Two-step Preparation Research Articles

Promoted Antitumor Activity of Myricetin against Lung Carcinoma Via Nanoencapsulated Phospholipid Complex in Respirable Microparticles.

Myricetin (MYR) flavonoid is well-recognized for its antioxidant, anti-inflammatory and anti-tumor potential. Introducing nanomedicine was the ultimate resort to solve the imperfections of this nutraceutical, namely solubility, stability and delivery issues. The study, thus, aims at developing inhalable microparticles comprising MYR solid lipid nanoparticles (SLNs) for lung cancer therapy. A two-step preparation procedure starting with complexation of MYR with the phospholipid Lipoid-S100, followed by nanoencapsulation in Gelucire-based, surfactant-free SLNs was developed. SLNs were characterized in terms of physicochemical properties, MYR loading, release behavior as well as anti-tumor potential and cellular uptake. Respirable microparticles were then obtained by spray drying SLNs with carbohydrate carriers. Their size, flowability and pulmonary deposition pattern were assessed. Optimized SLNs were 75.98nm in diameterwith a zeta-potential of -22.5mV, and an encapsulation efficiency of 84.5%. Attempts to ameliorate drug loading implicate MYR-phospholipid complexation (MYR-PH-CPX) prior to its entrapment in SLNs, which ensured 5-fold increase in drug loading. Viability assays were modified to guarantee MYR chemical stability. Superior antitumor activity of MYR-phospholipid-complex and 3-fold reduction in IC50 were accomplished with MYR-SLNs. This could be related to enhanced cellular uptake revealed by confocal imaging and doubled fluorescence intensity. SLNs entrapping MYR-PH-CPX were spray-dried with carbohydrate carriers to produce respirable microparticles. The latter ensured MMAD of 2.39μm and span index of 1.84, in addition to good flowability and > 80% release over 8h. Deposition experiments revealed MMAD of 2.77μm, FPF of 81.23 and EF of 93% indicating particle deposition in the targeted bronchial region. The study highlights the ability of phospholipid-complex on the nanoencapsulation, cellular uptake and antitumor activity of MYR. Formulation of respirable microparticles gives promises of efficacious therapy of lung carcinoma.

Thermoplastic Starch Composites With Titanium Dioxide and Vancomycin Antibiotic: Preparation, Morphology, Thermomechanical Properties, and Antimicrobial Susceptibility Testing

Biodegradable composites of thermoplastic starch (TPS), titanium dioxide particles (TiO2; average size 0.2 μm) and/or antibiotic (ATB; vancomycin) were prepared. For the preparation, we employed our recently developed two-step procedure, consisting of solution casting and melt mixing. The structure and properties of all samples was characterized thoroughly by microscopic, spectroscopic, diffraction, and rheological methods. It has been demonstrated that our two-step preparation procedure yields highly homogeneous TPS matrix with well dispersed TiO2 particles even for high filler concentrations (up to 20 %). The final TPS composites were sufficiently soft to be cut with a sharp blade at room temperature, the TPS matrix was fully biodegradable, the TiO2 filler was biocompatible, and the ATB could be released locally during the matrix degradation. Selected samples were tested for bacterial susceptibility using standard tube dilution test and disk diffusion test. The results proved that the ATB retained its bacteriostatic and bactericidal properties after the thermal processing of the composites. Therefore, the prepared TPS/TiO2/ATB composites represent a promising material for biomedical applications related to the local release of antibiotics.

