Sharif Digital Repository

Nanofibrous structures that mimic the native extracellular matrix and promote cell adhesion have attracted considerable interest for biomedical applications. In this study, GO-modified nanofibrous biopolymers (GO) were prepared by electrospinning blended solutions of chitosan (80 vol%), polyvinyl pyrrolidone (15 vol%), polyethylene oxide (5 vol%) containing GO nanosheets (0–2 wt%). It is shown that GO nanosheets significantly change the conductivity and viscosity of highly concentrated chitosan solutions, so that ultrafine and uniform fibers with an average diameter of 60 nm are spinnable. The GO-reinforced nanofibers with controlled pore structure exhibit enhanced elastic modulus and... 

Controlled growth of atomic monolayers of IV-VII transition metal dichalcogenides (TMDs) has provided unprecedented opportunities to fabricate modern optoelectronic nanodevices. However, synthesis of large-area and high quality two-dimensional TMDs is still challenging. We have synthesized WS2 and MoS2 nanosheets by atmospheric pressure chemical vapor deposition (APCVD) at wide-range of processing conditions. The nanostructures were analyzed by optical and confocal microscopy, atomic force microscopy, Raman spectroscopy, and X-ray diffraction to determine the thickness, lateral size and structure of the deposits. Through designing and performing of a set of controlled experiments as well as... 

Chalcostibite copper antimony sulfide (CuSbS2) micro- and nanoparticles with a different shape and size have been prepared by a new approach to hot injection route. In this method, sulfur in oleylamine (OLA) is employed as a sulfonating agent providing a simple route to control the shape and size of the particles, which enables the optimization of CuSbS2 for a variety of applications. The sulfur to metallic precursor ratio appears to be one of the most effective parameters along with the temperature and time for controlling the size and morphology of the particles. The growth mechanism study shows in addition to the CuSbS2 phase the presence of not previously observed intermediate phases... 

While the differentiation factors have been widely used to differentiate mesenchymal stem cells (MSCs) into various cell types, they can cause harm at the same time. Therefore, it is beneficial to propose methods to differentiate MSCs without factors. Herein, magnetoelectric (ME) nanofibers were synthesized as the scaffold for the growth of MSCs and their differentiation into neural cells without factors. This nanocomposite takes the advantage of the synergies of the magnetostrictive filler, CoFe 2 O 4 nanoparticles (CFO), and piezoelectric polymer, polyvinylidene difluoride (PVDF). Graphene oxide nanosheets were decorated with CFO nanoparticles for a proper dispersion in the polymer through... 

The planned design of nanocomposites combined with manageable production processes, which can offer controllability over the nanomaterial structure, promises the practical applications of functional nanomaterials. Hollow core-shell nanostructure architectures represent an emerging category of advanced functional nanomaterials, whose benefits derived from their notable properties may be hampered by complicated construction processes, especially in the sensing domain. In this regard, we designed a highly porous three-dimensional array of hierarchical hetero Cu(OH)2@CoNi-LDH core-shell nanotubes via a quick, very simple, green, and highly controllable three-step in situ method; they were... 

In this study, graphene oxide (GO) was synthesized via modified Hummer's method and exploited as an ideal enzyme immobilization support due to its exclusive chemical and structural features. Then, laccase from genetically modified Aspergillus was covalently immobilized onto GO (nanobiocatalyst). Enzymatic characterization of the nanobiocatalyst exhibited promising results: laccase loading of 156.5 mg g−1 and immobilization yield of 64.6% at laccase concentration of 0.9 mg/ mL. Further employment of various structural characterization techniques including Fourier Transform Infrared Spectroscopy (FTIR), X-ray Powder Diffraction (XRD), Scanning Electron Microscopy (SEM), Thermo-Gravimetric... 

Herein, we report the preparation of novel magnetic graphene oxide (GO) grafted with brush polymer via surface-initiated reversible addition-fragmentation chain transfer (SI-RAFT) polymerization and its application as a nanocarrier for magnetic- and pH-triggered delivery of doxorubicin anticancer drug. The RAFT agent, DDMAT, was firstly attached to the surface of magnetic GO nanosheets. The DDMAT-functionalized magnetic GO nanosheets were then used to polymerize glycidyl methacrylate (GMA) using an SI-RAFT method. Afterwards, the epoxy rings of the PGMA chains were opened with hydrazine (N2H4) moieties. The resulting nanocomposite was used as a drug carrier for doxorubicin (DOX) as an... 

