Analytical Methods
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2017
·Vol. 9
·期 31
·4533-4538
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IF 1.9
Fei Qu,Fangfang Xue,Jing Liu,Jinmao You
In this paper, a simple and green preparative strategy for synthesizing carbon nanodots (CNDs) is developed by a one-pot hydrothermal method, using ascorbic acid (AA) as the carbon source and polyethylene glycol (PEG) with a molecular weight of 1500 as the surface modification agent. Through changing the amount ratio of PEG-1500 to AA in the synthesis, we can obtain PEG-CNDs with different functions. For example, due to the thermosensitivity of PEG-1500, the as-prepared PEG1-CNDs exhibit unique temperature sensitivity when the mass ratio of PEG-1500 to AA is 24 : 1. A reversible change of PEG1-CNDs from the solid state to transparent solution with increasing temperature can be repeated several times. The optical transmittance signal of PEG1-CNDs linearly responds to temperature in the range of 20–65 °C. Besides, while the amount ratio of PEG-1500 to AA is 12 : 1, the obtained PEG2-CNDs lose thermal sensitivity and form a stable and fluorescent solution at room temperature. The emission of PEG2-CNDs can be quenched by Fe3+, while with the addition of paracetamol (PAR), the fluorescence is recovered because of forming chelates between Fe3+ and PAR. Under the optimized conditions, the linear range of PAR obtained is 0.03–30 μM with a detection limit of 13 nM. Finally, the proposed method is successfully applied to detect PAR in human serum and urine samples with satisfactory recoveries.
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RSC Advances
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2017
·Vol. 7
·期 37
·22722-22727
·
IF 3.108
Jing-Xiao Wang,De-Wei Ni,Shao-Ming Dong,Guang Yang,Yan-Feng Gao,Yan-Mei Kan,Xiao-Wu Chen,Yan-Peng Cao,Xiang-Yu Zhang
Nanocrystallized zirconium carbide (ZrC) powder was synthesized by an aqueous solution-based process using zirconium acetate and sucrose as starting reagents. Polyvinyl pyrrolidone (PVP) was used to combine the reactants to form a suitable precursor for ZrC. Through such a novel aqueous solution-based process, fine-scale mixing of the reactants is achieved in an environmentally friendly manner. The formed precursor can be converted to ZrC by carbothermal reduction reaction at 1600–1650 °C. Thanks to a limited amount of residual free carbon, the as-synthesized ZrC powder had an ultra-fine particle size (50–100 nm) and a low oxygen content less than 1.0 wt%. The conversion mechanisms from as-synthesized pre-ceramic precursor to ZrC powder were investigated systematically and revealed by means of FTIR, TG-DSC, XRD, Raman, SEM and TEM.
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FOOD HYDROCOLLOIDS
·
2017
·
IF 4.747
Huiqiong Yan,Xiuqiong Chen,Huangwang Song,Jiacheng Li,Yuhong Feng,Zaifeng Shi,Xianghui Wang,Qiang Lin
Although bacterial cellulose (BC) and bacterial cellulose nanocrystals (BCNs) have considered to be edible, non-toxic, biocompatible and biodegradable, there is still the dearth of reports of BC and BCNs as the emulsifiers of Pickering emulsions with respect to the applications in foods , cosmetics and medicines. In this work, BC with ultrafine network architecture and 8–40 nm crystalline microfibrils in diameter was produced by Acetobacter xylinum , and then it was hydrolyzed by sulfuric acid followed by the oxidation of hydrogen peroxide to prepare BCNs. The physicochemical properties of BC and BCNs were contrastively evaluated by FT-IR, XRD, TGA and dynamic light scattering (DLS). The emulsifying performances of BC and BCNs in the stabilization of olive oil Pickering emulsion were further evaluated by optical microscope (OM) and fluorescent microscope (FM). Experimental results showed that the sulfuric acid hydrolysis of BC induced the removal of the amorphous components and the cleavage of the crystalline microfibrils, making BCNs possess the initiating decomposition temperature of 350 °C, the crystallinity index (CrI) of 89.6%, average size of 259.6 nm with PDI of 0.26 and zeta potential at about −34.8 mV, which exhibited high thermal stability and good emulsifying performance in comparison with BC. Furthermore, the effects of pH and ionic strength on emulsion stability were also investigated. In comparison to BC, BCNs were more sensitive in response to the change of pH and ionic strength.
