Modares Journal of Biotechnology

Abstract DNA methylation detection by a novel fluorimetric nanobiosensor for early cancer diagnosis Quantum­ dots as a fluorescent probe are applied for cell biology, DNA transformation, biomedical imaging and cancer therapy. Biological based synthesis of nanoparticles would be more efficient and environment friendly rather than chemical approaches. In the present study, quantum dots have been synthesized through leaf methanolic extracts. The obtained results by UV-vis spectroscopy, TEM, FT-IR and fluorescence spectroscopy showed the presence of synthesized CdS quantum dots. Yellow and orange colors of obtained solution was also indicated the successful synthesis of CdS quantum dots. The maximum UV-Vis spectrum absorption of quantum dots was observed at 410 nm. Results of fluorescence analysis also showed that emission bands were at 475, 490 and 675 respectively which indicated the synthesis of different CdS quantum dots in different pH values. Obtained nanoparticle were spherical and at the range between 2-10 nm according to TEM analysis. FT-IR analysis also showed that the proteins, leucine and lysine amino acids, phenols and other functional groups present in physalis extracts would be determining factors for reducing CdS ions and converting them to quantum dots.

Abstract Gold nanoparticles have received considerable attention in recent years because of their promising applications in diagnostic imaging, biosensors, biolabels, and drug and gene delivery systems. The chemical methods of nanoparticle synthesis are the most widely and traditionally used methods. Production of nanoparticles by chemical methods causes contamination from precursor chemicals due to the use of toxic solvents and generation of hazardous by-products. On the other hand, the physical methods have low yield and high cost. Hence, there is an increasing need to develop low cost, non-toxic, biocompatible and environmentally benign processes for synthesis of metallic nanoparticles where the biological approaches for synthesis of nanoparticles gain importance. In this study, we investigated the biosynthesis of gold nanoparticles using Streptomyces sp. ERI-3. Streptomycessp.ERI-3 was isolated from the soil of Ahar Copper Mine (Ahar, Iran) and its biomass was incubated at 28ºC on a rotary shaker (200 rpm) for 48 h. The nanoparticles were characterized by means of UV-vis spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM).The nanoparticles exhibited maximum absorbance at 540 nm (special wavelength of gold nanoparticles) in UV-vis spectroscopy. The XRD spectrum of gold nanoparticles exhibited 2Ө values corresponding to the gold nanocrystals. The TEM micrographs revealed the extracellular and attached to cell surface formation of gold nanoparticles in the size range of 50-100 nm with spherical morphology.

Abstract In biological methods, microorganisms such as bacteria, fungi, actinomycets and yeasts are used to produce metal nanoparticles. Fungi are extremely good candidates in the synthesis of silver nanoparticles because of their ability to secrete large amounts of enzymes. The aim of this study was the biosynthesis of silver nanoparticles by Penicillium spp. isolated from the soil of plump and zinc mine in Zanjan city (Iran). After culturing, growth of colonies and isolation of Penicillium spp., 15 g of the fungal biomass was mixed into 1 mM silver solution for 72 h incubation. The production of silver nanoparticles was characterized by UV-vis spectroscopy, X-ray diffraction(XRD) and transmission electron microscopy. Among the sixteen kinds of isolated fungi, six species were recognized as Penicillium of which just the fungus Penicilliumbrevicompactum was found to be able to produce silver nanoparticles. The production of silver nanoparticles was preliminarily approved by observing the color change of the reaction solution from colorless to yellowish brown. The synthesis of silver nanoparticles was confirmed by observing the characteristic peak at 406-425 nm. The presence of crystalline silver nanoparticles was confirmed by observing peaks in (111), (200), (220), (311) in the XRD analysis. Transmission electron microscopy images showed that silver nanoparticles were produced in the size range of 50 -100 nm in spherical shape mainly extracellular at the surface of mycelium. The fungus was recognized to be Penicilliumbrevicompactumusing slide culture method, growth on Czapek yeast agar and Keratin-sucrose agar.