An efficient two-step preparation of photocrosslinked gelatin microspheres as cell carriers to support MC3T3-E1 cells osteogenic performance

Gelatin microspheres have been commonly used in tissue engineering, but their application is often limited by the uncontrollability and potential cytotoxicity of traditional chemical cross-linking method. Methylacrylamide modification and photocrosslinking provide a controllable and cytocompatible cross-linking method for gelatin hydrogels, however, microspheres fabricated by this single photopolymerization process is uncontrollable. In this study, we show that increasing the gelling ability of gelatin methacrylamide (GMA) at low temperatures is vital to prepare photocrosslinked gelatin microspheres, which in turn improves the controllability and compatibility of conventional chemical cross-linking methods. We detailed characterized the rheological performance with varying temperature and demonstrated that the gelling capability of GMA could be improved by increasing GMA solution concentration and reducing methacrylate substitution. The physicochemical properties of the photocrosslinked microspheres can be modulated via methacrylamide modification, as evidenced by the positive correlation between the physicochemical optimization of the hydrogel bulk and the degree of methacrylate substitution. Next, we successfully fabricated GMA spheres by a two-step process of low-temperature gelation followed by photopolymerization crosslinking. Finally, we show that the microcarriers exhibited favorable supporting for MC3T3-E1 cell proliferation, spreading, and osteogenic differentiation. This study provided a controllable and cytocompatible photocrosslinking procedure for GMA microspheres with broad application prospects, of course, not limited to cell microcarriers.

Research and Mechanism of Two-step Preparation of Acetamide from Microalgae under Hydrothermal Conditions

A two-step synthesis of acetamide under hydrothermal condition from microalgae, is presented. results showed that the best yield of acetamide and selectivity of acetic acid were 9.5 % and 60.1 % at 320 ℃ for 8 min with a NH3 supply of 30. Algae such as spirulina, cyanobacteria and autotrophic chlorella could also acquire acetamide, and lactic acid was found to be an important intermediate during the exploration of reaction pathways. These results demonstrated that it is possible to develop a process for conversion of microalgae biomass into acetamide.

Two-step synthesis of well-ordered layered graphite oxide with high oxidation degree

Chemical oxidation of graphite by strong oxidant in strong acid medium produces graphite oxide (GO) with a plausible oxidation degree, however the precursor is susceptible to exfoliation and structural deformations. In this work, we present a two-step preparation method of highly oxidized GO flakes with well-ordered layered structure. Firstly, graphite was electrooxidized in HClO4 electrolyte yielding electrochemically gathered graphite oxide (EGO). Next, EGO was chemically overoxidized by modified Hummers method to prepare overoxidized electrochemically gathered graphite oxide (OEGO). Due to the increased interlayer distances of EGO, MnO3+ ions are able to penetrate the interlayer spaces and oxidize the unreacted graphitic domains. Hence, the synthesized OEGO is characterized by minor structure deformation and high oxidation degree. In case of our investigations most of well-ordered layered domains have been preserved, in contrast to the GO obtained directly from graphite. It is also noted that the overoxidation of EGO mainly results in formation of hydroxyl and epoxy groups. Additionally, rinsing OEGO with acetone helps prevent the tearing of oxidized graphene layers by O2 evolution arising from the reaction of H2O2 with MnO2 precipitated on the surface of water-washed samples.

A Skin-Inspired Stretchable, Self-Healing and Electro-Conductive Hydrogel with A Synergistic Triple Network for Wearable Strain Sensors Applied in Human-Motion Detection.

Hydrogel-based strain sensors inspired by nature have attracted tremendous attention for their promising applications in advanced wearable electronics. Nevertheless, achieving a skin-like stretchable conductive hydrogel with synergistic characteristics, such as ideal stretchability, excellent sensing performance and high self-healing efficiency, remains challenging. Herein, a highly stretchable, self-healing and electro-conductive hydrogel with a hierarchically triple-network structure was developed through a facile two-step preparation process. Firstly, 2, 2, 6, 6-tetrametylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibrils were homogeneously dispersed into polyacrylic acid hydrogel, with the presence of ferric ions as an ionic crosslinker to synthesize TEMPO-oxidized cellulose nanofibrils/polyacrylic acid hydrogel via a one-pot free radical polymerization. A polypyrrole conductive network was then incorporated into the synthetic hydrogel matrix as the third-level gel network by polymerizing pyrrole monomers. The hierarchical 3D network was mutually interlocked through hydrogen bonds, ionic coordination interactions and physical entanglements of polymer chains to achieve the target composite hydrogels with a homogeneous texture, enhanced mechanical stretchability (elongation at break of ~890%), high viscoelasticity (maximum storage modulus of ~27.1 kPa), intrinsic self-healing ability (electrical and mechanical healing efficiencies of ~99.4% and 98.3%) and ideal electro-conductibility (~3.9 S m−1). The strain sensor assembled by the hybrid hydrogel, with a desired gauge factor of ~7.3, exhibits a sensitive, fast and stable current response for monitoring small/large-scale human movements in real-time, demonstrating promising applications in damage-free wearable electronics.

