谱仪分析确定叶提取物中还原剂和加帽剂的性质。此外，与革兰氏阳性细菌（金黄色葡萄球菌，枯草芽孢杆菌和黄球微球菌）相比，AgNPs对革兰氏阴性菌（大肠杆菌，肺炎克雷伯菌）具有更高的抗菌活性。）。除此之外，使用Moong Bean（Vigna radiata）种子对含有AgNP的溶液进行毒性分析。发现用AgNP溶液处理的种子显示出更好的发芽率，并且氧化应激酶活性与对照水平相当。这项研究表明，澳gratissimum叶提取物可用于生产具有潜在的抗菌活性的AgNPs的。需要进一步研究其抗菌活性，在植物中的吸收和转运的详细机制。