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We recently discovered that superparamagnetic iron oxide nanoparticles (SPIONs) can levitate plasma biomolecules in the magnetic levitation (MagLev) system and cause formation of ellipsoidal biomolecular bands. To better understand the composition of the levitated biomolecules in various bands, we comprehensively characterized them by multi-omics analyses. To probe whether the biomolecular composition of the levitated ellipsoidal bands correlates with the health of plasma donors, we used plasma from individuals who had various types of multiple sclerosis (MS), as a model disease with significant clinical importance. Our findings reveal that, while the composition of proteins does not show much variability, there are significant differences in the lipidome and metabolome profiles of each magnetically levitated ellipsoidal band. By comparing the lipidome and metabolome compositions of various plasma samples, we found that the levitated biomolecular ellipsoidal bands do contain information on the health status of the plasma donors. More specifically, we demonstrate that there are particular lipids and metabolites in various layers of each specific plasma pattern that significantly contribute to the discrimination of different MS subtypes, i.e., relapsing-remitting MS (RRMS), secondary-progressive MS (SPMS), and primary-progressive MS (PPMS). These findings will pave the way for utilization of MagLev of biomolecules in biomarker discovery and diagnosis of this and other complex disorders.

The physicochemical properties of nanomaterials depend on their size and shapes which are key factors for various biomedical applications. ZnO nanostructures were prepared with various shapes including nanospheres, nanoplates, and nanopyramids using hydrothermal method. ZnO nanoparticles (NPs) have antibacterial properties against Escherichia coli (E. coli) bacteria, and they have the ability to control or destroy them. Physicochemical properties of the prepared nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet-visible absorption spectroscopy (UV-Vis), and photoluminescence spectroscopy (PL). XRD analysis confirmed that formation of the wurtzite phase of zinc oxide NPs and PL results revealed low structural defects of the produced NPs. Antibacterial activity of the produced nanostructures was probed against gram-negative E. coli bacteria. The results of antibacterial experiments exhibited that ZnO nanopyramids prepared at temperature of 70 °C have a more inhibitory effect than nanospheres and nanoplates. These indicate that the antibacterial activity of ZnO NPs depends on the morphology and shape in addition to concentration of the nanomaterial.

The role of the 'file drawer' problem in nanomedicine, which partly drives the current limited clinical success of therapeutic nanoparticles, has been poorly investigated. We propose an integrated functioning of all stakeholders as the only effective way to address the file drawer problem in an efficient and timely manner.

Hydrogen peroxide (H2O2) is a by-product of some biochemical processes which is catalyzed by enzymes such as glucose oxidase (GOx), cholesterol oxidase (ChoOx), etc and its overproduction in living cells can trigger cancer growth and various diseases. Therefore, H2O2 sensing is of great importance in the determination of diseases as well as industries and environmental health plans. We produced ZnO-CuO nanofibers by electrospinning method for non-enzymatic electrochemical H2O2 sensing. The sensing properties of the carbon paste electrode (CPE) modified with ZnO (0.3 wt%)/CuO (0.7 wt%) nanofibers (named as ZnO3-CuO7) for detection of H2O2 were explored in phosphate-buffered saline (PBS) at pH ∼ 7.4 solution. The ZnO3-CuO7 nanofiber exhibited the lowest charge transfer resistance and the highest electrocatalytic performance among other modified electrodes for detection of H2O2 and considered as an optimized sample. The effect of scan rate and H2O2 concentration in the reduction process were also investigated by cyclic voltammetry (CV) and the mechanism for the electrochemical reaction of H2O2 at the surface of the optimized electrode was studied. The diffusion coefficient of H2O2 and the catalytic rate constant were evaluated by chronoamperometry as 1.65 × 10−5 cm2 s−1 and 6 × 103 cm3 mol−1 s−1, respectively. Furthermore, amperometric detection of H2O2 with a low detection limit of 2.4 µM and a wide linear range of 3 to 530 µM were obtained. Meanwhile, the optimized electrode displayed no recognizable response towards some biomolecules such as ascorbic acid, uric acid, dopamine and glucose. The obtained results confirmed that the modified electrode shows high sensitivity and selectivity as a H2O2 biosensor with improved reproducibility and stability.

We report on charge transport across self-assembled monolayers (SAMs) of short tau peptides by probing the electron tunneling rates and quantum mechanical simulation. We measured the electron tunneling rates across SAMs of carboxyl-terminated linker molecules (C6H12O2S) and short cis-tau (CT) and trans-tau (TT) peptides, supported on template-stripped gold (AuTS) bottom electrode, with Eutectic Gallium-Indium (EGaIn)(EGaIn) top electrode. Measurements of the current density across thousands of AuTS/linker/tau//Ga2O3/EGaIn single-molecule junctions show that the tunneling current across CT peptide is one order of magnitude lower than that of TT peptide. Quantum mechanical simulation demonstrated a wider energy bandgap of the CT peptide, as compared to the TT peptide, which causes a reduction in its electron tunneling current. Our findings also revealed the critical role of phosphorylation in altering the charge transport characteristics of short peptides; more specifically, we found that the presence of phosphate groups can reduce the energy band gap in tau peptides and alter their electrical properties. Our results suggest that conformational and phosphorylation of short peptides (e.g., tau) can significantly change their charge transport characteristics and energy levels.

