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During biological detection, the toxicity caused by probes to living organisms is neglected. In this study, an analyte-compensated fluorescent probe (NP-SN3) was constructed for the detection of H2S.

Hydrogen sulfide (H

As a signal molecule involved in autophagy, hydrogen sulfide (H

In this study, a well-dispersed Pd nanoparticle (NP)-supported RGO/Mn3O4 (G/M/Pd) composite was synthesized by a clean synthetic route, where galvanic replacement reaction simply occurred between Mn3O4 and a palladium salt, thereby avoiding the use of harsh reducing and capping agents. The G/M/Pd composite served as a robust catalyst for the catalytic oxidation of hydroquinone (HQ) to benzoquinone (BQ) with H2O2 in an aqueous solution. Oxidation was completed in only 4 min, with a turnover frequency (TOF) of 3613 h−1; this TOF is one hundred times those of previously reported Pd- and Ag-based catalysts. The superior performance was related to the electronic inductive effect between Mn3O4 and Pd NPs, which was verified by density functional theory calculations. Trapping experiments revealed that the oxidation of HQ was considerably related to the ·OH radicals generated from the decomposition of H2O2. In addition, the influencing factors were further investigated, including catalyst and HQ concentrations, solution pH, solvents, and various inorganic and organic interferences. Moreover, the G/M/Pd catalyst exhibits diverse applications for the catalytic oxidation of HQ derivatives with high TOFs.

This is great significant to establish a method that extends the small molecules fluorescence emission wavelength to the near-infrared region (NIR) for in vivo imaging. Hence, we firstly reported a novel fluorogenic scaffold QOH that could extend its fluorescence wavelength from (λem = 555 nm) to NIR (λem = 720 nm) with a large Stokes shift (120 nm) by forming its N-quaternization product (QMOH). In addition, the effect of the introduction of substituent at different modification sites and the properties of substituent on the optical properties of QOH were fully discussed by theoretical calculation. To investigate the possibility of QOH as probe construction, the compound Q-SH and QM-R were synthesized and applied to detect H2S and H2O2 in vitro and in vivo, respectively. This study provided an efficient strategy to extend fluorescence emission to NIR and design fluorescence probes with large ratio variation for accurately imaging biomarkers in biological system.

Hypochlorous acid (HOCl), mainly generated in mitochondria, plays a critical role in various physiological processes. To better understand the role and function of HOCl in mitochondria, herein, we present the design and synthesis of a Mito-QL reporter for probing the HOCl within mitochondria without other interference generated in living cells. Through the combination of TICT/ICT mechanisms, probe Mito-QL, with large stokes shift (203 nm) and low background fluorescence, exhibited excellent sensitivity (900-fold fluorescence enhancement) and selectivity towards HOCl (LOD = 2.4 nM). The co-location experiments confirmed that probe Mito-QL can firstly localize in the mitochondria and then react with HOCl in mitochondria. Also, the probe is capable of imaging endogenous and exogenous HOCl even the generation of HOCl during the ferroptosis of cells, which is beneficial for more efficient application in biological imaging.

In this study, a well-dispersed Pd nanoparticle (NP)-supported RGO/Mn

Palladium-cobalt alloy nanoparticles were synthesized and dispersed on carbon black support, aiming to have a less expensive catalyst. Catalytic behaviors of PdCo/C catalyst for the oxidation of hydroquinone (HQ) with H2O2 in aqueous solution were evaluated using high-performance liquid chromatography (HPLC). The results revealed that PdCo/C catalyst had better catalytic activity than an equal amount of commercial Pd/C and Co/C catalysts because of the d-band hybridization between Pd and Co. The effects of pH value, solvent, and various interferents including inorganic and organic compounds on the efficiency of HQ oxidation were further investigated. Furthermore, on the basis of mixed potential theory, comprehensive electrochemical measurements such as the open-circuit potential-time (OCP-t) technique and Tafel plot were efficient to assess the catalytic activity of the catalyst, and the results obtained were consistent with those of HPLC measurements. The efficient HQ oxidation was closely associated with the catalytic activity of PdCo nanoparticles because they accelerated the electron-transfer process and facilitated the generation of OH radicals.

