CuO nanoparticles supported on three‐dimensional nitrogen‐doped graphene as a promising catalyst for thermal decomposition of ammonium perchlorate

In the present work, CuO nanoparticles grown on three‐dimensional nitrogen‐doped graphene‐based frameworks (CuO@3D‐(N)GFs) were synthesized using a two‐step method. After the synthesis of three‐dimensional nitrogen‐doped graphene, CuO nanoparticles were deposited on it, by adding cupric acetate followed by thermal treatment. Different analysis methods were used to characterize the products. The as‐prepared nanocomposite was used as a promising catalyst for thermal decomposition of ammonium perchlorate (AP) as one of the most common oxidizer in composite propellants. Differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA) techniques were used to investigate the thermal decomposition of ammonium perchlorate. According to the DSC/TGA, high temperature decomposition of AP decreased to 111 °C in the presence of 4% CuO@3D‐(N)GFs and the total heat release (ΔH) from decomposition of AP increased to 1893 J g^?1 which is much more than 590 J g^?1 for pure AP.     

Nickel‐substituted cobalt ferrite nanoparticles supported on arginine‐modified graphene oxide nanosheets: Synthesis and catalytic activity

The amino acid arginine was used to modify the surface of graphene oxide nanosheets and then nickel‐substituted cobalt ferrite nanoparticles were supported on those arginine‐grafted graphene oxide nanosheets (Ni_0.5Co_0.5Fe₂O₄@Arg–GO). The prepared Ni_0.5Co_0.5Fe₂O₄@Arg–GO was characterized using flame atomic absorption spectroscopy, inductively coupled plasma optical emission spectrometry, energy‐dispersive spectroscopy, Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, Raman spectroscopy, X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy. The application of Ni_0.5Co_0.5Fe₂O₄@Arg–GO as a catalyst was examined in a one‐pot tandem oxidative cyclization of primary alcohols with o ‐phenylenediamine to benzimidazoles under aerobic oxidation conditions. The results showed that 2‐phenylbenzimidazole derivatives were successfully achieved using Ni_0.5Co_0.5Fe₂O₄@Arg–GO nanocomposite catalyst via the one‐pot tandem oxidative cyclization strategy.     

Anticancer and antibacterial potential of Rhus punjabensis and CuO nanoparticles

Abstract

The present study reports ecofriendly synthesis of CuO nanoparticles (NPs) using an extract of Rhus punjabensis as a reducing agent. NPs structural and composition analysis are evaluated by X-rays diffraction (XRD), Fourier transform infrared, Energy dispersive spectroscopy, Scanning electron microscopy, Transmission electron microscopy, and Thermal analysis. The NPs have pure single phase monoclinic geometry with spherical structure and high stability toward heat and with average particle size of about 36.6 and 31.27?nm calculated by XRD and SEM, respectively. NPs are tested for antibacterial, protein kinase (PK) inhibition, SRB cytotoxic, and NF-κB activities. Antibacterial activity is observed against B. subtilis and E. coli. Significant PK and SRB cytotoxic activity is observed with some NF-κB inhibition. NPs IC₅₀ values against HL-60 and PC-3 prostate cancer cells are 1.82?±?1.22 and 19.25?±?1.55?μg/mL. The results encourage further studies for antibacterial and anticancer drug development of NPs using animal models.     

Synthesis and characterization of red-luminescent graphene oxide functionalized with silica-coated Eu3+ complex nanoparticles

Traditional dye-doped fluorescent graphene oxide (GO) reveals a low quantum yield and a short life expectancy. Herein, red-luminescent silica-coated Eu(3+) complex nanoparticles were synthesized and covalently coupled to GO nanosheets by means of a carbodiimide-mediated amidation process. SEM and TEM studies demonstrated successful attachment of the silica-coated Eu(3+) complex nanoparticles onto the GO surface. Spectroscopic studies showed that the GO-nanoparticle conjugates exhibit strong luminescence, long lifetimes, as well as good photostability, which suggests that this new type of luminescent nanomaterial has the potential for highly sensitive time-resolved fluorescence cyto- and histochemistry imaging.     

Palladium oxide nanoparticles supported on graphene oxide: A convenient heterogeneous catalyst for reduction of various carbonyl compounds using triethylsilane

Palladium oxide nanoparticles supported on graphene oxide ‐ triethylsilane was found to be an effective reductive system for a broad range of reduction processes, including the reduction of various carbonyl compounds such as aromatic aldehydes to their corresponding alcohols or methyl arene compounds, aromatic ketones to their respective alcohols or saturated compounds, aromatic acyl chlorides to their reduced compounds. The desired products were obtained in good to excellent yields under mild conditions. The heterogeneous environmentally friendly catalyst can be easily separated from the reaction mixture through a simple filtration, facilitating purification of the prepared compounds.     