Magnetic levitation (MagLev) is a well-documented, robust technique for density measurements and separations. Although the potential of MagLev as an emerging tool in biotechnology has been recently investigated, the practical use of MagLev in diagnosis and disease detection merits further attention. This review highlights the diagnostic capacity of a simple and portable MagLev system and the possibilities and limitations of the MagLev technique for density-based separation, classification, and manipulation of soft matter and biological systems (e.g., cells, proteins), which in turn may pave the way for the discovery of disease-specific biomarkers.

Phase separation processes are increasingly being recognized as important organizing mechanisms of biological macromolecules in cellular environments. Well established drivers of liquid-liquid phase separation are multi-valency and intrinsic disorder. Here, we show that globular macromolecules may condense simply based on electrostatic complementarity. More specifically, phase separation of mixtures between RNA and positively charged proteins is described from a combination of multiscale computer simulations with microscopy and spectroscopy experiments. Condensates retain liquid character and phase diagrams are mapped out as a function of molecular concentrations in experiment and as a function of molecular size and temperature via simulations. The results suggest a more general principle for phase separation that is based primarily on electrostatic complementarity without invoking polymer properties as in most previous studies. Simulation results furthermore suggest that such phase separation may occur widely in heterogenous cellular environment between nucleic acid and protein components.STATEMENT OF SIGNIFICANCELiquid-liquid phase separation has been recognized as a key mechanism for forming membrane-less organelles in cells. Commonly discussed mechanisms invoke a role of disordered peptides and specific multi-valent interactions. We report here phase separation of RNA and proteins based on a more universal principle of charge complementarity that does not require disorder or specific interactions. The findings are supported by coarse-grained simulations, theory, and experimental validation via microscopy and spectroscopy. The broad implication of this work is that condensate formation may be a universal phenomenon in biological systems.

In the past decade, we witnessed limited success in the clinical translation of therapeutic nanoparticles (NPs). One of the main reasons for this limited success is our poor understanding of the biological identity of NPs. Herein, we report magnetic levitation (MagLev) as a complementary analytical tool to investigate the homogeneity of the created protein corona (PC) coated NPs through an ex vivo model. Our results demonstrate that the MagLev system not only has the capacity to separate corona coated NPs, but also enables us to study the homogeneity/heterogeneity of the PC. Our findings suggest that current ex vivo isolation methods cause a heterogeneous coverage of PC profiles at the surface of NPs. The MagLev technique, therefore, would be instrumental in identifying and separating fully PC coated NPs which, in turn, enables us to achieve more accurate information on protein corona composition. Ultimately, we believe that the MagLev technique can be used for the fast screening of the homogeneity of corona coated NPs before quantitative analysis of the corona profile/composition, hence definitely improving our fundamental understanding of nano-bio interfaces.

Surprisingly, the densities of proteins in solution, which are important fundamental biophysical quantities, have not been accurately measured. The lack of such data can limit meaningful interpretation of physical and chemical features of proteins and enzymes. Here, we demonstrate a new technique using superparamagnetic iron oxide nanoparticles (SPIONs) for magnetic levitation (MagLev), which promises to more precisely measure the density of proteins in solution. As a test of our new technique, we have levitated human plasma proteins using MagLev. By using standard density glass beads for calibration, MagLev showed that the levitated plasma proteins have a measured density in solution of 1.03 ± 0.02 g/cm

Crosslinking is one of the fundamental phenomena in polymer science, which happens by forming covalent bonds or relatively short sequences of chemical bonds to join two polymer chains. Crosslinking and the subsequent volume shrinkage of monomers/macromers result in changes in their corresponding density which can be measured using density-based measurement techniques (e.g., dilatometry). Here, we demonstrate a method that allows in situ monitoring of photopolymerization of water-soluble bifunctional macromers using magnetic levitation (MagLev) system. We use a hydrophobic paramagnetic solution to monitor the photopolymerization of water-soluble polyethylene glycol diacrylate (PEGDA) as a model of bifunctional macromers using a ring MagLev system. Based on changes in levitation heights (densities) after illumination of blue light, we have successfully monitored the double bond conversion of PEGDA 700 macromers at various polymerization conditions. Our findings suggest that MagLev can be used as a new and complementary analytical technique for rapid screening of the photopolymerization reactions and measurement of conversions using changes in the levitation height of the macromers.

