FOOD RESEARCH INTERNATIONAL
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2019
·
IF 3.579
Wei Xu,Nan Zhang,Zhentao Zhang,Pu Jing
Anthocyanins exist likely as complexes with flavones/metal ions in some plants. However, few studies indicate the complexation effects on bioactivities, i.e. antioxidant activities. The aim of this study was to evaluate effects of complexes of cyanidin-3-diglucoside-5-glucoside (CY3D5G) with rutin/Mg(II) on intrinsic antioxidant enzymes and mRNA expressions. All complexes exhibited cellular antioxidant activity in RAW264.7 cells, whereas half maximal effective concentration (EC 50 ) values of CY3D5G complexes were significantly lower than its alone. Combination indexes of CY3D5G-rutin, CY3D5G-Mg(II), and CY3D5G-rutin-Mg(II) complexes were < 1 ( p < .05), indicating of synergistic effects. Additionally, CY3D5G-Mg(II) rather than others significantly enhanced total antioxidant capacity, superoxide dismutase activity, and glutathione peroxidase activity while reducing malonic dialdehyde contents in H 2 O 2 -induced RAW264.7 cell model ( p < 0.05), which were further confirmed with the up-regulated mRNA expression of nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1), and the down-regulated p21 ( p < 0.05). Our results demonstrated that CY3D5G and its complexes might enhance cellular antioxidant activities via the Nrf2/HO-1 signaling pathway. Additionally, a synergistic antioxidant effect of CY3D5G in the present of rutin/ Mg(II) as regular food components was evident, suggesting anthocyanin might interact with dietary components such as Mg(II) or rutin in food matrix or biological systems and exhibit a stronger antioxidant activity than it alone. The Mg (II) that exhibited no antioxidant activities alone shows potential as a co-adjuvant for the anthocyanin antioxidant activity.
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Catalysis Science & Technology
·
2019
·Vol. 9
·期 10
·2673-2681
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IF 5.726
Bing Hu,Yazhi Yin,Zixin Zhong,Dengdeng Wu,Guoliang Liu,Xinlin Hong
Maximizing the Cu–ZnO interface is regarded as the best strategy to promote methanol synthesis activity over CuZn catalysts. Reducing the ZnO particle size can enhance the Cu–ZnO interaction, but its synthesis with a sub-5 nm size still remains a challenge. Moreover, the fabrication of an active powder catalyst with an inverse ZnO/Cu configuration is still very rare. In this work, we report a facile synthesis of inverse ZnO/Cu catalysts by direct calcination of Cu@ZIF-8 (zeolitic imidazolate framework-8). The particle size of ZnO and Cu can be tuned by changing the Cu loading as well as the calcination temperature. Importantly, inverse ZnO/Cu catalysts with sub-5 nm ZnO were obtained under gentle calcination at 623 K. In the CO2 hydrogenation reaction, the highest methanol synthesis activity reached 933 g kgcat−1 h−1 at 533 K and 4.5 MPa, with a high turnover frequency (TOF) of 0.013 s−1, over an optimized C2Z-623 catalyst, which exceeds the commercial CuZnAl catalyst (HiFuel R120, Johnson Matthey) and has ranked the top reported value over advanced CuZn catalysts under comparable conditions. Such excellent activity is attributed to the inverse structure of Cu particles covered by sub-5 nm ZnO, which promotes the intimate Cu–ZnO interface with enhanced SMSI. Moreover, we find that the methanol turnover frequency (TOF) monotonically increases with decreasing the particle size of ZnO as well as Cu. It is proposed that reducing the ZnO size favors the spillover of reducible ZnOx species onto the Cu surface while lowering the Cu size is responsible for the enhanced amount of exposed Cu steps for accommodating Zn species, both of which could facilitate the formation of Zn covered Cu steps as active sites for methanol synthesis.
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Journal of Energy Chemistry
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2018
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IF 3.886
Lei Hu,Ning Li,Xiaoli Dai,Yuqi Guo,Yetao Jiang,Aiyong He,Jiaxing Xu
The development of high-efficiency and low-cost catalysts is very crucial for the Meerwein-Ponndorf-Verley (MPV) reduction of biomass-derived 5-hydroxymethylfurfural (HMF) into 2,5-dihydroxymethylfuran (DHMF). In this work, an amorphous and mesoporous zirconium phosphonate catalyst (Zr-DTMP), which is a zirconium-containing organic-inorganic nanohybrid , was successfully designed and synthesized by the simple assembly of zirconium tetrachloride (ZrCl 4 ) and diethylene triaminepenta(methylene phosphonic acid) (DTMP). Satisfactorily, when Zr-DTMP was employed for the MPV reduction of HMF in the presence of 2-butanol ( sec BuOH), DHMF yield could be achieved as 96.5% in 3 h under a relatively mild reaction temperature of 140 °C. Systematic investigations indicated that this high catalytic activity should be mainly due to the cooperative role of enhancive Lewis acid site (Zr 4+ ) and Lewis base site (O 2− ) in activating the carbonyl group of HMF and dissociating the hydroxyl group of sec BuOH, respectively. Additionally, Zr-DTMP showed excellent catalytic stability, when it was successively used 5 recycles, its surface characteristics and textural properties still remained almost unchanged, and so, the catalytic activity was not obviously affected. More interestingly, Zr-DTMP could also be applied for the selective reduction of other biomass-derived carbonyl compounds , such as 5-methylfurfural (MF), furfural (FF), levulinic acid (LA), ethyl levulinate (EL) and cyclohexanone (CHN), into the corresponding products with high yields, which is beneficial to the effective synthesis of various valuable bio-based chemicals.
