In the present work, polydopamine (PDA) modified reduced graphene oxide (pRGO)/SnO2/Au nanoparticles (NPs) were synthesized. SnO2/AuNPs were prepared through the redox reaction between reductive stannous(II) ions and oxidative auric(III) ions without any other reagents, and then the as-prepared graphene oxide (GO) was reduced and stabilized with the help of DA followed by decorating with SnO2/AuNPs. The morphology and structure of the hybrid nanomaterials were characterized by Raman spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction analysis. Then we constructed electrochemical sensors based on the hybrid nanomaterials for the determination of dopamine (DA). Cyclic voltammetry (CV) results showed that the hybrid nanomaterials had better sensing performance than pRGO/AuNPs and pRGO. Differential pulse voltammetry (DPV) showed that the separation of oxidation peak potentials for ascorbic acid (AA)–DA, uric acid (UA)–DA and UA–AA was about 200 mV, 100 mV and 300 mV, respectively. The linear range for the detection of DA was from 0.008 μM to 20 μM with a coefficient of 0.9986. The detection limit was 5 nM (S/N = 3). These indicate the selective and sensitive detection of DA. Finally, the constructed sensors were also applied to detect DA in human real samples.

•One-step synthesis of acrylates at room temperature was firstly developed.•The in-situ catalytic strategy was firstly designed and confirmed.•Ester enolization and trioxane decomposition were firstly realized simultaneously.•Relative high yield and selectivity of acrylates were obtained.One-step synthesis of acrylates from acetates and trioxane via aldol reaction at 623 K–653 K was reported. But proceeding this process at room temperature is still a challenge due to ester activation and trioxane decomposition. Herein, series of acrylates were firstly achieved, with the one-step and in-situ catalytic strategy, from acetates (or propionates) and trioxane at 293 K. Selectivity of product reaches up to 94.4% with a 80.8% yield. 1H NMR confirmed the soft enolization of ester, the decomposition of trioxane was catalyzed by TMSOTf, and the generated ionic liquid has catalytic performance on aldol condensation step.Download high-res image (213KB)Download full-size image

•Ternary nanocomposites PAMAM-AuNPs/SnO2/graphenes nanosheets (GNs) were obtained with a facile method.•The obtained nanomaterial was used to construct the electrochemical sensor for the detection of dopamine (DA) in the presence of ascorbic acid.•The electrochemical sensor could be applied to the determination of DA in real samples.The nanocomposite of polyamidoamine (PAMAM) modified gold nanoparticles (pAuNPs)/SnO2/graphene sheets (GNs) was prepared by a new method. That is, the well dispersed AuNPs were prepared in the presence of PAMAM and resembled on the surface of 5,10,15,20-tetrakis (4-sulonatophenyl) porphyrin (H4TPPS2–) modified graphite oxide (GO) by electrostatic interaction. Then the well-distributed SnO2 was obtained from SnCl2 with the aid of GO and GO was reduced to graphene by hydrazine hydrate. The synthesized nanocomposite was characterized by Raman spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction analysis (XRD). Cyclic voltammetry (CV) experiment demonstrated that the nanocomposite exhibited excellent electrochemical performance for the detection of dopamine (DA). Then the quantitative detection of DA was carried out by differential pulse voltammetry (DPV) in the presence of ascorbic acid (AA). A linear range of 0.03–10 μM was obtained with a correlation coefficient of 0.9970. The detection limit was as low as 8 nM (S/N = 3). Moreover, the proposed method was applied for the determination of DA in real serum samples.A facile method for the preparation of polyamidoamine (PAMAM)–gold nanoparticles (AuNPs)/SnO2/graphenes nanosheets (GNs) nanocomposites is presented. Highly sensitive and selective detection of dopamine could be realized by the proposed method.Download high-res image (127KB)Download full-size image

•A dual-amplified electrochemical immunosensor based on Au/ZnO was fabricated.•C12N3 acted as the surfactants of Au/ZnO/RGO.•C18N3 acted as the reductant agents of Au@ZnO composite.•XRD, Raman, FT-IR, UV-Vis, SEM have been used for characterization.•Fabricated immunosensor showed excellent sensitivity and specificity.Herein, a dual signal amplification strategy was employed in fabricating ultrasensitive electrochemical immunosensor for alpha fetoprotein (AFP) detection, which was realized by utilizing of ZnO nanorods/Au nanopaticles hybridized reduced graphene nanosheet (Au/ZnO/RGO) and horseradish-peroxidase (HRP) bioconjugated detection antibody (Ab2) functionalized Au@ZnO (Ab2/HRP-Au@ZnO). During the fabrication of the immunosensor, a new kind of multiple-head surfactants CxN3 with different alkyl chain length played important roles such as acting as the surfactants of Au/ZnO/RGO and the reductant agents of Au@ZnO composite. Due to the good adsorption property and large surface area of Au/ZnO/RGO, plenty of the capture antibodies (Ab1) were immobilized on the electrode surface, and trace AFP was sensitively monitored. Furthermore, Ab2/HRP-Au@ZnO exhibited high affinity interaction with AFP through “sandwich” immunoreactions, along with the peroxidase-like catalytic activity of Au@ZnO, leading to a further enhancement in the sensitivity of the proposed immunosensor. The successful synthesis of the nanomaterials was characterized through a serious of techniques including Raman, XRD, FT-IR, SEM and UV–vis. Under the optimal conditions, two linear ranges of 0.02–10,000 and 10,000–100,000 pg mL-1 AFP with a lower detection limit of 0.01  pg mL-1 (S/N=3) was obtained. Especially, the proposed AFP immunosensor can be applied to detect human serum samples with satisfactory results, indicating a potential application in clinical monitoring of tumor biomarkers.

To obtain clean liquid fuel, a study was conducted on upgrading shale oil by hydroconversion. Various W–Ni catalysts were synthesized and characterized using XRD, BET, TG, H2-TPR, and NH3-TPD methods. The effects of tungsten content and calcination temperature on the physicochemical properties and activity of catalysts were systematically investigated. W–Ni/Al2O3 with 15 wt % W-loading and 550 °C calcination temperature was selected as the optimized catalyst. The product distribution of the primary aromatics in shale oil affected by hydrogenation, ring opening, and cracking reactions was discussed. Finally, key reaction parameters such as pressure, liquid hourly space velocity, and H2/oil volume ratio were optimized. Characteristics of gasoline and diesel fractions were also measured.