Herein, we report the preparation of novel magnetic graphene oxide (GO) grafted with brush polymer via surface-initiated reversible addition-fragmentation chain transfer (SI-RAFT) polymerization and its application as a nanocarrier for magnetic- and pH-triggered delivery of doxorubicin anticancer drug. The RAFT agent, DDMAT, was firstly attached to the surface of magnetic GO nanosheets. The DDMAT-functionalized magnetic GO nanosheets were then used to polymerize glycidyl methacrylate (GMA) using an SI-RAFT method. Afterwards, the epoxy rings of the PGMA chains were opened with hydrazine (N2H4) moieties. The resulting nanocomposite was used as a drug carrier for doxorubicin (DOX) as an... 

Herein, we have successfully fabricated NiVS/NiCuP nanostructures on Cu wire as a fiber electrode for high performance FSMSCs applications. The 3D NiCuP dendritic film was firstly deposited on Cu wire through the electrodeposition method, which not only act as a scaffold for deposition of the electroactive materials (NiV-LDH and NiV-S), but also served as a micro-porous current collector, supplied extra capacitances. Then, NiV-LDH nanosheets grown on 3D NiCuP film were obtained using a hydrothermal method. The sulfidation of NiV-LDH is carried out through an ion-exchange reaction of OH– with S2– to obtain NiVS, which maintains an ultrathin and porous structure, improves the electrical... 

Solar energy generation is one of the most efficient approach to solve emerging environment and energy challenges. In this context, solar assisted dissociation of water into oxygen and hydrogen utilizing scalable and high performance electrocatalysts plays key role since the produced hydrogen is a clean energy carrier. Here, cobalt based nanoflakes with metallic core and oxidized surface were grown on the designed carbonaceous layer for anodic oxygen evolution reaction (OER) using an electrochemical approach. Carbonaceous layers containing proper amount of carbon nanotubes (CNT) and reduced graphene oxide (rGO) species were used to optimize the system. Although higher weight percent of rGO... 

In this study, the Peganum harmala seed extract (PHSE) was used as a green reducing agent of graphene oxide with high deoxygenation capability. PHSE not only acts as a reducing agent of GO due to the high amount of nitrogen-rich compounds but also plays an essential role in the particles' active anti-corrosion performance improvement. In order to add more active inhibition property, the zinc cations were doped successfully on the chemical structure of GO nanosheets, and eventually, the RGO-PHSE-Zn nanocomposite was obtained. The FT-IR results and UV–visible achievements declared that the epoxide (-C-O-C-) functional groups attached to the surface of the GO nanosheets had been successfully... 

In this work, a novel carrier based-on modified graphene oxide was designed for co-delivery of hydrophobic and hydrophilic anticancer drugs (curcumin (Cur) and doxorubicin (DOX) as the model of drugs). The hydroxyl groups at the edges of graphene oxide (GO) sheets were used as the initiation sites for growing poly(epichlorohydrin) (PCH) chains. Then, hyperbranched polyglycerol (HPG) was grafted on the hydroxyl end groups of PCH (PCH-g-HPG). Pendant chlorines in the main chain of GO-PCH-g-HPG were replaced with hydrazine. The modification of GO sheets with oxygen-rich polymers increased water solubility of graphene oxide. Doxorubicin was loaded onto the nanocarrier by covalent bonding with... 

In this study, both CuO nanoparticles and ZnO nanorods were anchored on thermally-exfoliated g-C3N4 nanosheets (denoted as CZ@T-GCN) via isoelectric point-mediated annealing process as a novel nano-photocatalyst towards degradation of amoxicillin (AMOX). The features of prepared materials were characterized using BET, UV–vis DRS, XRD, FT-IR, XPS, FE-SEM, TEM, EIS and transient photocurrent techniques. These analyses demonstrated the successful formation of heterojunctions between components of CZ@T-GCN nanocomposite, which reflected in significantly increased electron-hole separation and enhanced degradation of AMOX as compared with pure substances. The investigation of influential operative... 

