MICROCHIMICA ACTA
·
2019
·Vol. 186
·期 3
·1-9
·
IF 5.479
Zhao Pengcheng,Chen Chao,Ni Meijun,Peng Longqi,Li Chunyan,Xie Yixi,Fei Junjie
An electrochemical dopamine sensor with a temperature-controlled switch was constructed by using a mixture of thermo-sensitive block copolymers (type tBA-PDEA-tBA), graphene oxide (GO) and multi-walled carbon nanotubes (MWCNTs). If the temperature is below 26 °C, the polymer on the glassy carbon electrode (GCE) is stretched, the distance between the MWCNTs is large, and the charge transfer resistance (R ct ) of the composite also is large. In the presence of dopamine, the electron transfer at the electrode is strongly retarded and in the “off” state. At above 38 °C, the polymer is shrunk and the R ct is much smaller. The presence of dopamine results in a rapid electron transfer at the GCE, and this is referred to as the “on” state. At temperatures between 26 and 38 °C, the polymer shrinks slightly and has a “spring-like” state. There is a linear relationship between the response current (typically measured at a potential as low as 0.16 V vs. Ag/AgCl) and temperature. The response to dopamine is linear in the 0.06 to 4.2 μM and 4.2 to 18.2 μM concentration range, and the detection limit is 42 nM. Conceivably, this approach provides a novel approach towards the design of electrochemical sensors based on the use of thermo-sensitive polymers.
Schematic presentation of reversible and temperature-controlled electrochemical response of dopamine on the thermo-sensitive block copolymers (tBA-PDEA-tBA) / multi-walled carbon nanotubes (MWCNTs) / graphene oxide (GO) / glassy carbon electrode (GCE).
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高影响因子
CELLULOSE
·
2019
·Vol. 26
·期 5
·3285-3297
·
IF 3.917
Gao Hejun,Du Jia,Liao Yunwen
Abstract A novel biological magnetic adsorbent was successfully constituted with sugarcane bagasse (SCB), polyetherimide (PEI) and Fe 3 O 4 . The physicochemical properties of the adsorbent (Fe 3 O 4 @PEI/SCB) were investigated by SEM, BET, VSM, XRD, TGA, FT-IR, XPS, TEM and UV–Vis. The adsorption capacity was measured using Cr(VI) and orange II as adsorbates. The effects of initial pH, dosage, contact time, and ionic strength on the adsorption capacity were investigated in detail. Fe 3 O 4 @PEI/SCB is a mesoporous material and the mass ratio of Fe 3 O 4 :PEI:SCB is about 5:2:15. Adsorption capacity could reach 182.28 mg/g and 1893.57 mg/g for Cr(VI) and orange II at room temperature, respectively. Fe 3 O 4 @PEI/SCB is a green and economical material, which is very easily regenerated, reused, and separated in the adsorption. The most important factor is the ionic strength and major adsorption interaction was electrostatic in this work. Graphical abstract
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BULLETIN OF MATERIALS SCIENCE
·
2019
·Vol. 42
·期 1
·1-7
·
IF 1.264
Hassan Mohamed,Ran Xiaoku,Yuan Ying,Luan Xiaoning,Dou De-Qiang
Ginsenoside transformation has received significant attention from scientists. The main objective of this study is to use immobilized enzymes in ginsenoside transformation. Factors affecting immobilization process were studied; carrageenan beads treated with polyethyleneimine and then activated using glutaraldehyde (GA) were used for snailase enzyme immobilization. The functionalized gel beads were characterized using Fourier transform infrared spectroscopy to verify the modification process. Furthermore, the optimum conditions for biotransformation of ginsenoside were also deliberated and showed that optimum biotransformation pH is 4.5 and 5–5.5 and temperature 50 and \(60^{\circ }\hbox {C}\) for free and immobilized snailase, respectively. Michaelis constants, \(K_{\mathrm{m}}\) and \(V_{\max }\) , were also studied. The immobilized enzyme retains 96% of its initial activity after being used 10 consecutive times. The results clearly suggested that ginsenoside transformation was performed using immobilized snailase; this process can reduce the transformation cost as the enzyme can be reused many times.
