多柱色谱技术进展

在色谱分析过程中，利用串联、并联或串并联结合的方式将多根色谱柱组合起来，可以实现高通量和高分辨的分离效果。相比于传统单柱色谱技术，多柱技术很好地满足了批量样品分析和复杂生物样品分离分析的需求，因此引起了广泛关注。该文对多柱技术在多维分离、芯片色谱、毛细管电泳、固定相筛选以及串联色谱等领域的应用进行了综述，并对其发展前景进行了展望。     

吗啡烷型生物碱类药物的化学发光分析法研究

雷氏盐（ＮＨ４Ｃｒ（ＮＨ３）２（ＳＣＮ）４）．Ｈ２Ｏ）是生物碱类物质的沉淀剂，经研究发现，雷氏盐可以催化鲁米诺与过氧化氢的化学发光反应，而吗啡烷型生物碱能沉淀雷氏盐，可导致鲁米诺－过氧化氢－雷氏盐体系化学发光强度的降低，根据这一发现，本文建立了吗啡烷型生物碱类药物（吗啡，青藤碱，可待因）的流动注射化学发光分析方法，方法有较低的检出限，较宽的线性范围和较好精密度用于一些药物的测定，结果较为满意。     

Cathodic electrochemiluminescence at double barrier Al/Al2O3/Al/Al2O3 tunnel emission electrodes

Double insulating barrier tunnel emission electrodes were fabricated by adding a new pure aluminum layer upon oxidized aluminum electrodes by vacuum evaporation and thermally oxidizing the new aluminum layer in air at room temperature. Resulting Al/Al₂O₃/Al/Al₂O₃ electrodes allow the use of various aluminum alloys in the electrode body necessary for hardness or shaping ability of the electrode while obtaining the luminescence properties of pure aluminum oxide. During electrical excitation of luminescent labels by cathodic hot electron injection into aqueous electrolyte solution, the background noise is mainly based on high-field-induced solid-state electroluminescence and F-center luminescence of the outer aluminum oxide film. The more defect states and/or impurity centers the outer oxide film contains, the higher is the background emission intensity. The present electrode fabrication method provides a considerable improvement in signal-to-noise ratio for time-resolved electrochemiluminescence (TR-ECL) measurements when the original native oxide film of the electrode body contains luminescence centers displaying long-lived luminescence. The excellent performance of the present electrodes is demonstrated by extremely low-level detection of Tb(III) chelates, luminol, Pt(II) coproporphyrin and Tb(III) labels in an immunometric immunoassay by time-resolved electrochemiluminescence.     

Polydiacetylene/Anti‐HBs Complexes for Visible and Fluorescent Detection of Hepatitis B Surface Antigen on a Nitrocellulose Membrane

The immunochromatographic assay (ICA) using a nitrocellulose (NC) membrane offers several advantages. This technique is a rapid and straightforward method in contrast to other immunoassays. Polydiacetylene (PDA) vesicles have unique optical properties, displaying red color and red fluorescence at the same time. In this system, red‐phase PDA vesicles are used as a fluorescent dye as well as a surface for immobilized hepatitis B surface antibody (HBsAb). PDA has a remarkable stability compared with other fluorescent dyes. In this study, the most suitable PDA/HBsAb complexes are introduced for detecting hepatitis B surface antigen (HBsAg). Then, the PDA/HBsAb complexes affixed antibody is attached to NC membrane, which has two lines to confirm detection of HBsAg. The main advantage of this system is that the detection of HBsAg can be observed in both visible and fluorescent images due to the optical properties of polydiacetylene. Detection of HBsAg is observed up to 0.1 ng mL⁻¹ by fluorescent analysis and confirmed by red line on the NC membrane up to 1 ng mL⁻¹ (HBsAg) using the naked eye. Consequently, these results show that PDA/HBsAb complexes were successfully applied to ICA for the diagnosis of hepatitis B.     

Biparametric multicommutated flow analysis system for determination of human serum phosphoesterase activity

A multicommutated flow analysis (MCFA) system constructed of microsolenoid valves and pumps offering simultaneous determination of activity of acid phosphatase (ACP) and alkaline phosphatase (ALP) in human serum samples has been developed. The MCFA system is based on optoelectronic flow-through detector made of two light emitting diodes and operating according to paired emitter detector diode (PEDD) principle. This photometric PEDD device has been dedicated for detection of p-nitrophenol (NP) generated in the course of enzymatic hydrolysis of p-nitrophenyl phosphate and optimized for the determination of NP in human serum samples. The developed PEDD-based MCFA system allows independent optimization of conditions for reaction and detection steps of photometric ACP and ALP bioassays. Moreover, it allows elimination of photometric interferences from serum matrix components according to two-points kinetic mode of measurement. The single measurement cycle takes 12 min, consists of four measurements (two for each phosphoesterase) and enables determination of serum ACP and ALP activities at physiological and pathological levels. The real analytical utility of the developed MCFA system has been confirmed by analysis of control sera as well as real human serum samples from healthy persons and oncological patients.     