Antibacterial nanoparticles offer great promise in various fields ranging from environmental to biomedical and biosensors. In this article we design a novel antibacterial material based on reduced graphene oxide (RGO) decorated with different shape of silver nanostructures. To control the size and shape of silver nanoparticles (AgNPs) on RGO sheets, composites of RGO decorated with different shape of AgNPs were synthesized using dimethylformamide (DMF) as reducing and coupling agent for reduction of graphene oxide (GO) and attachment of various shapes of AgNPs on RGO sheets. The results revealed that triangular AgNPs have highest antibacterial activity among different shapes of AgNPs against both gram-negative Escherichia coli (E. coli) and gram-positive Staphylococcus aureus (S. aureus) bacteria as representatives of bacteria species. In addition, results obtained in this study have showed that among different AgNPs/RGO nanocomposites, Ag triangles/RGO sample possess the best antibacterial property. It is suggested that the antibacterial activity of the prepared antibacterial platform, strongly depends on the shape of AgNPs on the surface of RGO, which could effectively use as antibacterial agent.

One of the most important progresses in the field of nano science and technology was partially due to the high surface to volume ratio of quasi one-dimensional silicon nanowires (SiNWs) with various applications in biological and chemical sensors, optoelectronic devices, catalysis, Li ion batteries and solar cells. In this study we have prepared a uniform forest of ultrathin SiNWs using plasma enhanced chemical vapor deposition method. Uniformly distributed SiNWs were obtained based on an Au layer containing gold nano-seeds with the average diameters ranging from 10 to 40 nm at various temperatures. The physicochemical properties of SiNWs were characterized using field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction (XRD), photoluminescence (PL) and high-resolution transmission electron microscopy. Microscopic assessments revealed that crystalline-amorphous core–shell SiNWs with different diameters and lengths ranging from 35 to 130 nm and ~ 0.7 to 1.9 µm are formed during the vapor–liquid–solid mechanism, respectively. The XRD spectra show that the main lattice directions are Si(111), Si(220) and Si(311) which confirm crystalline structure of synthesized NWs. The PL spectrum reveal two distinct emission peaks at wavelengths of about 480 nm (blue range) and 690 nm (red range) as sharp and a broad peak, respectively.

A heterostructure photocatalyst including metallic silver (Ag), gold (Au) in the form of nanoparticles (NPs) and titanium oxide (TiO2) nanofibers were fabricated using a combination of photodeposition and electrospinning techniques. In this procedure, electrospun TiO2 nanofibers were decorated by plasmonic Ag and Au NPs on the surface of nanofibers which were generated via photochemical reduction process. The synthesized Ag-Au/TiO2 nanocomposites which were considered as a favorable candidate for enabling the more access to visible-light in photocatalytic performance were subsequently characterized by field emission scanning electron spectroscopy (FESEM), transmission electron spectroscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and ultra-violet-visible (UV–vis) spectroscopy. UV–vis studies indicate the extension in the absorption region of composite toward the visible-light range have been occurred through the loading metallic nanoparticles into the TiO2 structure. Microscopic assessments in addition to EDS revealed that metallic NPs deposited on the surface of the fibers through photochemical reduction process. It was found that, the ratio of utilized Ag/Au in the final composite can significantly enhance the photocatalytic efficiency. It was suggested that introduction of the proper amount of noble metal NPs into the TiO2 matrix leads to the notable enhancement of visible-light decomposition of rhodamine B (Rh. B) as a model dye.

The heterogeneous titanium oxide-reduced graphene oxide-silver (TiO2/RGO/Ag) nanocomposites were successfully prepared by incorporation of two dimensional (2D) RGO nanosheets and spherical silver nanoparticles (NPs) into the 1D TiO2 nanofibers. The novel TiO2/RGO/Ag nanocomposites were synthesized by loading TiO2 nanofibers, prepared via electrospinning technique, on the RGO/Ag platform. The resulting nanocomposites have been characterized using various techniques containing transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and ultra-violet-visible (UV–vis) spectroscopy. Microscopic studies clearly verified the existence of TiO2 nanofibers with Ag NPs on the surface of RGO sheet and formation of TiO2/RGO/Ag nanocomposites. Moreover, the results of UV–vis spectroscopy demonstrated that TiO2/RGO/Ag nanocomposites extended the light absorption spectrum toward the visible region and significantly enhanced the visible-light photocatalytic performance of the prepared samples on degradation of rhodamine B (Rh. B) as a model dye. It was found that, incorporation of 50 µl RGO/Ag into the TiO2 nanofibers lead to a maximum photocatalytic performance. Also, the improvement of the inactivation of Escherichia coli (E. coli) bacteria under visible-light irradiation was revealed by introduction of RGO/Ag into the TiO2 matrix. The significant enhancement in the photo and bio-activity of TiO2/RGO/Ag nanocomposites under visible-light irradiation can be ascribed to the RGO/Ag content by acting as electron traps in TiO2 band gap.