Magnetic CuO nanoparticles supported on graphene oxide as an efficient catalyst for A3-coupling synthesis of propargylamines

Magnetically separable CuO nanoparticles supported on graphene oxide (Fe₃O₄ NPs/GO-CuO NPs) is synthesized and characterized for the preparation of propargylamines in EtOH, at 90℃. Fe₃O₄ NPs/GO-CuO NPs is found to be an efficient catalyst for the A³-coupling of aldehydes, amines, and alkynes through C-H activation. Both aromatic and aliphatic aldehydes and alkynes are combined with secondary amines to provide a wide range of propargylamines in moderate to excellent yields.     

High antibacterial activity and low toxicity of pyridoxal derivatives of chitosan and their nanoparticles

The pyridoxal derivatives of chitosan with various degrees of substitution (DS) were synthesized from low-, moderate- and high-molecular-weight chitosans by their reaction with pyridoxal followed by treatment with NaBH₄. The derivative of moderate molecular weight and high DS demonstrated a maximum antibacterial activity against S. aureus and E. coli. The nanoparticles of this derivative obtained by ionic gelation are nontoxic, and they exhibit a high in vitro antibacterial effect, which slightly exceeds that of ampicillin and gentamicin.     

结构稳定的CuO/TiO2纳米管的功能化溶胶修饰法制备及其催化CO氧化性能研究

以水热处理方法得到的钛酸纳米管为载体,采用含有醋酸铜的功能化钛溶胶对其进行一步浸渍修饰,制备结构稳定的CuO修饰TiO₂纳米管催化剂(CuO/TiO₂NTs)。通过XRD(X-射线衍射)、TEM(透射电子显微镜)、HR-TEM(高倍透射电子显微镜)、XPS(X-射线光电子能谱)、BET(氮气吸附-脱附法)、TPD(程序升温脱附法)等表征材料的结构和性质,并研究其催化CO氧化的性能。研究表明：经过溶胶浸渍处理过程,不仅将功能化铜组分负载在纳米管上,而且纳米管载体的耐热性能明显提高;催化剂载体、铜钛原子比及焙烧温度对催化剂的活性有明显影响,且400℃焙烧的Cu/Ti原子比为1∶5的CuO/TiO₂NTs的活性最高。     

结构稳定的CuO/TiO_2纳米管的功能化溶胶修饰法制备及其催化CO氧化性能研究

以水热处理方法得到的钛酸纳米管为载体,采用含有醋酸铜的功能化钛溶胶对其进行一步浸渍修饰,制备结构稳定的CuO修饰TiO2纳米管催化剂(CuO/TiO2NTs)。通过XRD(X-射线衍射)、TEM(透射电子显微镜)、HR-TEM(高倍透射电子显微镜)、XPS(X-射线光电子能谱)、BET(氮气吸附-脱附法)、TPD(程序升温脱附法)等表征材料的结构和性质,并研究其催化CO氧化的性能。研究表明:经过溶胶浸渍处理过程,不仅将功能化铜组分负载在纳米管上,而且纳米管载体的耐热性能明显提高;催化剂载体、铜钛原子比及焙烧温度对催化剂的活性有明显影响,且400℃焙烧的Cu/Ti原子比为1∶5的CuO/TiO2NTs的活性最高。     

Synthesis,Characterization, and Antibacterial Activity of Mg-Doped CuO Nanoparticles

This study aims to investigate the effect of magnesium (Mg) doping on the characteristics and antibacterial properties of copper oxide (CuO) nanoparticles (NPs). The Mg-doped CuO NPs were fabricated by the co-precipitation method. NPs were characterized by X-ray Powder Diffraction (XRD), Transmission Electron Microscope (TEM), Energy Dispersive X-ray (EDX) analysis, Fourier Transform Infrared Spectroscopy (FTIR), and Photoluminescence (PL). Broth microdilution, agar-well diffusion, and time-kill assays were employed to assess the antibacterial activity of the NPs. XRD revealed the monoclinic structure of CuO NPs and the successful incorporation of Mg dopant to the Cu_1−xMg_xO NPs. TEM revealed the spherical shape of the CuO NPs. Mg doping affected the morphology of NPs and decreased their agglomeration. EDX patterns confirmed the high purity of the undoped and Mg-doped CuO NPs. FTIR analysis revealed the shifts in the Cu–O bond induced by the Mg dopant. The position, width, and intensity of the PL bands were affected as a result of Mg doping, which is an indication of vacancies. Both undoped and doped CuO NPs exhibited significant antibacterial capacities. NPs inhibited the growth of Gram-positive and Gram-negative bacteria. These results highlight the potential use of Mg-doped CuO NPs as an antibacterial agent.     

