1.Investigation on Properties of Collagen Nanowires Quasiepitaxially Grown on Mica Lattice Plane
Deliang YANG ; Fanxi ZENG ; Ming SUN ; Wenhua GU ; Li LI
Chinese Journal of Analytical Chemistry 2017;45(4):465-470,中插1
Collagen fibrils and hydroxyapatite might recognize each other at the mesoscale by multiple cooperative interactions due to their intrinsically repetitive structured surfaces, and thus effectively directing the biomineralization, a biological process involving regulating the growth of bones, teeth and other organs. In this work, we developed a simple technique to prepare nanowire arrays of biological macromolecules by reversely using the biomineralization mechanism, with results similar to the hot wall epitaxy, a molecular beam deposition technique under vacuum. With this technique, we successfully cultured 5-10 μg/mL rat tail type I collagen monomer solutions into collagen nanowire arrays on the mica (001) lattice plane along one unique direction across the whole cleavage surface. The atomic force microscope experiments indicated that the nanowires in the arrays became more crowded with higher monomer concentration, but their width and height remained unchanged, about 60.0 nm and 1.5 nm, respectively. The collagen nanowire coating enhanced the hydrophilicity of the mica surface, reducing the contact angle from 25.8° to 9.5°. Based on the characterization results of electron back scattering diffraction and transmission electron microscope, the collagen nanowires were most likely to be oriented along the mica [110] direction, which validated the quasiepitaxial growth mechanism in more details.
2.Study on Binding Characteristics of Aminocarboxyl Chelating Ligands for Metal Ions
Bin CHEN ; Shihui WANG ; Rong LI ; An FAN
Chinese Journal of Analytical Chemistry 2017;45(9):1303-1308
The feasibility of frontal chromatography for determining the complexation stability constant KML and total mole of binding site Λo was demonstrated by the accuracy and precision binding experiments between metal ions (Cu2+, Ni2+ and Co2+) and chelating ligand (IDA), in which R2>0.98 and RSD <5%.To further prove the universality of the frontal chromatography, the changing rules of KML values between Cu2+, Ni2+, Co2+ and IDA, Asp, L-Glu were examined under NaAc-HAc, Na-PB and Tris-HCl buffer systems.The results showed that the binding strength of chelating ligands for metal ions followed IDA>Asp>Glu;binding strength of metal ions for chelate ligands followed Cu2+>Ni2+>Co2+;and the binding effect with NaAc-HAc buffer was the best.In aqueous solution, quantum computing of binding energy (ΔE) and gibbs free energy (ΔG) between chelating ligand and metal ion was performed at the M06/6-311++G (d, p) level.According to ΔE and ΔG, the binding rules between chelating ligand and metal ion were predicted theoretically.These rules were basically in agreement with above experimental results.The present work provided effective method for studying on binding characteristics of metal ions for aminocarboxyl chelating ligands, thus exhibited a good foundation for improving the stability of immobilized metal affinity chromatographic column and solving the leakage of metal ions from the column in the process of competitive elution.
3.Preparation and Properties of Tremella-like Fe-N-C Composite Catalyst for Oxygen Reduction Reaction
Yanping HUANG ; Hongyan YUAN ; Jian ZHANG ; Yahui YANG ; Hongtao LIU
Chinese Journal of Analytical Chemistry 2017;45(9):1297-1302
The Fe-N-C composite catalyst was prepared by the thermal decomposition of the chelate precursors based on Fe central ions and o-phenylenediamine ligands.It was observed from the scanning electron microscopy that the crumpled carbon micro-and nano-sheets were intertwined to form a free-standing tremella-like 3D structure.The N2 adsorption/desorption experiments revealed that the composite contained ample micro-and meso-pores and had a specific surface area of 290 m2/g.Graphitic C and multi-crystal Fe3C as main components were confirmed by the X-ray diffraction, and N-doping in the general form of graphite N and pyridine N was also verified by X-ray photoelectron spectroscopy.The electrochemical measurement showed that the tremella-like Fe-N-C composite catalyzed oxygen reduction through a four-electron path in an alkaline solution, and its activity was comparable to the commercial Pt/C catalyst.After 2000 cycles, the limited current density of the Fe-N-C catalytic electrode only decreased less than 5%, and the half-wave potential shift negatively 5 mV, which suggested that the Fe-N-C composite catalyst had better catalytic stability than the commercially used Pt/C catalyst.