In this study, we report a novel graphene decorated gold nanocage nanocomposite through thermal modification route as a hydrazine sensor. Gold nanocages were synthesized, using the galvanic replacement between silver nanocubes and aqueous gold solution. Graphene nanosheets were functionalized by reaction with N,N-dimethylformamide (DMF) at relatively high temperature to generate chemically modified graphene (CMG). Surface topography and thickness of CMG nanosheets were obtained by atomic force microscopy (AFM). Ultraviolet visible (UV–vis) spectroscopy, scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), Fourier transformed infrared spectroscopy (FTIR) and transmission electron microscopy (TEM) were used to characterize the physicochemical properties of gold nanocage/CMG nanocomposite. The electrochemical behaviour of sensor was investigated using cyclic voltammetry (CV), amperometry and electrochemical impedance spectroscopy (EIS). It was found that the gold nanocage/CMG modified glassy carbon electrode (GCE) exhibits low oxidation potential (0.17 V) with two linear ranges from 6 μM to 30 μM and 30 μM to 1.7 mM for sensing hydrazine with detection limit of 0.5 μM. The modified electrode exhibits good selectivity for hydrazine amperometric response in the presence of common ions and some biological interfering species and it can be easily prepared which makes it reproducible. Furthermore, the present sensor exhibits high level of stability for the determination of hydrazine.

Iron oxide nanoparticles were synthesized for the first time using electrical arc discharge between a pair of highly pure titanium electrode without using metallic iron electrodes in iron chloride salt solution. The produced nanoparticles were characterized using various analyses such as X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS). XRD and XPS analyses showed formation of α-Fe2O3 phase. Microscopic studies on the obtained samples revealed formation of rice like iron oxide nanostructures at 10 minutes of electrical discharge which changed to semi-spherical shape after calcination at 600 oC for 2 hours. The results of Dynamic Light Scattering (DLS) analysis demonstrated formation of 24 nm particles with almost narrow distribution of 11nm, which are increased in size and distribution width by heat treatment. The obtained results verify the potential ability of this technique to achieve monodispersed iron oxide nanoparticles with narrow distribution in a very short time

The adult myocardium has a limited regenerative capacity following heart injury and the lost cells are primarily replaced by fibrotic scar tissue. Suboptimal efficiency of current clinical therapies to resurrect the infarcted heart results in injured heart enlargement and remodeling to maintain its physiological functions. These remodeling processes ultimately leads to ischemic cardiomyopathy and heart failure (HF). Recent therapeutic approaches (e.g., regenerative and nanomedicine) have shown promise to prevent HF post-myocardial infarction in animal models. However, these preclinical, clinical, and technological advancements have yet to yield substantial enhancements in the survival rate and quality of life of patients with severe ischemic injuries. This could be attributed largely to the considerable gap in knowledge between clinicians and nano-bioengineers. Development of highly effective cardiac regenerative therapies requires connecting and coordinating multiple fields, including cardiology, cellular and molecular biology, biochemistry and chemistry, and mechanical and materials sciences, among others. This review is particularly intended to bridge the knowledge gap between cardiologists and regenerative nanomedicine experts. Establishing this multidisciplinary knowledge base may help pave the way for developing novel, safer, and more effective approaches that will enable the medical community to reduce morbidity and mortality in HF patients.

Colloidal silver nanocubes (NCs) were successfully synthesized by reduction of silver nitrate with ethylene glycol and polyvinylpyrrolidon as capping agent. The effect of solar light irradiation on the formation and morphology of silver NCs was investigated. Moreover, altering the amount of sodium sulfide was used to control the morphology and shape of primary silver seeds. Scanning electron microscopy, transmitting electron microscopy, X-ray diffraction and UV-vis spectroscopy were used to characterize silver NCs. The samples prepared under the solar light irradiation do not possess cubic shape while highly monodispersed silver NCs were obtained in dark room conditions. For dark room synthesis, a decrease of the amount of Na2S by only 10 μL resulted in formation of mixture of silver nanospheres and nanowires in addition to NCs instead of the monodispersed silver NCs. However, similar increase of the amount of sodium sulfide results in distortion of cubic geometry of particles. The results suggest that solar light has a negative effect on the shape evolution of the primary silver seeds.

Triangular silver nanostructures represent a novel class of nanomaterials with tunable surface plasmon resonance (SPR). By controlling the size and geometry of these structures, their SPR peaks could be tuned from the visible to the near-infrared region with numerous applications in optoelectronic, sensors, nanomedicine and specially cancer diagnosis and treatment. In this study, triangular silver nanostructures were prepared by photoinducing of spherical silver nanoparticles (NPs) with an average diameter of 10 nm. Transmission electron microscopy (TEM) and ultra violet visible (UV–Vis) spectroscopy were used to characterize silver triangles. We have found that uniform triangular silver nanostructures can be obtained using an appropriate visible-light illumination to the primary spherical silver NPs. TEM images indicated that formation of triangular structures depends on the intensity of light source. The effect of intensity of visible-light source on the geometry and size distribution of silver triangles was investigated. It was found that formation of triangular structures in addition to their size and shape evolution strongly depends on the intensity of the light illumination. Furthermore, a comparative study on the antibacterial activities of silver triangles of different sizes reveals that silver triangles experience a size-dependent interaction with the gram-negative Escherichia coli bacteria.

