Nano Material Research Laboratory, Department of Chemistry, Indian Institute of Technology (BHU), Varanasi 221005, U.P., India.
Nano Material Research Laboratory, Department of Chemistry, Indian Institute of Technology (BHU), Varanasi 221005, U.P., India.
Mater Sci Eng C Mater Biol Appl. 2017 Feb 1;71:1004-1019. doi: 10.1016/j.msec.2016.11.013. Epub 2016 Nov 8.
The AgNPs synthesized by green method have shown great potential in several applications such as biosensing, biomedical, catalysis, electronic etc. The present study deals with the selective colorimetric detection of Fe using photoinduced green synthesized AgNPs. For the synthesis purpose, an aqueous extract of Croton bonplandianum (AEC) was used as a reducing and stabilizing agent. The biosynthesis was confirmed by UV-visible spectroscopy where an SPR band at λ 436nm after 40s and 428nm after 30min corresponded to the existence of AgNPs. The optimum conditions for biosynthesis of AgNPs were 30min sunlight exposure time, 5.0% (v/v) AEC inoculum dose and 4mM AgNO concentration. The stability of synthesized AgNPs was monitored up to 9months. The size and shape of AgNPs with average size 19.4nm were determined by Field Emission Scanning Electron Microscope (FE-SEM) and High-Resolution Transmission Electron Microscope (HR-TEM). The crystallinity was determined by High-Resolution X-ray Diffractometer (HR-XRD) and Selected Area Electron Diffraction (SAED) pattern. The chemical and elemental compositions were determined by Fourier Transformed Infrared Spectroscopy (FTIR) and Energy Dispersive X-ray Spectroscopy (EDX) respectively. The Atomic Force Microscopy (AFM) images represented the lateral and 3D topological characteristics of AgNPs. The XPS analysis confirmed the presence of two individual peaks which attributed to the Ag 3d3/2 and Ag 3d5/2 binding energies corresponding to the presence of metallic silver. The biosynthesized AgNPs showed potent antibacterial activity against both gram-positive and gram-negative bacterial strains as well as antioxidant activity. On the basis of results and facts, a probable mechanism was also proposed to explore the possible route of AgNPs synthesis, colorimetric detection of Fe, antibacterial and antioxidant activity.
采用绿色方法合成的 AgNPs 在生物传感、生物医药、催化、电子等多个领域具有巨大的应用潜力。本研究采用光诱导绿色合成的 AgNPs 对 Fe 进行选择性比色检测。为了合成目的，使用 Croton bonplandianum 的水提物（AEC）作为还原剂和稳定剂。通过紫外-可见光谱法确认了生物合成，在 40s 后出现 λ 436nm 的 SPR 带，在 30min 后出现 λ 428nm 的 SPR 带，表明 AgNPs 的存在。AgNPs 生物合成的最佳条件为 30min 阳光照射时间、5.0%（v/v）AEC 接种剂量和 4mM AgNO3 浓度。合成 AgNPs 的稳定性监测时间长达 9 个月。通过场发射扫描电子显微镜（FE-SEM）和高分辨率透射电子显微镜（HR-TEM）确定 AgNPs 的尺寸和形状，平均尺寸为 19.4nm。通过高分辨率 X 射线衍射仪（HR-XRD）和选区电子衍射（SAED）图案确定结晶度。通过傅里叶变换红外光谱（FTIR）和能量色散 X 射线光谱（EDX）分别确定化学和元素组成。原子力显微镜（AFM）图像表示 AgNPs 的横向和 3D 拓扑特征。XPS 分析证实存在两个单独的峰，归因于 Ag 3d3/2 和 Ag 3d5/2 的结合能，对应于金属银的存在。生物合成的 AgNPs 对革兰氏阳性和革兰氏阴性细菌菌株均表现出强大的抗菌活性和抗氧化活性。基于结果和事实，还提出了一个可能的机制，以探索 AgNPs 合成、Fe 比色检测、抗菌和抗氧化活性的可能途径。
