Biocompatible ZnO/Au nanocomposites for ultrasensitive DNA detection using resonance Raman scattering

A novel method for identifying DNA microarrays based on ZnO/Au nanocomposites functionalized with thiol-oligonucleotide as probes is descried here. DNA labeled with ZnO/Au nanocomposites has a strong Raman signal even without silver acting as a surface-enhanced Raman scattering promoter. X-ray photoelectron spectra confirmed the formation of a three-component sandwich assay, i.e., constituted DNA and ZnO/Au nanocomposites. The resonance multiple-phonon Raman signal of the ZnO/Au nanocomposites as a spectroscopic fingerprint is used to detect a target sequence of oligonucleotide. This method exhibits extraordinary sensitivity and the detection limit is at least 1 fM.     

无表面活性剂条件下一锅法制备金属/氧化锌复合材料用于催化二氧化碳加氢制甲醇反应

Catalytic hydrogenation of CO₂ to methanol is an important chemical process owing to its contribution in alleviating the impacts of the greenhouse effect and in realizing the requirement for renewable energy sources. Owing to their excellent synergic functionalities and unique optoelectronic as well as catalytic properties, transition metal/ZnO (M/ZnO) nanocomposites have been widely used as catalysts for this reaction in recent years. Development of size-controlled synthesis of metal/oxide complexes is highly desirable. Further, because it is extremely difficult to achieve the strong-metal-support-interaction (SMSI) effect when the M/ZnO nanocomposites are prepared via physical methods, the use of chemical methods is more favorable for the fabrication of multi-component catalysts. However, because of the requirement for an extra H₂ reduction step to obtain the active metallic phase (M) and surfactants to control the size of nanoparticles, most M/ZnO nanocomposites undergo two- or multi-step synthesis, which is disadvantageous for the stable catalytic performance of the M/ZnO nanocomposites. In this work, we demonstrate facile one-pot synthesis of M/ZnO (M = Pd, Au, Ag, and Cu) nanocomposites in refluxed ethylene glycol as a solvent, without using any surfactants. During the synthesis process, Pd and ZnO species can stabilize each other from further aggregation by reducing their individual surface energies, thereby achieving size control of particles. Besides, NaHCO₃ serves as a size-control tool for Pd nanoparticles by adjusting the alkaline conditions. Ethylene glycol serves as a mild reducing agent and solvent owing to its capacity to reduce Pd ions to generate Pd crystals. The nucleation and growth of Pd particles are achieved by thermal reduction, while the ZnO nanocrystals are formed by thermal decomposition of Zn(OAc)₂. X-ray diffraction patterns of the M/ZnO and ZnO were analyzed to study the phase of the nanocomposites, and the results show that no impurity phase was detected. Transmission electron microscopy (TEM) was used to study the morphology and structural properties. In addition, X-ray photoelectron spectroscopy analysis was performed to further confirm the formation of M/ZnO hybrid materials, and the results confirm SMSI between Pd and ZnO. Inductively coupled plasma mass spectrometry was used to check the actual elemental compositions, and the results show that the detected atomic ratios of Pd/Zn were consistent with the values in the theoretical recipe. To investigate the effects of the Pd/Zn molar ratios and the added amount of NaHCO₃ on Pd size, the average sizes of Pd particles were calculated, and the results were confirmed by TEM observation. The Cu/ZnO/Al₂O₃ composite is a widely known catalyst for hydrogenation of CO₂ to methanol, and other M/ZnO composites are also catalytic for this reaction. Therefore, different M/ZnO hybrids were further studied as catalysts for hydrogenation of CO₂ to methanol, among which Pd/ZnO (1 : 9) demonstrated the best performance (30% CO₂ conversion, 69% methanol selectivity, and 421.9 g_methanol·(kg catalyst·h)^-1 at 240 ℃ and 5 MPa. The outstanding catalytic performance may be explained by the following two factors: first, Pd is a good catalyst for the dissociation of H₂ to give active H atoms, and second, SMSI between Pd and ZnO favors the formation of surface oxygen vacancies on ZnO. Moreover, most M/ZnO composites exhibit excellent performance in methanol selectivity, especially the Au/ZnO catalyst, which has the highest methanol selectivity (82%) despite having the lowest CO₂ conversion. Hopefully, this work would provide a simple route for synthesis of M/ZnO nanocomposites with clean surfaces for catalysis.     

