JOURNAL OF CHROMATOGRAPHY A
·
2020
·
IF 4.049
Muhammad Mujahid Ali,Zhiyuan Zhu,Mengyu Wang,Dilshad Hussain,Xia Gao,Jianfeng Wang,Zhenxia Du
Endogenous glycopeptides are significantly important in diverse pathological and physiological systems, but their direct analysis is severely hampered by their low abundance and presence of interfering species in biological fluids. In this study, we synthesized the amine-functionalized titanium metal-organic framework (NH 2 -MIL-125(Ti)) by a simple hydrothermal method, characterized and used for glycopeptides enrichment. The designed separation media is highly hydrophilic and stable which is suitable for hydrophilic interaction chromatography (HILIC). To make the process smooth, simple, reliable, and robust, NH 2 -MIL-125(Ti) crystals were packed in pipette-tip using hydrophilic melamine foam, as supporting frit. Free amine groups, present in the structure imparted hydrophilicity and a unique pattern of porosity, contributing to the size exclusion effect that excluded the large-sized proteins up to 1:700 peptide to protein ratio. The prepared MOF particles possessed regular porosity, high surface area, good hydrophilicity, and offered an in-tip flow-based set-up enhanced the enrichment performance for N -linked glycopeptides. The affinity material showed a detection limit of 1 fmol.µL −1 and selectivity up to 1:1000 (HRP digest to BSA digest). Moreover, repeatability and reusability were evaluated up to five rounds of enrichment using the same affinity tip, and scanning electron microscopic images revealed no structural changes in the MOF crystals. Finally, the MOF packed in pipette tip was applied to selectively capture the N- linked endogenous glycopeptides from a healthy saliva sample and 64 unique endogenous glycopeptides were identified. These results demonstrated the excellent potential of NH 2 -MIL-125(Ti) based affinity tip for glycopeptides which can be used to enrich trace glycopeptide biomarkers from the biological fluids.
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高影响因子
Sustainable Energy & Fuels
·
2019
·Vol. 3
·期 12
·3455-3461
·
IF 4.912
Bomin Feng,Xiuju Wu,Yanli Niu,Wei Li,Yunxi Yao,Weihua Hu,Chang Ming Li
Fe/N–C catalysts show great potential for the oxygen reduction reaction (ORR) but their catalytic activity should be further improved for practical application. Here, we report a high performance Fe/N–C hollow sphere with excellent ORR activity in both alkaline and acidic solutions. It is synthesized via pyrolysis of a melamine/Fe-incorporated polydopamine nanosphere precursor at 800 °C in an argon atmosphere. The N-rich melamine in the precursor affords abundant N dopants to form dense Fe–Nx active sites and also facilitates the formation of micropores in the catalyst via the gasification effect, together improving the ORR activity. The as-reported Fe/N–C catalyst outperforms the Pt/C catalyst in basic media (45 mV more positive half wave potential), approaches the Pt/C catalyst in acidic media (55 mV lower half wave potential), and exhibits impressive performance in Zn–air primary batteries.
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ANALYTICA CHIMICA ACTA
·
2019
·
IF 5.256
Huan Liu,Yue Hua,Yuanyuan Cai,Luping Feng,Shuai Li,Hua Wang
A nanocomposite nanozyme has been fabricated through mineralizing gold-silver bimetals into Hemin (Hem)-coupled melamine (MA) polymer matrix for visual colorimetric analysis of H 2 O 2 and glucose. Catalytic Hem was cross-linked onto MA scaffold for the mineralization of Au–Ag bimetals yielding the rod-like nanocomposite of MA-Hem/Au–Ag. It was discovered that the resulting nanocomposite could present high aqueous stability and especially improved catalysis, which was more than four-fold higher than that of native Hem. Catalytic kinetics studies indicate that the prepared nanocomposite nanozyme could present much higher affinities to the substrates than those of native Hem or even horseradish peroxidase . Herein, the so mineralized Au–Ag bimetals with the “silver effect” would act as “nanowires” for promoting the electron transferring of nanocomposite nanozyme. Moreover, the Hem-coupled MA polymer matrix with high specific surface area could ensure the high adsorption capacity for the reactant substrates and targeting analytes. The application feasibility of the developed nanocomposite nanozyme was demonstrated subsequently by the colorimetric assays for H 2 O 2 and glucose separately in milk and blood samples, with the linear ranges of 0.010–2.50 mM and 0.0050–2.0 mM, respectively. Such a bimetal mineralization-based fabrication route may open a new door toward the design of diverse nanocomposites nanozymes with improved catalysis and adsorption performances.