Poor detection of low-abundant proteins is a common problem in most current protein identification schemes. This is attributed partially to the existence of high-abundant protein. Therefore, selective removal of specific proteins prior to analysis is in great demand. In response these needs, we previously described two kinds of ion exchange groups functionalized SBA-15 synthesized by direct silylanization reaction. Herein, we designed and synthesized strong anion, cation and zwitterion functionalized SBA-15 via atom transfer radical polymerization (ATRP). The previous and current materials were characterized and theirs adsorption abilities for some model proteins (bovine serum albumin (BSA), hemoglobin (Hb), myoglobin (Mb) and lysozyme (Lys)) were evaluated. The results demonstrated that different functionalized SBA-15 is capable to selective removal of certain proteins in protein mixture. It also indicated that this sample preparation technique could be potentially applied to reduce the complexity on protein identification for biological samples with a wide dynamic range.

We proposed a facile approach for the synthesis of zinc sulfur-coated poly (3,4-ethylenedioxythiophene)-reduced graphene oxide hybrids film (ZnS-PEDOT-rGO) by using thioacetamide (TAA) as the reducing agent. The ZnS-PEDOT-rGO hybrids film modified glassy carbon-rotating disk electrode (GC-RDE) was then developed for the sensitive simultaneous determination of three deoxyribonucleic acid (DNA) bases: guanine (G), adenine (A), and thymine (T). By cyclic voltammetry (CV), this electrochemical sensor showed a good photoelectronic effect, and the peak currents of G, A, and T increased obviously. Some kinetic parameters were estimated by linear sweep voltammetry (LSV). Under the optimal conditions, the magnified anodic peak currents represented the excellent analytical performance of simultaneous detection of G, A, and T in a wide linear range and low detection limit. This proposed method also has been successfully applied to the assessment of G, A, and T contents in real-life samples, such as herring sperm DNA samples, milk powder and urine sample from human beings, with satisfactory results. The obtained results were also compared to HPLC of analysis for those three DNA bases and no significant differences were found. By the treatment of the experimental data, the electrochemical reaction mechanisms of G, A, and T all involved a two-electron-two-proton-transfer process.

Based on the excellent properties of dopamine (reduction, self-polymerization and adhesion), we designed a one-step and environment-friendly reduction route to synthesize and simultaneously functionalize polydopamine (PDA)–Ag–reduced graphene oxide (RGO) hybrid. The obtained PDA–Ag–RGO hybrid was characterized by transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, FT-IR and UV–vis analysis. Silver nanoparticles were uniformly dispersed on the surface of RGO sheets and coated with a thin PDA film. The hybrid exhibited good dispersivity in polar solvents (water and acetonitrile). Compared with Ag–RGO hybrid prepared via NaBH4 reduction and commercial Pd/C catalyst, PDA–Ag–RGO hybrid had better catalytic activity for the oxidation of hydroquinone to benzoquinone in the presence of H2O2. Moreover, the hybrid still retained superior catalytic activity over multiple cycles.

An electrochemical sensor based on Au nanoparticles (AuNPs)–poly(diallyldimethylammonium chloride) (PDDA)-functionalized graphene (AuNPs–PDDA-G) nanocomposite was fabricated for the sensitive detection of alkannin. The nanocomposite was characterized by X-ray diffraction, ultraviolet/visible spectra, scanning electron microscopy, and transmission electron microscopy. Cyclic voltammetry and differential pulse voltammetry were used to investigate the electrochemical behaviors of alkannin on the AuNPs–PDDA-G nanocomposite film-modified glassy carbon electrode. This electrochemical sensor displayed satisfactory analytical performance for alkannin detection over a range from 5.0 nmol L−1 to 3.0 μmol L−1 with a detection limit of 1.4 nmol L−1 (S/N = 3). Moreover, the sensor also exhibited good reproducibility and stability, and could be used for the detection of alkannin in real samples with satisfactory results.

β-Cyclodextrin functionalized reduced graphene oxide hybrid nanosheets (β-CD-RGO) were successfully prepared by using l -ascorbic acid ( l -AA) as the reducing agent under a mild condition and used as enhanced material for sensitivity determination of diethylstilbestrol (DES). In 0.1 M PBS (pH 7.0), the redox peak currents of DES increased significantly on β-CD-RGO modified glassy carbon electrode (β-CD-RGO/GCE), suggesting that the composite film not only shows excellent electronic properties of RGO sheets but also exhibits high supramolecular recognition capability of β-CD. The experimental conditions were optimized and the kinetic parameters were investigated. Under the optimal conditions, the reduction peak current of DES increased linearly with increasing the concentration in the range from 0.01 to 13 μM with the detection limit of 4 nM (S/N = 3). The developed electrochemical sensor exhibited high selectivity, good stability and reproducibility, and also successfully determined DES in milk samples with satisfactory results.

