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One-drop Self-assembly and Size Control of Organic Nonlinear Optical Crystal DSNS Nanowires
摘要： In this study, we demonstrate a one-drop self-assembly method for fabricating nanowires (NWs) of organic second-order nonlinear optical (NLO) material, 4-N, N-dimethylamino-4'-N'-methyl- stilbazolium 2-naphthalenesulfonate (DSNS). By controlling the parameters of the self-assembly process, we successfully controlled the length of DSNS from a few micrometers to millimeters. The obtained NWs have very high surface quality with surface roughness <150 pm, which is highly beneficial for fabricating integrated optical devices. DSNS NW has the same triclinic crystal structure as that of bulk crystal and exhibits excellent second-order NLO and fluorescent properties, which could provide wide opportunities for on-chip optoelectronic devices and integrated photonic systems. Furthermore, the one-drop self-assembly method only requires reagents in microgram quantities, and thus this method is extremely environment-friendly.
关键词： one-drop self-assembly,organic nanowire,size control,nonlinear optical material
更新于2025-09-23 15:23:52
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Size-controlled synthesis of gold nanoparticles by ultrafine bubbles and pulsed ultrasound
摘要： Size-controlled gold nanoparticles (AuNPs) were synthesized by ultrasonic irradiation of HAuCl4 aqueous solutions with the aid of ultrafine bubbles (UFBs) in the absence of any capping and reducing agents. Upon addition of air-UFBs, the mean diameter of the spherical AuNPs decreased. This result was attributed to the sonochemical reduction of gold ions in aqueous solution being accelerated by the UFBs. Moreover, the AuNPs were stable in a solution containing UFBs because AuNPs electrostatically adsorbed onto UFBs, whose lifetime in water was very long. Compared with the mean diameter of AuNPs synthesized with argon-, nitrogen- and oxygen-UFBs, that of AuNPs synthesized with air-UFBs was smaller. Pulsed ultrasound delivered with the same time-averaged power as continuous-wave irradiation further decreased the mean diameter of the AuNPs. Size-controlled synthesis of AuNPs without the use of a capping or reducing agent was successful through optimization of the number air-UFBs and the pulsed ultrasound conditions.
关键词： Gold nanoparticles,Size control,Ultrasound,Pulse wave,Ultrafine bubbles,Colloidal stabilization
更新于2025-09-19 17:13:59
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Synthesis and Characterization of Thiolate-Protected Gold Nanoparticles of Controlled Diameter
摘要： Gold nanoparticles (AuNPs) have been the focus of many studies owing to their unique optical and electronic properties and versatile applications. However, synthesis of stable and homogeneous AuNPs with a particular choice of size is still a challenge. In this study we describe a direct synthesis approach to produce stable and monodisperse water-soluble AuNPs with a tightly controlled diameter in the 1.7?2.4 nm range. We controlled the size by changing only the sodium hydroxide (NaOH) concentration in the synthesis. Gel electrophoresis, transmission electron microscopy (TEM), and solution X-ray scattering showed that the AuNPs had narrow size-distributions. We further showed that AuNPs of the di?erent sizes were clearly distinguishable in TEM micrographs, paving the way to dual-target labeling. The reactivity of the AuNPs toward DNA and proteins was also demonstrated. We utilized this reactivity to label tail-anchored proteins embedded in the membrane of the anticancer nanodrug Doxil as a means to target it to speci?c cell types. The gold-labeling enabled the precise localization of the tail-anchored proteins in cryo-TEM images of the therapeutic liposomes.
关键词： thiolate-protected,bioconjugation,cryo-TEM,tail-anchored proteins,synthesis,size control,Gold nanoparticles,Doxil
更新于2025-09-16 10:30:52
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Size-Programmed Synthesis of PbSe Quantum Dots via Secondary Phosphine Chalcogenides
摘要： In the most common syntheses of colloidal nanocrystal quantum dots (QDs) the size of the particle increases monotonically with reaction time. We have discovered a PbSe QD synthesis whereby size can be easily controlled by varying the side-chains of a secondary phosphine selenide precursor. The reaction runs to completion, and thus a desired QD diameter can be achieved by simply selecting an appropriate secondary phosphine. Quenching of the reaction to select a desired QD size is not required. For different secondary phosphine selenides, measurements of the precursor conversion rate show a direct relationship with final QD size, while P=Se bond strength calculations show an unexpected inverse relationship between QD size and P=Se bond strength. Finally, it is also demonstrated that secondary phosphine selenide precursors can provide an effective route for IV-VI QD syntheses on the large scale.
关键词： colloidal synthesis,size control,IV-VI QDs,secondary phosphine selenide,PbSe quantum dots
更新于2025-09-12 10:27:22
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Obtaining of nanoparticles of Sc, Ti, V, Cr, Mn, Fe, Co, Ni with controlled sizes and properties using laser ablation
摘要： Using laser ablation, nanoparticles of Sc, Ti, V, Cr, Mn, Fe, Co, Ni with controlled sizes and properties were obtained. To obtain nanoparticles of a given size, not only ablation of massive targets was used, but fragmentation (exposure to a mixture of micro- and nanoparticles by laser radiation). The evolution of the particle size distribution function in the process of their laser fragmentation is investigated and its key parameters determining it are established, such as the energy density of a laser beam in a medium and the peak power of laser radiation. Different schemes for introducing laser radiation into colloidal systems have been used. To obtain nanoparticles that do not contain oxide films, organic alcohols (ethanol and propanol-2) were used as the working fluid. The obtained nanoparticles met the following criteria: 1). at least 95% of the particles in the preparation have the specified diameter; 2). The shape of the nanoparticles is close to spherical; 3). The composition of the nanoparticles does not include a significant amount of impurities and oxides; 4). In most of the nanoparticles, a metal crystal lattice is observed, although under certain conditions it is possible to obtain nanoparticles, both with the outer oxide layer and entirely consisting of oxides. The stability of the obtained colloid nanoparticles was investigated. It is assumed that the solvent is saturated with molecular hydrogen to prevent oxidation of nanoparticles during storage.
关键词： size control,laser ablation,nanoparticles,transition metals,oxidation prevention
更新于2025-09-11 14:15:04
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Carbon coated TiO2 nanoparticles prepared by pulsed laser ablation in liquid, gaseous and supercritical CO2
摘要： We report on the synthesis of TiO2 nanoparticles using nanosecond pulse laser ablation of titanium in liquid, gaseous and supercritical CO2. The produced particles were observed to be mainly anatase-TiO2 with some rutile-TiO2. In addition, the particles were covered by a carbon layer. Raman and X-ray diffraction data suggested that the rutile content increases with CO2 pressure. The nanoparticle size decreased and size distribution became narrower with the increase in CO2 pressure and temperature, however the variation trend was different for CO2 pressure compared to temperature. Pulsed laser ablation in pressurized CO2 is demonstrated as a single step method for making anatase-TiO2/carbon nanoparticles throughout the pressure and temperature ranges 5–40 MPa and 30–50 °C, respectively.
关键词： core-shell particles,pulsed laser ablation,nanoparticle size control,supercritical fluids
更新于2025-09-11 14:15:04