Journal of nanoscience and nanotechnology最新文献

Micro and nano structures of quartz schist, plagioclase granite, and granitic gneiss in the Xiaomei Shear Zone located in southeastern Hainan Island, China are observed using Scanning Electron Microscope (SEM). Ultramicroscopic analyses indicate that three types of nanoparticles were found in the samples, including spherical nanoparticles, agglomerated nanoparticles and nanofibers. These nanoparticles are mainly developed in the fracture zones. The more fractures there are, the more nanoparticles are developed. Energy dispersive spectrometer (EDS) and X-ray diffraction (XRD) are used to ascertain the composition of the nanoparticles. The results suggest that the nanoparticles are mainly composed of silicate, dolomite and calcite, rich in O, Si, Al, Ca. Based on our results, we suggest that nanoparticle formation is a complex, plastic-brittle transition process. Thermal decomposition driven by steady shearing possibly forms well-organized nanoparticles, while fast-moving dislocations by shock-like stress release possibly forms radial nanofibers.

The aim of this paper was to use chromatographic tools for validating an analytical method for the tacrolimus (TAC) determination in polymeric nanocapsules and for identifying the drug degradation products after alkaline stress. A rapid Ultra-High-Performance Liquid Chromatography coupled with photo-diode array (UHPLC-PDA) method was successfully performed using the following chromatographic conditions: the Shimadzu Shim-pack XR-ODS III C18 column (100 mm×2.00 mm, 2.2 μm), the mobile phase consisting of methanol and acidified ultrapure water (89:11 v/v), the flow rate of 0.55 mL·min^-1, and the ultraviolet (UV) detection at 235 nm. This method was validated as per International Council for Harmonisation (ICH) guidelines. In addition, a TAC forced degradation assay was carried out after alkaline stress and its degradation products were investigated using Liquid Chromatography coupled tandem mass spectroscopy (LC-MS/MS). The calibration curve was linear in the range of 100.0-300.0 μg·mL^-1 (r >0.9999). Accuracy was confirmed by the TAC recovery of 96.55 to 98.19%. Precision (intraday and interday) were demonstrated by relative standard deviation lower than 0.89% and 3.25%, respectively. Selectivity and robustness were also proved. The method developed it was successfully applied to quantify TAC from polymeric nanocapsules, showing a high loading efficiency rate (>96.47%). The main drug degradation product observed in a multiple reaction monitoring (MRM) experiment was m/z 844, confirming the susceptibility of TAC under alkaline conditions; this finding was first time described.

Facile preparation of a tumoral-stimuli-activated theranostic nanoparticle with simple constituents remains a challenge for tumor theranostic nanosystems. Herein we design a simple reductionresponsive turn-on theranostic nanoparticle for achieving fluorescent imaging and phototherapy combination. The theranostic nanoparticle is prepared by a simple one-step dialysis method of reduction active amphiphilic hyperbranched poly(β-amidoamines) and a near-infrared (NIR) dye indocyanine green (ICG). The fluorescence of ICG is quenched by the aggregation-caused quenching (ACQ) effect. The fluorescent intensity of free ICG at 816 nm was ∼40 times as high as that of particulate ICG. After reductive nanoparticles incubated with dithiothreitol (DTT), the size of the nanoparticles increased from 160 nm to 610 nm by Dynamic light scattering (DLS). As nanoparticles were internalized by cancer cells, the disulfide bonds would be cleaved by intracellular reduction agents like glutathione (GSH), leading to the release of entrapped ICG. The released ICG regained its fluorescence for self-monitoring the release and therapeutic effect of ICG by fluorescence spectra and the quantitative evaluation of NIR fluorescence intensity. Remarkably, nanoparticles can also reinforce antitumor efficacy through photodynamic therapy and GSH depletion property. This study provides new insights into designing turn-on theranostic systems.