Needle-like silicon nanowires (SiNWs) were successfully synthesized on gold-coated silicon substrates using a very high frequency plasma enhanced chemical vapor deposition method (VHF-PECVD). The prepared samples were characterized by field emission scanning electron microscopy (FESEM) with energy dispersive X-ray spectroscopy (EDX), high resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD) and photoluminescence (PL). XRD analysis confirmed formation of single crystalline SiNWs along (111) crystalline planes and microscopic studies revealed formation of NWs with diameters ranging from 10 to 100 nm and lengths of a few micrometers. Furthermore, the presence of gold nanoparticles on the tip of the NWs verified the vapor–liquid–solid growth mechanism of SiNWs. It was also demonstrated that SiNWs are composed of well-crystallized silicon cores and an amorphous shell. The obtained results verified potential application of such structures in field emission displays.

In the present work, iron-functionalized TiO2 nanofibers have been successfully synthesized by an electrospinning system and the resulting nanofibers were characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and ultra-violet-visible spectroscopy. Microscopic studies revealed that TiO2 nanofibers with average diameters of ~60 to 65 nm were formed during the electrospinning process while their diameters increased to ~85 to 90 nm by iron functionalization. Moreover, the photocatalytic activities of pristine and iron-functionalized TiO2 nanofibers were measured by photodegradation of methyl orange (MO) as a model dye under visible-light irradiation. It was found that iron-functionalized TiO2 nanofibers extended the light absorption spectrum toward the visible region and noticeably improved the photodegradation of MO under visible-light irradiation. Furthermore, there is an optimum amount of FeCl3 to reach to the highest photocatalytic performance of iron-functionalized TiO2 nanofibers under visible-light.

In this study, carbon nanotubes (CNTs) were synthesized on Fe Catalyst/Portland cement substrate using chemical vapor deposition (CVD) method. The effect of synthesis parameters including reaction temperature, synthesis time and catalyst weight percentage on the characteristics of CNTs were investigated. In this regard, FE-SEM and TEM images were applied to characterize size and morphology of CNTs. Phase identification of cement compounds and catalyst particle sizes at different temperatures were studied using XRD. Finally the relation between the abundance of CNTs and synthesis time was investigated by TGA. Experimental results show that the average diameter and yield of CNTs increases with increasing the reaction temperature, synthesis time and catalysts contents.

A fast and facile approach for decomposition of model organic dyes through high voltage corona discharge in solution was presented. A comparative study of the significant potential of this technique for degradation of 8 different types of standard organic compounds such as Phenol Red (PR), Methyl Orange (MO), Diamine Green B (DGB), Pyrogallol Red (PYR), Bromocresol Green (BCG), Bromochlorophenol Blue (BCB), Naphtol Green B (NGB) and Crystal Violet (CV) has been performed. The decomposition rate of dyes under corona discharge was evaluated by measuring the changes in absorption peak of model dye at different discharge times using ultraviolet–visible absorption spectroscopy (UV–vis). The results revealed that corona discharge at ambient air significantly enhanced the degradation rate of standard dyes. In addition, a possible mechanism for degradation of dye molecules under corona discharge process was proposed based on our observations. It has been found that this process, which is based on the most efficient energetic species, is much more powerful than other conventional methods such as photocatalytic materials.

We report the enhancement of room temperature photoluminescence (PL), field emission and photocatalytic properties of ZnO nanorods (NRs) decorated by gold NPs (Au-ZnO NRs) prepared using hydrothermal process. The results of X-ray diffraction (XRD) analysis confirmed formation of gold NPs (NPs) and wurtzite phase of ZnO in the final nanostructures. Microscopic studies revealed that uniform ZnO NRs were formed and gold NPs are well decorated on the surface of the NRs. It was shown that both reaction time and concentration of HAuCl4 play a crucial role in photocatalytic, field emission and PL properties of Au-ZnO NRs. We suggest that there is a correlation between the shape of the NRs and concentration of HAuCl4 which causes the maximum PL intensity and stronger field emission properties. The ultraviolet (UV) and visible-light photocatalytic performance was successfully demonstrated for the photodegradation of Methylene blue (MB) as a model dye. Field emission studies revealed that by introducing gold NPs into the ZnO NRs the emission current increases. We have found that the shape of the nanostructure has a crucial role in the field emission properties and at higher reaction times, where the aspect ratio of the ZnO NRs decreases, the emission current also decreases.