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CHINESE JOURNAL OF CHEMISTRY
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2017
·Vol. 35
·期 12
·1861-1868
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IF 1.852
Lijiang Lei,Yang Zhou,Yuwang Han,Hongman Zhang
Procalcitonin (PCT) is a sensitive and specific biomarker for sepsis diagnosis and widely used as a biomarker to improve the diagnosis of bacterial infections and to guide the antibiotic therapy. In our work, an improved up-converting nanoparticle (UCP) technology based on the immunochromatographic assay (UPT-ICA) was developed for rapid and quantitative detection of PCT. In order to further improve the accuracy, sensitivity and stability of the assay on the basis of our previous study, the UCP coupling with monoclonal antibody of PCT (UCP-Ab1) was freeze-dried under certain conditions. And the detections of PCT levels with UCP-Ab1 conjugates before and after freeze-drying were evaluated. The results show that, compared to the UCP-Ab1 conjugates without freeze-drying, the detection sensitivity of freeze-dried UCP-Ab1 is slightly improved, having a lower immunochromatogragh background and better stability. This improved method can provide a rapid, accurate, and relatively easy way for the clinical detection of PCT.
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RSC Advances
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2017
·Vol. 7
·期 37
·23021-23026
·
IF 3.108
Jing Zhao,Ling Wang,Dan Xu,Zhisong Lu
Silver nanoparticles (AgNPs) have been extensively studied as antimicrobial materials, but their capability of suppressing aflatoxin production has not been investigated. In this work, AgNPs with an average size of 4.5 nm were synthesized to inhibit the growth of Aspergillus flavus (A. flavus). Based on the anti-fungal assay, the concentration of 5 μg mL−1 was chosen to study the direct inhibiting effects of AgNPs on aflatoxin production. Results show that AgNP treatment could significantly decrease secretion of aflatoxin B1 from A. flavus. Real-time measurements of O2− with an electrochemical sensor reveal that the AgNPs could trigger the release of O2− from fungal mycelia. A mechanism involving O2− release is proposed to explain AgNP-caused depression of aflatoxin production from A. flavus. This is the first attempt to study AgNP-induced inhibition on aflatoxin generation and its possible mechanisms.
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TALANTA
·
2016
·
IF 4.035
Ruihua Tang,Hui Yang,Jane Ru Choi,Yan Gong,Jie Hu,Shangsheng Feng,Belinda Pingguan-Murphy,Qibing Mei,Feng Xu
Lateral flow assays (LFAs) hold great promise for point-of-care testing, especially in resource-poor settings. However, the poor sensitivity of LFAs limits their widespread applications. To address this, we developed a novel device by integrating dialysis-based concentration method into LFAs. The device successfully achieved 10-fold signal enhancement in Human Immunodeficiency Virus (HIV) nucleic acid detection with a detection limit of 0.1 nM and 4-fold signal enhancement in myoglobin (MYO) detection with a detection limit of 1.56 ng/mL in less than 25 min. This simple, low-cost and portable integrated device holds great potential for highly sensitive detection of various target analytes for medical diagnostics, food safety analysis and environmental monitoring.
