Investigation of voltammetric enzyme-linked immunoassay based on a new system of HAP-H2O2-HRP

By introducing heterocyclic compound to immunoassay system as an electrochemical substrate for the fist time, a new voltammetric enzyme-linked immunoassay system of 3-hydroxyl-2-aminopyridine (HAP)-H(2)O(2)-horseradish peroxidase (HRP) has been developed. HAP was oxidized with H(2)O(2) catalyzed by HRP, and the resulting electroactive product produced a sensitive voltammetric peak at potential of -0.36 V (vs. SCE) in Britton-Robinson (BR) buffer solution. The process of the enzyme-catalyzed reaction and the electro-reduction of the product have been investigated in detail. The linear range for detection of free HRP was from 4.0x10(-13) to 1.0x10(-9) g/mL with a detection limit of 1.2x10(-13) g/mL. The new system has been successfully applied for the assay of alpha-fetoprotein (alphaFP) in human serum ranging from 0.1 to 200 ng/mL with a detection limit of 0.1 ng/mL, which was 10 times lower than that of traditional spectrophotometric enzyme-linked immunosorbent assay (ELISA) method. HAP-H(2)O(2)-HRP voltammetric enzyme-linked immunoassay showed a promising alternative approach in the detection of alphaFP in clinical diagnosis.     

A novel approach to the taxane ABC ring system through chemical conversion from C19-diterpenoid alkaloid deltaline

A novel approach to the highly functionalized taxane ABC ring system through chemical conversion of the C₁₉-diterpenoid alkaloid deltaline (1) was achieved in six steps (1→17) in 18% overall yield mainly by Grob fragmentation, fission of the Δ⁹⁽¹⁴⁾ double bond, followed by aldol condensation, and Pelletier's cleavage process.     

Automation of nanoflow liquid chromatography-tandem mass spectrometry for proteome and peptide profiling analysis by using a monolithic analytical capillary column

An automated nano-LC-MS/MS platform without trap column was established, which only used a 20 cm lauryl methacrylate-ethylene dimethacrylate (LMA-EDMA) monolithic capillary column to allow preconcentration and separation of peptides. The monolithic column had the advantages of good permeability and low backpressure resulting in higher flow rates for capillary columns. Tryptic digests of bovine albumin and yeast protein extract were tested using the monolithic column system. High proteomic coverage using this approach were demonstrated in this study. Furthermore, peptide samples extracted from mouse liver were separated by using the monolithic column system combined with size-exclusion chromatography prefractionation. This monolithic column system might be a promising alternative for the automated system previously using a trap column for routine proteome and peptide profiling analysis.     

新城疫病毒流式微球免疫检测新方法

本研究基于新城疫病毒多克隆抗体的制备及优化,以聚苯乙烯微球作为蛋白质载体建立免疫检测体系,建立了快速检测新城疫病毒的流式细胞术新方法。以藻红蛋白荧光染料对新城疫多克隆抗体荧光标记,取1μL荧光微球与100μL新配制的单克隆抗体溶液反应,依次加入一定量待测抗原和藻红蛋白标记的多克隆抗体,漩涡振荡10s,室温振荡反应充分,形成双抗体夹心复合物,用流式细胞仪进行检测。采用ELISA法对免疫试剂进行了匹配性筛选实验,优选了试剂用量,并与传统ELISA方法进行了对比分析。实验结果表明,单克隆抗体350mg/L、多克隆抗体300mg/L时可获得最佳分析效果,与传统的ELISA方法呈现出良好的相关性,不与鸡传染性支气管炎病毒、鸡痘病毒、鸡马立克氏病病毒等发生交叉反应。     

Phenol Inhibition and Restoration of the Bioactivity of Anaerobic Granular Sludge

Inhibition and restoration of different concentrations of phenol on the bioactivity of anaerobic granular sludge were investigated with laboratory-scale equipment. It indicated that phenol concentration lower than 50 mg/l show no inhibitory effect on bioactivities of granular sludge. However, methane productivity, extracellular polymeric substances (EPS) content, and coenzyme F(420) activity were decreased by varying degrees when phenol concentration adopted for inhibition ranged between 50 and 400 mg/l. Noticeably, methane productivity could be fully or partly restored in case the phenol was removed after 24 h of phenol inhibition.     

