APPLIED SURFACE SCIENCE
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2019
·
IF 5.155
Zhixiang Ye,Li Lin,Ziyang Tan,Yu-Jia Zeng,Shuangchen Ruan,Jian Ye
Gap-enhanced Raman tags (GERTs) with built-in Raman molecules show excellent surface-enhanced Raman scattering (SERS) performance and great potential for biomedical applications. In this work, we add a silver (Ag) shell to gold (Au) single-shell GERTs (Au@BDT@Au) to form Au-Ag hybrid multi-shell nanoparticles . It is found that this modification enhances the SERS performance of the NPs and that the thickness of the Ag shell is a key factor in determining the enhancement. Double-shell bimetallic GERTs with a Au core, Au shell and exterior 2 nm-thickness silver shell (Au@BDT@Au@BDT@Ag) show the best SERS performance and good photostability. Moreover, we utilize the double-shell bimetallic GERTs to develop a new kind of SERS-based lateral flow immunoassay (LFIA), acheiving limit of detection as low as 0.7 mIU/mL (0.077 ng/mL). We demonstrated a simple way to fabricate sub-100 nm multi-shell bimetallic GERTs for use as SERS probes with strong Raman signals with potential for in vivo and in vitro application as bioimaging and biosensing probes.
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MICROCHIMICA ACTA
·
2019
·Vol. 186
·期 4
·1-8
·
IF 5.479
Mei He,Wang Xuedong,Zeng Tai,Huang Ling,Wang Qun,Ru Daoping,Huang Tongliang,Tian Falin,Wu Huimin,Gao Jimin
Gold nanobipyramids were synthesized by a seed-mediated growth method and then supported by multi-walled carbon nanotubes (denoted as AuNBP/MWCNTs). The electrocatalytic activity of the AuNBP/MWCNTs on a glassy carbon electrode (GCE) towards direct glucose oxidation and hydrogen peroxide reduction was superior to that of AuNBPs and MWCNTs. The modified GCE, operated at a typical working voltage of +0.15 V (vs. SCE) and in 0.1 M NaOH solution, exhibits a linear response in the 10 μM to 36.7 mM glucose concentration range with a 3.0 μM detection limit (at S/ N = 3) and a sensitivity of 101.2 μA mM −1 cm −2 . It also demonstrates good sensitivity towards hydrogen peroxide in at pH 7 solution at a working potential of −0.50 V (vs. SCE), with a linear response range from 5.0 μM to 47.3 mM, a sensitivity of 170.6 μA mM −1 cm −2 and a detection limit of 1.5 μM.
A electrochemical sensing platform based on the use of gold nanobipyramids and multi-walled carbon nanotubes nanocomposites (AuNBP/MWCNTs) is described for the determination of glucose and hydrogen peroxide.
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CHEMICAL ENGINEERING SCIENCE
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2019
·
IF 3.372
Jun Zhang,Kaijun Dong,Weimin Luo
A facile and mild method for the catalytic production of 2,5-dimethylfuran (DMF) from 5-hydroxymethylfurfural (HMF) was developed, which utilized commercial PdCl 2 as the catalyst together with the green, non-toxic and low-cost hydride source, polymethylhydrosiloxane (PMHS). A synergistic effect among hydrogen donor, in situ generated metallic Pd 0 species and acid site HCl in the reaction played a key role in DMF formation. Gratifyingly, the desirable yield of hydrodeoxygenation product DMF as high as 89.7% from HMF was attained at room temperature (298 K) in 0.5 h. Meanwhile, biomass derived sugars also could be converted into DMF in relative high efficiency via a one-pot reaction in the present system. A plausible pathway for the hydrodeoxygenation of HMF into DMF in the present system was also proposed. The study thus highlights a new perspective for a simple, green, and efficient hydrodeoxygenation of biomass derivatives under milder conditions, employing a readily available, inexpensive and practical catalytic system of PdCl 2 -PMHS-ethanol, but without any external hydrogen supplies and pre-reduction treatments.