Determination of Sudan dyes in chili products by micellar electrokinetic chromatography-MS/MS using a volatile surfactant

A new MEKC-MS/MS method was developed for the determination of four Sudan dyes in chili products. The separation and MS detection conditions were optimized to achieve fast, efficient, selective, and sensitive determination of Sudan I, Sudan II, Sudan III, and Sudan IV dyes. The target compounds were extracted from chili samples with acetonitrile and cleaned by freeze-out. This two-step sample preparation led to excellent extraction efficiency and minimal matrix effect. The analytical performance of the method was very good, with r2 ≥ 0.9914 and limits of quantification lower than 22 μg kg−1. The precision was below 15.7%. The recovery for spiked samples ranged from 84.4 to 99.6%, with relative standard deviations less than 8.0%. For all evaluated samples, the matrix effects did not exceed ± 10%. The applicability of the proposed method was demonstrated with 20 chili products, two of which were found to contain Sudan I and IV residues.

A strategy for visual optical determination of glucose based on a smartphone device using fluorescent boron-doped carbon nanoparticles as a light-up probe

Boronic acid-doped carbon nanoparticles were prepared and are shown to undergo aggregation induced emission (AIE). The nanoparticlecomposite is a viable fluorescent probe for glucose determination by using the RGB technique and a smartphone. The structure and the chemical composition of the doped carbon nanoparticles were confirmed by SEM, TEM, FTIR and UV-vis spectroscopy. The combination of 4-carboxyphenylboronic acid with o-phenylenediamine and rhodamine B endowed the hybrid with high fluorescence intensity (quantum yield 46%). Compared with conventional two-step preparation of boronic acid-basedfluorescent probes for glucose, the present one step synthesis strategy is simpler and more effective. The addition of glucose causes the formation of covalent bonds between the cis-diols group of glucose molecules and boronic acid moiety. Fluorescent intensity can be quantified using dual wavelengths simultaneously, where both increases, as the target analytes bind to the bronic acid. These variations was monitored by the smartphone camera, and the green channel intensities of the colored images were processed by using the RGB option of a smartphone. The assay works in the 32μM to 2mM glucose concentration range and has an 8μM detection limit. The method was successfully used for the assay of glucose in diluted human serum. Graphical abstractThe fluorometric method wasdeveloped for determination of glucose using boron doped carbon nanoparticles (BCNBs). TheBCNPs aggregate after covalent binding between the cis-diols of glucose and boronic acid. The green channel of the imagesis recorded by a smartphone camera.

Experimental characterization of magnetic field effects on heat transfer coefficient and pressure drop for a ferrofluid flow in a circular tube