Recent developments of metallic nanoparticles and their catalytic activity in organic reactions

During the last two decades, with the development of nanotechnology, various nanomaterials have been designed and generated. Among them, hybrid organic–inorganic nanoparticles as a particular immobilizing carrier of the catalyst active sites have shown an important contribution in the current research studies. This is due to the large area and loads of active sites. This prominent review is focused on the novel various exa about the immobilization of nanoparticles with organic compounds as versatile and efficient catalysts in organic syntheses.     

三芥子酸甘油酯类似物的合成及抑菌活性

以N-(2-溴乙基)邻苯二甲酰亚胺或N-(4-溴丁基)邻苯二甲酰亚胺和硫氢化钠为起始原料,通过取代、肼解、亲核加成等反应合成了10个三芥子酸甘油酯(erucin)类似物,通过核磁共振氢谱、碳谱及质谱对其结构进行了确认。采用比浊法初步测试了其对大肠杆菌、金黄色葡萄球菌、白色葡萄球菌、藤黄八叠球菌、枯草芽孢杆菌、蜡状芽孢杆菌和四联球菌等7种菌的生长抑制活性,测试结果显示,化合物对测试菌种都表现出较好的生长抑制活性,其中苄硫乙基-1-硫代异硫氰酸酯(5e)和苄硫基丁基-1-硫代异硫氰酸酯(5j)活性最高,对大肠杆菌的最低生长抑制浓度仅为7.8μg/m L,对金黄色葡萄球菌的最低生长抑制浓度也仅为15.6μg/m L和31.2μg/m L。     

Hydrazide functionalized magnetic nanoparticles for specific extraction of N‐terminal serine and threonine peptides

In this study, we present hydrazide functionalized magnetic nanoparticles as a sorbent prepared by a new and facile method. Scanning electron microscope and Fourier transform infrared were used for characterizing the synthesized nanoparticles. The ability of the sorbent to extract N‐terminal serine and threonine peptides was evaluated. The peptides were modified by oxidation of the hydroxyl group in the 1,2‐amino alcohol structure before extraction. These aldehyde‐forms of peptides were specifically bonded to the hydrazide groups of the sorbent. The formed hydrazone bonds were cleaved in the presence of hydroxylamine reagent. Finally, the oximated peptides were released and quantified with a high‐performance liquid chromatography–diode array spectroscopy. The effects of experimental parameters including extraction time, elution time and elution volume on extraction efficiency were also investigated. The required time for the extraction process to reach equilibrium and elution time was only 8 h. The adsorption efficiency of the sorbent was 79 and 77% for peptides with N‐terminal serine and threonine, respectively. The sorbent showed good specificity for extracting the peptides. In addition, the extraction efficiency of the sorbent remained constant in the presence of a non‐N‐terminal serine and threonine peptide as interference.     

1,2,4-噁二唑类化合物的合成及抗菌活性研究

以对溴苯腈为原料,通过多步反应合成了一系列3-(吗啉苯基)-5-取代-1,2,4-异噁唑类化合物和3-(吗啉苯基)-5-取代-4,5-二氢-1,2,4-噁二唑类化合物,并用1HNMR、13C NMR和MS进行了结构确证。这些化合物对测试的部分革兰氏阳性菌,如金黄色葡萄球菌、耐甲氧西林金黄色葡萄球菌、表皮葡萄球菌、粪肠球菌显示出一定的抗菌活性,但与噁唑烷酮类上市药物利奈唑胺相比,抗菌活性有明显下降。这一结果表明对于化合物的抗菌活性,1,2,4-噁二唑杂环不如噁唑烷酮结构有效。     

还原态氧化石墨烯载Pd纳米催化剂对甲酸氧化的电催化性能

采用改进的Hummers法氧化石墨后,对其超声剥离成氧化石墨烯水溶液,继之通过乙二醇还原Pd金属离子和氧化石墨烯,得到了还原态氧化石墨烯（RGO）负载Pd纳米催化剂,并用于甲酸的电催化氧化.透射电子显微镜和X射线衍射结果显示：负载于RGO上的Pd粒子平均粒径为3.8nm,其优先在RGO的褶皱和边缘处生长.电化学测试表明：RGO上残存的含氧基团降低了Pd催化剂受CO毒化的程度,Pd/RGO催化剂表现出了较商业化Pd/C更高的电催化活性和更好的稳定性.     