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CHEMOSPHERE
·
2019
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IF 5.108
Rongji Cui,Suxia Ma,Jie Wang,Shujun Sun
The catalytic gas-phase H 2 O 2 oxidation of NO was achieved over Fe-based catalysts supported on montmorillonite K10, γ-alumina and ZSM-5. ESR tests illustrate that the three catalysts can catalyze decomposition of H 2 O 2 yielding highly reactive hydroxyl radicals , of which Fe/K10 has the fastest rate, followed by Fe/γ-alumina. Fe 3+ in Fe/K10 and Fe/γ-alumina show lower density of electron cloud due to a strong interaction between Fe 3+ and the support, which benefits the electron transfer from the H 2 O 2 to Fe 3+ , thus favoring the production of hydroxyl radicals. Fe species exist on the surface of Fe/K10 mainly in the form of Fe 2 O 3 , whereas Fe species of Fe/γ-alumina and Fe/ZSM-5 exist mainly in the form of Fe 3 O 4 , and it is found that Fe 2 O 3 is more active than Fe 3 O 4 in catalytic gas-phase H 2 O 2 oxidation of NO. Interestingly, Fe/ZSM-5 has the lowest efficiency in generating hydroxyl radicals, its NO removal efficiency is 90%, which is much higher than 47.5% for Fe/γ-alumina and 62.3% for Fe/K10. In-situ IR results suggested that Fe/ZSM-5 are dual functional in oxidation of NO, that is, whether both Fe ion sites and Brønsted acid sites collectively provide the catalytic functionality. In the meantime, a possible reaction mechanism on catalytic gas-phase H 2 O 2 oxidation of NO over Brønsted acid sites is proposed.
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Polymers
·
2018
·Vol. 10
·期 2
·137
·
IF 2.935
Peihong Li,Xiaoman Hou,Lijie Qu,Xueyan Dai,Chunling Zhang
Poly(N-isopropylacrylamide) (PNIPAM) is a widely-studied polymers due to its excellent temperature sensitivity. PNIPAM-MAPOSS hybrid hydrogel, based on the introduction of acrylolsobutyl polyhedral oligomeric silsesquioxane (MAPOSS) into the PNIPAM matrix in the presence of polyethylene glycol, was prepared via radical polymerization. The modified hydrogels exhibited a thick, heterogeneous porous structure. PEG was used as a pore-forming agent to adjust the pore size. MAPOSS reduced the swelling ratios of gels, and decreased the LCST, causing the hydrogels to shrink at lower temperatures. However, its hydrophobicity helped to improve the temperature response rate. The incorporation of rigid MAPOSS into the polymer network greatly increased the compressive modulus of the hydrogel. It is worth noting that, by adjusting the amount of MAPOSS and PEG, the hydrogel could have both ideal mechanical properties and swelling behavior. In addition, hydrogel containing 8.33 wt % MAPOSS could achieve stable and sustained drug release. Thus, the prepared PNIPAM-MAPOSS hybrid hydrogel can serve as drug carrier for 5-fluorouracil and may have potential application in other biomedical fields.Keywords:hybrid hydrogel;MAPOSS;mechanical properties;swelling;drug release
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Canadian Journal of Chemistry
·
2018
·Vol. 96
·期 12
·
IF 1.084
Guanhong Liu,Peipei Ren,Fan Yang,Xuekai Dou,Jun Wang,Youtao Song
Two novel isomeric colorimetric probes are established for simultaneous determination of copper ions using 2-hydroxy-5-methoxybenzaldehyde fluorescein hydrazone (5-HMBA-FH) and 2-hydroxy-3-methoxybenzaldehyde fluorescein hydrazone (3-HMBA-FH). They are synthesized by reacting fluorescein hydrazide with 2-hydroxy-5-methoxybenzaldehyde and 2-hydroxy-3-methoxybenzaldehyde, respectively, and then characterized by 1H-NMR, 13C-NMR, and infrared spectrum. The addition of copper ions to the solutions of two novel colorimetric probes can generate the obviously peaks at 498 nm in UV–vis absorption spectra along with a rapid colour change from colourless to dark yellow. The detection limits of the method for Cu2+ ion were 3.442 × 10−6 mol/L and 3.682 × 10−6 mol/L separately for 5-HMBA-FH and 3-HMBA-FH, respectively. The additions of other metal ions hardly affect the determination of copper ions. The proposed method was successfully applied to the analysis of Cu2+ ions in various samples. This method possesses high sensitivity, high simplicity, and minimized interference and will provide a great advantage in detecting copper ions in the environment, food, and medical applications.