Nanoemulsions were prepared using polyglycerol esters as emulsifiers. The effects of emulsifiers, oils, and polyols on the phase behavior of nanoemulsions were analyzed by phase diagram method using caprylic acid capric triglyceride (318), mineral oil, and squalane (Squ) as oils respectively. Various factors affecting the area of the oil-in-water (O/W) nanoemulsion were investigated. The results showed that hydrophilic polyglyceryl-4 laurate was beneficial to the formation of translucent nanoemulsions, while lipophilic polyglyceryl-4 oleate could synergize the emulsification performance and was more conducive to the formation of nanoemulsions; the type of oil could affect the emulsifying ability of the emulsifier. It was found that it was beneficial to form translucent nanoemulsion when caprylic acid capric triglyceride was adopted as oil. However, it was almost impossible to form translucent nanoemulsions when mineral oil and squalane were used as oils. The addition of water-soluble jojoba ester was beneficial to the formation of O/W emulsion. In addition, glycerin can improve the polarity of the aqueous medium, enhance the affinity between emulsifiers and aqueous medium, and help to form a translucent nanoemulsion.

The increase of harmful carbon monoxide (CO) caused by incomplete combustion can affect human health even lead to suffocation. Therefore reducing the CO discharged by vehicles or factories is urgent to improve the air quality. The spinel cobalt (II, III) oxide (Co₃O₄) is an active catalyst for CO abatement. In this study, we tried to fabricate dispersing Co₃O₄ via the dispersion-precipitation method with acetic acid, formic acid, and oxalic acid as the chelating dispersants. Then, the asprepared samples were calcined at 300 ºC for 4 h to obtain active catalysts, and assigned as Co(A), Co(F) and Co(O) respectively, the amount of the dispersants used are labeled as I (0.12 mole), II (0.03 mole) and III (0.01 mole). For comparison, another CoAP sample was prepared via alkaliinduced precipitation and calcined at 300 ºC. All samples were characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), scanning electron microscope (SEM), and nitrogen adsorption/desorption system, and the catalytic activity focused on the CO oxidation. The influence of chelating dispersant on the performance of abatement of CO was pursued in this study. Apparently, the results showed that the chelating dispersant can influence the catalytic activity of CO abatement. An optimized ratio of dispersant can improve the performance, while excess dispersant lessens the surface area and catalytic performance. The series of Co(O) samples can easily donate the active oxygen since the labile Co-O bonding and indicated the preferential performance than both Co(A) and Co(F) samples. The nanorod Co(O)-II showed preferential for CO oxidation, T₅₀ and T₉₀ approached 96 and 127 ºC, respectively. Also, the favorable durability of Co(O)-II sample maintains 95% conversion still for 50 h at 130 ºC and does not emerge deactivation.

Supercapacitor with high specific capacity is desirable for various energy storage and high powerdensity applications. Though Graphene has been the preferred material for high current density, nanocomposites have been attempted to increase the specific capacitance. Hydrothermal synthesis of cadmium sulfide/graphene (CdS/G) nanocomposite with CdS nanoparticles anchored/decorated over the graphene sheets is reported. The structural studies reveal the hexagonal phase of the prepared materials. The specific surface area (BET) and porosity is found to increase upon nanocomposite formation. The electrochemical characteristics such as cyclic voltammetry (CV), GCD and EIS of the CdS/G nanocomposite have been investigated. The capacitance of CdS/G nanocomposite almost doubled to 248 Fg^-1 indicating the enhanced performance of the nanocomposite system and in addition it also showed excellent cycling stability of 74.8 percent after 1000 cycles. The supercapacitor investigated retained the initial energy density after charge-discharge, at 0.5 A/g for 1000 cycles. The graphene nanosheets increased the specific surface area and interfacial electron transfer of the composite material. It enhances the specific capacitance and cyclic stability of the supercapacitor device.

