JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
·
2015
·Vol. 120
·期 1
·1009-1025
·
IF 2.042
Wang Xue-Jie,You Jin-Zong
The thermal decomposition processes for ten pyrimidine nucleoside analogs were measured with thermogravimetry and differential scanning calorimetry. The IR spectra, high-performance liquid chromatography, and liquid chromatography–mass spectrometry of pyrimidine nucleoside analogs and their residues of thermal decomposition at various temperatures were determined. The molecular bond orders of pyrimidines and pyrimidine nucleoside analogs were calculated with an ab initio method from the GAMESS program. We then discuss mechanisms of thermal decomposition in these pyrimidine nucleoside analogs. The results indicate that there are four types of mechanisms. The decomposition mechanism depends on the relative strength of the peptide bond and the amide bond within pyrimidine ring and whether or not accompanied by oxidation reaction. The substituent groups affect the thermal stability and the thermal decomposition mechanism of pyrimidine nucleoside analogs. Increasing the number of electron-donating groups on the pyrimidine ring and furan ring will enhance the peptide bond, and will elevate the temperature of thermal decomposition. There is a positive correlation between the molecular bond orders calculated by quantum chemistry and the thermal decomposition temperature of pyrimidine nucleoside analogs. The stronger the weakest bond order, the higher the decomposition temperature. The molecular bond orders thus can be used as a basis to judge molecular thermal stability for analog compounds with similar molecular structure, size, and energy.
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Analytical Methods
·
2014
·Vol. 6
·期 12
·4366-4372
·
IF 1.938
Lina Ma,Lan Ma,Min Su,Zhenxin Wang
Herein, a gold nanoparticle (GNP)-based colorimetric aptasensor has been developed for detecting adenosine with exonuclease III (Exo III) assisted recycling amplification. In this aptasensor, two kinds of single-stranded oligonucleotide functionalized GNP probes (Oligo 1-GNPs and Oligo 2-GNPs) are firstly hybridized with one complementary single-stranded oligonucleotide (linker) with the motif of adenosine aptamer, resulting in the formation of GNP aggregates (cross-linked GNPs). In the presence of adenosine, the linker would form a double-stranded DNA (dsDNA) with a recessed 3′-terminus due to its structural switching property, which would lead to disassembly of the cross-linked GNPs. However, upon the addition of Exo III, the dsDNA is enzymatically digested from the 3′-hydroxyl termini, liberating the adenosine. The released adenosine can then interact with another linker and a new round of enzymatic digestion is started. Therefore, remarkable signal amplification is achieved because the disassembly of cross-linked GNPs is strongly dependent on the free adenosine in the reaction mixture. The experimental results demonstrate that the Exo III-assisted GNP-based colorimetric aptasensor is more sensitive (ca. 10 times) than that without Exo III amplification. The Exo III-assisted GNP-based colorimetric aptasensor detects adenosine downs to 5.6 nM, with a linear relationship from 10 nM to 1 mM. Moreover, the Exo III-assisted GNP-based colorimetric aptasensor has been successfully applied to detect Jinshuibao capsule (JSBC) containing adenosine in both a buffer solution and a diluted human serum, demonstrating that this assay has great potential to be employed for detecting adenosine in real samples.
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BIOSENSORS & BIOELECTRONICS
·
2015
·
IF 6.409
Xiao-Jing Xing,Wan-Lu Xiao,Xue-Guo Liu,Ying Zhou,Dai-Wen Pang,Hong-Wu Tang
We developed a fluorescent aptasensor based on the making use of double-stranded DNA (dsDNA)/graphene oxide (GO) as the signal probe and the activities of exonuclease I (Exo I). This method takes advantage of the stronger affinity of the aptamer to its target rather than to its complementary sequence (competitor), and the different interaction intensity of dsDNA, mononucleotides with GO. Specifically, in the absence of target, the competitor hybridizes with the aptamer, preventing the digestion of the competitor by Exo I, and thus the formed dsDNA is adsorbed on GO surface, allowing fluorescence quenching . When the target is introduced, the aptamer preferentially binds with its target. Thereby, the corresponding nuclease reaction takes place, and slight fluorescence change is obtained after the introduction of GO due to the weak affinity of the generated mononucleotides to GO. Adenosine (AD) was chosen as a model system and tested in detail. Under the optimized conditions, smaller dissociation constant ( K d , 311.0 µM) and lower detection limit (LOD, 3.1 µM) were obtained in contrast with traditional dye-labeled aptamer/GO based platform ( K d =688.8 µM, LOD=21.2 µM). Satisfying results were still obtained in the evaluation of the specificity and the detection of AD in human serum, making it a promising tool for the diagnosis of AD-relevant diseases. Moreover, we demonstrated the effect of the competitor on the LOD, and the results reveal that the sensitivity could be enhanced by using the rational competitor. The present design not only constructs a label-free aptamer based platform but also extends the application of dsDNA/GO complex in biochemical and biomedical studies.