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BIOSENSORS & BIOELECTRONICS
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2019
·
IF 9.518
Lilin Ge,Bin Li,Houxi Xu,Wenyuan Pu,Hang Fai Kwok
A simple and feasible electrochemical immunosensing protocol with glucometer readout was designed for the detection of low-abundance disease-related biomarker (alpha-fetoprotein; AFP) on the basis of backfilling rolling cycle amplification (RCA) with invertase-DNA 2 conjugates on the detection antibody. The assay consisted of the immunoreaction, RCA reaction, DNA 2 -invertase hybridization and glucose measurement. Initially, a sandwiched immunoreaction was carried out between anti-AFP capture antibody-coated microplate between nanogold-labeled pAb 2 detection antibody conjugated with DNA 1 primer (DNA 1 -AuNP-pAb 2 ) in the presence of target ATP . Thereafter, the carried primers triggered the RCA reaction in the presence of circular DNA template, polymerase and dNTP, to produce numerous repeated oligonucleotide sequences for hybridization with many invertase-DNA 2 conjugates. The carried invertase molecules accompanying the hybridization reaction hydrolyzed sucrose into glucose, thereby resulting in the amplification of the detectable signal on a handheld personal glucometer (PGM). Under optimum conditions, the developed immunoassay exhibited high sensitivity for the quantitative screening of AFP within a dynamic range of 0.1–100 ng mL −1 at a low detection limit of 0.087 ng mL −1 . Other biomarkers and proteins did not interfere the signals of this system. In addition, this method was utilized to determine human serum samples containing target AFP, and received well-matched results with the referenced enzyme-linked immunosorbent assay (ELISA) method.
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ACS Applied Materials & Interfaces
·
2019
·
IF 8.456
Wenfang Deng,Yi Peng,Hui Yang,Yueming Tan,Ming Ma,Qingji Xie,Shaowei Chen
Detection of hydrogen peroxide is of great significance for clinical diagnosis and biomedical research. Ratiometric detection represents an effective method that is generally based on horseradish peroxidase. In the present study, ruthenium ion-complexed carbon nitride (Ru–C3N4) nanosheets are found to serve as a peroxidase mimic and can catalyze the conversion of o-phenylenediamine to fluorescent 2,3-diaminophenazine in the presence of H2O2. The produced 2,3-diaminophenazine also results in the apparent quenching of the Ru–C3N4 photoluminescence due to the inner filter effect. These unique characteristics can be exploited for the construction of an effective, peroxidase-free ratiometric fluorescence framework for the detection of H2O2 and glucose, which has also been used in the successful detection of glucose in human serum. Results from this study not only demonstrate a new peroxidase mimic but also provide a novel ratiometric fluorescence platform for the detection of H2O2 and metabolites involving reactions of H2O2 generation in the absence of horseradish peroxidase.
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Journal of Materials Chemistry B
·
2019
·Vol. 7
·期 22
·3576-3581
·
IF 5.047
Xianqi Feng,Jun Xu,Yanxia Liu,Wenpeng Zhao
In this study, a novel and facile glucose detection system based on inverse opal hydrogels (IOHGs) was developed. Based on the intuitive structural colour, the gel sensors could be used for the detection of carbohydrates containing 1,2-cis-diol groups and diagnosis of diabetes without the assistance of sophisticated analysis instruments. Compared to the case of traditional opal sensors, the stable network structure of the IOHG samples endowed them with reusability for multiple times, which could suffer 10 cyclic detections without any reduction in sensitivity; possessing the combined advantages of high sensitivity, a stable network, and easy processing, IOHGs might open up a new avenue and propose a promising prospect in the detection and identification of diverse organic compounds.
