Indian Journal of Microbiology ( IF 2.1 ) Pub Date : 2021-09-07 , DOI: 10.1007/s12088-021-00976-w Lalita Singh 1 , Reena Antil 1 , Pushpa Dahiya 1
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Abstract
Green synthesis of nanoparticles is an important tool to reduce the harmful effects associated with traditional methods. In the present investigation, we have synthesised gold nanoparticles (AuNPs) using aqueous extract prepared from fresh aerial parts (leaf and stem) of Vernonia cinerea as bioreducing agent. The visual indication of change in colour from pale yellow to brown to ruby-red indicated the successful formation of the AuNPs. Characterization of nanoparticles was carried out by UV–visible spectroscopy, X-ray crystallography (XRD), Transmission electron microscopy (TEM) and Energy dispersive X-ray analysis (EDX). UV–Vis spectra showed a specific peak at 546 nm which was the initial confirmation of the biosynthesized AuNPs. TEM images showed spherical and triangular shape of AuNPs with an average size of 25 nm. From FTIR spectrum, different functional groups were identified that could be responsible for the formation, stabilization, and capping of biosynthesized AuNPs. Aqueous plant extract and biosynthesised AuNPs were separately tested for their antimicrobial activity against six bacterial strains and four fungal strains. Biosynthesised AuNPs (2 mg/ml) showed significantly high zone of inhibition against the selected bacterial strains as compared to the aqueous plant extract. Maximum zone of inhibition (18.2 mm) was observed with AuNPs against Streptococcus pyogenes whereas comparatively less value (12.5 mm) was recorded with the plant extract. Interestingly, the inhibitory activity observed against bacterial strains was even better than ampicillin. Antifungal activity recorded with AuNPs (5 mg/ml) was maximum (17.4 mm) against R. oryzae and it was higher than positive control (17.00 mm) and plant extract (13.2 mm).The present study clearly showed that AuNPs coated with Vernonia cinerea extract were as good as positive control in inhibiting bacterial and fungal growth. In addition, these AuNPs also showed good antioxidant potential which was comparable to ascorbic acid.
Graphical abstract
中文翻译：
斑鸠菊提取物涂层 AuNPs 的抗菌和抗氧化潜力
摘要
纳米粒子的绿色合成是减少与传统方法相关的有害影响的重要工具。在本次调查中，我们使用从斑鸠菊的新鲜地上部分（叶和茎）制备的水提取物合成了金纳米粒子 (AuNP)作为生物还原剂。颜色从淡黄色变为棕色再变为宝石红色的视觉指示表明 AuNP 已成功形成。通过紫外可见光谱、X 射线晶体学 (XRD)、透射电子显微镜 (TEM) 和能量色散 X 射线分析 (EDX) 对纳米粒子进行表征。紫外-可见光谱在 546 nm 处显示出一个特定的峰，这是对生物合成的 AuNP 的初步确认。TEM 图像显示 AuNP 呈球形和三角形，平均尺寸为 25 nm。从 FTIR 光谱中，确定了可能负责生物合成 AuNP 的形成、稳定和封端的不同官能团。分别测试了水性植物提取物和生物合成的 AuNP 对六种细菌菌株和四种真菌菌株的抗菌活性。与水性植物提取物相比，生物合成的 AuNPs (2 mg/ml) 对选定的细菌菌株显示出显着高的抑制区。使用 AuNPs 观察到最大抑制区 (18.2 mm)化脓性链球菌而植物提取物记录的值相对较低（12.5 毫米）。有趣的是，观察到的对细菌菌株的抑制活性甚至优于氨苄青霉素。AuNPs (5 mg/ml) 对米根霉的抗真菌活性最高 (17.4 mm)，高于阳性对照 (17.00 mm) 和植物提取物 (13.2 mm)。本研究清楚地表明，AuNPs 涂有斑鸠菊灰霉病提取物在抑制细菌和真菌生长方面与阳性对照一样好。此外，这些 AuNPs 还显示出与抗坏血酸相当的良好抗氧化潜力。
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