The development of noble-metal-free electrocatalysts with enhanced active sites is of great significance for the production of renewable energy on large scale. Ultrathin transition metal compounds (e.g., phosphides and sulfides) have unique structural features but their stability and electroactivity must still be improved for practical applications. We propose a new strategy to synthesis ultrathin sheets of Ni-Cu-Co transition metals on porous nickel and self-assemble them into yarn-shaped microspheres. Enhance catalytic activity and stability are then attained by thermochemical phosphorization without morphological modifications. We employed various analytical techniques including XRD, SEM,... 

Nickel-zinc batteries as safe and economic energy storage devices suffer from lack of high electrochemical performance of cathode materials. Herein, a new cathode material for rechargeable Ni/Zn batteries is introduced based on various compositions of mixed metal oxide (MMO) through a calcination process of nickel-vanadium layered double hydroxide at different temperatures. The results demonstrated that the prepared sample at 500 °C presents the best electrochemical properties such as a good electrochemical discharge capacity (278.4 mAh g-1 at 0.5 A g-1), good cycle life (capacity retention of 74% after 1000 cycles at 5 A g-1), and excellent rate capability (177 mAh g-1 at 5 A g-1). These... 

Demand for high-capacity, long cycle life, and aqueous batteries based on abundant metals such as nickel, zinc, aluminum, and so on is rising in the energy storage field. In this study, we design a hierarchical morphology as a nanosheet-built microsphere of nickel vanadium layered double hydroxide (NiV LDH) with conductive agents graphene oxide (GO) and multiwalled carbon nanotubes (CNTs) through a low-cost hydrothermal synthesis method. The experimental results demonstrate that the graphitic structures and functional groups of the GO and CNT play an important role in controlling nucleation, growth speed, size, and finally morphology of hierarchical nanosheets. The electrochemical results... 

Evolution of renewable energies in the era of the modernized world has been strongly tied up to the incessant development of high-performance energy storage systems benefiting from both high energy and power densities. In the present work, binder-free positive electrodes are fabricated via a facile electrochemical deposition route in which copper oxide nanorods (CuO NRs) directly grown onto the copper foam (CF) are decorated with bimetallic cobalt-zinc sulfide nanoarrays (Co-Zn-S NAs). The fabricated Co-Zn-S@CuO-CFs represent promising specific capacity of 317.03 C.g−1 at 1.76 A.g−1, along with superior cyclic stability (113% retention after 4500 cycles). Negative electrodes were further... 

Active edge sites of MoS2 nanosheets exhibit promising futures for hydrogen evolution reaction (HER), comparable with remarkable performances of highly cost platinum. However, 3D structures of MoS2 suffer from a lack of high mobility and unexposed active sites which lower the electrocatalytic activity. In this study, we show that there is a balance between increasing the active sites on the one hand and managing the charge transfer to facilitate the reaction on the other hand, and achieving this balance increases the efficiency of the electrocatalyst tremendously. For this purpose, we directly attached exfoliated MoS2 nanosheets onto carbon cloth (CC) substrate as a 3D network of conductive... 

Although important advances have been acquired in the field of electrocatalysis, the design and fabrication of highly efficient and stable non-noble earth-abundant metal catalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) remain a significant challenge. In this study, we have designed a superior bifunctional catalyst for OER and HER in alkaline media based on the Co-Mo-P/Zn-Co-S multicomponent heterostructure. The as-prepared multicomponent heterostructure was successfully obtained via a simple three-step hydrothermal-sulfidation-electrodeposition process consisting of star-like Co-Zn-S covered with Co-Mo-P. The structure and morphology evaluation of the... 

A highly controllable, green, and rapid strategy is demonstrated for fabricating of highly sensitive non-enzymatic glucose sensing platforms. Carbon nanohorns (CNHs) were decorated onto the screen-printed electrodes. Binary nickel-cobalt sulfide (NiCo-S) nanosheets (NSs) were then deposited on CNH-casted electrodes by a facile and scalable method. Following detailed structural characterization and the electrocatalytic activity of the fabricated NiCo-S/CNH electrodes towards electro-oxidation of glucose was examined in detail. The proposed electrodes operated within two distinct linear dynamic ranges of 0.001- 0.330 mM and 0.330 - 4.53 mM with sensitivities of 1842 µA.mM−1.cm−2 and 854...