Effect of different physical factors on the synthesis of spherical gold nanoparticles towards cost‐effective biomedical applications

Gold nanoparticles (AuNPs) have great potential to contribute to numerous application fields of biomedicine, which are highly dependent on their physicochemical properties, such as size and shape. Due to the final characteristics, nanoparticles (NPs) are primarily affected by different factors of reaction conditions; the present study aimed to evaluate the effects of manipulating the main physical parameters of the Turkevich method to optimise the fabrication of citrated capped AuNPs in a spherical shape, desirable final size, and efficiency. For this purpose, various experiments of citrate‐capped spherical AuNPs synthesis were designed to study the roles of a wide range of initial pH values and temperature of reaction, Na₃Cit/HAuCl₄ molar ratio, and two order reagent additions, method I and method II, in the final characterisations and reaction efficacy. Prepared NPs synthesised with different experiments were characterised by dynamic light scattering, UV‐Visible, and fourier transform infrared spectroscopy. Furthermore, NPs obtained from optimised synthesis conditions were more detailed using UV‐Visible, transmission electron microscopy, and XRD. The findings indicated that the final size and synthesis efficacy of citrated capped spherical AuNPs were significantly affected by all studied synthesis parameters and the order addition of reagents. The higher initial reaction temperature and Na₃Cit/HAuCl₄ Molar ratio provided a smaller particle size with desirable synthesis efficacy. Besides, final optimised NPs were provided in cubic crystal structures, and each NP''s single crystal was obtained. In sum, our findings indicated that optimising synthesis conditions could improve size distribution, morphology, crystallite size, and structures of final NPS, as well as efficiency, which is a principal factor associated with future cost‐effective productions on large scales. Further studies are needed in this regard.     

Controlled synthesis of spherical CuS hierarchical structures

Spherical CuS hierarchical structures organized by nanoparticles were synthesized by the reaction of CuCl₂·2H₂O and sodium O-isopropyldithiocarbonate (xanthate, C₃H₇OCSSNa) in N,N-dimethylformamide (DMF) at 70 °C for 12 h. The product was characterized by X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM). The result shows that the hierarchical CuS spheres were of 300-500 nm and aggregated by numerous particles with an average diameter of about 10 nm. A possible mechanism for the formation of CuS hierarchical structures is proposed, and an optical study has also been carried out.     

Influence of CTAB surfactant on structural and optical properties of CuS and CdS nanoparticles by hydrothermal route

Metal sulphide CuS and CdS nanoparticles capped with Cetyltrimethylammonium bromide (CTAB) were synthesized by hydrothermal method. Structural, morphological, chemical composition, optical and luminescent properties were evaluated by different analytical techniques. X-ray diffraction (XRD) analysis of the CTAB capped metal sulfide nanoparticles reveals the formation of hexagonal structure. High-resolution transmission electron microscopy (HRTEM) images show that the morphology of the capped copper sulphide samples consists of hexagonal structure and capped cadmium has spherical shape and also confirms the crystalline nature of the particles with distinct lattice fringes. In FTIR spectroscopy, the composition of the CTAB capped CuS and CdS nanoparticles have been confirmed. The analysis of photoluminescence (PL) and optical transition show a red shift due to the reduction of band gap energy and it is attributed to the low defects and high crystallinity. The optical studies indicate that CuS and CdS nanoparticles with CTAB can be suitable for optoelectronic devices and photovoltaic applications.     

Composition and crystallinity of silicon nanoparticles synthesised by hot wire thermal catalytic pyrolysis at different pressures

The effect of pressure on the structure and composition of silicon nanoparticles synthesized by hot wire thermal catalytic pyrolysis (HW-TCP) of pure silane has been investigated. Light brown powders were produced at silane pressures of 10 and 50 mbar, at a flow rate of 50 sccm, using a tungsten filament at temperatures of 1900 °C and 1800 °C respectively. As determined by transmission electron microscopy and X-ray diffraction, the particles produced at lower pressure have sizes around 10 nm, whereas those produced at higher pressure are typically 50 nm. High resolution transmission electron microscopy (HR-TEM) shows a surface layer of between 2 and 5 nm thickness, which was confirmed by X-ray photoemission spectroscopy to be an oxide shell. Both X-ray diffraction and HR-TEM confirm a high degree of crystallinity in both sets of particles, with Raman spectroscopy indicating an increase in crystalline fraction with synthesis pressure.     