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TALANTA
·
2015
·
IF 3.545
Qing Wang,Yao Long,Lin Yao,Li Xu,Zhi-Guo Shi,Lanying Xu
A mixed-mode chromatographic stationary phase , C18-DTT (dithiothreitol) silica (SiO 2 ) was prepared through “thiol-ene” click chemistry. The obtained material was characterized by fourier transform infrared spectroscope, nitrogen adsorption analysis and contact angle analysis. Chromatographic performance of the C18-DTT was systemically evaluated by studying the effect of acetonitrile content, pH, buffer concentration of the mobile phase and column temperature. It was demonstrated that the novel stationary phase possessed reversed phase liquid chromatography (RPLC)/hydrophilic interaction liquid chromatography (HILIC) mixed-mode property. The stop-flow test revealed that C18-DTT exhibited excellent compatibility with 100% aqueous mobile phase. Additionally, the stability and column-to-column reproducibility of the C18-DTT material were satisfactory, with relative standard deviations of retention factor of the tested analytes (verapamil, fenbufen , guanine , tetrandrine and nicotinic acid) in the range of 1.82–3.72% and 0.85–1.93%, respectively. Finally, the application of C18-DTT column was demonstrated in the separation of non-steroidal anti-inflammatory drugs, aromatic carboxylic acids , alkaloids, nucleo-analytes and polycyclic aromatic hydrocarbons . It had great resolving power in the analysis of various compounds in HILIC and RPLC chromatographic conditions and was a promising RPLC/HILIC mixed-mode stationary phase.
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MICROCHIMICA ACTA
·
2014
·Vol. 182
·期 1
·185-192
·
IF 3.719
Wang Huiqi,Feng Wei,Jia Qiong
We show that graphene oxide functionalized with 3-aminophenylboronic acid represents a useful new adsorbent for the selective enrichment of the nucleosides, adenosine, guanosine, uridine, and inosine, which then were quantified by capillary electrophoresis. The analytes were separated within 10 min using a borate buffer of pH 9.3 (containing sodium dodecyl sulfate) at an operating voltage of 25 kV, a temperature of 20 °C, a sample injection time of 5 s, and with UV detection at 254 nm. The effects of sample pH, sample flow rate, eluent type, and eluent flow rate were optimized. Under the optimized conditions, the enrichment factor was determined to be 10. A linear relationship was obtained over the 0.1 to 100 μg mL −1 concentration range, with regression coefficients of >0.9991. The intra-day and inter-day relative standard deviations of this method were in the range of 3.1–5.0 % and 4.8–7.5 %, respectively. The method was applied to the determination of the nucleosides in (spiked) traditional Chinese medicine injection samples, and recoveries ranged from 70.8 to 106.7 %.
Graphene oxide functionalized with 3-aminophenylboronic acid was prepared for the enrichment of nucleosides combined with capillary electrophoresis. After optimizing various experimental parameters, the method was successfully applied to the determination of nucleosides in traditional Chinese medicine injection samples.
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NEW JOURNAL OF CHEMISTRY
·
2017
·Vol. 41
·期 15
·7133-7141
·
IF 3.269
Yue Hu,Wei Huang,Yukui Tong,Qinfei Xia,Miaomiao Tian
Boronate-affinity hollow molecularly imprinted polymers (h-MIPs) were prepared and applied to the selective enrichment of four nucleosides in traditional Chinese medicine injection samples, followed by HPLC detection. The synthesis mechanism of the h-MIPs was studied. Due to a large amount of boronic acid groups were introduced by 3-aminophenylboronic acid (APBA) in the outermost polymer shell of the MIPs, which was of great importance for improving the enrichment efficiency of the nucleosides. Furthermore, owing to the hollow structure of the h-MIPs, more binding cavities were located on the inner and outer surfaces of the h-MIPs, which could facilitate the removal of template molecules from the polymers and the rebinding of the target molecules to the polymers. Under optimal conditions, the detection limits of the four nucleosides were in the range of 0.012–0.033 μg mL−1. At the different spiked levels, the recoveries of the nucleosides were in the range of 63.8–108.9%. The proposed method was successfully applied to determine four nucleosides in five injection samples. The boronate-affinity h-MIPs provided a promising selective enrichment platform for precise nucleoside analysis.