Crystal structure and magnetic properties of a unique 3D coordination polymer constructed from flexible aliphatic tricarballylic acid ligands featuring linear trimeric Manganese(II)-based, metal carboxylate chains

A novel linear trimeric-based, Mn(II)–carboxylate chain well separated by long-linking flexible aliphatic tricarballylic acid ligands in a 3D coordination polymer [Mn₃(C₆H₅O₆)₂(H₂O)₄]_n (1, C₆H₅O₆CH (COO⁻)(CH₂COO⁻)₂, TCA) exhibits low-dimensional antiferromagnetic order at 3.0 K. Such magnetic behavior is arises from the alternate Antiferro–Antiferro–Antiferro′ (J₁ J₁ J₂) repeating interactions sequence, based on the nature of the binding modes of Mn(II)-carboxylate chain and the effect of interchains arrangement of 1. The reported carboxylate-bridged metal chain systems display a new structurally authenticated example of linear homometallic spin arranged antiferromagnet among metal carboxylates.     

Quantitative study of interactions between oxygen lone pair and aromatic rings: substituent effect and the importance of closeness of contact

Current models describe aromatic rings as polar groups based on the fact that benzene and hexafluorobenzene are known to have large and permanent quadrupole moments. This report describes a quantitative study of the interactions between oxygen lone pair and aromatic rings. We found that even electron-rich aromatic rings and oxygen lone pairs exhibit attractive interactions. Free energies of interactions are determined using the triptycene scaffold and the equilibrium constants were determined by low-temperature 1H NMR spectroscopy. An X-ray structure analysis for one of the model compounds confirms the close proximity between the oxygen and the center of the aromatic ring. Theoretical calculations at the MP2/aug-cc-pVTZ level corroborate the experimental results. The origin of attractive interactions was explored by using aromatic rings with a wide range of substituents. The interactions between an oxygen lone pair and an aromatic ring are attractive at van der Waals' distance even with electron-donating substituents. Electron-withdrawing groups increase the strength of the attractive interactions. The results from this study can be only partly rationalized by using the current models of aromatic system. Electrostatic-based models are consistent with the fact that stronger electron-withdrawing groups lead to stronger attractions, but fail to predict or rationalize the fact that weak attractions even exist between electron-rich arenes and oxygen lone pairs. The conclusion from this study is that aromatic rings cannot be treated as a simple quadrupolar functional group at van der Waals' distance. Dispersion forces and local dipole should also be considered.     

Phase transitions of LiAlO2 at high pressure and high temperature

This work presents a comprehensive study on phase transitions in LiAlO₂ system at high pressures and temperatures (0.5-5.0 GPa and 300-1873 K, respectively), as well as the phase stability for polymeric phases of LiAlO₂ in the studied P-T space by X-ray diffraction (XRD). Besides the previously described polymorphic hexagonal α-phase, orthorhombic β-phase and tetragonal δ-phase, a possible new phase of LiAlO₂ was observed after the tetragonal γ-LiAlO₂ sample was treated at 5.0 GPa and 389 K. The stable regimes of these high-pressure phases were defined through the observation of coexistence points of the polymeric phases. Our results revealed that LiAlO₂ could experience structural phase transitions from γ-LiAlO₂ to its polymorphs at lower pressures and temperatures compared to the reported results. Hexagonal α-LiAlO₂ with highly (003) preferential orientation was prepared at 5.0 GPa and 1873 K.     

Rich-defect carbon nanotubes for highly sensitive detection of Dopamine

Dopamine (DA) plays an essential role in the central nervous, renal, hormonal and cardiovascular systems. Various modified carbon nanotubes (CNT)-based dopamine sensors have been reported, but inexpensive, highly sensitive plain CNT-based ones are seldom studied. In this work, a facile and inexpensive CNT-based DA sensor is made by rich-defect multi-walled carbon nanotubes (RD-CNT) via an ultrasound method. The defect and elemental states of the RD-CNT are systematically studied by transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), Raman spectroscopy, X-ray powder diffraction (XRD) and X-ray-photoelectron spectroscopy (XPS). Results show that massive holes and cracks exist in RD-CNT. The level of defects increases from the additional exposed edges. The electrochemical characterizations indicate that the electrochemical sensor has the highest sensitivity of 438.4 μA/(μM ⋅ cm²) among all carbon materials-based DA sensors while well meeting the clinically required detection range and selectivity. The DA sensor was further used to detect live healthy human serum and live PC12 cells with satisfactory results, thus holding great promise for an inexpensive but sensitive DA sensor in practical applications of clinical diagnosis and biological research.