Surface plasmon resonance biosensor based on water-soluble ZnO-Au nanocomposites

A wavelength modulation surface plasmon resonance biosensor based on ZnO-Au nanocomposites for the detection of human IgM was developed. Self-assembly technique has the advantages of flexibility, simplicity and the precise control of film component and was applied to the building of the sensor. The ZnO-Au nanocomposites are in a dumbbell-like shape and can be immobilized on the Au film through 1,6-hexanedithiol by covalent attachment. Meanwhile the activated ZnO nanocrystals can be used to connect protein. The biosensor based on ZnO-Au nanocomposites was used to detect human IgM. Some experimental conditions were examined and optimized. In the selected conditions, the modified biosensor exhibits a satisfactory response for human IgM in the concentration range of 0.30-20.00 μg mL⁻¹. However, the biosensor without ZnO-Au nanocomposites shows a response for human IgM in the concentration range of 1.25-20.00 μg mL⁻¹. Compared with the biosensor based on Au film, when the biosensor based on the ZnO-Au nanocomposites was applied, the sensitivity for determination of human IgM is significantly enhanced.     

有序介孔碳CMK-3负载金纳米微粒复合材料的制备和表征

分别采用等体积浸渍-甲醛还原、等体积浸渍-氢气还原及溶胶负载法在介孔碳CMK-3上负载金纳米微粒;利用透射电镜和粉末X射线衍射仪对比分析了采用3种方法得到的复合材料的微结构和相组成;并测定了采用溶胶负载法得到的不同金含量的复合材料的热稳定性.结果表明,所制备的金纳米微粒的尺寸因制备方法不同而呈现明显差异;负载于复合材料中的金纳米微粒具有很好的热稳定性.     

Molecular dynamics simulations of inverse sodium dodecyl sulfate (SDS) micelles in a mixed toluene/pentanol solvent in the absence and presence of poly(diallyldimethylammonium chloride) (PDADMAC)

Well-aligned ZnO nanorods (NRs) were grown on indium-tin-oxide (ITO) slide by the hydrothermal method and used as templates for preparing ZnO/Au composite nanoarrays. The optical and morphological properties of ZnO/Au composites under various HAuCl(4) concentrations were explored via UV-vis absorption spectroscopy, photoluminescence (PL) and scanning electron microscopy (SEM). The density and size of gold nanoparticles (Au NPs) on ZnO NRs can be controlled by adjusting the concentration of HAuCl(4). The optimal ZnO/Au composites display complete photocatalytic degradation of methyl blue (MB) within 60 min, which is superior to that with pure ZnO NRs prepared by the same method. The reason of better photocatalytic performance is that Au NPs act as electron traps and it prevents the rapid recombination of electrons and holes, resulting in the improvement of photocatalytic efficiency. The photocatalytic performance of ZnO/Au composites is mainly controlled by the density of Au NPs formed on ZnO NRs. The application in rapid photodegradation of MB shows the potential of ZnO/Au composite as a convenient catalyst for the environmental purification of organic pollutants.     

可循环SERS基底ZnO/Ag纳米材料合成和表征

利用简易、绿色、一锅煮的水热法合成了花状氧化锌/银复合纳米材料。然后利用各种光谱和显微技术对复合物进行了表征,并讨论了其表面增强拉曼(SERS)性能和光催化性能。结果表明氢氧化钠的量对于这种复合纳米材料的形貌和性能具有重要的调节作用。和其他形貌的氧化锌/银复合纳米材料相比较,花状氧化锌/银复合纳米材料具有最佳的光催化性能。同时进一步以花状氧化锌/银复合纳米材料作为SERS基底研究其表面增强拉曼性能,结果表明这种复合材料同时具有很好的表面增强拉曼性能。光催化和表面增强拉曼结果表明这种花状氧化锌/银复合纳米材料有望在有机物检测中作为一种具有很好的可循环性的新表面增强拉曼基底材料。     