Graphene-based nanomaterials contain unique physicochemical properties and have been widely investigated due to a variety of applications particularly in cancer therapy. Furthermore, Ag has been known for its extensive historical background for biomedical applications. Therefore, conjugation of shape-selective Ag nanostructures with graphene may provide new horizons for pharmaceutical applications such as cancer treatments. Here we report on the synthesis of Ag nanoparticles (NPs)/reduced graphene oxide (AgNPs/RGO) conjugate nanomaterials containing various shapes of AgNPs by a novel and simple synthesis route using the deformation of dimethylformamide (DMF) as the reducing and coupling agent. The cytotoxicity and anticancer properties of AgNPs, AgNPs/RGO conjugate nanomaterials, RGO and graphene oxide (GO) were probed against MDA-MB-231 cancer and MCF-10A normal human breast cells in vitro. The AgNPs/RGO nanocomposites exhibited a strong anticancer effect by penetration and apoptosis in cancer cells as well as the lowest influence on the viability of normal cells. It was found that cancer cell viability not only depends on the geometry of Ag nanostructures but also on the interaction between AgNPs and RGO nanoplatelets. It is suggested that AgNPs/RGO conjugate nanomaterials with various shapes of AgNPs is a promising therapeutic platform for cancer therapy.

One of the most significant advances in nanoscience and nanotechnology was partially driven by plasmonic effect of some noble metal nanostructures with different shapes and sizes. By controlling the geometry of metal nanostructures, their surface plasmon resonance (SPR) peaks could be tuned from the visible to the near-infrared region with various applications in sensors, optoelectronic, nanomedicine, and specifically cancer therapy. In this study, we have prepared gold nanoboxes (NBs) using the galvanic replacement between Ag nanocubes (NCs) and aqueous gold solution. Ultraviolet visible (UVvis) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and transmitting electron microscopy (TEM) were used to characterize silver NCs and gold NBs. The primary silver NCs were synthesized by conventional polyol method at the presence of sodium sulfide to highly tune the shape and size of the NCs. Optimized cubic silver nanostructures were obtained at 90 μl of sodium sulfide injection into the solution. Moreover, the effect of quality of the cubic structure on the shape and uniformity of gold NBs was investigated. Gold NBs with hollow interior structure and SPR peak ranging from 480 to 800 nm were successfully obtained at different injection volumes of HAuCl4 into the solution. It was demonstrated that increasing the volume of HAuCl4 solution to about 3 mL can increase the pore number and size until the primary structure collapses into small pieces. It was also found that the concentration of gold NBs and the corresponding SPR peak intensities decrease due to pore size enhancement and decline of charge density on the surface of metal hollow nanostructures.

We present an innovative approach for synthesis of zinc oxide–graphene (ZnO–G) hybrid nanostructures through combination of improved hummer and arc discharge methods in liquid. A detailed study of the considerable visible-light photocatalytic activities of these nanostructures for the degradation of Phenol red (PR) and Methyl orange (MO) as standard organic compounds under the irradiation of 90 W halogen light for 2 h has been performed. The ZnO–G nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer Emmett Teller (BET) and ultra violet–visible absorption spectroscopy (UV–vis). The results revealed that the ZnO–G nanostructures extended the light absorption spectrum toward the visible region and remarkably enhanced the photodegradation of standard dyes under visible-light irradiation. It has been confirmed that the ZnO–G nanostructures could be excited by visible-light ( E ∼ 2.6 eV). The major enhancement in the photocatalytic activity of ZnO–G nanostructures under visible-light irradiation can be attributed to the effect of electron transport among ZnO nanoparticles (NPs) and graphene sheets. A mechanism for photocatalytic degradation of organic pollutants over ZnO–G photocatalyst was proposed based on our observations.

CNT–TiO 2 nanocomposites were prepared through (i) simple mixing of as prepared CNTs and TiO 2 nanoparticles (NPs), (ii) simple mixing of as prepared CNTs and TiO 2 NPs followed by heat treatment and (iii) simple mixing of as prepared CNTs and TiO 2 NPs followed by UV illumination. The synthesis of CNTs and TiO 2 NPs were performed individually by arc discharge in water and sol–gel methods, respectively and characterized by X-ray diffraction (XRD), ultra violet and visible spectroscopy (UV–vis), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The visible-light photocatalytic performance of CNT–TiO 2 nanocomposites was successfully demonstrated for the degradation of Rhodamine B (Rh. B) as a model dye at room temperature. It is found that CNT–TiO 2 nanocomposites extended the light absorption spectrum toward the visible region and considerably improved the photocatalytic efficiency under visible-light irradiation. The visible-light photocatalytic activities of CNT–TiO 2 nanocomposites in which CNTs are produced by arc discharge in deionized (DI) water at 40, 60 and 80 A arc currents and combined through three different protocols are also investigated. It was found that samples prepared at 80 A arc current and 5 s arc duration followed by UV illumination revealed best photocatalytic activity compared with the same samples prepared under simple mixing and simple mixing followed by heat treatment. The enhancement in the photocatalytic property of CNT–TiO 2 nanocomposites prepared at 80 A arc current followed by UV illumination may be ascribed to the quality of CNTs produced at this current, as was reported before.