In this paper, an experimental study is performed to characterize the effect of constant and alternative magnetic fields on pressure drop and heat transfer coefficient for a ferrofluid in laminar flow in a circular straight tube. The ferrofluid considered in this study is prepared using Fe3O4 nanoparticles. The verification of the size of nanoparticles is accomplished using TEM images and DLS distribution. A two-step preparation method is used to produce a ferrofluid with 0.5 and 1 wt%. The ferrofluid is stabilized using a surfactant and ultrasonic waves. The Zeta potential is employed to evaluate the stability of the ferrofluid, and the VSM to check its magnetization property. An uncertainty analysis is also performed where a maximum uncertainty of 1.8% is obtained. Experimental results are first compared with those of Shah and London equation for pure water as the working fluid. The Nusselt (Nu) number is enhanced using a ferrofluid instead of pure water for various Reynolds (Re) numbers. Next, two constant and alternative magnetic fields of 770 and 1300 G with four different Patterns are applied. The Nu number is improved by using a constant magnetic field. It is found that the Nu number is enhanced by 11.85 and 14.8% by using an alternative magnetic field with a frequency of 10 and 100 Hz, respectively. Further increase in the frequency (above 100 Hz up to 1000) does not lead to a positive outcome.

Synthesis of heterostructure δ-MnO2/h-MoO3 nanocomposite and the enhanced photodegradation activity of methyl orange in aqueous solutions

The growing extent of dye pollution by human activities has engendered an urgent need for removing of them through adjustable approaches. The adsorption–photocatalytic technique is attractive and widely employed to address the above issue, since it could achieve pollutant mineralization by the reactive species generated under the light irradiation without other chemicals. In this paper, a series of δ-MnO2/h-MoO3 nanocomposites was successfully synthesized by a simple two-step method. The structure and morphology of the as-prepared nanocomposite have been assessed by XRD, FESEM, TEM, XPS and BET surface area measurements, and the optical properties were detected by the UV–Vis diffuse reflectance, photoluminescence (PL) and photocurrent measurements. Photocatalytic performances of the prepared δ-MnO2/h-MoO3 nanocomposite were evaluated through photodegradation of dyes in solution under simulated sunlight irradiation. After a simple two-step preparation process, the specific surface area (SBET) of the δ-MnO2/h-MoO3 composite was increased by about 4.5 times compared to the pure δ-MnO2 and h-MoO3, and this may result in a great adsorption property for the nanocomposite. With a broader absorption edge, high electron transfer efficiency and lower recombination efficiency of the photogenerated electrons and holes, the photocatalytic activity of the heterostructure δ-MnO2/h-MoO3 composites was improved heavily compared to the single-phase samples. Especially, when 20 mg of δ-MnO2 (0.6 g)/h-MoO3 composite was used to degrade methyl orange (MO) aqueous solution (100 mL, 15 mg L−1), the degradation efficiency could reach 80.55% within 115 min under simulated sunlight irradiation. Additionally, the photodegradation cyclic tests showed that the nanocomposite exhibited excellent stability, as the degradation efficiency reaches 71.02% within 95 min after four cycles, which makes it to have a bright prospect of industrial application. Finally, the reasonable mechanism for the enhanced photocatalytic activity of the heterostructure δ-MnO2/h-MoO3 composites was investigated by active species trapping experiments, and the results showed that the synergistic effect between δ-MnO2 and h-MoO3 as well as the unique flower ball-stick morphology of composites lead to an excellent photocatalytic performance.

Natural nanofiber-based stacked porous nitrogen-doped carbon/NiFe2O4 nanohybrid nanosheets

The traditional hydrolysis/hydrothermal two-step preparation method of carbon/inorganic nanohybrid material usually exhibit the disadvantage of aggregation and precipitation. Therefore, the above method has certain difficulty in the synergistically regulation of the aggregation morphology and microscopic morphology of carbon/inorganic nanohybrid materials. In this paper, cellulose nanofiber and chitin nanofiber are used as the carrier material of inorganic nanomaterials, which can maintain the uniform and stable dispersed state during the hydrolysis of metal ions and hydrothermal treatment. The uniform inorganic nanoparticles uniformly distributed in the randomly stacked nanosheets even if the total content of metal ions increases to 6 mmol. The natural nanofibers/NiFe2O4 nanoparticles composite nanosheets with adjustable stacked pore structure can be prepared from natural nanofibers/NiFe2O4 nanoparticles composite hydrogel via unidirectional freeze-shaping. The carbonization temperature and carbonization time are more effective in synergistically regulation of the stacked porous nitrogen-doped carbon/NiFe2O4 nanohybrid nanosheets. Extending carbonization time or increasing carbonization temperature not only allows the growth of inorganic nanomaterials, but also causes damage to the nanosheets (such as broken pore and the small, wrinkled morphology of the nanohybrid nanosheets). NC/NiFe2O4-1.5/700/3 exhibits the highest gravimetric capacitance (up to 458 F g−1 at a constant current density of 0.5 A g−1).