4.Accurate Detemination of Isotopic Abundance of Intracellular Metabolites of Saccharopolysporaerythraea Based on Ultra Performance Liquid Chromatography-Triple Quadrupole Mass Spectrometry
Han MOU ; Ming HONG ; Xiaoyun LIU ; Minchao LI ; Mingzhi HUANG ; Ju CHU ; Yingping ZHUANG ; Siliang ZHANG
Chinese Journal of Analytical Chemistry 2017;45(9):1264-1270
A method for measuring 13C isotopic abundance of intracellular metabolites of Saccharopolysporaerythraea by ultra-high performance liquid chromatography (UPLC)-triple quadrupole mass spectrometry was established.First, the chromatographic conditions of UPLC were optimized, and then the MS conditions such as unique tube lens voltage, collision energy, and ion pair were optimized.On the bases of length of the parent and daughter ions carbon chains and whether the daughter ions contain 13C atoms, the one-to-one method, one-to-many method and SIM method were established for measuring 13C isotopic abundance.Then these methods were used to measure naturally labeled intracellular metabolite standards and 13C labeled samples, and according to the gap between the experimental value and the theoretical value, the best method was established for each metabolite of different characteristics.The results showed that one-to-one method was most effective for measuring the metabolites of daughter ions not containing 13C atoms represented by sugar phosphates, one-to-many method was the best for measuring the metabolites of both parent and daughter ions containing 13C short carbon chains represented by carboxylic acids, SIM method could play a role in measuring the metabolites of both parent and daughter ions containing 13C long carbon chains represented by coenzyme A.This method had a good measurement precision and could be applied to the measurement of Saccharopolysporaerythraea intracellular metabolites, which contributed to the consequent study of metabolic mechanism and the efficient expression of erythromycin.
5.Synthesis of Boronic Acid-functionalized Soluble Dendrimers and Its Application in Detection of Human Liver Microsomal Glycoprotein Based on Enzyme-linked Immunosorbent Assay
Tiantian LI ; Liyuan ZHANG ; Zhenlong YU ; Xiaochi MA ; Sa DENG
Chinese Journal of Analytical Chemistry 2017;45(9):1259-1263
The glycoproteins in the biological sample are low abundance and are susceptible to be inhibited and interfered by other non-glycoproteins.An enrichment step is usually required before the glycoprotein analysis, but the operation steps of conventional solid-phase-based glycoprotein enrichment methods are difficult to be compatible with the most classical enzyme-linked immune sorbent assay (ELISA) technique.In this study, a novel water-soluble dendrimer based boronic acid capture (DBC) material was developed using PAMAM 4.0 as the carrier and boronic acid as the affinity group.The method was applied to the detection of glycoproteins in human liver microsomes using ELISA.In this study, the DBC enrichment conditions were optimized by model glycoprotein, and then its sensitivity and anti-interference ability were investigated.This method was applied to the enrichment of glycoproteinsin human liver microsomal.The results showed that the enrichment selectivity of DBC for glycoprotein could be up to 100000 folds, and the enrichment signal of glycoprotein could be increased by 100 times.Therefore, the ELISA method using DBC as a novel enrichment material for glycoprotein had high sensitivity and selectivity in detection of biological samples with only one simple incubation step, which was useful for glycoproteins researches.