Preparation and properties of polymer/zinc oxide nanocomposites using functionalized zinc oxide quantum dots

Poly(methyl methacrylate) (PMMA)/zinc oxide (ZnO) or carbazole polymer (PCEM)/ZnO nanocomposites, which are composed of high molecular weight PMMA or PCEM with narrow molecular weight distributions and ZnO nanoparticles, were successfully prepared by atom transfer radical polymerization (ATRP) initiated by 2-bromo-2-methylpropionyl (BMP) group (ZnBM) introduced onto the ZnO nanoparticle surfaces. Introduction of the BMP group onto the ZnO surfaces was achieved by esterification of OH group of the ZnO surfaces. The chemically attached OH group-having ZnO nanoparticles (ZnHM) were fabricated by sol-gel reaction from zinc acetate dihydrate, followed by treatment of the ZnO nanoparticles with 2-hydroxypropionic acid (HPA). The ZnHM nanoparticles showed one UV absorption and two emission bands: UV emission peak and broad visible emission band, while the ZnBM exhibited broad UV absorption and no emission spectra. The PMMA/ZnO nanocomposites displayed UV absorption and photoluminescent (PL) band with blue emission on the basis of the ZnHM nanoparticles, where the ZnO nanoparticles dispersed homogeneously in the PMMA matrix. The PCEM/ZnO nanocomposites depicted UV emission peak due to the carbazole unit in the UV range, but no visible emission. Thermal properties of the PMMA/ZnO nanocomposites were improved by dispersion of the ZnO nanoparticles into the PMMA, but the PCEM/ZnO nanocomposites showed no improvement of the thermal properties.     

Au纳米粒子负载的ZnO空心球复合材料的光生电荷转移行为及光催化活性

通过简单的两步法合成了不同负载量的Au/ZnO空心球。采用扫描电子显微镜(SEM),X射线衍射(XRD),X射线光电子能谱(XPS)及紫外-可见漫反射光谱(UV-Vis DRS)对样品的形貌、结构、组成和晶相等进行一系列的表征。以罗丹明B (RhB)为目标降解物,探究了Au/ZnO空心球的光催化活性。结果表明,适量Au修饰的ZnO光催化剂在混合光下20 min内对RhB的降解率达到73%。利用表面光电压谱(SPS)和瞬态光电压(TPV)技术,探讨了Au修饰后对ZnO光诱导电荷转移行为与光催化性能之间的关系。结果表明,混合光照下Au/ZnO空心球光降解性能的提高主要归因于作为电子受体的Au纳米粒子与ZnO之间形成的强的电子相互作用。适量Au纳米粒子的负载能够提高ZnO空心球中光生载流子的分离效率,相应地延长载流子的传输时间,增加光生电荷的寿命,从而促进其光催化活性的提高。     

可循环SERS基底ZnO/Ag纳米材料合成和表征

利用简易、绿色、一锅煮的水热法合成了花状氧化锌/银复合纳米材料。然后利用各种光谱和显微技术对复合物进行了表征,并讨论了其表面增强拉曼（SERS）性能和光催化性能。结果表明氢氧化钠的量对于这种复合纳米材料的形貌和性能具有重要的调节作用。和其他形貌的氧化锌/银复合纳米材料相比较,花状氧化锌/银复合纳米材料具有最佳的光催化性能。同时进一步以花状氧化锌/银复合纳米材料作为SERS基底研究其表面增强拉曼性能,结果表明这种复合材料同时具有很好的表面增强拉曼性能。光催化和表面增强拉曼结果表明这种花状氧化锌/银复合纳米材料有望在有机物检测中作为一种具有很好的可循环性的新表面增强拉曼基底材料。     

Synthesis and characterization of novel poly(1-naphthylamine)/zinc oxide nanocomposites: Application in catalytic degradation of methylene blue dye