Effect of dealumination on the catalytic performance of Cr-containing Beta zeolite in carbon dioxide assisted propane dehydrogenation

New active and selective catalysts for propane to propene dehydrogenation in assistance of CO2 (CO2-PDH) were prepared by chromium incorporation in siliceous SiBeta. The Cr-containing SiBeta zeolite catalysts were obtained by two-step postsynthesis preparation procedure which consist, in the first step, removal of aluminum from TEABeta zeolite with Si/Al of 17 by treatment with nitric acid solution to obtain an aluminium-free SiBeta support with Si/Al ratio of 1000 and, in the second step, various amounts of Cr were introduced into the siliceous SiBeta zeolite structure by wet impregnation. The well correlation between the number of redox Cr sites and propene yield up to 2 wt % of Cr has been determined. Comparing of catalytic activity of Cr-containing Beta zeolite catalysts with the identical Cr content (2 wt % of Cr) supported on SiBeta and AlBeta revealed that the dealumination has great impact on catalytic properties. Low acidity of SiBeta is suitable for achieving high selectivity to propene (above 80 %) while high acidity of starting AlBeta promotes propane cracking to lighter hydrocarbons. Moreover, in switch operation mode between propane dehydrogenation in presence and absence of CO2 the formation rate of propene raises in mode with CO2 only over Cr-containing SiBeta zeolite catalyst, while over Cr-containing AlBeta zeolite catalyst a negative effect on the rate of propene formation was observed.

Selective deposition of platinum hemispheres on the {100} facets of synthetic diamond

In this work, a two-step preparation method of diamond-metal heterostructures, in which platinum particles are attached to the {100} facets of diamond microcrystals, was elaborated. At the first step, silver particles are deposited on the {100} facets of the synthetic diamond crystals by the powder annealing method. At the second step, the microcrystals having silver particles deposited on their surface are treated by aqueous solution of hexachloroplatinic acid H2PtCl6. The treatment results in the formation of hollow platinum hemispheres on the {100} facets of the diamond crystals. Detailed morphological studies of the synthesized heterostructures have been conducted to reveal a nanocrystalline structure of the hollow platinum hemispheres. Diamond-noble metal heterostructures of these morphology and composition have been synthesized and investigated for the first time.

High Efficiency and Eco-Friendly TEPA-Functionalized Adsorbent with Enhanced Porosity for CO2 Capture

In this study, the goal is to design a new CO2 capture platform along with an emerging nan-adsorbent development. Surface property changes occurred in the two-step preparation of halloysite nanotub...

Nonvolatile photoelectric memory with CsPbBr3 quantum dots embedded in poly(methyl methacrylate) as charge trapping layer

Abstract Nonvolatile organic field-effect transistor (OFET) photoelectric memories have attracted tremendous attention due to special photoelectric memory mechanism and application area, such as image capture and light information storage. Unfortunately, conventional two-step preparation method of floating gate and tunneling layer is complex and not conducive to large-area. Here, a nonvolatile OFET photoelectric memory with perovskite quantum dots (QDs) embedded in poly(methyl methacrylate) (PMMA) as charge trapping layer is reported. The photoelectric memory can effectively accumulate and release photo-generated carriers during photo- or photoelectric programming operations and electrical erasing operation. The memory characteristics of the photoelectric memory are comparable to that of traditional memories with two-step preparation technique of floating gate and tunneling layer. In addition, the memory device presents well retention time and endurance property even after being exposed to air for two weeks. Hence, the memory using QDs/PMMA composites as charge trapping layer shows great potential for the application in photoelectric devices.

