CHINESE JOURNAL OF ANALYTICAL CHEMISTRY
·
2018
·
IF 0.824
Qiang LI,Yuan-Yuan LI,Nan ZHU,Zhu-Xian GAO,Tian-Jun LI,Tong ZHOU,Yu-Long MA
Graphene oxide (GO) was covalently coupled to the surface of amino silica gel by amide bond. β -cyclodextrin ( β -CD) was further chemically bonded with GO to prepare a novel chiral stationary phase. The resulting material was characterized by Fourier transform-infrared (FT-IR) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), elemental analysis and thermogravimetric analysis (TGA). The separation of seven enantiomers was improved in varying degrees. Meanwhile, the stationary phase showed typical characteristics of hydrophilic interaction chromatography (HILIC), and four small nucleoside molecules were separated with the mobile phase of methanol-acetonitrile-water (45:45:10, V/V ) in the HILIC mode. In addition, the separation mechanism of the stationary phase was further explored by studying the effects of mobile phase composition, temperature and pH value on the analyte retention. The low temperature was conducive to the separation of analytes at 20–60 °C. The addition of protonated solvent methanol significantly decreased the retention time of the four analytes. The change of pH affected the degree of protonation of the analyte, the interaction between analytes and the stationary phase, and retention time of analytes. The results showed that GO and β -CD played a synergistic effect in the chiral resolution of the chromatographic stationary phase. The retention of analytes in HILIC was attributed to their mixed-mode retention mechanisms including hydrophilic interaction, electrostatic interaction, hydrogen bonding, π-π stacking and so on.
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JOURNAL OF CHROMATOGRAPHY A
·
2014
·
IF 4.258
Chusheng Liu,Weijia Chen,Guangxin Yuan,Yao Xiao,Jacques Crommen,Shihai Xu,Zhengjin Jiang
In order to investigate the effects of the crosslinker on the separation performance of polar zwitterionic sulfoalkylbetaine-type monolithic columns, three crosslinkers, i.e. 1,4-bis(acryloyl)piperazine (PDA), ethylene dimethacrylate (EDMA) and N , N ′-methylenebisacrylamide (MBA), were copolymerized with the hydrophilic monomer N , N -dimethyl- N -acryloyloxyethyl- N -(3-sulfopropyl)ammonium betaine (SPDA). The chromatographic properties of the three hydrophilic sulfoalkylbetaine-type monolithic columns, including column efficiency, permeability, porosity and separation mechanism, were systematically compared using scanning electron microscopy or micro-HPLC. Good selectivity in micro-HPLC separations was achieved on all three monolithic columns. The results indicate that the polarity of sulfoalkylbetaine-type monolithic columns may be related to the polarity of the crosslinker, which further affects column selectivity and efficiency. A particularly high column efficiency (100,000 plates/m) was obtained on the novel poly(SPDA- co -PDA) monolithic column at a linear velocity of 1 mm/s using thiourea as test analyte. A higher resolution was also observed for nucleobases, nucleosides and hydrophilic organic acids on this novel poly(SPDA- co -PDA) monolithic column compared to the other two columns.
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TALANTA
·
2014
·
IF 3.511
Wei Yin,Huihui Chai,Renhua Liu,Changhu Chu,John A. Palasota,Xiaohui Cai
Iminodiacetic acid (IDA) is dicarboxylic acid amine, which may produce stronger interaction with polar or charged compounds than bidentate α,β-amino acid. In this article, a novel type of tridentate zwitterionic HILIC stationary phase was prepared by covalently bonding N-benzyl IDA on silica gel via copper( I ) catalyzed Huisgen azide-alkyne 1,3-dipolar cycloaddition (CuAAC). The structure of this stationary phase and all related intermediates was confirmed by NMR, FT-IR, MS spectrum and elemental analysis . The new stationary phase showed good HILIC characteristics and high column efficiency (the theoretical plate number is up to 44000 plates m −1 in the case of guanosine) in the application of separation of polar compounds, including organic acids , organic bases, as well as highly polar and hydrophilic compounds, such as cephalosporins and carbapenems . Most of them displayed good peak shape and selectivity.
