Sharif Digital Repository

The plasmonic effects of infiltrated silver (Ag) nanoparticles, with different contents, inside a nanostructured TiO2 film on the photovoltaic performance of dye-sensitized solar cells (DSSCs) are explored. The synthesized Ag nanoparticles are immobilized onto deposited TiO2 nanoparticles by a new strategy using 3-mercaptopropionic acid (MPA), a bifunctional linker molecule. Transmission electron microscope (TEM) images show that monodispersed Ag and polydispersed TiO2 nanoparticles have an average diameter of 12 ± 3 nm and 5 ± 1 nm, respectively. Moreover, Fourier transform infrared spectroscopy (FTIR) analysis reveals that Ag nanoparticles were successfully functionalized and capped with... 

Introduction: In recent years, the use of cost-effective, multifunctional, environmentally friendly and simple prepared nanomaterials/nanoparticles have been emerged considerably. In this manner, different synthesizing methods were reported and optimized, but there is still lack of a comprehensive method with multifunctional properties. Materials and Methods: In this study, we aim to synthesis the copper oxide nanoparticles using Achillea millefolium leaf extracts for the first time. Catalytic activity was investigated by in situ azide alkyne cycloaddition click and also A3 coupling reaction, and optimized in terms of temperature, solvent, and time of the reaction. Furthermore, the... 

Three different spinel metal oxide catalytic systems including NiFe2O4, CuFe2O4 and CoFe2O4 were synthesized using co-precipitation technique and their catalytic activities were compared to each other in α-arylation of oxindole derivatives under the optimized reaction conditions. Both nickel ferrite and copper ferrite magnetic nanoparticles show approximately the same behavior in these reactions but cobalt ferrite ones indicate slightly different properties and were not as good as the other two catalysts. These superparamagnetic catalysts allowed that α-arylation of different types of oxindoles will occur in high yields under mild conditions and at very short times  

A highly sensitive and simple indirect spectrophotometric method has been developed for the determination of trace amounts of inorganic mercury (Hg2 +) in aqueous media. The method is based on the inhibitory effect of Hg2 + on the activity of horseradish peroxidase (HRP) in the oxidation of ascorbic acid by hydrogen peroxide followed by the reduction of Au3 + to Au-NPs by unreacted ascorbic acid and the measurement of the absorbance of localized surface plasmon resonance (LSPR) peak of gold nanoparticles (at 530 nm) which is directly proportional to the concentration of Hg2 +. Under the optimum conditions, the calibration curve was linear in the concentration range of 1-220 ng mL- 1. Limits... 

Spectrophotometric analysis method based on the combination of the principal component analysis (PCA) with the feed-forward neural network (FFNN) and the radial basis function network (RBFN) was proposed for the simultaneous determination of paracetamol (PAC) and p-aminophenol (PAP). This technique relies on the difference between the kinetic rates of the reactions between analytes and silver nitrate as the oxidizing agent in the presence of polyvinylpyrrolidone (PVP) which is the stabilizer. The reactions are monitored at the analytical wavelength of 420 nm of the localized surface plasmon resonance (LSPR) band of the formed silver nanoparticles (Ag-NPs). Under the optimized conditions, the... 

ZnO nanoparticles (NPs) and submicron aggregates (SMAs) were synthesized via a simple precipitation method by changing the amount of zinc acetate di-hydrate in absolute ethanol and synthesis time. Synthesized NPs and SMAs were characterized by FE-SEM, EDS, XRD, PL, and DRS and were used to fabricate dye-sensitized solar cells (DSSCs). The SMAs synthesized at moderate concentration (0.022 M) and with poly-dispersed distribution of the aggregates showed lower density of deep localized trap states as well as enhanced scattering features in comparison to NP-based electrode. As a result, power conversion efficiency (η) of about 2.56% with improved current density (Jsc) of 8.51 mA/cm2 were... 

Gold nanoparticles (Au NPs) were synthesized by co-deposition of RF-sputtering and RF-PECVD from acetylene gas and Au target on the carbon nanotubes (CNTs). The CNTs were prepared by thermal chemical vapor deposition (TCVD) and Pd nanoparticles catalyst. TEM image shows that high-density and uniform distribution of Au NPs were grown on the CNTs. XRD analysis indicates that Au NPs have fcc crystal structure and CNTs have a good graphite structure. Raman spectroscopy results suggest that our sample includes double-walled CNTs. It is resulted that intensity of D-band reduces and G-band intensity raises and radial breathing mode (RBM) is changed by immobilizing of Au NPs on the CNTs. Raman... 