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Polymers
·
2018
·Vol. 10
·期 8
·873
·
IF 2.935
Cui-jiao Zhang,Zhi-yan Gao,Qiu-bo Wang,Xian Zhang,Jin-shui Yao,Cong-de Qiao,Qin-ze Liu
Adding melamine as additives in food products will lead to many diseases and even death. However, the present techniques of melamine detection require time-consuming steps, complicated procedures and expensive analytical apparatus. The fluorescent assay method was facile and highly sensitive. In this work, a fluorescence resonance energy transfer (FRET) system for melamine detection was constructed based on conjugated polymer nanoparticles (CPNs) and gold nanoparticles (AuNPs). The energy transfer efficiency is up to 82.1%, and the system is highly selective and sensitive to melamine detection with a lower detection limit of 1.7 nmol/L. Moreover, the interaction mechanism was explored. The results showed that the fluorescence of CPNs were firstly quenched by AuNPs, and then restored after adding melamine because of reducing FRET between CPNs and AuNPs. Lastly, the proposed method was carried out for melamine detection in powdered infant formula with satisfactory results.Keywords:fluorescent assay;fluorescence resonance energy transfer;conjugated polymer nanoparticles;gold nanoparticles;melamine
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高影响因子
RSC Advances
·
2018
·Vol. 8
·期 61
·34877-34882
·
IF 2.936
Xue Han,Zhixin Qin,Mengyao Zhao,Jiajia Song,Fei Qu,Fengli Qu,Rong-Mei Kong
The illegal adulteration of melamine in dairy products for false protein content increase is a strong hazard to human health. Herein, a simple and sensitive colorimetric method was developed for the quantification of melamine in dairy products based on a Cu2+-hydrogen peroxide (H2O2)-3,3′,5,5′-tetramethylbenzidine (TMB) system. In this strategy, Cu2+ exhibits peroxidase-like activity and can catalyze the oxidation of TMB to oxidized TMB (oxTMB) in the presence of H2O2 with a blue colour change of the solution. However, the presence of melamine quickly interacts with H2O2 leading to the consumption of H2O2 and thus strongly hinders the oxidation of TMB. Under the optimal conditions, the absorbance change of oxTMB has a linear response to the concentration of melamine from 1 to 100 μM with a detection limit of 0.5 μM for melamine. The proposed method has many merits including more simplicity, good selectivity, and more cost-effectiveness without using any nanomaterials. The method was further successfully applied to detect melamine in dairy products including milk and infant formula powder.
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Analytical Methods
·
2014
·Vol. 6
·期 12
·4124-4129
·
IF 1.938
Yanfeng Nong,Xiaoguo Ma,Shaofeng Fan,Yumian Yu
This paper describes a fast and low-cost method for determination of melamine, an emerging environmental contaminant, in soil and sediment using ultrasonic-assisted extraction coupled with high performance liquid chromatography. The parameters used for sample pretreatment and chromatographic analysis were tested and optimized. The samples were extracted by 5% (v/v) ammonia in methanol with ultrasonic assistance for 5 min, followed by centrifugation and nitrogen blowing, without a cleaning procedure such as solid phase extraction. Chromatographic separation was achieved by a cyano column using acetonitrile/water (5/95, v/v) as the mobile phase containing no ion-pair reagent, and the quantification was carried out by an external standard method. An excellent linearity for melamine was obtained over the concentration range of 0.05–5 mg kg−1 with a correlation coefficient of 0.9999. The limit of detection (S/N = 3) and the limit of quantification (S/N = 10) for melamine were 0.01 mg kg−1 and 0.04 mg kg−1, respectively. The recovery for melamine ranged from 95.0% to 105.9%, with relative standard deviations (RSDs) (n = 3) of 1.6–5.3%. The proposed method was shown to be simple, rapid, cheap, sensitive and accurate, and was applied to the analysis of melamine in soil and sediment samples with satisfactory results.