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ANALYTICAL AND BIOANALYTICAL CHEMISTRY
·
2015
·Vol. 407
·期 12
·3525-3529
·
IF 3.436
Cheng Ting,Li Huihui,Ma Ying,Liu Xiaoyan,Zhang Haixia
2,4-Difluoro-3-formyl-phenylboronic acid (DFFPBA)-modified magnetic attapulgite (ATP-Fe 3 O 4 -NH 2 -DFFPBA) was synthesized and employed to capture and enrich cis -diol-containing biomolecules. The resulting material exhibited a high saturation magnetization value of 20.71 emu/g, allowing the absorbent to be conveniently magnetically separated. Combining the Fe 3 O 4 nanoparticles with the high specific surface area of attapulgite yielded a material with a high capture capacity (13.78 mg/g) for adenosine. Furthermore, ATP-Fe 3 O 4 -NH 2 -DFFPBA was found to possess remarkable selectivity for adenosine at a low molar ratio of adenosine/2-deoxyadenosine (1:500). The potential applications of this material were explored by using it to extract five nucleosides from urine samples, and the results demonstrate that it can decrease matrix interference and selectively enrich analytes.
Boronic-acid-functionalized magnetic attapulgite could selectively enrich the nucleosides in urine samples with the help of an external magnet
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BIOSENSORS & BIOELECTRONICS
·
2015
·
IF 6.409
Ying Zhu,Xiao-chun Hu,Shuo Shi,Ru-ru Gao,Hai-liang Huang,Yan-yan Zhu,Xiao-yan Lv,Tian-ming Yao
We report here an ultrasensitive strategy based on the recognition-induced conformational alteration of aptamer and fluorescence turn-on abilities of guanine-rich (G-rich) DNA sequence in proximity to silver nanoclusters for adenosine triphosphate (ATP), adenosine (A) and thrombin (TB) detection. Herein, we designed two tailored DNA sequences noted as complementary DNA (abbreviated as c-DNA) and signal probe DNA (abbreviated as s-DNA), respectively. c-DNA is designed as a special structure consisting of a sequence complementary to aptamer at the 3′-end and a guanine-rich DNA sequence at the 5′-end; s-DNA contains a cytosine-rich sequence responsible for Ag NCs templated synthesis at the 3′-end and a link sequence (part of aptamer) complementary to partial of the c-DNA at the 5′-end. In the presence of target, the aptamer associated with the target, resulting in the formation of duplex DNA (dsDNA), the DNA–Ag NCs thereafter could close to the guanine-rich sequence, leading to enhanced fluorescence signal readout. The widespread application of the sensing system is achieved success in the detection of three biomolecules . ATP, adenosine and thrombin in the range of 0.5-8.0 μM, 0.5-7.0 μM and 50-900 nM could be linearly detected with the detection limits of 91.6 nM, 103.4 nM and 8.4 nM, respectively. This label-free and turn-on fluorescent sensing system employing the mechanism proposed here turns out to be sensitive, selective, and convenient for the detection of biomolecules without washing and separation steps.
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RSC Advances
·
2015
·Vol. 5
·期 128
·106161-106170
·
IF 3.84
Li Gao,Jin Du,Chaozhan Wang,Yinmao Wei
Boronate adsorbents have been widely used in the extraction of cis-diol-containing molecules, but most do not have efficient capacity due to limited binding sites on their surface. In this work, a high binding capacity dendrimer-modified boronate affinity material (SiO2@dBA) was synthesized via introducing tris(2-aminoethyl)amine as branching points and using poly(amidoamine) as the main dendrimeric scaffold before modification by boronate groups. The high density of amino groups on the dendrimer supplied a large number of binding sites for modifying boronate groups. Thus the adsorption capacity (676.8 μmol g−1 for catechol, 771.3 μmol g−1 for dopamine, 770.0 μmol g−1 for adrenaline) of SiO2@dBA was greatly improved. Moreover, when coupled with large-volume injection and online column-switching solid phase extraction, SiO2@dBA was able to capture cis-diols from 10 000-fold interference and enrichment factors reached up to 497–514, which was 26- to 51-fold higher than those of analogous non-dendrimer materials. Especially, the proposed method exhibited a striking low limit of detection, 0.24 ng mL−1 for cytidine, 0.52 ng mL−1 for uridine, 0.37 ng mL−1 for guanosine, 0.67 ng mL−1 for adenosine. Finally, the method was successfully applied to online determination of trace nucleosides in healthy human urine. In conclusion, the prepared adsorbent has potential to effectively enrich a large range of trace cis-diol substances in real samples.