High-Throughput Synthesis and Characterization of Aryl Silicones by Using the Piers–Rubinsztajn Reaction

Arylsilicones are widely exploited for their thermal and optical properties. The creation of phenylsilicone elastomers with specific physical properties is typically done by a “one-off” formulation and test process. Herein, it is demonstrated that high-throughput synthesis methods can be used to rapidly prepare a series of arylsilicone elastomers and then the relative impact of different aryl groups on their physical properties is assessed. Aromatic groups were incorporated into polydimethylsiloxane (PDMS) elastomers by exploiting the relative reactivity of different functional groups in the Piers–Rubinsztajn reaction. To analyze trends in the silicone mechanical properties as a function of increasing aryl concentration—structure/property relationships—libraries of elastomers were both quickly synthesized and characterized by using high-throughput suites starting from low viscosity silicone oils/monomers in 96-well plates. Liquid handling parameters were optimized to effectively work with the silicones. Incorporating aryl instead of alkyl crosslinkers into the PDMS backbone increased the silicone elastomer modulus by approximately 50 % (at a crosslink density of 6 %); elastomers prepared with an aromatic crosslinker with three contact points led to much higher moduli compared with those with one contact point at the same crosslink density. When located at precise rather than random points on the silicone chains, diphenylsilicones had lower moduli than analogous monophenylsilicones.     

Synthesis,characterization, DNA binding,cytotoxicity and molecular docking properties of three novel butterfly-like complexes with nitrogen-containing heterocyclic ligands

Three novel complexes, namely [Nd·L₁·HCOO·(H₂O)₄] ( 1 ), [Pr·L₁·HCOO·(H₂O)₄] ( 2 ) and [In·L₂·Cl·(H₂O)₂] ( 3 ) (L₁ = 1,1-bis(5-(pyrazin-2-yl)-1,2,4-triazol-3-yl)methane, L₂ = 1,1-bis(5-(pyrazin-2-yl)-1,2,4-triazol-3-yl)ketone), were synthesized and characterized. The molecular structures of 1 – 3 were confirmed using single-crystal X-ray diffraction. All three obtained complexes are zero-dimensional and connected to each other by hydrogen bonds. In 1 and 2 the metal is surrounded by nine donors and 3 has seven coordination sites. The interaction of 1 – 3 with calf thymus DNA (CT-DNA) was explored using UV absorption spectra and fluorescence spectra. The intrinsic binding constants of 1 – 3 with CT-DNA are about 1.9 × 10⁴, 1.4 × 10⁴ and 1.1 × 10⁴, respectively. Stern–Volmer quenching plots of 1 – 3 have slopes of 0.1508, 0.134 and 0.1205, respectively. The ability of these complexes to cleave pBR322 plasmid DNA was demonstrated using gel electrophoresis assay. Apoptosis studies of the three novel complexes showed a significant inhibitory effect on HeLa cells. Furthermore, MTT assays were used to evaluate the anticancer activity of the three complexes. The cytotoxicity study indicated that complex 1 possesses a higher inhibitory rate of HeLa cells than the other complexes. Especially, the efficacy of 1 was shown to be the highest for cisplatin at 24 h. A further molecular docking technique was introduced to understand the binding of the complexes toward the target DNA.     

Identification of Compounds that Selectively Stabilize Specific G‐Quadruplex Structures by Using a Thioflavin T‐Displacement Assay as a Tool

Small molecules are used in the G‐quadruplex (G4) research field in vivo and in vitro, and there are increasing demands for ligands that selectively stabilize different G4 structures. Thioflavin T (ThT) emits an enhanced fluorescence signal when binding to G4 structures. Herein, we show that ThT can be competitively displaced by the binding of small molecules to G4 structures and develop a ThT‐displacement high‐throughput screening assay to find novel and selective G4‐binding compounds. We screened approximately 28 000 compounds by using three different G4 structures and identified eight novel G4 binders. Analysis of the structural conformation and stability of the G4 structures in presence of these compounds demonstrated that the four compounds enhance the thermal stabilization of the structures without affecting their structural conformation. In addition, all four compounds also increased the G4‐structure block of DNA synthesis by Taq DNA polymerase. Also, two of these compounds showed selectivity between certain Schizosaccharomyces pombe G4 structures, thus suggesting that these compounds or their analogues can be used as selective tools for G4 DNA studies.     

Surface‐Tension‐Confined Microfluidics and Their Applications

This article is a brief overview of the emerging microfluidic systems called surface‐tension‐confined microfluidic (STCM) devices. STCM devices utilize surface energy that can control the movement of fluid droplets. Unlike conventional poly(dimethylsiloxane)‐based microfluidics which confine the movement of fluids by three‐dimensional (3D) microchannels, STCM systems provide two‐dimensional (2D) platforms for microfluidics. A variety of STCM devices have been prepared by various micro‐/nanofabrication strategies. Advantages of STCM devices over conventional microfluidics are significant reduction of energy consumption during device operation, facile introduction of fluids onto 2D microchannels without the use of a micropump, increased flow rate in a special type of STCM device, among others. Thus, STCM devices can be excellent alternatives for certain areas in microfluidics. In this Minireview, fabrication methods, operating modes, and applications of STCM devices are introduced.     

Determination of cysteine,homocysteine, cystine,and homocystine in biological fluids by HPLC using fluorosurfactant‐capped gold nanoparticles as postcolumn colorimetric reagents

We have demonstrated for the first time the suitability of fluorosurfactant‐capped spherical gold nanoparticles as HPLC postcolumn colorimetric reagents for the direct assay of cysteine, homocysteine, cystine, and homocystine. The success of this work was based on the use of an on‐line tris(2‐carboxyethyl)phosphine reduction column for cystine and homocystine. Several parameters affecting the separation efficiency and the postcolumn colorimetric detection were thoroughly investigated. Under the optimized conditions, cysteine, homocysteine, cystine, and homocystine in human urine and plasma samples were determined. Detection limits for cysteine, homocysteine, cystine, and homocystine ranged from 0.16–0.49 μM. The accuracy in terms of recoveries ranged between 94.0–102.1%. This proposed method was rapid, inexpensive, and simple.