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Journal of Inorganic and Organometallic Polymers and Materials
·
2019
·Vol. 29
·期 4
·1192-1197
·
IF 1.637
Zhao YingRui,Yang Chao,Zhang HongYan,Qiang Gen,Fan HuiLing
Two kinds of ZnO/SiO 2 composite (labled as SZ-1 and SZ-2) were synthesized by sol–gel method and characterized by X-ray diffraction (XRD) patterns, XPS (X-ray photoelectron spectroscopy) spectra and Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectra. Water adsorption on the prepared sample was studied by in situ DRIFT. The as-synthesized SZ-1 and SZ-2 sample have different surface property due to the various aging methods in the sample preparation processes, thus showing different results of water adsorption. The adsorption sites (Si atom in Si–O–Si bond) on the surface of SZ-2 for water molecule are occupied by the –OCH 3 group and the hydrophilicity of SZ-2 is weaker, in comparison to SZ-1, which inhibits the formation of water film and ultimately decreases desulfurization performance of SZ-2. So, the desulfurization performance can be changed by altering the hydrophilicity of sorbent.
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JOURNAL OF RADIOANALYTICAL AND NUCLEAR CHEMISTRY
·
2019
·Vol. 319
·期 3
·1219-1225
·
IF 1.186
Dai Ying,Cao Bin,Zhong Shimin,Xie Guanbao,Wang Youqun,Liu Yuhui,Zhang Zhibin,Liu Yunhai,Cao Xiaohong
Comparing with the traditionally immiscible two-phase extraction, the homogeneous liquid–liquid extraction technique shows potential in industrial separation engineering due to nearly infinite contact interface. In this work the ionic liquid (IL) compounds such as N -(carboxymethyl)- N , N -dimethylethanaminium bis-trifluoromethane-sulfonimide ([DHbet][Tf 2 N]) and N -(carboxyethyl)-trimethylammonium bistrifluoromethane-sulfonimide ([THbet][Tf 2 N]) were synthesized. The homogeneous extraction behaviors of europium with two ILs were studied as functions of solution pH, ionic strength, contact time, and initial europium concentration. The results indicated that both homogeneous extractions were dependent on pH and independent on ionic strength. The extraction capacities for [DHbet][Tf 2 N] and [THbet][Tf 2 N] were 3.29 mmol/L and 3.16 mmol/L, respectively. ILs could be recovered using 1.0 M hydrochloric acid. The mole-ratio method indicated the formation of a mononuclear complex between the europium ion and IL. Total europium extraction efficiencies of more than 91% for [DHbet][Tf 2 N] and more than 90% for [THbet][Tf 2 N] were obtained by quadruple-stage countercurrent extraction. The result proves the feasibility of the homogeneous liquid–liquid extraction technique as an alternative option for europium separation from aquatic solution.
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JOURNAL OF MATERIALS SCIENCE
·
2018
·Vol. 54
·期 4
·3648-3660
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IF 2.993
Liao Xiaofeng,Li Hongqiang,Su Xiaojing,Zhan Haomiao,Lai Xuejun,Zeng Xingrong
With the deteriorating environmental pollution by oil spill accidents and industrial sewage emissions, stimuli-responsive superwettable materials have been of considerable interest for its intriguing application in oil–water separation. Herein, we report a facile room temperature method to fabricate mussel-inspired cotton fabric with pH-responsive superwettability, by combining in situ generation of silver particles to construct roughness with self-assembly of long alkyl thiols terminated with methyl and carboxyl groups to endow hydrophobicity and responsiveness. The fabricated pH-responsive cotton fabric showed superhydrophobicity with water contact angle (WCA) up to 153° under acidic and neutral conditions while superhydrophilicity with WCA at 0° under alkaline condition. Importantly, the cotton fabric was successfully applied in bidirectional oil–water separation, exhibiting high separation efficiency and excellent reversibility. Furthermore, the pH-responsive cotton fabric also demonstrated superior self-cleaning property and antibacterial activity to E. coli and S. aureus . Our method to construct pH-responsive cotton fabric is simple, and no special techniques, chemicals or control of atmosphere is required. Our findings conceivably stand out as a new tool to fabricate functional superwettable materials and surfaces with responsiveness to external stimuli for various oil-pollution treatments and other potential applications.