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ANALYTICA CHIMICA ACTA
·
2015
·
IF 4.513
Chaozhan Wang,Huanhuan Xu,Yinmao Wei
Boronate affinity adsorption is uniquely selective for cis-diol-containing molecules. The preparation and application of boronate affinity materials has attracted much attention in recent years. In this work, a high-capacity boronate affinity adsorbent was prepared by surface-initiated reversible addition–fragmentation chain transfer polymerization (SI-RAFT). Commercial aminated poly(glycidyl methacrylate) (PGMA) microspheres were modified with the chain transfer agent (CTA) S-1-dodecyl-S-(α,α-dimethyl-α-acetic acid)trithiocarbonate (DDATC). Boronate-affinity adsorbents were then prepared via SI-RAFT polymerization employing 3-acrylamidophenylboronic acid (AAPBA) as the monomer . The Fourier transform infrared spectroscopy (FT-IR), nitrogen adsorption and desorption measurements have proven the successful grafting of AAPBA on PGMA microspheres surface. The boronate affinity adsorbents thus prepared possess much higher adsorption capacity (99.2 µmol/g of adenosine) and both faster adsorption and desorption speed towards ribonucleosides , the adsorption and desorption could be completed in 2 min. The high selectivity of the adsorbents to ribonucleosides was verified in the presence of a large excess of deoxynucleosides. The boronate affinity adsorbents were then employed for sample pretreatment before HPLC analysis of ribonucleosides in serum. The ribonucleosides were effectively enriched by boronate affinity dispersive solid-phase extraction (BA-DSPE), with high mass recoveries and good precision. The simultaneous determination of uridine and guanosine in calf serum was achieved by utilizing the standard addition method, their contents were determined to be 170 ± 11.6 ng/mL and 39.6 ± 4.4 ng/mL respectively. The results proved that the prepared boronate affinity materials could be applied for sample pretreatment of cis-diol containing molecules in biological samples.
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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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JOURNAL OF SEPARATION SCIENCE
·
2016
·Vol. 39
·期 12
·2365-2373
·
IF 2.741
Li Gao,Yinmao Wei
Various cotton fiber based boronate-affinity adsorbents are recently developed for the sample pretreatment of cis -diol-containing biomolecules, but most do not have efficient capacity due to limited binding sites on the surface of cotton fibers. To increase the density of boronate groups on the surface of cotton fiber, polyhedral oligomeric silsesquioxanes were used to modify cotton fiber to provide plentiful reactive sites for subsequent functionalization with 4-formylphenylboronic acid. The new adsorbent showed special recognition ability towards cis -diols and high adsorption capacity (175 μg/g for catechol, 250 μg/g for dopamine, 400 μg/g for adenosine). The in-pipette-tip solid-phase extraction was investigated under different conditions, including pH and ionic strength of solution, adsorbent amount, pipette times, washing solvent, and elution solvent. The in-pipette-tip solid-phase extraction coupled with high-performance liquid chromatography was used to analyze four nucleosides in urine samples. Under the optimal extraction conditions, the detection limits were determined to be between 5.1 and 6.1 ng/mL (S/N = 3), and the linearity ranged from 20 to 500 ng/mL for these analytes. The accuracy of the analytical method was examined by studying the relative recoveries of analytes in real urine samples with recoveries varying from 83 to 104% (RSD = 3.9–10.2%, n = 3).
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