فصلنامه نانو مقیاس
سال ششم شماره 1 (پیاپی 21، بهار 1398)

In this work, at first thiolated graphene quantum dot tio-GQD was synthesized. Characterization of the synthesized compound was caried out by the use of infrared spectroscopy. The obtained results confirm that the thiolated graphene quantum dot was succesfully synthesized. The size of these nanoparticles was investigated by TEM. On the base of achieved images, the average dimeters of nanoparticles were estimated about 50 nm. The oxidized GQD were thiol functionalized with cysteamine. In the following the prepared nanoparticles were applied for the determination of trace amount of mercury. The limit of detection was obtained 0.160 μM and linear concentration rang 0.5 µM to 1 mM. Finaly the synthesized thiolated graphene quantum dot was applied for the determination of mercury in the real samples and selectivity with satisfactory results.

Cupric oxide CuO thin films were synthesized on ITO substrate using thermal oxidation route. Samples were made using a Cu-layer deposited by PVD method in two cases: in the absence and presence of an adhesive oxide layer on the substrate. Samples were characterized by FESEM images, XRD and UV-Vis. spectra. We found that while the surface of the sample without adhesive layer is covered by nanograins, but sample with the adhesive layer is covered by rough nano-grains contained of very fine grains, about 30 nm or less. The XRD spectra of the samples indicated a polycrystalline structure in monoclinic phase with the main orientations of 111 and 1 ̅11. Among these samples, one with an adhesive layer has a better physical conditions i.e. bigger crystallite sizes, smaller band gap and higher optical absorbance. Finally, photoconductivity effect in metal-semiconductor-metal MSM structure was investigated using a red LED lamp.

Escherichia coli E.coli is the most important species that causes dysentery. Present study was conducted to investigate the synergistic antimicrobial effects of Nano-selenium and lactobacillus on E.coli to suggest anti-diarrhea bio-drug. The antimicrobial effects of experimental treatments against E.coli were evaluated by disk diffusion and well diffusion methods as a measure of the growth inhibition zone. Moreover, the minimum inhibitory concentration MIC and minimum bactericidal concentration MBC were determined by micro-dilution method. The results of the well and disk diffusion methods showed that in both tests, the highest growth inhibition zone of the "Nano selenium-loaded lactobacillus" treatment on the standard strain of E.coli was 23/6 and 23/36 mm respectively. The results of MIC and MBC determination showed that in all experimental periods, "Nano selenium-loaded lactobacillus" and "Nano-selenium lactobacillus" treatments with 590/7 and 615/38 μg/ml for MIC and 955/32 and 1195/67 μg/ml for MBC had the lowest amounts compared to other treatments P<0.05. The results of this experiment confirmed the anti-diarrhea ability of "Nano selenium-loaded lactobacillus" treatment. Therefore, provided that this test be repeated in future studies and ensured the accuracy of these results, manufacturing of bio-drug with this formulation may be advised for prevention or treatment of diarrheal disease.

Herein, the optical properties of CdS and Carbon quantum dots QDs for the first time under gamma irradiation was studied. The CdS QDs were synthesized by a rapid, facile and low cost microwave assisted method and carbon QDs extracted from orange juice by hydrothermal method. The samples were exposure by gamma ray with source of Co-60 within 0-20 kGy. The results showed that gamma irradiation suppress the photoluminescence PL intensity of QDs. A linear relation between PL intensity and logarithmic dose of gamma was found for the matrixed CdS QDs deposited top of glass. The initial size of CdS QDs was indicated about 3.4 nm by transmission electron microscopy TEM. For water-soluble CdS QDs and powdered carbon QDS, PL intensity was decreased as dose of 20 kGy gamma irradiation. These results shows that the luminescent nanostructure can be a new candidate for dosimetry.

In this work, we report on the fabrication, morphology, and electrical and optical characterization of sandwich devices of bromo indium phthalocyanine thin film nanostructures in aluminum electrodes using electron beam evaporation in a high vacuum which are promising for sensing applications. We investigate the influence of both parameters of temperature and frequency on the conduction mechanism to deter-mine the transport process of the charge carriers. Result demonstrates that the capacitance and the loss factor decrease with increasing the frequency and increase for high temperatures. The behavior of the ca-pacitance and loss factor fits well with the model of Goswami and Goswami and the results imply the domination of the hopping theory. In addition, analysis of absorption spectrum indicates that the optical band gap energy is 3eV. Furthermore, morphological analysis demonstrates that all films have a smooth surface with homogeneous small crystal grains with a nanoscale size order of 40 ±10nm. Thus, tempera-ture and frequency dependent experiments of optical and electrical parameters of the bromo indium phthalocyanine thin film nanostructures show their potential to be employed for developing a multifunc-tion sensor.

In this paper, Fe3O4 magnetic nanoparticles were synthesized by a co-precipitation method at room temperature with and without magnetic field during the synthesizing process. Their magnetic properties were measured by vibrating sample magnetometer (VSM) instrument. VSM was used for studding the paramagnetic properties of the nanoparticles and the effect of the magnetic field on the magnetic properties of nanoparticles. The results showed that the sample synthesized in the presence of magnetic field has the saturation magnetization value as about 42 emu/gr. The saturation magnetization value for the synthesized sample in the absence of magnetic field is about 64 emu/gr. The X-ray diffraction (XRD) pattern revealed the low crystallinity for the synthesized nanoparticles in the presence of magnetic field in comparison with synthesized nanoparticles in the absence of magnetic field. The Fourier-transform infrared (FTIR) spectroscopy confirmed the chemical bond formation of the magnetic nanoparticles. The scanning electron microscopy (SEM) images showed the morphology of the nanoparticles. The reduction of saturation magnetization value and the crystallinity of nanoparticles can be related to the magnetic dipole orientation by the magnetic field during the synthesizing.

In this paper, an efficient method for the synthesis of Reduced Graphene Oxide/Magnetite RGO/Fe3O4 nanocomposite is presented. The properties of RGO/Fe3O4 nanocomposite were investigated using FT-IR, XRD, VSM and SEM. The average size of Fe3O4 nanoparticles on graphene substrates was obtained 22 ± 5 nm using SEM images. The VSM results demonstrate that there is no apparent change in the properties of magnetite nanoparticles in RGO/Fe3O4 nanocomposite. Therefore, this nanocomposite could be appropriate for magnetic applications. In cyclic voltammetry studies, oxidation current enhancement was observed when magnetite nanoparticles loaded on graphene substrates, which could make RGO/Fe3O4 nanocomposite as an efficient electrochemical sensor.