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PROGRESS IN ORGANIC COATINGS
·
2013
·
IF 1.848
Xiaofeng Wang,Bibo Wang,Weiyi Xing,Gang Tang,Jing Zhan,Wei Yang,Lei Song,Yuan Hu
A novel melamine-based hyperbranched polyphosphonate acrylate (MHPA), successfully synthesized via the Michael addition polymerization of 2-(2-amino-ethylamino)-4,6-bisethylamino-1,3,5-triazine with tri(acryloyloxyethyl) phosphate, was blended with the epoxy acrylate (EA) to prepare UV-cured flame retardant coatings. The study of their flammability revealed that MHPA can improve the flame retardancy and the sample with 45 wt% MHPA (EA3) showed a good intumescent behavior when combusted. The results of their thermal degradation displayed that MHPA had a dual effect on the thermal stability of EA: leading to its earlier degradation catalyzed by acidic species from the relatively weak phosphorus-bearing parts, but improving the thermal stability of the char layer at high temperature due to the formed intumescent phosphorus–carbon compounds. Besides, the total release amount of gas products of EA3 was much lower than that of pure EA and various flammable gases like hydrocarbons and highly toxic CO were also reduced
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MICROCHIMICA ACTA
·
2015
·Vol. 182
·期 11
·1983-1989
·
IF 3.741
Liu Guangyang,Yang Xin,Li Tengfei,Yu Hailong,Du Xinwei,She Yongxin,Wang Jing,Wang Shanshan,Jin Fen,Jin Maojun,Shao Hua,Zheng Lufei,Zhang Yanxin,Zhou Pan
We report on a method for the determination of the herbicide atrazine in tap water samples using melamine-modified gold nanoparticles (Mel-AuNPs). If a solution containing atrazine is added to a solution of such NPs, a color change occurs from wine-red to blue. This is due to a transition from monodisperse to aggregated Mel-AuNPs and caused by strong hydrogen bonding between atrazine and melamine. The color change can be monitored by a UV–vis spectrophotometer or with bare eyes. The ratio of the absorbances at 640 and 523 nm is linearly related to the logarithm of the atrazine concentration in the 0.165 to 16.5 μM range, and (with different slope) in the 16.5 μM to 330 μM range. The detection limit of atrazine is as low as 16.5 nM (S/N = 3). The method was successfully applied to the determination of atrazine in spiked tap water and gave recoveries that ranged from 72.5 % to 102.3 %.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2014
·
IF 2.235
Jing-Xiu Hu,Hao Shang,Jin-Gui Wang,Liang Luo,Qiang Xiao,Yi-Jun Zhong,Wei-Dong Zhu
Melamine based microporous organic polymers (MBMOPs) have been prepared via a one-pot polymerization using the Schiff base reaction. Various techniques such as FT-IR, Ar adsorption, SEM, TEM, and TG have been used to characterize the textural structure, porosity, and stability of the synthesized MBMOPs. The adsorption isotherms of CO2 and N2 on MBMOPs have been accurately measured at pressures up to 118 kPa and different temperatures. Ascribed to the specific affinity of amine groups for CO2, the robust microporous MBMOPs display excellent CO2 adsorption performance in terms of both capacity, up to 2.8 mmol g–1 at 273 K and 118 kPa, and selectivity over N2. Dual-site Langmuir (DSL) or single-site Langmuir (SSL) model describes well the equilibrium data for the adsorption of CO2 or N2 on MBMOPs, respectively. The binary gas adsorption isotherms predicted by the ideal adsorbed solution theory (IAST) show that the prepared MBMOPs exhibit very high selectivities for CO2 over N2, up to 83.7, for equimolar mixtures of CO2 and N2 at 298 K and 100 kPa. The dynamic CO2 adsorption capacity and selectivity against N2 over MBMOPs have been experimentally investigated by breakthrough column technique at 1 bar and 298 K, indicating that a complete separation is available. Remarkably, CO2 capture–regeneration experiments indicate that MBMOPs can be easily regenerated by only purging with He or N2 rather than by raising the temperature, suggesting that MBMOPs are promising candidates of pressure swing adsorption (PSA) adsorbents for the separation of CO2–N2.