6.Synthesis of Naphthalimide-based Biothiols Probe and Detection of Amino Acids Containing Sulfhydryl Groups
Jing GUO ; Qingwen LIU ; Jianshi DU ; Xiangyi KONG ; Yan SONG ; Qingbiao YANG ; Qing ZHAO ; Yaoxian LI
Chinese Journal of Analytical Chemistry 2017;45(9):1330-1338
A novel probe (DNSBN) towards biothiols on the basis of 4-hydroxynaphthalimide as fluorophores and 2, 4-dinitrobenzenesulfonyloxy group as specific recognition site was designed and synthesized.The result of absorption and fluorescence spectral analyses indicated that the probe had high sensitivity and selectivity towards cysteine (Cys), homocysteine (Hcy) and glutathione (GSH), and the detection was not affected by other 17 kinds of natural amino acids.Meanwhile, it was confirmed that DNSBN was a ratiometric probe through the fluorescence titration experiment, and the fluorescent intensity at 555 nm had a high linear relationship with biothiols concentration in the range of 0-20 μmol/L.The detection limits (3σ) of Cys, Hcy and GSH were 25.9, 92.0 and 77.9 nmol/L, respectively.The absorption, emission and mass spectra indicated that biothiols could be engaged in nucleophilic substitution reaction with 2,4-dinitrobenzenesulfonate, which induced the sulfonic esters decomposed.With the departure of receptor unit, the d-PeT progress (donor-excited photoinduced electron transfer) was blocked with an obvious colorimetric and fluorescence change.Finally, HeLa cell imaging experiments verified that DNSBN had good biocompatibility and could be used to detect exogenous biothiols.
7.Improvement of Detection Sensitivity of Triglyceride with Methylamine Formate as Ionization Enhancer in Reversed Phase Liquid Chromatography-Electrospray Ionization Mass Spectrometry
Haiyan ZHAO ; Can GONG ; Xu XU
Chinese Journal of Analytical Chemistry 2017;45(9):1323-1329
A novel ionization enhancer, methylamine formate, was proposed for improving the detection sensitivity of triglyceride in edible oil by reversed phase liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS).The commonly used isopropanol-acetonitrile-methanol-water and isopropanol-acetonitrile were selected as the mobile phase.By using a reversed phase C18 column, and taking the corn oil in isopropyl alcohol as sample solution, we compared methylamine formate with ammonium formate, as ionization enhancers, for their effect on the detection sensitivity of triglyceride by LC-ESI-MS after screening other different ionization enhancers, such as formic acid, acetic acid, ammonium formate, ammonium acetate, butyl formate, dibutylamine formate, triethylamine formate, diethylamine formate, methylamine formate, and ethylamine formate.The result indicated that, by using methylamine formate, the mass spectral peak response and the signal to noise ratio for trilinoleic glyceride component were 5 times higher than that of ammonium formate.The effect of the concentration of methylamine formate ionization enhancer, the flow rate of the mobile phase and the flow rate of nebulizing gas on the detection of methylamine formate were investigated.The concentration of triglyceride components in corn oil starting to form aggregates was similar in different mobile phases in the electrospray process according to measurement of the relationship between corn oil concentrations and the total ion chromatogram peak area of triglyceride.In particular, the peak area of trilinolein was linear with its concentration in the range of 7×10-7-2×10-4 mol/L (R2=0.9997), but increased slower in the higher concentration range.According to the experimental data, the mechanism for improvement of detection sensitivity of methylamine formate was suggested as that the addition of methylamine mono-charged ions with hydrophobic groups had lower solvation energy, which made the enriched addition ions easily evaporation from the droplet surface, thus improving the electrospray ionization efficiency.This method provided an effective way to improve the detection sensitivity of triglyceride in edible oil by LC-ESI-MS.