Preparation,Antibacterial Activity,and Catalytic Application of Magnetic Graphene Oxide-Fucoidan in the Synthesis of 1,4-Dihydropyridines and Polyhydroquinolines

Polymer-coated magnetic nanoparticles are emerging as a useful tool for a variety of applications, including catalysis. In the present study, fucoidan-coated magnetic graphene oxide was synthesized using a natural sulfated polysaccharide. The prepared BaFe₁₂O₁₉@GO@Fu (Fu=fucoidan, GO=graphene oxide) was characterized using Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX) analysis, vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA), Raman spectroscopy, and X-ray diffraction (XRD). The catalytic proficiency of BaFe₁₂O₁₉@GO@Fu was investigated in the synthesis of 1,4-dihydropyridine and polyhydroquinoline derivatives. Excellent turnover numbers (TON) and turnover frequencies (TOF) (6330 and 25320 h⁻¹) testify to the high efficiency of the catalyst. Moreover, the antimicrobial activity of BaFe₁₂O₁₉@GO@Fu was evaluated against Escherichia coli (E. coli), and Staphylococcus aureus (S. aureus) through the Agar well diffusion method, indicating that BaFe₁₂O₁₉@GO@Fu has antibacterial activity against S. aureus.     

Chemo‐selective reduction of nitro and nitrile compounds using Ni nanoparticles immobilized on hyperbranched polymer‐functionalized magnetic nanoparticles

The nitro and nitrile groups in aromatic and aliphatic compounds containing various reducible substituents such as carboxylic acid, ketone, aldehyde and halogen are selectively reduced to the corresponding amines in water as a green solvent with excellent yields by employing NaBH₄ in the presence of Fe₃O₄@PAMAM/Ni(0)‐b‐PEG nanocatalyst. The morphology and structural features of the catalyst were characterized using various microscopic and spectroscopic techniques. The designed catalyst system because of it being covered with hydrophilic polymers is soluble in a wide range of solvents (e.g. water and ethanol) and suitable for immobilizing and stabilizing Ni nanoparticles in aqueous mediums. In addition, the catalyst can be easily recovered from a reaction mixture by applying an external magnetic field and can be reused up to six runs without significant loss of activity.     

AgPt nanoparticles supported on magnetic graphene oxide nanosheets for catalytic reduction of 4‐nitrophenol: Studies of kinetics and mechanism

Ag_x Pt_100−x (x  = 0, 25, 50, 75 and 100) nanoparticles were grown on the surface of magnetic graphene oxide nanosheets (Fe₃O₄@GO) for the first time. The as‐prepared nanocomposites were characterized using various techniques such as Fourier transform infrared spectroscopy, powder X‐ray diffraction, field emission scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, transmission electron microscopy, Brunauer–Emmett–Teller surface area analysis, vibrating sample magnetometry and thermogravimetric analysis. The Fe₃O₄@GO‐Ag_x Pt_100−x catalysts were applied in the reduction of 4‐nitrophenol (4‐NP) to 4‐aminophenol using sodium borohydride (NaBH₄). The synthesized nanocomposites exhibited excellent catalytic performance in the reduction of 4‐NP with high recyclability for five consecutive runs. The Fe₃O₄@GO‐Ag₇₅Pt₂₅ nanocomposite exhibited the best catalytic activity with a rate constant as high as 140.6 × 10⁻³ s⁻¹. The obtained kinetic data were modelled with the Langmuir–Hinshelwood equation. The energy of activation and thermodynamic parameters including enthalpy, entropy of activation and activation Gibbs free energy were calculated.     

Alga-mediated facile green synthesis of silver nanoparticles: Photophysical,catalytic and antibacterial activity

A facile, convenient and green method has been employed for the synthesis of silver nanoparticles (AgNPs) using dried biomass of a green alga, Chlorella ellipsoidea. The phytochemicals from the alga, as a mild and non-toxic source, are believed to serve as both reducing and stabilizing agents. The formation of silver nanoparticles was confirmed from the appearance of a surface plasmon resonance band at 436 nm and energy dispersive X-ray spectroscopy. The transmission electron microscopy images showed the nanoparticles to be nearly spherical in shape with different sizes. A dynamic light scattering study revealed the average particle size to be 220.8 ± 31.3 nm. Fourier transform infrared spectroscopy revealed the occurrence of alga-derived phytochemicals attached to the outer surface of biogenically accessed silver nanoparticles. The powder X-ray diffraction study revealed the face-centred cubic crystalline structure of the nanoparticles. The as-synthesized biomatrix-loaded AgNPs exhibited a high photocatalytic activity for the degradation of the hazardous pollutant dyes methylene blue and methyl orange. The catalytic efficiency was sustained even after three reduction cycles. A kinetic study indicated the degradation rates to be pseudo-first order with the degradation rate being 4.72 × 10⁻² min⁻¹ for methylene blue and 3.24 × 10⁻² min⁻¹ for methyl orange. The AgNPs also exhibited significant antibacterial activity against four selected pathogenic bacterial strains.