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AAPS PHARMSCITECH
·
2017
·Vol. 19
·期 2
·541-550
·
IF 2.451
Liu Daichun,Galvanin Federico,Yu Ying
The purpose of this study was to prepare ginkgolide B (GB) lyophilized powder for injection with excellent appearance and stable quality through a formulation screening and by optimizing the freeze-drying process. Cremophor EL as a solubilizer, PEG 400 as a latent solvent, and mannitol as an excipient were mixed to increase the solubility of GB in water to more than 18 times (about from 2.5 × 10 −4 mol/L (0.106 mg/mL) to 1.914 mg/mL). Formulation screening was conducted by orthogonal design where the content of GB in the solution before lyophilization (using external standard method of HPLC) and reconstitution time after lyophilization were the two evaluation indexes. The optimized formulations were GB in an amount of 2 mg/mL, Cremophor EL in an amount of 16% ( v / v ), PEG 400 in an amount of 9% ( v / v ), mannitol in an amount of 8% ( w / v ), and the solution pH of 6.5. Through four single-factor experiments (GB adding order, preparation temperature of GB solution, adding amount, and adsorption time of activated carbon), the preparation process of GB solution was confirmed. The glass transition temperature of maximally GB freeze-concentrated solution was − 17.6°C through the electric resistance method. GB lyophilized powder began to collapse at − 14.0°C, and the fully collapsed temperature was − 13.0°C, which were determined by freeze-drying microscope. When the collapse temperature was determined, the primary drying temperature was obtained. Thereby, the freeze-drying curve of GB lyophilized powder was initially identified. The freeze-drying process was optimized by orthogonal design, the qualified product appearance and residual moisture content were the two evaluation indexes. The optimized process parameters and process were (1) shelf temperature, decreased from room temperature to − 45.0°C, at 0.5°C/min in 2 h; (2) shelf temperature increased from − 45.0 to − 25.0°C, at 0.1°C/min, maintained for 3 h, and the chamber pressure was held at 10 Pa; (3) shelf temperature was increased from − 25.0 to − 15.0°C at 0.1 °C/min, maintained for 4 h, and the chamber pressure was held at 10 Pa; and (4) shelf temperature was increased from − 15.0 to 20.0°C at 1.0 °C/min, maintained for 4 h, and the chamber pressure was raised up to 80 Pa. In these lyophilization process conditions, the products complied with relevant provisions of the lyophilized powders for injection. Meanwhile, the reproducibility was satisfactory. Post-freezing annealing had no significantly beneficial effects on shortening the freeze-drying cycle and improving the quality of GB lyophilized powder.
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APPLIED CATALYSIS B-ENVIRONMENTAL
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2017
·
IF 9.446
Lingyun Jiang,Lipeng Zhou,Jinyu Chao,Huiting Zhao,Tianliang Lu,Yunlai Su,Xiaomei Yang,Jie Xu
Conversion of biomass derived carbohydrates to alkyl levulinates is an important process due to the wide application of alkyl levulinates as chemicals and biofuel additives. Efficient conversion of cheap and abundant glucose to alkyl levulinates over easily separated and regenerated solid catalyst is highly desirable. Here, the transformation of glucose to methyl levulinate (MLE) was studied over dual solid acid catalysts. The synergistic effect of solid Brønsted (B) acid and solid Lewis (L) acid was observed. A combined catalyst system consisting of both B acid and L acid was found to be more efficient for the production of MLE from glucose. 62% yield of MLE was given over the combined catalyst of SO 4 2− /ZrO 2 and Sn-Beta prepared by postsynthesis method at 170 °C for 24 h. The roles of L acid sites of SO 4 2− /ZrO 2 and Sn-Beta, and B acid sites of SO 4 2− /ZrO 2 were discussed in detail. Alternative biomass-derived carbohydrates also gave moderate to good yields of MLE. Recyclability studies indicated that the combined catalyst system can be reused without significant change in the yield of MLE, proving its easy recovery and thermal stability during regeneration.
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INORGANIC CHEMISTRY
·
2017
·
IF 4.857
Lan Wang,Xiaojiao Kang,Daocheng Pan
Assisted with polyethylenimine, 4.0 L of water-soluble AgInS2 quantum dots (AIS QDs) were successfully synthesized in an electric pressure cooker. As-prepared QDs exhibit yellow emission with a photoluminescence (PL) quantum yield up to 32%. The QDs also show excellent water/buffer stability. The highly luminescent AIS QDs are used to explore their dual-functional behavior: detection of hydrogen peroxide (H2O2)/glucose and cell imaging. The amino-functionalized AIS QDs show high sensitivity and specificity for H2O2 and glucose with detection limits of 0.42 and 0.90 μM, respectively. A linear correlation was established between PL intensity and concentration of H2O2 in the ranges of 0.5–10 μM and 10–300 μM, while the linear ranges were 1–10 μM and 10–1000 μM for detection of glucose. The AIS QDs reveal negligible cytotoxicity on HeLa cells. Furthermore, the luminescence of AIS QDs gives the function of optical imaging.