The organic–inorganic poly(1-naphthylamine)/ZnO (PNA/ZnO) nanocomposites were synthesized by in situ chemical oxidative polymerization of 1-naphthylamine monomer and ZnO nanomaterials for the photocatalytic degradation of methylene blue (MB) dye under visible light. The surface properties of PNA molecules were altered by adding the ZnO nanomaterials. The crystalline and the optical properties of PNA/ZnO nanocomposites were improved with the increased contents of ZnO nanomaterials in PNA molecules due to the effective interaction of PNA to the surface of ZnO nanomaterials. The prepared PNA/ZnO nanocomposites presented moderate photocatalytic MB dye degradation of ~22% under visible light. The occurrence of dye degradation under visible light might attribute to high-charge separation of ē-h⁺ pairs at the interfaces of PNA and ZnO nanomaterials in its excited state under light irradiation.     

Surface-plasmon-enhanced band emission of ZnO nanoflowers decorated with Au nanoparticles

A simple strategy was used to enhance band emission through the transfer of defect emission from ZnO to Au by using the energy match between the defect emission of ZnO and the surface plasmon absorbance of Au NPs through decorating the surface of ZnO nanoflowers with Au nanoparticles (Au NPs). The ZnO nanostructure, which was comprised of six nanorods that were attached on one side in a flower-like fashion, was synthesized by using a hydrothermal method. The temperature-dependent morphology and detailed growth mechanism were studied. The influence of the density of the Au NPs that were deposited onto the surface of ZnO on photoluminescence was investigated to optimize the configuration of the ZnO/Au system in terms of the maximum band emission. The sequential transfer of defect energy from ZnO to Au and electron transfer from excited Au to ZnO was proposed as a possible mechanism for the enhanced band emission.     

Surface‐Plasmon‐Enhanced Band Emission of ZnO Nanoflowers Decorated with Au Nanoparticles

A simple strategy was used to enhance band emission through the transfer of defect emission from ZnO to Au by using the energy match between the defect emission of ZnO and the surface plasmon absorbance of Au NPs through decorating the surface of ZnO nanoflowers with Au nanoparticles (Au NPs). The ZnO nanostructure, which was comprised of six nanorods that were attached on one side in a flower‐like fashion, was synthesized by using a hydrothermal method. The temperature‐dependent morphology and detailed growth mechanism were studied. The influence of the density of the Au NPs that were deposited onto the surface of ZnO on photoluminescence was investigated to optimize the configuration of the ZnO/Au system in terms of the maximum band emission. The sequential transfer of defect energy from ZnO to Au and electron transfer from excited Au to ZnO was proposed as a possible mechanism for the enhanced band emission.     

Magnetically separable ZnO/ZnFe2O4 and ZnO/CoFe2O4 photocatalysts supported onto nitrogen doped graphene for photocatalytic degradation of toxic dyes

Advanced oxidation processes (AOPs) counting heterogeneous photocatalysis has confirmed as one of the preeminent method for waste water remediation. In the present work, we have successfully fabricated novel visible-light-driven nitrogen-doped graphene (NG) supported magnetic ZnO/ZnFe₂O₄ (ZnO/ZF/NG) and ZnO/CoFe₂O₄ (ZnO/CF/NG) nanocomposites. ZnO synthesized via direct precipitation method. Hydrothermal method was used for the preparation of nitrogen-doped graphene supported magnetic ZnO/ZF (ZnO/ZnFe₂O₄) and ZnO/CF (ZnO/CoFe₂O₄) nanocomposites. The procured materials were scrutinized by assorted characterizations to acquire information on their chemical composition, crystalline structure and photosensitive properties. The absorption and photocatalytic performance of photocatalysts were studied via UV–Visible spectra. Photodegradation performance of the synthesized nanocomposites was estimated toward mineralization of methyl orange (MO) and malachite green (MG) dyes in aqueous solution. The high surface area of ZnO/ZF/NG and ZnO/CF/NG was suitable for adsorptive removal of MO and MG dyes. The photodegradation performance of heterojunction photocatalysts was superior to bare photocatalyst in 140 min under visible-light irradiation. Spectrophotometer, GC–MS (Gas chromatography–mass spectrometry) elucidation was carried out to expose the possible intermediates formed. Both ZnO/ZF/NG and ZnO/CF/NG were rapidly isolated from the aqueous phase by applying an external magnetic field in 20 sec and 2 min, respectively. The photocatalytic performance and stability of ZnO/ZF/NG and ZnO/CF/NG nanocomposites were confirmed by conducting 10 consecutive regeneration cycles. Owing to recyclability of ZnO/ZF/NG and ZnO/CF/NG, these heterogeneous nanocomposites might be used as cost-effective for treatment of discarded water. The observations endorse that the synthesized ternary heterogeneous nanocomposites facilitates wastewater decontamination using photocatalytic technology.     