A nanocomposite of silica-polydiphenylamine doped with silver nanoparticles (Ag-SiO2-PDPA) was successfully synthesized by the sol-gel process. For its preparation, PDPA was mixed with butanethiol capped Ag nanoparticles (NPs) and added to the silica sol solution. The Ag NPs were stabilized as a result of their adsorption on the SiO2 spheres. The surface characteristic of nanocomposite was investigated using scanning electron microscopy (SEM). In this work the Ag-SiO2-PDPA nanocomposite was employed as an efficient sorbent for micro-solid-phase extraction (μ-SPE) of some selected pesticides. An amount of 15 mg of the prepared sorbent was used to extract and... 

Developments of sensitive, rapid, and cheap systems for identification of a wide range of biomolecules have been recognized as a critical need in the biology field. Here, we introduce a simple colorimetric sensor array for detection of biological thiols, based on aggregation of three types of surface engineered gold nanoparticles (AuNPs). The low-molecular-weight biological thiols show high affinity to the surface of AuNPs; this causes replacement of AuNPs' shells with thiol containing target molecules leading to the aggregation of the AuNPs through intermolecular electrostatic interaction or hydrogen-bonding. As a result of the predetermined aggregation, color and UV-vis spectra of AuNPs... 

Readily prepared copper nanoparticles supported on CeO2 have been found to effectively catalyse the 1,3-dipolar cycloaddition (CuAAC) of a variety terminal alkynes and organic azides generated in situ from sodium azide and different organic halides furnishing the corresponding 1,2,3-triazoles in excellent yields. Cu nanoparticles supported on CeO2 have been characterized by X-ray diffraction analysis, energy dispersive X-ray analysis, scanning electron microscope and transmission electron microscope. The salient features of the present protocol are shorter reaction time, mild reaction conditions, reusability of the catalyst, and applicability to a wide range of substrates. © 2016 Elsevier... 

A nanocomposite consisting of polythiophene–silver was prepared and implemented as a desired sorbent for headspace needle trap extraction. Colloidal silver nanoparticles (Ag NPs) with narrow size distribution and high stability were synthesized in water–in–oil microemulsion. This simple procedure was adapted to prepare highly monodispersed Ag NPs, starting from an initial synthesis in sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles. Polythiophene (PT) was synthesized by chemical oxidative polymerization in the presence of anhydrous ferric chloride while its polymeric structure was confirmed by Fourier transform infrared spectrometry (FTIR). Eventually, the prepared PT was... 

A highly sensitive and selective sunlight-driven photoelectrochemical sensor for the direct detection and reduction of chromium(VI) was developed based on single crystal rutile titanium dioxide nanorods decorated with gold nanoparticles. Under sun simulator illumination via the amperometric technique, these Au decorated TiO2 photoelectrodes exhibited the highest sensitivity (13.94 μA μM−1) ever reported among Au-based electrodes for Cr(VI) detection, with a very low detection limit (S/N = 3) of 0.006 μM and wide linear concentration range from 0.01 μM to 50 μM. Measurements in real water samples such as laboratory and river water also showed excellent anti-interference and recovery... 

Vacuum residue cracking has been successfully conducted under supercritical water condition in presence of various metal oxide nanocalysts, namely NiO, CuO, ZnO, Co2O3, and Cr2O3 synthesized at supercritical water. The cracking experiments were carried out at 450 °C. Three species of cracking: maltene, asphaltene, and coke were then weighed and their corresponding speciation was defined. Gas chromatography-mass spectrometry (GC–MS), nuclear magnetic resonance spectroscopy (NMR), thermogravimetric analysis (TGA), and elemental analysis (CHNS) tests were utilized to prove the performance of upgrading reactions. It was revealed that NiO showed the best performance among other catalyst, in which... 