Vertically aligned silicon nanowires (SiNWs) have been successfully synthesized using pure silane gas as a precursor by very high frequency plasma enhanced chemical vapor deposition (VHF-PECVD) method. The effect of the growth temperature on the morphology, structure and photoluminescence properties of SiNWs has been studied. The SiNWs were needle-liked materials with the length of a few microns having the diameters of tens of nanometers near the bottom and a few nanometers at the top. Thinner nanowires have been obtained at the higher growth temperature process. High resolution transmission electron microscopy confirms that the nanowires are composed of a crystalline silicon core with an oxide shell. The PL spectrum of the Si nanoneedles have shown two emission bands around 450 nm and ~750, which originate from the defects related to oxygen fault in the oxide shell and interfaces between the crystalline Si core and the oxide shell, respectively.

Silver-doped TiO2 hybrid nanolayers (NLs) were prepared via the sol–gel method using TiCl4 as a precursor, and the products were characterized by X-ray diffraction, atomic force microscopy, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. A detailed study of the visible light hydrophilicity of Ag–TiO2 NLs by evaluating the contact angle of water droplets on the surface of the layers has been performed. Furthermore, a series of experiments was carried out in order to find the optimum value of dopant concentration. The results revealed that the Ag–TiO2 hybrid NLs extended the light absorption spectrum toward the visible region and considerably enhanced the hydrophilicity of TiO2 NLs under visible light irradiation. The significant enhancement in the visible light hydrophilicity activity of TiO2 NLs under visible light irradiation can be ascribed to the generation of a new electronic state acting as an electron trap in TiO2 and responsible for narrowing the band gap of TiO2 and shifting its optical response from the ultraviolet to the visible light region.

Nano-scale and single crystals of a new tris-chelate Zn(II) compound, {[Zn(DADMBTZ)3](SCN)2⋅4H2O}n, (1), {DADMBTZ = 2,2′-diamino-5,5′-dimethyl-4,4′-bithiazole} have been synthesized by the reaction of zinc(II) sulfate, ammonium thiocyanate and DADMBTZ using sonochemical and branched tube methods, respectively. The new nanoparticles were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and FT-IR spectroscopy. Compound (1) was structurally characterized by single crystal X-ray diffraction. Compound (1) form a tris-chelate complex with nearly C3 symmetry. The coordination number of zinc atom in the compound is six with coordinated environments of distorted octahedral, ZnN6. In reaction with DADMBTZ, the ligand DADMBTZ acts as bidentate in compound to form five-membered chelate rings with the same internal angles in coordination polyhedron. The crystal packing is mainly stabilized by N–H- - - -N hydrogen bonding interactions. The thermal stability of compound (1) was studied by thermal gravimetric (TG) and differential thermal analyses (DTA). ZnS nanostructures were obtained by direct thermolyses of compound (1) at 400 °C under argon atmosphere. The ZnS nanoparticles were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy.

Silver and nitrogen doped TiO2 nanoparticles (NPs) were synthesized via sol–gel method. The physicochemical properties of the achieved NPs were characterized by various methods including X-Ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and ultra violet–visible absorption spectroscopy (UV–vis). Both visible-light photocatalytic activity and antimicrobial properties were successfully demonstrated for the degradation of Rhodamine B (Rh. B.), as a model dye, and inactivation of Escherichia coli (E. coli), as a representative of microorganisms. The concentration of the employed dopant was optimized and the results revealed that the silver and nitrogen doped TiO2 NPs extended the light absorption spectrum toward the visible region and significantly enhanced the photodegradation of model dye and inactivation of bacteria under visible-light irradiation while double-doped TiO2 NPs exhibited highest photocatalytic and antibacterial activity compared with single doping. The significant enhancement in the photocatalytic activity and antibacterial properties of the double doped TiO2 NPs, under visible-light irradiation, can be attributed to the generation of two different electronic states acting as electron traps in TiO2 and responsible for narrowing the band gap of TiO2 and shifting its optical response from UV to the visible-light region.

Mn-doped ZnS nanoparticles (NPs) were prepared with dopants at various concentrations using a facile, simple and inexpensive wet chemical method at room temperature. The physicochemical properties of NPs were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible absorption spectroscopy (UV–vis) and photoluminescence (PL). XRD analysis confirmed formation of ZnS with zinc blende structure and average crystallite size of about 2 nm. TEM analysis revealed formation of hyperfine NPs with rather good uniformity. The room temperature photoluminescence (PL) spectrum of ZnS:Mn 2+ exhibited an orange-red emission around 600 nm. The maximum PL intensity was observed for 7.5% Mn doped ZnS. The photocatalytic performance of ZnS:Mn 2+ was successfully demonstrated for degradation of three different model dyes (i.e. Rhodimine B (Rh. B), Bromocresol Green (BCG) and Bromochlorophenol Blue (BCB)). The results revealed that not only was there a remarkable difference in photocatalytic performance of Mn doped ZnS for all three different dyes at different dopant concentrations but also photocatalytic activity was decreased by Mn doping.