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Journal of Inorganic and Organometallic Polymers and Materials
·
2018
·Vol. 29
·期 2
·423-428
·
IF 1.754
Liu Jian-Ping,Zhang Han-Yu,Wang Jun
We developed a seepage method for fabricating a non-enzymatic glucose sensor based on a hybrid of polypyrrole (PPy), silver amalgam (AgHg) and natural biomineralization hydroxyapatite (BioHAP). The fabricated sensor (PPy/BioHAP/AgHg) with unique structure presents a synergistic effect of the hybrid for glucose sensing. Many active sites on BioHAP help to adsorb glucose molecules. AgHg is used as the source of Ag for electrocatalyzing glucose oxidation. PPy forms a wonderful tubular array in BioHAP, improving its conductivity. The sensitivity and the limit of detection reach 2.21 µA M cm −2 and 0.27 mM for glucose ( S / N = 3), respectively. It also shows a good selectivity to ascorbic acid, uric acid and dopamine.
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JOURNAL OF SOLID STATE ELECTROCHEMISTRY
·
2018
·Vol. 23
·期 1
·269-276
·
IF 2.509
Wang Zenghao,Xie Yongshuai,Xu Chonghe,Shi Shuying,Wang Lin,Zhang Guanghui,Wang Xinqiang,Zhu Luyi,Xu Dong
Lithium-ion batteries have been receiving more and more attention because of the energy crisis. As an important subassembly of lithium-ion batteries, the separator greatly affects the safety of the batteries. Herein, we report for the first time, a novel method fabricated separator by mixing zirconia fibers with polyvinylidene fluoride (PVDF) via papermaking process. The separators possess abundant pores and uniform structure after the phase inversion process. The separator properties were systematically studied at different proportion of PVDF. We find that when the content of PVDF is 40%, the separator has high porosity (77.69%), high electrolyte uptake (523.3%), and excellent thermal stability (thermal shrinkage ratio is 0% at 500 °C). In addition, the rate capability, cycle performance, and ionic conductivity are also investigated. We anticipate that the papermaking method of zirconia fibers will provide a strategy to fabricate a promising separator for enhanced electrochemical performance and high safety of lithium-ion batteries.
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JOURNAL OF POLYMER RESEARCH
·
2019
·Vol. 26
·期 7
·1-7
·
IF 1.53
Deng Hongyang,Xu Yewei,Lei Hong,Lei Yonglin,Huo Jichuan,Zhang Lin
3,5-bis(2-benzimidazolyl) pyridine (3,5-BP) is synthesized and a series of benzimidazolyl and pyridyl-containing poly (ether ether ketone) s (mPEEK-BPs) with precise structures and high yield are prepared through a nucleophilic displacement reaction of 3,5-BP, m-dihydroxybenzene and 4,4′-difluorobenzophenone. X-ray diffraction results show that mPEEK-BPs are amorphous. All the synthesized polymers posses high glass transition temperatures ( T g = 211~270 °C) and high thermal stability ( T d5% = 506~549 °C in N 2 , 471~564 °C in air). The polymers have good solubilities in common organic solvents. With the increase of benzimidazole and pyridine units content, the thermal properties and solubility of the as-prepared polymers improved. Additionally, the resulted polymers exhibit excellent fluorescence performance and the fluorescence emission peak appears at 425 nm.