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NEUROGASTROENTEROLOGY AND MOTILITY
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2019
·Vol. 31
·期 5
·e13556
·
IF 3.803
Yong Li,Tingting Yang,Qing Yao,Songsong Li,En Fang,Yankun Li,Chao Liu,Weimin Li
Background Intestinal barrier dysfunction is a key etiologic factor of irritable bowel syndrome (IBS). Metformin improves intestinal barrier function, although the underlying mechanism has yet to be fully explained. This study evaluates the protective effect of metformin on colonic barrier integrity and explores the underlying cellular mechanisms. Methods IBS-like rats were induced by maternal separation. Metformin was administered daily by gavage at 08:30, and rat pups were then separated from their mother. Visceral hyperalgesia and depression-like behaviors were evaluated by colorectal distension, sucrose preference tests, and forced swimming tests. Intestinal integrity was analyzed using sugar probes and transmission electron microscopy. Inflammatory factors and the levels of corticotropin-releasing factor were assessed by PCR and ELISA. The number of mast cells was evaluated by toluidine blue staining. Protein expression and localization were determined using Western blot and immunochemistry. Key Results Metformin pretreatment (a) reduced visceral hypersensitivity to colorectal distension, immobility time and enhanced sucrose consumption; (b) decreased urine lactulose/mannitol ratio and sucralose output; (c) inhibited the dilation of tight junction and prevented claudin-4 translocation; (d) inhibited mast cell activation and downregulated the expression of IL-6, IL-18, tryptase, PAR-2, and ERK activation; (e) inhibited claudin-4 phosphorylation at serine sites and interactions between clau-4 and ZO-1. Conclusions & Inferences Metformin may block mast cell activation to reduce PAR-2 expression and subsequently inhibit ERK activation and clau-4 phosphorylation at serine sites to normalize the interaction of clau-4 and ZO-1 and clau-4 distribution. Metformin may be clinically beneficial for patients with IBS or IBS-like symptoms.
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JOURNAL OF SURFACTANTS AND DETERGENTS
·
2019
·Vol. 22
·期 6
·1515-1520
·
IF 1.672
Jiazhi Chen,Yuan Li,Xiaotian Chen,Yuliang Mai,Minjie Gao,Junjie Zhang,Xi Wang
A general and efficient method, involving sand-milling pretreatment and base-catalyzed transesterification of sucrose and fatty acid methyl ester (FAME), was presented for the solvent-free synthesis of sucrose esters. A metastable homogeneous paste with a solid particle size of 13 μm ( D 50 ) was obtained by milling at 1000 rpm for 1 h. This reaction mixture generated a total SE yield of 88.2% with a methyl stearate (MS) conversion of 91.4% using K 2 CO 3 as a catalyst at 135 °C for 3 h at a stirring rate of 500 rpm, while those without milling ( D 50 , 153 μm) yielded a total sucrose fatty acid esters (SE) of 49.3% with a MS conversion of 83.1% under the same reaction conditions. The reaction kinetics revealed that the reaction mixture with milling pretreatment displays a shorter induction time and a faster reaction rate for the formation of SE. The promotion of the solvent-free synthesis of SE in the current study could be attributed to the reduction of solid particle sizes and the increased compatibility of solid–liquid phases. We believe that this strategy could be used as a general way for strengthening other heterogeneous reactions in the organic synthesis.
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MICROCHIMICA ACTA
·
2019
·Vol. 186
·期 9
·1-8
·
IF 5.479
Peng Yage,Dong Wenfei,Wan Le,Quan Xiaosai
Molybdenum disulfide quantum dots (MoS 2 QDs) are used in a fluorometric method for the determination of folic acid (FA) based on fluorescence quenching. The MoS 2 QDs synthesized by a hydrothermal method possess bright blue fluorescence (with excitation/emission maxima of 325/415 nm), quantum yield of 3.7%, and excellent storage stability in solution (30 days in the refrigerator). Their fluorescence is quenched by FA, and intensity decreases linearly in the 0.1 to 125 μM FA concentration range. The detection limit is 0.1 μM (at S/ N = 3), and the relative standard deviation (for n = 5) is 2.8% for 25 μM concentrations of FA. Studies on the quenching mechanism suggest that the effect is due to static quenching. The FA in commercial FA tablets was successfully determined.
Schematic representation of the hydrothermal method for the preparation of molybdenum disulfide quantum dots (MoS 2 QDs) with about 2.7 ± 0.5 nm diameter using Na 2 MoO 4 and L-cysteine as Mo and S sources, and the fluorescence method for the determination of folic acid (FA) based on fluorescence quenching of MoS 2 QDs.