Arginine (Arg) functionalized graphene (Arg-G) nanocomposite was produced successfully by an environment-friendly method, and the morphology of the nanocomposite was characterized by transmission electron microscopy (TEM), Raman spectra, etc. Based on Arg-G nanocomposite, an electrochemical sensor was fabricated for sensitive detection of bisphenol A (BPA). The electrochemical behaviors of BPA on Arg-G modified glassy carbon electrode (GCE) were investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Experimental parameters, such as the accumulation potential and time, scan rate, and the pH value of buffer solution were optimized. Under the optimized conditions, the oxidation peak current was proportional to BPA concentration in the range between 5.0 nmol/L and 40.0 μmol/L with the correlation coefficient of 0.9986 and the limit of detection of 1.1 nmol/L (S/N = 3). Moreover, the fabricated electrode also exhibited good reproducibility and stability. The proposed sensor was successfully employed to determine BPA in real plastic products and the recoveries were satisfactory.

The mechanisms related to the initial stages of the nucleation and growth of antimony selenide (Sb2Se3) semiconductor compounds onto the indium-doped tin oxides (ITO) coated glass surface have been investigated using chronoamperometry (CA) technique. The fabrication was conducted from nitric acid bath containing both Sb3+ and SeO2 species at ambient conditions. No underpotential deposition (UPD) of antimony and selenium onto ITO substrate was observed in the investigated systems indicating a weak precursor-substrate interaction. Deposition of antimony and selenium onto ITO substrate occurred with large overvoltage through 3D nucleation and growth mechanism followed by diffusion limited growth. FE-SEM and XRD results show that orthorhombic phase Sb2Se3 particles with their size between 90 and 125 nm were obtained and the atomic ratio for antimony and selenium was 2:2.63 according to the EDX results. (C) 2011 Elsevier B.V. All rights reserved.

Monodisperse CoPt3 nanocrystals (NCs) have been synthesized in oleylamine solution by an organic solvothermal method. The NCs were ellipsoidal particles with a diameter around 6.6 nm and length around 10 nm with a good single crystal structure. Using CoPt3 NCs as catalysts, large-area boron nanowires with diameters ranging from 30 to 50 nm were successfully prepared by chemical vapor deposition using a C/B/B2O3 mixture as the precursor. Structural analysis indicated that these nanowires were single crystalline with a β-rhombohedral structure. Measurement of the field emission properties of boron nanowire films showed that the boron nanowires have good field emission characteristics. Open image in new window

In this paper the fabrication and characterization of IV–VI semiconductor Pb1−xSnxSe (x = 0.2) thin films on gold substrate by electrochemical atomic layer deposition (EC-ALD) method at room temperature are reported. Cyclic voltammetry (CV) is used to determine approximate deposition potentials for each element. The amperometric I–t technique is used to fabricate the semiconductor alloy. The elements are deposited in the following sequence: (Se/Pb/Se/Pb/Se/Pb/Se/Pb/Se/Sn …), each period is formed using four ALD cycles of PbSe followed by one cycle of SnSe. Then the deposition manner above is cyclic repeated till a satisfactory film with expected thickness of Pb1−xSnxSe is obtained. The morphology of the deposit is observed by field emission scanning electron microscopy (FE-SEM). X-ray diffraction (XRD) pattern is used to study its crystalline structure; X-ray photoelectron spectroscopy (XPS) of the deposit indicates an approximate ratio 1.0:0.8:0.2 of Se, Pb and Sn, as the expected stoichiometry for the deposit. Open-circuit potential (OCP) studies indicate a good p-type property, and the good optical activity makes it suitable for fabricating a photoelectric switch.