Since that pathogenic bacteria are major threats to human health, this paper describes the fabrication of an effective and durable sensing platform based on gold nanoparticles/carbon nanoparticles/cellulose nanofibers nanocomposite (AuNPs/CNPs/CNFs) at the surface of glassy carbon electrode for sensitive and selective detection of Staphylococcus aureus (S. aureus). The AuNPs/CNPs/CNFs nanocomposite with the high surface area, excellent conductivity, and good biocompatibility was used for self-assembled of the thiolated specific S. aureus aptamer as a sensing element. The surface morphology of AuNPs/CNPs/CNFs nanocomposite was characterized with field emission scanning electron microscopy... 

Molecular dynamic simulation was performed to calculate the configurational entropy and the free energy for colloidal silver nanoparticles (Ag NPs) in 1-Ethyl-3-methylimidazolium Hexafluorophosphate [EMim][PF6] ionic liquid (IL). Furthermore, the density functional theory (DFT) was used to get the potential interaction between the metal surface and ion in IL. The effect of size and temperature on the configurational entropy and the free energy of colloidal Ag NPs were investigated. Then, it was compared with the gas phase. The Tsallis nonextensivity of entropy was investigated for different sizes of colloidal Ag NPs and it was shown that sub-extensivity of entropy occurs for colloidal Ag... 

Monolithic dye-sensitized solar cells are conventionally fabricated using carbon composite layer as the counter electrode. In the current research, the brittle carbon composite layer is replaced with a metal foil, aiming to decrease the device series resistance and using less catalyst material in counter electrode. This metallic structure has also an advantage of mechanical strength and decreases the fabrication complexity. The counter electrode is prepared by electrodepositing Cr film followed by electrodepositing Pt nanoparticles on a metal foil. As the porous spacer layer, different composite layers of SiO2, TiO2, and Al2O3 are investigated and the best results are obtained for TiO2... 

Synthesis of colloidal metal oxides with controllable size and morphology is burgeoning field of research in nanoscience. Low band gap gray Zn/ZnO colloidal nanoparticles were fabricated by plasma-liquid interaction of DC arc discharge in water. Scanning electron microscopy, X-ray diffraction and UV–vis spectroscopy were employed for morphology, crystal structure and optical characterizations respectively. Optical emission spectroscopy was used to investigate the plasma properties during the synthesis and formation mechanism of nanoparticles. Nanoparticles with different size and shape were fabricated only by adjusting discharge current during synthesis without introducing any chemical... 

Nanotechnology has illustrated significant potentials in biomolecular-sensing applications; particularly its introduction to anti-doping detection is of great importance. Illicit recreational drugs, substances that can be potentially abused, and drugs with dosage limitations according to the prohibited lists announced by the World Antidoping Agency (WADA) are becoming of increasing interest to forensic chemists. In this review, the theoretical principles of optical biosensors based on noble metal nanoparticles, and the transduction mechanism of commonly-applied plasmonic biosensors are covered. We review different classes of recently-developed plasmonic biosensors for analytic determination... 

Development of simple and rapid methods for identification of pesticides, due to their broad usage and harmful effects on mammals, has been known as a critical demand. Herein, we have introduced a silver nanoparticle (AgNP)based colorimetric sensor array for simultaneous identification of Azinphosmethyl (AM)and Phosalone (PS)pesticides. In the presence of the target pesticides, unmodified AgNPs at various pHs (4.5, 5.5 and 9.5)showed different aggregation behaviors. As a result of aggregation, the color and UV–Vis spectra of AgNPs changed differentially, leading to distinct response patterns for AM and PS. The aggregation induced spectral changes of AgNPs, were used to identify AM and PS... 

In the current study, two series of antimicrobial dressings conjugated with silver sulfadiazine (SSD) and silver nanoparticles (AgNPs) were developed and evaluated for chronic wound healing. Highly porous polycaprolactone (PCL)/polyvinyl alcohol (PVA) nanofibers were loaded with different concentrations of SSD or AgNPs and compared comprehensively in vitro and in vivo. SSD and AgNPs indicated a strong and equal antimicrobial activity against S. aureus. However, SSD had more toxicity against fibroblast cells over one week in vitro culture. An in vivo model of wound healing on male Wistar rats was developed with a full thickness wound. All the wound dressings indicated enough flexibility and...