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NEW JOURNAL OF CHEMISTRY
·
2017
·Vol. 41
·期 17
·9230-9235
·
IF 3.269
Xin Shen,Lei Xu,Wanying Zhu,Bingzhi Li,Junli Hong,Xuemin Zhou
In this paper, a novel turn-on fluorescence aptasensor has been designed for adenosine detection based on fluorescence resonance energy transfer (FRET) from single-stranded DNA labeled carbon dots (ssDNA-CDs) to aptamer modified gold nanoparticles (aptamer-AuNPs). In the absence of adenosine, the fluorescence of ssDNA-CDs was quenched by aptamer-AuNPs via the formation of an aptamer–ssDNA duplex. The introduced adenosine competed to displace ssDNA-CDs by specifically binding to the aptamer, resulting in the recovery of the quenched fluorescence of ssDNA-CDs. Under optimized conditions, the increase in fluorescence intensity was proportional to the concentration of adenosine with a linear range of 10–500 nM and allowed a limit of detection as low as 4.2 nM. In addition, this method was successfully applied to adenosine determination in human serum samples with satisfactory results.
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MICROCHIMICA ACTA
·
2017
·Vol. 184
·期 8
·2629-2636
·
IF 4.58
Cai Tianpei,Zhang Haijuan,Rahman A. F. M. Mustafizur,Shi Yan-Ping,Qiu Hongdeng
Carbon dots derivatized from N-(β-aminoethyl)-γ-aminopropyl-methyldimethoxysilane (AEAPMS) were coated onto silica microparticles. These particles (Sil-CDs) are shown to be an excellent stationary phase for use in hydrophilic interaction chromatography. Analytes including sulfonamides, nucleosides and bases, flavones and amino acids can be well separated on this stationary phase. Compared to a silica stationary phase functionalized with AEAPMS only, the Sil-CDs show enhanced separation performance. The selectivity factors of three nucleosides and bases (1.02–1.09) and four sulfonamides (1.04–1.11) on AEAPMS functionalized silica stationary phase were improved to 1.10–1.20 and 1.13–1.15 respectively on Sil-CDs stationary phase. This is attributed to the higher number of surface functional groups due to the introduction of carbon dots. The successful application of the Sil-CDs stationary phase highlights the potential of carbon dots as a modified material in chromatography.
Schematic presentation of the preparation of silanized carbon dots coated onto silica microparticles. The material represents a new stationary phase for hydrophilic interaction chromatography. It shows improved separation performance compared to a silane-only functionalized silica stationary phase.
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JOURNAL OF SEPARATION SCIENCE
·
2016
·Vol. 39
·期 7
·1347-1356
·
IF 2.741
Ting Cheng,Shuqiang Zhu,Bin Zhu,Xiaoyan Liu,Haixia Zhang
The nucleoside or modified nucleoside level in biological fluids reflects the pathological or physiological state of the body. Boronate affinity absorbents are widely used to selectively extract nucleosides from complex samples. In this work, a novel functionalized absorbent was synthesized by attaching 4-mercaptophenylboronic acid to gold nanoparticles on modified attapulgite. The surface of the attapulgite was modified by poly(acryloyloxyethyltrimethyl ammonium chloride) by atom transfer radical polymerization, creating many polymer brushes on the surface. The resultant material exhibited superior binding capacity (30.83 mg/g) for adenosine and was able to capture cis -diol nucleosides from 1000-fold interferences. Finally, to demonstrate its potential for biomolecule extraction, this boronate affinity material was used to preconcentrate nucleosides from human urine and plasma.