Ternary Ag/Polyaniline/Au nanocomposites: Preparation,characterization and electrochemical properties

Ternary Ag/Polyaniline/Au nanocomposites were synthesized successfully by immobilizing of Au nanoparticles (NPs) on the surface of Ag/Polyaniline (PANI) nanocomposites. Ag/PANI nanocomposites were prepared via in situ chemical polymerization of aniline in the presence of 4-aminothiophenol (4-ATP) capped silver colloidal NPs. Then, uniform gold (Au) NPs were assembled on the surface of resulted Ag/PANI nanocomposites through electrostatic interaction to get Ag/Polyaniline/Au nanocomposites. The nanocomposites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), ultraviolet visible spectroscopy (UV-Vis), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). Moreover, Ag/PANI/Au nanocomposites were immobilized on the surface of a glassy carbon electrode and showed enhanced electrocatalytic activity for the reduction of H₂O₂ compared with Ag/PANI.     

Visible light-excited surface plasmon resonance charge transfer significantly improves the photocatalytic activities of ZnO semiconductor for pollutants degradation

To effectively address environmental pollution, we synthesized Au-loaded ZnO nanocomposites and applied for the photocatalytic degradation of 2-chlorophenol (2-CP) under visible light irradiation. The as-prepared nanophotocatalysts delivered much improved photocatalytic degradation activities as compared to the bare ZnO nanoparticles and 32% of the pollutant was degraded with 2AuZnO in 1 hr. These improved photoactivities are attributed to the extended visible light absorption due to the surface plasmon resonance property of the loaded Au nanoparticles. Moreover, Au nanoparticles played important role in charge separation by inducting excited electrons to the conduction band of ZnO photocatalyst and surface catalysis as confirmed from photoluminescence spectra and amount of the generated hydroxyl radicals. The trapping experiments confirmed that positive holes were the major degrading species during the photocatalytic degradation of 2-CP. This work provides a feasible way to improve the photocatalysis by introducing a proper amount of noble metals over the surface of semiconductor photocatalysts.     

碳纳米管/氧化锌纳米复合材料的制备及其形貌控制

0引言碳纳米管(CNT)优良的力学、电学、热学性能使其在材料、储能、传感等许多领域都有广泛的应用前景,近年来,以碳纳米管为载体制备的纳米复合材料因其独特的应用潜力而受到广泛关注:彭峰等[1]用FeSO4-H2O2体系修饰碳纳米管,成功地制备了由碳纳米管负载的Fe2O3催化剂;Chen等[2]用溶胶凝胶法制备了CNT/SnO复合材料,作为Li离子电池阴极材料,测试表明它的电化学性能比单独的CNT和SnO材料都有所增强;Jitianu等[3]用溶胶凝胶和水热方法得到不同形貌的TiO2/CNT复合结构,这种新型的纳米复合材料在光催化方面有着重要的应用前景。纳米Z…     