We prepared a binary transition metal oxide material of nickel tungstate nanoparticles (NiWO4-NPs) through a simple co-precipitation method. The synthesized NPs were characterized using field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS) techniques. NiWO4-NPs represent nearly spherical morphologies with an average size of ~97 nm and tungstate as a dominant phase. Carbon paste electrode (CPE) modified with NiWO4-NPs (NiWO4-NPs/CPE) was used for electrooxidation of formaldehyde in alkaline solution. Cyclic voltammetry demonstrated that NiWO4-NPs/CPE electrode can decrease the overpotential for formaldehyde oxidation while increasing the current density in comparison to CPE. The results revealed that the CPE modified with calcined NiWO4-NPs (NiWO4-cal-NPs/CPE) shows less current response to formaldehyde oxidation compared with the amorphous sample. Moreover, the variation of scan rate and concentration of formaldehyde were investigated on the electrooxidation of formaldehyde and the results indicated that the electrooxidation on the NiWO4-NPs/CPE electrode is a diffusion-controlled mechanism. The diffusion coefficient and catalytic rate constant of formaldehyde, evaluated by chronoamperometry, were 40.4 × 10−4 cm2 s−1 and 1.37 × 104 cm 3 mol−1 s−1, respectively. Furthermore, we show that the prepared sensor has a wide linear range of 8 μM to 1 mM and low detection limit of 3.6 μM.

Using liquid phase deposition method on cellulose substrate, TiO2 nanofibres were prepared with TiCl4 as a precursor. TiO2 nanofibres were obtained after heat treatment of the cellulose template. The remaining product was composed of micron-size TiO2 fibres with a nanofiber microstructure. It is shown that nanofibres are formed through the aggregation of TiO2 nanoparticles. X-ray diffraction analysis of the as-prepared solution indicates the formation of crystalline TiO2 anatase phase. EDX analysis was employed to measure the adsorbed mass of TiO2 on cellulose substrate. The effect of deposition time on the growth and morphology was investigated by scanning electron microscopy. Transmission electron microscopy studies demonstrate fine microstructures composed of 10–15 nm nanoparticles. Surface area of the TiO2 fibres, measured by Brunauer, Emmett and Teller analysis, was about 104 m2 g−1. Photodegradation of Rhodamine B as a standard dye shows that the prepared samples have a high photocatalytic activity ...

We report studies on the growth of gold nanoparticles by a seed-mediated approach in solution. The synthetic method is adapted from one we published earlier (Ashkarran et al. Appl. Phys. A 2009, 96, 423). The synthesized gold nanoparticles were characterized by X-ray diffraction (XRD), dynamic light scattering (DLS), UV-Vis spectroscopy, optical imaging and atomic force microscopy (AFM). Optical absorption spectroscopy of the prepared samples at 15 A arc current in HAuCl4 solution shows a surface plasmon resonance around 520 nm. It is found that sodium citrate acts as a stabilizer and surface capping agent of the colloidal nanoparticles. The intensity of the plasmonic peak of the prepared gold nanoparticles for 1 minute arc duration gradually increases due to seed mediation for up to 6 hours. The formation time of gold nanoparticles at higher seed concentrations is less than that at lower seed concentrations.

Noble metals nanostructures, particularly silver, have attracted much attention in the fields of electronics, chemistry, physics, biology and medicine due to their unique properties which are strongly dependent on the size and shape of metal nanomaterials. This study discusses on silver nanostructures with different geometries including wire, cube, sphere and triangle prepared using solution-phase method and applied for antibacterial activities. X-ray diffraction (XRD), Ultra Violet Visible (UV-Vis) spectroscopy, Dynamic Light Scattering (DLS) and electron microscopy studies of different types of silver nanostructures revealed distinct optical and structural properties of an individual silver nanostructure. We have also evaluated the antibacterial activity of different shapes of silver nanostructures against Escherichia coli (E.coli), Bacillus and Staphylococcus. Results presents shape dependent antimicrobial activity of silver nanostructures.

Silicon (Si) core–shell nanowires (NWs) were successfully prepared by very high frequency plasma-enhanced chemical vapor deposition technique, and the effect of silane (SiH4) gas flow rates on physicochemical properties of silicon NWs was investigated. Field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy were used to characterize SiNWs. Structural properties and morphology of NWs were studied as a function of SiH4 gas flow rate. Microscopic analysis revealed the formation of SiNWs with average tip and stem diameters ranging from 18 to 30 and 21 to 67 nm, respectively. Furthermore, the average length of Si NWs calculated based on the FESEM images was about 300–1800 nm. We have found that the growth of SiNWs increased with increasing in SiH4 gas flow rate. XRD, Raman spectra in addition to high-resolution TEM, verified the formation of crystalline SiNWs. A possible growth mechanism was suggested based on our observations.