Ghareib Mohamed, Tahon Medhat Abu, Saif Mona Mostafa, El-Sayed Abdallah Wafaa
Department of Biological and Geological Sciences Faculty of Education, Ain Shams University, Roxy11757, Cairo, Egypt.
Department of Chemistry, Faculty of Education, Ain Shams University, Roxy 11757, Cairo, Egypt.
Iran J Pharm Res. 2016 Fall;15(4):915-924.
The development of green approaches for the biosynthesis of silver nanoparticles (AgNPs) is of prime significance in the field of nanotechnology research. A fast and eco-friendly protocol for the biosynthesis of extracellular AgNPs using culture supernatant (CS) from the fungus was studied in this work. This CS was proved as a potential new source for the extracellular biosynthesis of AgNPs. The AgNPs were formed at 100 C and pH 9 within four min of contact between CS and 1mM silver nitrate (AgNO) solution. Nitrate reductase (NR) was confirmed to play a pivotal role in the biosynthesis of AgNPs. The enzyme expressed its highest activity at 80 C and pH 9. At 100 C the enzyme retained 70% of its original activity for one hour. The half-life (T) of the enzyme activity was calculated to be 1.55 h confirming its thermostability. The produced AgNPs were characterized by UV-Vis spectroscopy, high resolution-transmission electron microscope (HR-TEM) and x-ray diffraction (XRD). These NPs showed an absorption peak at 415 nm in UV-Vis spectrum corresponding to the plasmon resonance of AgNPs. Transmission electron micrographs revealed the production of monodispersed spherical NPs with average particle size 14 nm. XRD spectrum of the NPs confirmed the formation of metallic crystalline silver. It was also suggested that the aromatic amino acids play a role in the biosynthesis process. The current research provided an insight on the green biosynthesis of AgNPs including some mechanistic aspects using a new mycogenic source.
银纳米颗粒（AgNPs）生物合成绿色方法的开发在纳米技术研究领域具有至关重要的意义。本研究探索了一种利用真菌培养上清液（CS）进行细胞外AgNPs生物合成的快速且环保的方案。该CS被证明是细胞外生物合成AgNPs的潜在新来源。在CS与1mM硝酸银（AgNO₃）溶液接触的四分钟内，于100℃和pH 9条件下形成了AgNPs。已证实硝酸还原酶（NR）在AgNPs的生物合成中起关键作用。该酶在80℃和pH 9时表现出最高活性。在100℃时，该酶在一小时内保留了其原始活性的70%。计算得出该酶活性的半衰期（T₁/₂）为1.55小时，证实了其热稳定性。通过紫外可见光谱、高分辨率透射电子显微镜（HR-TEM）和X射线衍射（XRD）对所制备的AgNPs进行了表征。这些纳米颗粒在紫外可见光谱中于415nm处显示出吸收峰，对应于AgNPs的等离子体共振。透射电子显微镜照片显示生成了平均粒径为14nm的单分散球形纳米颗粒。纳米颗粒的XRD光谱证实了金属结晶银的形成。研究还表明芳香族氨基酸在生物合成过程中发挥作用。当前的研究为AgNPs的绿色生物合成提供了见解，包括使用新的真菌源的一些作用机制方面。