Microwave-assisted synthesis of ceria nanoparticles

Nanocrystalline ceria (CeO₂) particles have been successfully prepared by microwave-assisted heating technique from an aqueous solution containing ammonium Ce(IV) nitrate and sodium hydroxide. Further thermal treatment of the as-prepared powder at 500 °C resulted in the formation of the well-crystallized CeO₂ nanoparticles with an average crystal size of about 8 nm, varying with the heating temperature. The as-prepared powder and the CeO₂ nanoparticles were examined using X-ray diffraction (XRD) and transmission electron microscope (TEM) techniques. It was found that the morphologies of the synthesized powder show from rod-like for the as-prepared sample to sphere-like for the heat-treated nanoparticles. Mechanism of CeO₂ nanocrystallite growth during annealing is primarily investigated.     

One-pot room temperature synthesis of biopolymer-capped ZnSe nanoparticles

The synthesis of monodispersed, starch-capped ZnSe nanoparticles via a facile, “green” and environmentally benign route at room temperature is being reported. The nanoparticles exhibited strong quantum confinement effect with respect to the bulk ZnSe. The transmission electron microscopy (TEM) image indicated that the particles were well dispersed and spherical in shape. The X-ray diffraction (XRD) analysis showed that the ZnSe nanoparticles were of the wurtzite structure, with average particle diameter of about 3.50 nm. The Fourier transform infrared (FT-IR) spectrum confirmed the presence of starch as passivating agent.     

Design and synthesis of polymetallic nanoparticles and their catalytic applications

High-temperature hydrogen reduction reactions enable the synthesis and processing of binary metal oxide composite nanoparticles starting from titanium, ruthenium, and silicon, while the use of a surface modifier and an organic surfactant enables the synthesis of catalytic thin films from binary semiconductor oxides. Surface characterization by XRD, SEM, TEM, AFM, Raman spectroscopy, and BET measurements indicate that the incorporation of binary oxide particles into the semiconductor materials altered the surface properties and morphology of the nanoparticles while the surface modifier and organic surfactant loading can be experimentally adjusted to obtain thin films of varying morphological characteristics.     

Electrochemical bulk synthesis and characterisation of hexagonal-shaped CuO nanoparticles

A simple and efficient two-step hybrid electrochemical–thermal route was developed for the bulk synthesis of CuO nanoparticles using aqueous sodium nitrate electrolyte and Cu electrodes in an undivided cell under galvanostatic mode at room temperature. The influence of electrolyte concentration on the synthesis of CuO nanoparticles was studied at 1.0?A/dm² current density. Electrochemically generated precursor was calcined for an hour at different levels of temperature in the range 200–900°C. The calcined samples were characterised by XRD, TG-DTA, XPS, SEM/EDAX, TEM, FT-IR and UV–Vis spectral methods. The crystallite sizes were estimated and the thermal behaviour of as-prepared compound was examined. Rietveld refinement of X-ray data shows results matching the monoclinic structure with the space group of C2/c (no. 15). The TEM result revealed that the particle sizes were in the order of 30–50?nm diameter and 120–200?nm length. The blue shift was noticed in UV–Vis absorption spectra. All samples of CuO exhibited randomly oriented hexagonal morphology.     

Chitosan as template for the synthesis of ceria nanoparticles

Cerium oxide (CeO₂), nanoparticles were prepared using chitosan as template, cerium nitrate as a starting material and sodium hydroxide as a precipitating agent. The resultant ceria–chitosan spheres were calcined at 350 °C. The synthesized powders were characterized by, XRD, HRTEM, UV–vis, FTIR, and TG-DTA. The average size of the nanoparticles obtained was ∼4 nm and BET specific surface area ∼105 m² g⁻¹. Blueshifts in the ultraviolet absorption spectra have been observed in cerium oxide nanocrystallites. The band-gap was found to be 4.5 eV. The blueshifts are well explained for diameters down to less than a few nanometers by the change in the electronic band structure.     