In this paper the formation and characterization of the I-III-VI 2 semiconductor compound CuInS 2 (CIS) on gold substrate at room temperature by electrochemical atomic layer deposition (EC-ALD) method are reported. Optimum deposition potentials for each element are determined using cyclic voltammetry (CV) technique and Amperometric I – t method is used to prepare the semiconductor compound. These thin films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM) and Fourier transform infrared spectroscopy (FT-IR). XRD results indicate that the CIS thin films have a (1 1 2) preferred orientation. The XPS analyses of the films reveal that Cu, In and S are present in an atomic ratio of approximately 1:1:2. And their semiconductor band gaps are found to be 1.50 eV by FT-IR.

Atomic layers of antimony can be electrodeposited onto the Se monolayer covered Au electrode in the underpotential region. In this paper, the formation and dissolution kinetics of antimony monolayer on the Se monolayer covered Au electrode are investigated using cyclic voltammetry (CV) and chronoamperometry (CA) techniques. Scanning-rate-dependent CV experiments reveal that the peak current of underpotential deposition (UPD) wave of antimony is not a linear function of the scanning rate, υ, but scales as υ 2/3. Similar behavior is observed when the Antimony monolayer is stripped from the modified substrate. These results indicate the character of monolayer formation and dissolution by a two-dimensional nucleation and growth mechanism. Additionally, current density−time transient obtained through CA experiments also reveal that both the deposition and stripping of the antimony monolayer involve an instantaneous nucleation and two-dimensional growth process.

The article reports on electroless deposition of copper films onto p-silicon (1 0 0) using different seed (co-seed) layers of Pd, PtPd and AuPd. The dependence of the compositions and morphologies of different seed layers on resultant Cu films were comparatively studied in detail by atomic force microscopy (AFM), field emission scanning electron microscope (FE-SEM) and X-ray photoelectron spectroscopy (XPS). The activities of electroless copper deposition on the p-silicon (1 0 0) with different seed (co-seed) layers were evaluated by polarization curve. It is concluded that the bimetallic AuPd seed displayed the highest catalytic activity for electroless copper deposition, and followed by the order of PtPd > Pd.

Pt nanoparticles attached to the carbon nanotubes (CNTs)-modified polyimide (PIs) materials were successfully synthesized. Field emission scanning electron microscope (FE-SEM) and X-ray photoelectron spectroscopy (XPS) were used to characterize this nanocomposite film, which has excellent stability and flexibility. The electrochemical study found that the Pt/PI/CNTs nanocomposite film exhibited remarkable electrocatalytic activity towards the oxidation of methanol and nitrite.

Quaternary compound semiconductor Cu2ZnSnS4 (CZTS), which appears to be a promising candidate for the absorber of a thin film type solar cell, was grown on polycrystalline Ag substrates by electrochemical epitaxial method. The elements were deposited in the following sequence: S/Sn/S/Cu/S/Zn/S/Cu… , the order being one cycle of SnS, one cycle of ZnS and two cycles of CuS. Morphology of the deposit has been characterized by field emission scanning electron microscopy (FE-SEM) with an energy dispersive X-ray (EDX) analyzer. X-ray diffraction (XRD) studies showed a (112) preferred orientation for the deposit. X-ray photoelectron spectroscopy (XPS) of the deposit indicated an approximate ratio 2:1:1:4 of Cu, Zn, Sn, and S, the expected stoichiometry for the deposit, and similar results have been obtained from EDX data. Near IR absorption measurements of the deposit at room temperature indicated a direct band gap of 1.5 eV, and open-circuit potential (OCP) studies indicated a good p-type property, both of which were suitable for fabricating a thin film solar cell.

Studies of the electrochemical optimization of ZnSe thin film deposition on polycrystalline Au substrates using electrochemical atomic layer epitaxy are reported. Electrochemical aspects were characterized by means of cyclic voltammetry, differential pulse voltammetry, and coulometry. To study the growth mechanism of the underpotential deposition in the formation of ZnSe, the effects of Zn and Se deposition potentials and a Se-stripping potential were adjusted to optimize the deposition program. The deposit, grown using the optimized program, was proved to be a single-phase ZnSe compound with a strong (220)-preferred orientation by X-ray diffraction analysis, and scanning electronic microscopy observation shows the deposit consisted of nanoscale particles with an average size about 100 nm. The right 1:1 stoichiometric ratio of Zn to Se according to the coulometry suggests that ZnSe is formed.