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ACS Sustainable Chemistry & Engineering
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2016
·
IF 5.267
Li Duan,Li-Li Dou,Long Guo,Ping Li,E-Hu Liu
Deep eutectic solvents (DESs) are emerging as green and sustainable solvents for efficient extraction of bioactive compounds or drugs. This work aimed to comprehensively evaluate the potential and effectiveness of DESs for extraction of different types of natural compounds from biomass. Five Chinese herbal medicines including Berberidis Radix, Epimedii Folium, Notoginseng Radix et Rhizoma, Rhei Rhizoma et Radix, and Salviae Miltiorrhizae Radix et Rhizoma were selected to assess the efficiency of DESs on extraction of alkaloids, flavonoids, saponins, anthraquinones, and phenolic acids, respectively. Totally 43 types of choline chloride-, betaine-, and l-proline-based DESs with different polarity, viscosity, composition, and solubilization abilities were tailored to test their extraction efficiency, and the operation conditions were statistically optimized using response surface methodology to produce the most efficient process. In this work, DES solvents were first introduced to extract alkaloids and anthraquinones. The results indicated that most prepared DESs proved to be efficient solvents for extraction of alkaloids, but lower extractability for anthraquinones. The extraction capacity of DES may be correlated with their physical–chemical properties, including H-bonding interactions, polarity, viscosity, and pH. This study demonstrated that DESs were suitable green extraction solvents for selectively and efficiently extracting bioactive compounds from biomaterials.
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BIORESOURCE TECHNOLOGY
·
2016
·
IF 4.917
Tingwei Zhang,Wenzhi Li,Zhiping Xu,Qiyu Liu,Qiaozhi Ma,Hasan Jameel,Hou-min Chang,Longlong Ma
A novel carbon solid acid catalyst was synthesized by the sulfonation of carbonaceous material which was prepared by carbonization of sucrose using 4-BDS as a sulfonating agent. TEM, N 2 adsorption–desorption, elemental analysis, XPS and FT-IR were used to characterize the catalyst. Then, the catalyst was applied for the conversion of xylose and corn stalk into furfural in GVL. The influence of the reaction time, temperature and dosage of catalyst on xylose dehydration were also investigated. The Brønsted acid catalyst exhibited high activity in the dehydration of xylose, with a high furfural yield of 78.5% at 170 °C in 30 min. What’s more, a 60.6% furfural yield from corn stalk was achieved in 100 min at 200 °C. The recyclability of the sulfonated carbon catalyst was perfect, and it could be reused for 5 times without the loss of furfural yields.
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ACS Applied Materials & Interfaces
·
2016
·
IF 7.145
Jin-Wen Liu,Ying Luo,Yu-Min Wang,Lu-Ying Duan,Jian-Hui Jiang,Ru-Qin Yu
Graphitic carbon nitride (g-C3N4) nanosheets, an emerging graphene-like carbon-based nanomaterial with high fluorescence and large specific surface areas, hold great potential for biosensor applications. Current g-C3N4 nanosheets based fluorescent biosensors majorly rely on single fluorescent intensity reading through fluorescence quenching interactions between the nanosheets and metal ions. Here we report for the first time the development of a novel g-C3N4 nanosheets-based ratiometric fluorescence sensing strategy for highly sensitive detection of H2O2 and glucose. With o-phenylenediamine (OPD) oxidized by H2O2 in the presence of horseradish peroxidase (HRP), the oxidization product can assemble on the g-C3N4 nanosheets through hydrogen bonding and π–π stacking, which effectively quenches the fluorescence of g-C3N4 while delivering a new emission peak. The ratiometric signal variations enable robust and sensitive detection of H2O2. On the basis of the glucose converting into H2O2 through the catalysis of glucose oxidase, the g-C3N4-based ratiometric fluorescence sensing platform is also exploited for glucose assay. The developed strategy is demonstrated to give a detection limit of 50 nM for H2O2 and 0.4 μM for glucose, at the same time, it has been successfully used for glucose levels detection in human serum. This strategy may provide a cost-efficient, robust, and high-throughput platform for detecting various species involving H2O2-generation reactions for biomedical applications.
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