Two-Step Preparation of an Amidoxime-Functionalized Chelating Resin for Removal of Heavy Metal Ions from Aqueous Solution

A novel amidoxime-functionalized chelating resin (PAO-g-PS) was prepared through a two-step method. First, poly (acrylonitrile) was grafted onto chloromethylated polystyrene beads via surface-initi...

Two-step preparation of hierarchical porous carbon from KOH-activated wood sawdust for supercapacitor

Interconnected hierarchical porous carbons were synthesized via KOH-assisted hydrothermal pretreatment and carbonization of wood sawdust. KOH-assisted hydrothermal treatment can remove the lignin from sawdust and on the other hand, the presence of KOH facilitates the creation of macro and mesopores during the carbonization. Base-assisted hydrothermal treating time plays an important role in determining the pore structure of carbons, thus affecting their electrochemical performance. The resulting porous carbons show the highest specific capacitance of 303 F g−1 in a current density of 1 A g−1, high energy density of 17.75 W h kg−1 at a power density of 436 W kg−1, and an outstanding cycling stability. As a facile synthesis route for porous carbons from wood sawdust, such method has the potential to be directly used for industrial production, and the efficient uses of wood residue are important for sustainable development.

Heat transfer improvement in simulated small battery compartment using metal oxide (CuO)/deionized water nanofluid

Improving the heat transfer coefficient of working fluids is essential for achieving the best performance of manufacturing systems. As a replacement of conventional working fluids, nanofluids have a high potential for improving this heat transfer coefficient. However, nanofluids are seldom implemented in actual systems, and several factors should be considered before actual application. Accordingly, this study investigated the thermophysical properties and heat transfer rate of CuO/deionized water nanofluid with and without sodium dodecyl sulfate (SDS) surfactants. Three different volumetric concentrations of the nanofluid were prepared using a two-step preparation method. The experimental steps were divided into two phases: static and dynamic. In these experiments, the thermophysical properties of the prepared nanofluids and the heat transfer coefficient were measured using an apparatus designed based on an actual heat exchanger for a lithium ion polymer battery compartment. The effects of flow rate and surfactants on the heat transfer rate of the nanofluids with varying volumetric concentrations of 0.08%, 0.16%, and 0.40% were analyzed. The results indicate that the heat transfer rate increases considerably as the flow rate increases from 0.5 L/min to 1.2 L/min and with the presence of surfactants. The highest heat transfer rate was obtained at a 0.40% volumetric concentration of CuO/deionized water nanofluid with SDS surfactant.

Enhancing Oil Production Using Silica-Based Nanofluids: Preparation, Stability, and Displacement Mechanisms

A novel two-step preparation of a silica nanofluid (Si-NF) with potential for light oil recovery is herein presented. It was observed that a Si-NF, prepared by dispersing silica nanoparticles (Si-NPs) in poly(vinyl alcohol) (1%) under carbon dioxide gas bubbling, is stable for 30 days at a temperature as high as 55 °C without any visible sedimentation. Unstable Si-NFs formed siliceous gels whose strength depends on Si-NP load. The spectral characterization revealed that prepared Si-NFs consisted of silanols, carbonyls, and alcohols. As part of an effort to enhance the light oil production (API 31°), 1, 0.5, and 0.1 wt % Si-NPs were injected in waterflooded Berea sandstone at 55 °C. An increase in oil as high as 7.6% was achieved for the Si-NF with the highest Si-NP load (1 wt % Si-NP). Oil production encompassed the discontinuity of Si-NFs, channel plugging, wettability, and interfacial tension alterations.

Two-step Preparation of Trazodone and Its Corrosion Inhibition Mechanism for Carbon Steel

Two-step Preparation of Trazodone and Its Corrosion Inhibition Mechanism for Carbon Steel