8.Characteristics Analysis of Metal Elements in Sediments and Habitat Mussels from India Ocean Hydrothermal Area
Jingxi LI ; Chengjun SUN ; Fenghua JIANG ; Li ZHENG ; Shuai WANG ; Junhui CHEN ; Xiaoru WANG
Chinese Journal of Analytical Chemistry 2017;45(9):1316-1322
The concentrations and distributions of trace metals and rare earth elements (REE) in sediment and mussel samples collected from the India Ocean hydrothermal area were analyzed.The metal correlation between organisms and sediments was investigated, and the ecological and chemical characteristics of REE were also explored.The results showed that, the trace metals in sediments were mainly Fe (96.6 mg/kg), Mn (1.14 mg/kg) and Zn (322.6 μg/kg), and Fe had high ratio of 98.15% by normalized calculation, which indicated that the available sediments in this studying hydrothermal area mainly consisted of iron ore substances.Trace metals and REE distributions all had good correlation between deep-sea sediments and deep-sea mussels, and the correlation coefficients were 0.991 for trace metals and 0.996 for REE.The contents and distributions of metal elements in deep-sea mussels were different from those in offshore mussels.The REE distributions in sediments and mussels showed obvious fractionation phenomenon, and the enrichment of LREE in mussels was significant.Through the REE patterns, Eu and Gd in sediments and mussels all showed anomalies, and Eu had a significant abnormal phenomenon in deep-sea sediments and deep-sea mussels.Besides, δEu values were 9.50, 10.68 and 0.23 in deep-sea sediments, deep-sea mussels and offshore mussels, respectively, and δCe were 2.21, 2.71 and 4.38, which showed that the enrichment sources of REE in offshore mussels and deep-sea mussels were different, and the REE in sediments and mussels from the India Ocean were homologous.
9.Distribution and Speciation of Lead in Moss Collected from a Lead-Zinc Mining Area by Micro-X-Ray Fluorescence and X-Ray Absorption Near Edge Structure Analysis
Chinese Journal of Analytical Chemistry 2017;45(9):1309-1315
Moss has high tolerance and accumulating capacity to heavy metal.In this study, the distribution of heavy metal elements in moss sampled from lead-zinc mine was analyzed by X-ray fluorescence spectrometry.The speciation of lead was analyzed by X-ray absorption near-edge spectroscopy.Research showed that the contents of Pb, Zn, Cd and As in the moss of the mining area were extremely high, and their maximum concentration were 1.06 mg/g , 1.23 mg/g, 30.5 μg/g, 13.2 μg/g, respectively.Besides, the shoots especially the new tissue of the moss were the major sites for accumulation and storage of heavy metals.The micro-distribution characteristics varied among Hypnum plumaeforme and Brachytheciumprocumbens, indicating the difference of different species of moss in absorption pathway, accumulation and tolerance mechanisms for heavy metal.Linear combination fitting results indicated that the main lead speciation in moss was lead phosphate (78%) and lead oxide (22%), which suggested that the precipitation of lead phosphate might be the main mechanism of tolerance for moss.
10.Support Vector Regression for Non-invasive Detection of Human Hemoglobin
Jingze YUAN ; Qipeng LU ; Jingli WANG ; Haiquan DING ; Hongzhi GAO ; Chunyang WU ; Wanxia LI
Chinese Journal of Analytical Chemistry 2017;45(9):1291-1296
To facilitate noninvasive diagnosis of anemia, high-performance and portable near infrared (NIR) spectrometer for human blood constituents was designed and fabricated based on linear variable filter (LVF).Meanwhile, the performance of support vector regression (SVR) model for quantitative analysis of human hemoglobin (Hb) was investigated.Spectral data were collected noninvasively from 100 volunteers by self-designed LVF-NIR spectrometer, then divided into calibration set, validation set 1 and 2.To establish a robust SVR model, grid search method was applied to optimize the penalty parameter and kernel function parameter c=5.28, g=0.33.Then, Hb levels in the validation 1 and 2 sets were quantitatively analyzed.The results showed that the root mean square error of prediction (RMSEP) were 10.20 g/L and 10.85 g/L, respectively, and the relative RMSEP (R-RMSEP) were 6.85% and 7.48%, respectively.The results indicated that the SVR model had high prediction accuracy to Hb level and adaptability to different samples, and could satisfy the requirements of clinical measurement.Based on the SVR algorithm, the self-designed LVF-NIR spectrometer has a wide application prospect in the field of non-invasive anemia diagnosis.