Controllable synthesis and characterization of novel copper-carbon core-shell structured nanoparticles

A facile hydrothermal method was developed for preparing copper-carbon core-shell structured particles through a reaction at 160 °C in which glucose, copper sulfate pentahydrate and cetyltrimethylammonium bromide were used as starting materials. The original copper-carbon core-shell structured particles obtained were sized of 100-250 nm. The thickness of carbonaceous shells was controlled ranging from 25 to 100 nm by adjusting the hydrothermal duration time and the concentrations of glucose in the process. Products were characterized with transmission electron microscopy, X-ray diffraction, energy dispersive spectroscopy, Fourier transform infrared spectroscopy. Since no toxic materials were involved in the preparation, particles with stable carbonaceous framework and reactive surface also showed promising applications in medicine, electronics, sensors, lubricant, etc.     

不同商品化聚丙烯腈基碳纤维的微观结构研究

利用X射线衍射对比研究了日本东丽、东邦和国产3种牌号聚丙烯腈(PAN)基碳纤维的微观结构。通过分析不同牌号的PAN基碳纤维晶体结构与石墨晶体结构的区别,以及不同牌号的PAN基碳纤维力学性能与微观结构的关系,表明了引起PAN基碳纤维力学性能差异的主要因素为石墨化程度、内部缺陷、晶粒尺寸大小以及晶粒排列规整程度。     

Synthesis of cobalt boride nanoparticles using RF thermal plasma

Nanosize cobalt boride particles were synthesized from the vapor phase using a 30 kW–4 MHz radio frequency (RF) thermal plasma. Cobalt and boron powder mixtures used as precursors in different composition and feed rate were evaporated immediately in the high temperature plasma and cobalt boride nanoparticles were produced through the quenching process. The X-ray diffractometry (XRD) patterns of cobalt boride nanoparticles prepared from the feed powder ratio of 1:2 and 1:3 for Co:B showed peaks that are associated with the Co₂B and CoB crystal phases of cobalt boride. The XRD analysis revealed that increasing the powder feed rate results in a higher mass fraction and a larger crystalline diameter of cobalt boride nanoparticles. The images obtained by field emission scanning electron microscopy (FE-SEM) revealed that cobalt boride nanoparticles have a spherical morphology. The crystallite size of the particles estimated with XRD was found to be 18–22 nm.     

Effect of the preparation route,PEG and annealing on the phase stability of Fe3O4 nanoparticles and their magnetic properties

Fe₃O₄ nanoparticles are synthesised via two different methods: (1) co-precipitation of Fe²⁺ and Fe³⁺ ions and (2) oxidative alkaline hydrolysis of Fe²⁺ ions under atmospheric pressure using different protective agents (PEG 200 and PEG 3000) and urea as a base. The preparation method and the polyethylene glycol (PEG) used are concurrently affecting the phase stability of the formation of the iron oxides: the co-precipitation method using PEG 200 (E4a) or PEG 3000 (E4b) leads to the formation of different ratios of Fe₂O₃ and Fe₃O₄, whereas the oxidative hydrolysis of Fe²⁺ using PEG 200 gives Fe₃O₄ (E2) powder as a major product. The average crystallites size of E4a and E4b is almost identical, i.e. around 19?nm but the saturation magnetisation of E4b is three times larger than that of E4a. The sample E2 shows the highest saturation magnetisation value 74?emu/g, with an average crystallites size of 71?nm. Transmission electron microscopy analysis confirmed that the E2 sample shows the presence of needles crystals with typical sizes around 10 and 50?nm and its selected area diffraction (SAD) shows a typical diffraction of the spinel structure of magnetite. On the other hand, E4b sample shows elongated nanoparticles with typical sizes around 24?nm and its SAD confirmed the presence of a mixture of Fe₂O₃ and Fe₃O₄ as many dispersed spots were obtained.     