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Frontiers in Chemistry
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2018
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IF 4.155
Zeng Mengyan,Chen Kun,Tan Junyan,Zhang Jie,Wei Yongge
Oxidizing aldehydes to generate carboxylic acids is a crucial reaction in nature and in chemical industry. The aldehyde oxidation, an easily achieved process in liver cells, is inert toward autoxidation in industrial production and difficultly achieved under enzymatic condition (in water, at pH 7, at room temperature). Herein, we prepared a supramolecular catalyst which are nanospheres assembled in aqueous media by chromium centered Anderson polyoxometalates Na3[CrMo6O18(OH)3] (namely, CrMo6) and cationic pillar[5]arenes (namely, P5A) with 10 positive charges which can be used as the phase transfer catalysts (PTCs). This supramolecular catalyst was exploited on aldehydes oxidation under enzymatic condition with relatively good conversion. Through DLS monitoring, the diameters of nanospheres were variable while changing the charge ratios of the ionic complexes (P5A-CrMo6), and it is probably because of the closer charge ratios causing the more compact assemblies. Also, the nano-morphologies were monitored by TEM and SEM, and the nanostructures were characterized by zeta potential, the X-ray energy-dispersive spectroscopy (EDS), elemental analysis.
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FUEL PROCESSING TECHNOLOGY
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2018
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IF 3.956
Feng Huang,Wenzhi Li,Qingchuan Liu,Tingwei Zhang,Shengxin An,Dawei Li,Xifeng Zhu
A carbon solid acid was made by grafting benzenesulfonic acid groups on the tobacco stem-derived porous carbon, which was prepared from waste tobacco stem by simple carbonization . The catalyst was characterized by scanning electron microscope (SEM), N 2 adsorption-desorption, Fourier transform infrared spectroscopy (FT-IR), elemental analysis (EA), pyridine FT-IR spectroscopy and X-ray photoelectron spectroscopy (XPS). The catalyst exhibited excellent catalytic activity for 5-hydroxymethylfurfural (HMF) production from fructose and glucose in γ-valerolactone/water solvent, and high yields of HMF reached 93.7 and 43.8%, respectively. In addition, the high yields of total furans derived from fructose and glucose reached 96.8 and 54.1%, respectively. The benzenesulfonic acid group grafted onto the surface of inner pores of carbon allowed reusing the catalyst for at least five runs without obvious activity reduction. The good performance of the tobacco stem-derived carbon solid acid was determined by the unique surface active sites, such as high density of Brønsted acid, Lewis acid sites, oxygen-containing weak acidic sites and protonated nitrogen-containing functional groups. This study offered a promising approach for efficient carbohydrate conversion.
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Reaction Kinetics Mechanisms and Catalysis
·
2018
·Vol. 125
·期 2
·1055-1070
·
IF 1.515
Zhao Xinhong,Duan Weiting,Zhang Xiaoxiao,Ji Dong,Zhao Yu,Li Guixian
A modified solvent-free method has been developed to synthesize FeAPO-5 zeolite catalysts with hierarchical porous structure as well as high crystallinity and iron content. The effects of mechanochemical and low-temperature pretreatment, as well as the addition of hydrogen peroxide and seed crystals on the synthesis of FeAPO-5 were studied in detail. The composition and structural features of relatively pure resultant products were deeply analyzed by XRD, SEM, ICP-AES, CHN analysis, TG–DTA, UV–Vis diffuse reflectance spectroscopy and N 2 physisorption. Most importantly, low-temperature pretreatment towards H 2 O 2 -containing precursor mixtures can to a great degree improve the crystallinity of FeAPO-5 molecular sieve. Significantly, compared to the conventional micron-sized microporous FeAPO-5 zeolite, the hierarchical FeAPO-5 catalysts created by this modified solvent-free method show superior performance in phenol hydroxylation, in which the one with a high content of framework iron species exhibits the best catalytic performance, giving phenol conversion of about 40% and dihydroxybenzene selectivity of up to 80% at 50 °C within 3 h reaction time.