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SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
·
2017
·
IF 2.536
Nan Gao,Pengcheng Huang,Fangying Wu
In this study, we have developed a method for rapid, highly efficient and selective detection of melamine . The negatively charged citrate ions form an electrostatic layer on gold nanoparticles (AuNPs) and keep the NPs dispersed and stable. When citrate-capped AuNPs were further modified with Triton X-100, it stabilized the AuNPs against the conditions of high ionic strength and a broad pH range. However, the addition of melamine caused the destabilization and aggregation of NPs. This may be attributed to the interaction between melamine and the AuNPs through the ligand exchange with citrate ions on the surface of AuNPs leading Triton X-100 to be removed. As a result, the AuNPs were unstable, resulting in the aggregation. The aggregation induced a wine red-to-blue color change, and a new absorption peak around 630 nm appeared. Triton X-100-AuNPs could selectively detect melamine at the concentration as low as 5.1 nM. This probe was successfully applied to detect melamine in milk. Furthermore, paper-based quantitative detection system using this colorimetric probe was also demonstrated by integrating with a smartphone.
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JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2017
·
IF 4.233
Jiucun Chen,Hui You,Liqun Xu,Tianhao Li,Xianquan Jiang,Chang Ming Li
Oil leakages often cause fatal disasters for environmental pollution but an efficient treatment of the oil spills is still very challenging. Sponge-substrates with superhydrophobicity and superoleophilicity have been attracted much attention for oil/water separation. In this study, an inexpensive commercial melamine sponge was chemically modified for the uses of oil spills treatment by oil/water separation. Inspiring from the superhydrophobic property of lotus leaf, pyrrole was polymerized by a simple vapor-phase deposition to encapsulate the raw melamine-formaldehyde (MF) sponge. The as-formed thin polypyrrole walls were utilized as reducing reagent to generate Ag nanoparticles on the capsuled sponge. Accordingly, a superhydrophobic melamine sponge with a two-tier hierarchical structure was achieved after fluorination , and this material was applied to absorb oil from water. The absorption capacity, absorption rate and recyclability were investigated. This superhydrophobic sponge exhibited an efficient and fast oil/water separation performance in complicated environment and could be applied in industrial production because of its low cost and simple fabrication procedure. This study presents a facile strategy for the fabrication of efficient oil sorbents based on a two-tier hierarchical structure, providing a novel means for the upgrading of engineered sorption materials.
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MICROCHIMICA ACTA
·
2016
·Vol. 184
·期 1
·279-287
·
IF 4.831
Wang Rong,Xu Yi,Wang Renjie,Wang Chunyan,Zhao Huazhou,Zheng Xiangquan,Liao Xing,Cheng Li
This article describes a microfluidic SERS chip-based rapid and high-throughput method for the determination of chemical and biological analytes, specifically of melamine. The chip consists of an indium tin oxide (ITO) glass plate modified with silver-gold nanocomposites (Ag-Au NCs) and a polydimethylsiloxane (PDMS) cover plate. The chip has five parallel microfluidic channels. The ITO glass provides electrical conductivity and has a smooth surface which makes it well suited for the deposition of the Ag-Au NC by electrodeposition and galvanic replacement. This technique allows good control of the morphology and composition of the composite. Under optimized conditions, the microfluidic SERS chip provides excellent sensitivity for 4-mercaptobenzoic acid (4-MBA). The detection limit is 0.1 nM and the SERS enhancement factor is 2.7×10 10 . The chip exhibits good stability over time and good reproducibility, with a RSD of 8.6 % between the 5 micro-channels. The chip was successfully applied to the determination of melamine in milk with a 10 nM detection limit and an analytical range from 10 nM to 0.1 mM. It is demonstrated that the microfluidic SERS chip developed here shows great promise for use in biochemical assays.
A microfluidic SERS chip employing gold nanocomposites (Ag-Au NCs) as SERS-active substrate was fabricated. Its SERS enhancement factor is 2.7⋅10 10 . The chip was applied to determinate melamine in milk with detection limit of 10 nM.
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