金纳米颗粒在不同包裹介质中的超快等离子体动力学

Herein, we prepared four samples, namely gold/poly(sodium-p-styrenesulfonate) (Au/PSS), gold/silicon dioxide (Au/SiO₂), gold/titanium dioxide (Au/TiO₂), and gold/cuprous oxide (Au/Cu₂O) core/shell nanocomposites, to investigate how the surrounding medium affects the ultrafast plasmon dynamics of Au nanoparticles (NPs). We recorded femtosecond transient absorption spectra of Au NPs in Au/PSS, Au/SiO₂, Au/TiO₂, and Au/Cu₂O core/shell nanocomposites at various time delays. We found that the spectral features in the femtosecond transient absorption spectra of Au NPs in Au/TiO₂ and Au/Cu₂O core/shell nanocomposites were dramatically different from those of Au NPs in Au/PSS and Au/SiO₂ core/shell nanocomposites. A comprehensive analysis of the ultrafast plasmon dynamics of Au NPs in the core/shell nanocomposites revealed that following excitation of the resonance plasmon band of Au NPs, the exited electrons could be efficiently transferred into the conduction bands of TiO₂ and Cu₂O in Au/TiO₂ and Au/Cu₂O core/shell nanocomposites.     

Sol–gel derived ZnO/porous silicon composites for tunable photoluminescence

ZnO/porous silicon nanocomposites were fabricated by spin-coating the sol?Cgels of zinc acetate onto the top surface of porous silicon films. The photoluminescent properties of ZnO/porous silicon nanocomposites were investigated as a function of the concentration of zinc cations in the sol?Cgels. Characterizations with scanning electron microscopy, X-ray diffractometry and photospectroscopy indicated that ZnO nanocrystals were embedded into the spongy nanostructures of porous silicon after heat treatment at 245?°C for 20?min in air. The recorded photoluminescence exhibited that orange to green?Cblue emissions were achieved for the ZnO/porous silicon nanocomposites as the concentration of zinc cations in the sol?Cgels increased from 4 to 260?mM. The mechanisms on the tunability of the photoluminescence were discussed for the ZnO/porous silicon nanocomposites. Our results have demonstrated that the incorporation of green?Cblue phosphors into the porous matrix of porous silicon represents one endeavor to tune the photoluminescence of porous silicon across the visible spectral region.     

Microwave-assisted solution synthesis and photocatalytic activity of Ag nanoparticles supported on ZnO nanostructure flowers

Ag nanoparticles supported on the surface of three-dimensional (3D) flower-like ZnO nanostructure were synthesized by a microwave-assisted solution method. The obtained products were characterized by X-ray diffraction analysis, field-emission scanning electron microscopy, Fourier-transform infrared spectroscopy, Raman spectrophotometry, X-ray photoelectron spectroscopy, and photoluminescence spectroscopy. The analytical results confirmed homogeneously distributed Ag nanoparticles supported on the surface of flower-like ZnO nanostructure. The photocatalytic effect of the heterostructure Ag/ZnO nanocomposites was investigated using photodegradation under ultraviolet (UV) light of methylene blue as model dye. The heterostructure Ag/ZnO nanocomposites exhibited much higher photocatalytic activity than pure ZnO flowers. The improved photocatalytic properties are attributed to formation of a Schottky barrier at the metal–semiconductor interface of the Ag/ZnO nanocomposites.     

聚乳酸/氧化锌柱撑皂石纳米复合材料制备与性能及结构表征

通过微波水解法制备了ZnO柱撑皂石,并以其为加工助剂制备了聚乳酸(PLA)/ZnO柱撑皂石纳米复合材料.通过X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、对ZnO柱撑皂石及PLA/ZnO柱撑皂石纳米复合材料的结构进行了表征,并对其力学性能和热稳定性能进行了测试.微观结构分析表明,ZnO柱撑皂石呈现剥离状,并均匀分散在PLA基质中.力学性能研究表明0.3%ZnO柱撑皂石的加入有助于改善PLA复合材料的断裂伸长率.SEM分析表明PLA复合材料的断面发生明显改变,表现良好韧性;DSC结果显示纳米ZnO柱撑皂石可以降低复合材料的玻璃化转变温度、结晶温度,有助于提高PLA复合材料的结晶度,与XRD分析相吻合;热重分析表明ZnO柱撑皂石可以提高PLA复合材料的热稳定性.测试结果表明,ZnO柱撑皂石在PLA基质中起到了异相成核的作用,促进了PLA基质的结晶.