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Catalysts
·
2019
·Vol. 9
·期 8
·648
·
IF 3.444
Xiao-Qing Gong,Chuan-Wan Wei,Jia-Kun Xu,Xiao-Juan Wang,Shu-Qin Gao,Ying-Wu Lin
The encapsulated enzyme system by metal-organic frameworks (MOFs) exhibits great potential in biofuel cells, pharmaceuticals, and biocatalysis. However, the catalytic efficiency and the enzymatic activity are severely hampered due to enzyme leaching and deficiency of storage stability. In this study, we immobilized cytochromec(Cytc) into dimethylimidazole-copper (Cu(Im)2) by biomimetic mineralization, and constructed a bioinorganic hybrid material, termed Cytc@Cu(Im)2. Encapsulated Cytcin Cu(Im)2with a nanosheet structure exhibited significantly improved catalytic efficiency, enzymatic activity and kinetic performance. The catalytic efficiency (kcat/Km) for Cytc@Cu(Im)2was ~20-fold higher compared to that of free Cytc. Moreover, the increased activity was not affected by long-term storage. Based on this system, we further constructed a multi-enzyme composite with glucose-oxidase (GOx), termed GOx-Cytc@Cu(Im)2, which exhibited greatly improved enzymatic activity, stability, and excellent selectivity for the detection of low concentrations of glucose. This strategy may provide new insights into the design of enzymes with high activity and stability, as well as the construction of multi-enzyme systems.Keywords:enzymatic immobilization;biomimetic mineralization;multi-enzyme;bioinorganic hybrid material;biosensors
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MICROCHIMICA ACTA
·
2019
·Vol. 186
·期 8
·1-10
·
IF 5.479
Zhu Yanyan,Zhang Xuan,Sun Jiameng,Li Meng,Lin Yulong,Kang Kai,Meng Yang,Feng Zhongliang,Wang Jing
Ultrafine platinum nanoparticles are grown on a 3D graphene framework (GF–Pt) via a hydrothermal method. The material, when placed on a glassy carbon electrode (GCE), displays enhanced electrocatalytic activity towards glucose oxidation. This is assumed to be the result of the numerous easily accessible active sites, an enlarged electrochemically active area, and the presence of multiple electron/ion transport channels. The modified GCE can be operated at a low potential (− 0.15 V vs. Ag/AgCl) has linear responses in the 0.1 μM − 0.01 mM and 0.01 mM – 20 mM glucose concentration range, and a 30 nM detection limit. It was applied to the rapid determination of glucose in human serum samples.
Schematic presentation of a glassy carbon electrode modified with ultrafine Pt nanoparticles grown on a graphene framework (GFs–Pt). GFs–Pt presents enhanced electrocatalytic activity towards glucose oxidation. GFs–Pt is used in a sensitive non-enzymatic amperometric glucose sensor.
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Journal of Ginseng Research
·
2019
·
IF 4.029
Lele Li,Li Ma,Yunlong Guo,Wenlong Liu,Yang Wang,Shuying Liu
Background The reports about valuable oligosaccharides in ginseng are quite limited. There is an urgent need to develop a practical procedure to detect and analyze ginseng oligosaccharides. Methods The oligosaccharide extracts from ginseng were permethylated by solid-phase methylation method and then were analyzed by ultra-high-performance liquid chromatography-Q-Orbitrap/MS. The sequence, linkage, and configuration information of oligosaccharides were determined by using accurate m/z value and tandem mass information. Several standard references were used to further confirm the identification. The oligosaccharide composition in white ginseng and red ginseng was compared using a multivariate statistical analysis method. Results The nonreducing oligosaccharide erlose among 12 oligosaccharides identified was reported for the first time in ginseng. In the comparison of the oligosaccharide extracts from white ginseng and red ginseng, a clear separation was observed in the partial least squares-discriminate analysis score plot, indicating the sugar differences in these two kinds of ginseng samples. The glycans with variable importance in the projection value large than 1.0 were considered to contribute most to the classification. The contents of oligosaccharides in red ginseng were lower than those in white ginseng, and the contents of maltose, maltotriose, maltotetraose, maltopentaose, maltohexaose, maltoheptaose, maltooctaose, maltononaose, sucrose, and erlose decreased significantly ( p < 0.05) in red ginseng. Conclusion A solid-phase methylation method combined with liquid chromatography–tandem mass spectrometry was successfully applied to analyze the oligosaccharides in ginseng extracts, which provides the possibility for holistic evaluation of ginseng oligosaccharides. The comparison of oligosaccharide composition of white ginseng and red ginseng could help understand the differences in pharmacological activities between these two kinds of ginseng samples from the perspective of glycans.
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