Cuprous oxide and copper thin films were potentiostatically electro-deposited over indium-tin oxide (ITO) coated glass substrate with two different aqueous electrolytes: 0.1 M KNO3 solution in comparison with the 0.05 M CH3COOH/CH3COONa (pH=5.7) solution. Cyclic voltammetry (CV) was used to determine the optimal deposition potentials. A single pair redox peaks were observed in the CV for 0.05 M CuSO4 in the buffer solution, while two redox couples were observed in the KNO3 solution. X-ray diffraction (XRD) and X-ray photo spectroscopy (XPS) revealed that in the buffer electrolyte the deposition for Cu2O, Cu and co-deposition alloy were formed at more negative potentials than in the KNO3. Furthermore, periodic structure can be obtained by controlling the deposition potentials in KNO3 with CuSO4 solution. The structural and morphological properties of the films have been investigated by means of scanning electron microscopy (SEM) and atomic force microscopy (AFM).

To synthesize monodisperse palladium nanoparticles dispersed on reduced graphene oxide (RGO) sheets, we have developed an easy and scalable solvothermal reduction method from an organic solution system. The RGO-supported palladium nanoparticles with a diameter of 3.8 nm are synthesized in N-methyl-2-pyrrolidone (NMP) and in the presence of oleylamine and trioctylphosphine, which facilitates simultaneous reduction of graphene oxide and formation of Pd nanocrystals. So-produced Pd/RGO was tested for potential use as electrocatalyst for the electro-oxidation of formic acid. Pd/RGO catalyzes formic acid oxidation very well compared to Pd/Vulcan XC-72 catalyst. This synthesis method is a new way to prepare excellent electrocatalysts, which is of great significance in energy-related catalysis.

Monodisperse iron oxide nanocrystals were synthesized by a simplified method using iron chloride as precursor. In the presence of Cl ions, the as-produced iron oxide nanocrystals preferred a cubic shape with {100} facets exposed. The function of halogens including Cl and Br ions on stabilizing {100} facets of spinel structured iron oxides, rather than the regulation of thermolysis kinetics and surfactants, was found influential on the shape control of nanocubes in this organic phase approach. The synthesis can be also extended for cobalt ferrite nanocubes and cobalt oxide polyhedrons.

Magnesium-doped boron nanoswords were synthesized via a thermoreduction method. The as-prepared nanoswords are single crystalline and β-rhombohedral (β-rh) phase. Electrical transport measurements show that variable range hopping conductivity increases with temperature, and carrier mobility has a greater influence than carrier concentration. These results are consistent with the three dimensional Mott’s model (M. Cutler and N. F. Mott, Phys. Rev. 181, 1336 (1969)) besides a high density of localized states at the Fermi level compared with bulk β-rh boron. Conductivity of Mg-doped boron nanoswords is significantly lower than that of “pure” (free of magnesium) boron nanoswords. Electron energy loss spectroscopy studies confirm that the poorer conductivity arises from silicon against magnesium doping.

Gold nanorods with aspect ratios of from 1 (particles) to 31.6 were synthesized by the seed-mediated method and packed in a highly ordered structure on a large scale on silicon substrates through capillary force induced self-assembly behaviour during solvent evaporation. The gold nanorod surface exhibits a strong enhancing effect on Raman scattering spectroscopy. The enhancement of Raman scattering for two model molecules (2-naphthalenethiol and rhodamine 6G) is about 5-6 orders of magnitude. By changing the aspect ratio of the Au nanorods, we found that the enhancement factors decreased with the increase of aspect ratios. The observed Raman scattering enhancement is strong and should be ascribed to the surface plasmon coupling between closely packed nanorods, which may result in huge local electromagnetic field enhancements in those confined junctions.

A novel electrode material based on graphene oxide (GO)-polypyrrole (PPy) composites was synthesized by in situ chemical oxidation polymerization. Palladium nanoparticles (NPs) with a diameter of 4.0 nm were loaded on the reduced graphene oxide(RGO)-PPy composites by a microwave-assisted polyol process. Microstructure analysis showed that a layer of coated PPy film with monodisperse Pd NPs is present on the RGO surface. The Pd/RGO-PPy catalysts exhibit excellent catalytic activity and stability for formic acid electro-oxidation when the weight feed ratio of GO to pyrrole monomer is 2 : 1. The superior performance of Pd/RGO-PPy catalysts may arise from utilization of heterogeneous nucleation sites for NPs and the greatly increased electronic conductivity of the supports.