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TALANTA
·
2016
·
IF 4.035
Huihui Li,Ting Cheng,Shuxia Wang,Xinyue Zhu,Haixia Zhang
Boronate affinity materials have been widely used for selective capture of cis-diol-containing molecules, but most do not have sufficient extraction efficiency. We have prepared boronic acid-functionalized attapulgite, and then it was coated with imidazolium-based ionic liquid , 1-dodecyl-3-methylimidazolium bromide (C 12 mimBr), via physical self-assembly process. The extraction efficiency of the material increased dramatically after coated with C 12 mimBr, and its enrichment ratios for nucleosides increased by 9- to 282-fold. Besides, the C 12 mimBr-coated adsorbent did not lose selectivity and was able to capture cis-diols in the presence of a 100-fold excess of interferences. C 12 mimBr-coated material was applied to selective enrichment of nucleosides from human urine. The limits of detection and the limits of quantification were in the range of 0.06–0.46 ng mL −1 and 0.20–1.53 ng mL −1 , respectively. Reproducibility of the method was determined with relative standard deviations≤9.9%. The recoveries of the target nucleosides from spiked human urine were in the range of 87.8–109.6%. In our preception, self-assembly ionic liquid layer can serve as a promising alternative to improve the extraction efficiency of boronate affinity materials.
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JOURNAL OF CHROMATOGRAPHY A
·
2017
·
IF 3.981
Chusheng Liu,Haibin Li,Qiqin Wang,Jacques Crommen,Haibo Zhou,Zhengjin Jiang
The quest for higher column efficiency is one of the major research areas in polymer-based monolithic column fabrication. In this research, two novel polymer-based HILIC monolithic columns with 400 μm I.D. × 800 μm O.D. were prepared based on the thermally initiated co-polymerization of N,N -dimethyl- N -(3-methacrylamidopropyl)- N -(3-sulfopropyl) ammonium betaine (SPP) and ethylene glycol dimethacrylate (EDMA) or N,N’ -methylenebisacrylamide (MBA). In order to obtain a satisfactory performance in terms of column permeability, mechanical stability, efficiency and selectivity, the polymerization parameters were systematically optimized. Column efficiencies as high as 142, 000 plates/m and 120, 000 plates/m were observed for the analysis of neutral compounds at 0.6 mm/s on the poly(SPP- co -MBA) and poly(SPP- co -EDMA) monoliths, respectively. Furthermore, the Van Deemter plots for thiourea on the two monoliths were compared with that on a commercial silica based ZIC-HILIC column (3.5 μm, 200 Å, 150 mm × 300 μm I.D.) using ACN/H 2 O (90/10, v/v) as the mobile phase at room temperature. It was noticeable that the Van Deemter curves for both monoliths, particularly the poly(SPP- co -MBA) monolith, are significantly flatter than that obtained for the ZIC-HILIC column, which indicates that in spite of their larger internal diameters, they yield better overall efficiency, with less peak dispersion, across a much wider range of usable linear velocities. A clearly better separation performance was also observed for nucleobases, nucleosides, nucleotides and small peptides on the poly(SPP- co -MBA) monolith compared to the ZIC-HILIC column. It is particularly worth mentioning that these 400 μm I.D. polymer-based HILIC monolithic columns exhibit enhanced mechanical strength owing to the thicker capillary wall of the fused-silica capillaries.
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JOURNAL OF CHROMATOGRAPHY A
·
2016
·
IF 3.926
Jialiang Guo,Yuan Xiao,Yuanjing Lin,Jacques Crommen,Zhengjin Jiang
Low column efficiency for enantioseparations in capillary liquid chromatography (CLC) is a major problem commonly encountered with β -cyclodextrin ( β -CD) functionalized polymer-based monoliths. In order to investigate the effect of the crosslinker type on enantioseparation performance, three commonly used crosslinkers, i.e. 1,4-bis(acryloyl)piperazine (PDA), ethylene dimethacrylate (EDMA) and N , N -methylenebisacrylamide (MBA), were copolymerized using the one-pot approach with glycidyl methacrylate-mono-6-amino-6-deoxy- β -CD (GMA-NH 2 - β -CD) as functional monomer. The three monolithic columns, including poly(GMA-NH 2 - β -CD- co -PDA) and poly(GMA-NH 2 - β -CD- co -MBA), as well as the previously reported column poly(GMA-NH 2 - β -CD- co -EDMA) were systematically compared with respect to morphology, permeability, β -CD density, retention mechanism and efficiency. The enantioseparation ability of each column was evaluated using 14 chiral compounds, including mandelic acid derivatives, profens, N -derivatized amino acids, and herbicides, as test substances. The β -CD-functionalized monolith with MBA as crosslinker was found to exhibit higher polarity, higher column efficiency and better enantioseparation performance than those with PDA or EDMA as crosslinker.
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