Enhanced permeation and retention (EPR) effect, the mechanism by which nanodrugs accumulate in tumors and acquire superior curative effect. The questions of these mechanisms occur because of limited clinical transformation of engineered nanomaterials after 30 years. The difference of EPR limits the therapeutic effect of nanodrugs in the individual patient. Evaluation of the EPR effect in the individual patient will aid in selecting patients who will accumulate higher amounts of nanotherapeutics and show better therapeutic efficacy. Based on varied TIMP1/MMP-9 in serum, an aggregation-induced emission luminogen probe was designed and constructed to detect and evaluate the EPR effect in model mouse. The result showed that the ratio of TIMP1/MMP-9 (in the range 0.2-1.2) and fluorescence intensity of the probe were negative linear correlation and the effects of BSA-rhodamine accumulation in tumor were individualized differences as well as correlated with the relative ratio of TIMP-1/MMP-9 in serum. Our data support the development of these biomarkers probes based on the personalized nanotherapy of tumor.

Noble metal nanoparticles have special properties in optical, electronic, and physical chemistry due to their high surface area and volume. With the development of electronic printing technology, inkjet printing has gradually replaced traditional spin coating and blade coating, since it leads to more material savings and a faster batch production, and the pattern can be easily designed by a computer. In this study, Ag nanoparticles were prepared by a chemical reduction method. Non-toxic, environment-friendly agents were selected to fabricate a single-shape, uniform-size, crystal-form, and monodisperse product. The effects of the reducing agent ratio and the stabilizer ratio on the size, shape, and stability of the nanoparticles are discussed. The silver nanoparticles were characterized by an ultraviolet-visible spectrophotometer (UV-vis) and a transmission electron microscope (TEM). In addition, in order to prepare conductive ink that can stably disperse for a long time and that can be applied to inkjet printing on a PET flexible substrate at a lower sintering temperature, a sintering agent and a commercial surfactant were added. The experimental results show that the best addition ratio of the precursor to the reducing agent and the stabilizer is 1:6:1. The conductive silver ink was printed and treated by a70 mM NaCl solution, and the electric resistivity was 5.17×10^-4 Ω· cm.

In this paper we study the Electron Statistics in Heavily Doped N Type-Intrinsic-P Type-Intrinsic structures of non-linear optical, tetragonal and opto-electronic materials in the presence of magnetic quantization. It is found taking such heavily doped structures of Cd₃As₂, CdGeAs₂, InAs, InSb, Hg_1-xCd_xTe, In_1-xGa_xAs_yP_1-y as examples that the Fermi energy (E_F) oscillates with inverse quantizing magnetic field (1/B) and increases with increasing electron concentration with different numerical magnitudes which is the signature of respective band structure. The numerical value of the Fermi energy is different in different cases due to the different values of the energy band constants.

Pristine TiO₂ and x% Ru/TiO₂ catalysts with different wt.% of Ru (x%= 1.5%, 2%, 2.5% and 3%) were synthesized using sol-gel and simple impregnation methods. Different characterization techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), High-resolution transmission electron microscope (HR-TEM), Inductively coupled plasma-optical emission spectrometry (ICP-OES) and Thermogravimetry/Differential thermal analysis (TG/DTA) were used to study the physicochemical and morphological properties. The XRD patterns of the as-prepared pristine TiO₂ catalyst showed high crystalline nature. The HR-TEM images revealed that the Ru nanoparticles (NPs) were evenly dispersed on the TiO₂ surface. The prepared catalysts were evaluated for their catalytic activity towards the liquid phase hydrogenation of ethyl levulinate under mild reaction conditions (ambient H2 pressure). Among the various catalysts, 2.5% Ru/TiO₂ catalyst showed the maximum catalytic activity of 79% ethyl levulinate (EL) conversion with 82% selectivity of γ-valerolactone (GVL). The recyclability test revealed that the most active 2.5% Ru/TiO₂ also showed the highest stability of the catalyst under optimized experimental conditions.