Microwave-hydrothermal synthesis of perovskite bismuth ferrite nanoparticles

Hydrothermal microwave method (HTMW) was used to synthesize crystalline bismuth ferrite (BiFeO₃) nanoparticles (BFO) in the temperature of 180 °C with times ranging from 5 min to 1 h. BFO nanoparticles were characterized by means of X-ray analyses, FT-IR, Raman spectroscopy, TG-DTA and FE-SEM. X-ray diffraction results indicated that longer soaking time was benefit to refraining the formation of any impurity phases and growing BFO crystallites into almost single-phase perovskites. Typical FT-IR spectra for BFO nanoparticles presented well defined bands, indicating a substantial short-range order in the system. TG-DTA analyses confirmed the presence of lattice OH⁻ groups, commonly found in materials obtained by HTMW process. Compared with the conventional solid-state reaction process, submicron BFO crystallites with better homogeneity could be produced at the temperature as low as 180 °C. These results show that the HTMW synthesis route is rapid, cost effective, and could be used as an alternative to obtain BFO nanoparticles in the temperature of 180 °C for 1 h.     

Energy-dispersive X-ray reflectivity and GID for real-time growth studies of pentacene thin films

We use energy-dispersive X-ray reflectivity and grazing incidence diffraction (GID) to follow the growth of the crystalline organic semiconductor pentacene on silicon oxide in-situ and in real-time. The technique allows for monitoring Bragg reflections and measuring X-ray growth oscillations with a time resolution of 1 min in a wide q-range in reciprocal space extending over 0.25-0.80 Å^− 1, i.e. sampling a large number of Fourier components simultaneously. A quantitative analysis of growth oscillations at several q-points yields the evolution of the surface roughness, showing a marked transition from layer-by-layer growth to strong roughening after four monolayers of pentacene have been deposited.     

Preparation of CuS nanoparticles embedded in poly(vinyl alcohol) nanofibre via electrospinning

Poly(vinyl alcohol) (PVA)/CuS composite nanofibres were successfully prepared by electrospinning technique and gas-solid reaction. Scanning electron microscopic (SEM) images showed that the average diameter of PVA/CuS fibres was about 150–200 nm. Transmission electron microscopy (TEM) proved that a majority of CuS nanoparticles with an average diameter of about 15–25 nm are incorporated in the PVA fibres. X-ray diffraction (XRD) analyses and electron diffraction pattern also revealed the forming of CuS crystal structure in the PVA fibres.     

One-pot synthesis of CuFeSe2 cuboid nanoparticles

Ternary semiconducting CuFeSe₂ nanocrystals of a particular shape and size were successfully synthesized using a cost-effective and simple one-pot chemical route. X-ray powder diffraction and field emission scanning electron microscopy results indicated that the as-synthesized CuFeSe₂ comprised cuboid nanoparticles with dimensions of 50–150 nm as well as a tetragonal phase. Elemental analysis yielded an atomic ratio of Cu:Fe:Se of 1:1.06:2.17. The synthesis temperature and the solvent octadecylamine were significant in determining the structural phases and morphologies of the final products. The optimal condition for synthesizing the tetragonal CuFeSe₂ phase with cuboid nanoparticles was a reaction temperature of 200 °C for 1 h in octadecylamine solvent. A possible mechanism of the formation of ternary CuFeSe₂ nanoparticles with controllable shapes is discussed.     

X-ray synthesis of nickel–gold composite nanoparticles

We developed a novel approach to prepare Ni–Au composite nanoparticles using synchrotron radiation X-rays. Ni–Au particles dispersed in aqueous solutions were synthesized with two different irradiation strategies. The first is by exposing to X-rays a mixed electroless solution of Ni and Au at two different temperatures, trying to nucleate Ni nanoparticles homogeneously at room temperature and to deposit Au subsequently on them at the high temperature of 70 °C. The second strategy is to change the pH value of the mixed solution, directly leading to the formation of Ni–Au nanoparticles. In both cases, the Ni–Au composite nanoparticles were successfully formed, as confirmed by the observed ferromagnetic behavior and by the evolution of the Au surface plasmon resonance band.