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ENZYME AND MICROBIAL TECHNOLOGY
·
2018
·
IF 2.932
Juan Han,Yunfeng Cai,Yun Wang,Lei Gu,Chunmei Li,Yanli Mao,Wenli Zhang,Liang Ni
In this work, a novel Ni 2+ &AABOB bifunctional core–shell magnetic composite nanoparticles (MNPs), Fe 3 O 4 @p(AABOB-co-AIM-Ni 2+ ), were synthesized for the immobilization of horseradish peroxidase (HRP). Two kinds of interaction are simultaneously incorporated to improve the stability and reusability of immobilized HRP: one is the coordination between Ni 2+ and amide group in HRP, and the other is the interaction of the wulff-type boronic acid group with cis-diol-containing HRP which belongs to a type of glycoproteins. Accordingly, the proposed approach achieved high enrichment capacity (174.75 mg/g, protein/beads), and the activity of immobilized HRP still achieved 80% after reuse for 5 cycles. The degradation efficiency of phenol in the presence of immobilized HRP reached 93% within 10 min, which was significantly higher than that of free HRP only about 50% within 20 min. In addition, the immobilized HRP can be easily separated from the reaction solution by an external magnetic field.
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Energy Technology
·
2017
·Vol. 6
·期 9
·1633-1641
·
IF 2.789
Fei Li,Guang Zhang,Yinghua Song
Herein, a facile method for constructing acid-base and Cr III species multi-functionalized multi-walled carbon nanotubes (CNTs) catalyst was reported. Acid and base, i.e., −SO 3 H and −NH 2 groups, were first grafted on CNTs to synthesize CNTs−SO 3 H−NH 2 bi-functional catalyst. Then the obtained CNTs−SO 3 H−NH 2 catalyst was further functionalized with Cr III species for further enhancement of acidity. The catalytic activity of fabricated catalysts were systematically studied for the one-pot conversion of cellulose to 5-hydroxymethylfurfural (HMF) in an ionic liquid solvent system. Results indicated that in the one-pot cellulose to HMF reaction, acidic sites were necessary for dissolved cellulose hydrolysis and fructose dehydration process, and the isomerization of glucose to fructose can be regarded as rate determining step. Co-existed base and Lewis acid sites were found to promote glucose isomerization to fructose, and Brønsted acid sites direct the dehydration of reactively formed fructose to HMF. And under the optimal conditions, the highest HMF yield of 40.2 % was achieved by multi-functional CNTs−SO 3 H−NH 2 −Cr III catalyst. Moreover, the fabricated catalyst in this study revealed excellent stability for recycle use in HMF production from cellulose.
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BIOSENSORS & BIOELECTRONICS
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2017
·
IF 7.78
Jie-Qiong Chen,Shi-Fan Xue,Zi-Han Chen,Shengqiang Zhang,Guoyue Shi,Min Zhang
A novel label-free ratiometric fluorescent probe is developed for the detection of H 2 O 2 based on GelRed/[G 3 T] 5 /Tb 3+ hybrid, in which GelRed (a nucleic acid dye) intercalated into the designed single-stranded DNA [G 3 T] 5 (i.e. GelRed/[G 3 T] 5 ) acts as a stable build-in reference with red emission and Tb 3+ sensitized by [G 3 T] 5 (i.e. [G 3 T] 5 /Tb 3+ ) as a sensitive response signal with green fluorescence. With the successive addition of Hg 2+ and cysteine (Cys) to GelRed/[G 3 T] 5 /Tb 3+ , the fluorescence of [G 3 T] 5 /Tb 3+ can be effectively quenched and recovered respectively, while the fluorescence of GelRed/[G 3 T] 5 remains unchangeable. Combined with these properties, we have demonstrated its application for label-free ratiometric fluorescence detection of H 2 O 2 with self-calibration. The sensing mechanism is based on the specific reaction between H 2 O 2 and Cys, the resulting disulfide reverses the Cys-mediated fluorescence changes of [G 3 T] 5 /Tb 3+ . This method is further applied to the monitoring of oxidase-related reactions. As the glucose oxidase (GOx)-biocatalyzed oxidation of glucose and the acetylcholine esterase/choline oxidase (AChE/ChOx) cascade yield H 2 O 2 , such two biocatalytic processes are successfully examined utilized our proposed method, indicating its potential broad applications in biomedical analysis. In addition, we have also demonstrated its feasibility for oxidase-based visual biosensing, in which only a handheld UV lamp is used. Importantly, coupled with our proposed visual biosensing, a realtime quantitative scanometric assays has been also demonstrated by using a smartphone with easy-to-access color-scanning APP as the detection platform. Compared to traditional methods, the proposed design is cost-effective, simple to prepare and easy-to-use without fluorescence labeling or chemical modification.
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