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APPLIED MICROBIOLOGY AND BIOTECHNOLOGY
·
2019
·Vol. 103
·期 15
·6119-6128
·
IF 3.67
Zhang Wenhe,Zhu Tianhui,Li Hengyu,Qin Fengyu,Zhang Feiting,Zhang Rui,Jia Xian,Qin Bin,You Song
Biocatalytic reduction catalyzed by aldo-keto reductases (AKRs) is a valuable approach for asymmetric synthesis of chiral alcohols. In this study, four novel aldo-keto reductases with significant activity and stereoselectivity toward a variety of α-keto esters and halogen-substituted acetophenones were identified by genome mining. Through analysis of the crystal structure and multiple-sequence alignment of the starting AKR YvgN from Bacillus subtilis , residues F25 and W113 were proposed as the key positions that might control the stereoselectivity of YvgN. F25S and F25S/W113F variants of YvgN were able to improve its activity and stereoselectivity toward some α-keto ester compounds and halogen-substituted acetophenone derivatives. In addition, similar enhancement of catalytic activity and stereoselectivity was also found in the other three AKRs with corresponding mutations of starting YvgN.
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高影响因子
MICROCHIMICA ACTA
·
2019
·Vol. 186
·期 5
·1-6
·
IF 5.479
Ma Haiyan,Xue Ning,Wu Shujie,Li Zongbing,Miao Xiangmin
The authors describe a method for detection of Hg 2+ by using positively charged gold nanoparticles ((+)AuNPs) as a quencher of the fluorescence of DNA-capped silver nanoclusters (DNA-AgNCs) which are negatively charged. In the presence of Hg 2+ , a DNA duplex is formed through T-Hg 2+ -T coordination chemistry. The duplex can be digested by exonuclease III to form smaller DNA fragments. This leads to the release of the AgNCs and the recovery of fluorescence, best measured at excitation/emission wavelengths of 460/530 nm. The (+)AuNPs and Hg 2+ are also released and can be reused for target recycling signal amplification. Based on these findings, a method is worked out for the determination of Hg 2+ that works in the 5.0 pM to 10 nM concentration range and has a detection limit as low as 2.3 pM. It is highly selective because of the highly specific formation of T-Hg 2+ -T bonds.
By using ultrastable and positively charged gold nanoparticles as fluorescence quenchers and exonuclease assisted signal amplification, a method is developed for the sensitive and selective detection of Hg 2+ in water samples.
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MICROCHIMICA ACTA
·
2019
·Vol. 186
·期 7
·1-10
·
IF 5.479
Yue Yuhua,Jiang Li,Li Zhen,Yuan Jie,Shi Haizhu,Feng Shun
A glassy carbon electrode (GCE) was consecutively modified with amino groups and phosphate groups, and then loaded with Zr(IV) ions. Fourier transform infrared spectrophotometry, field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy and cyclic voltammetry were used to characterize the morphologies and electrochemical properties. The sensor was used to detect p-nitrophenyl-substituted organophosphorus pesticides, with methyl-parathion (MP) as the model analyte. Under optimized conditions, the oxidation current of square wave voltammetry (typically measured at around −0.28 V vs. saturated calomel electrode) increases linearly in the 1.0 to 100 ng mL −1 MP concentration range, and the detection limit is 0.25 ng mL −1 (at a signal to noise ratio of 3). Average recoveries from (spiked) real water samples are 99.9–102.2%, with relative standard deviations of 0.3–2.6% ( n = 3) at three levels. The reliability and accuracy of the method was validated by HPLC.
Zr(IV) modified GCE is prepared via three steps. The electrode shows high specificity and selectivity towards methyl‐parathion. And the linear range is 1.0 ‐ 100.0 ng mL‐ 1 with the detection limit as low as 0.25 ng mL‐ 1 with SWV.
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