Quantification of taurine and amino acids in mice single fibrosarcoma cell by microchip electrophoresis coupled with chemiluminescence detection

A method based on MCE coupled with chemiluminescence (CL) detection was developed for the determination of taurine (Tau) and amino acids including alanine (Ala), glycine (Gly), tryptophan (Trp), glutamic acid (Glu) and aspartic acid (Asp) present in mice single fibrosarcoma (S180) cells. Cell injection, loading, cytolysis, electrophoretic separation and CL detection were integrated onto a simple double‐T microfluidic chip. The intracellular constituents were electrophoretically separated within 150 s. The CL detection was based on the enhancement effects of Tau and amino acids on the CL reaction of luminol with H₂O₂ and Cu²⁺. The average amounts of Tau, Trp, Gly, Ala, Glu and Asp in per S180 cell from a cell population were 4.73, 1.23, 2.65, 1.94, 1.61 and 1.99 fmol. Ten S180 cells were analyzed, and the contents of Tau, Trp, Gly, Ala, Glu and Asp in mice single S180 cells were found to be in the range of 1.78–8.84, 0.95–2.31, 1.08–6.87, 1.03–4.05, 0.84–2.61 and 0.82–3.68 fmol, respectively. This work demonstrates that MCE coupled with CL detection is a useful analytical tool that is simple, quick and highly sensitive for single‐cell analysis.     

Magnetocaloric properties in a FeNiGaMnSi high entropy alloy

We investigated a new Fe_26.7Ni_26.7Ga_15.6Mn₂₀Si₁₁ high entropy alloy (HEA) without the rare earth element. The structural, magnetic and magnetocaloric properties of the resulting materials are presented. The HEAs successfully is produced by the arc melting with suction casting method. The crystal structures are characterised through multiphase Rietveld refinement of X-ray diffraction data. The structure of the HEAs was found to be the body centred cubic (bcc). In the magnetic measurements, the ferromagnetic to paramagnetic transition was obtained in the range of 300–400 K. With the employed suction casting method; the Fe_26.7Ni_26.7Ga_15.6Mn₂₀Si₁₁ HEA shows the best magnetocaloric properties as 1.59 Jkg⁻¹K⁻¹ maximum magnetic entropy change (0–2 T) and 75.68 Jkg^-1 refrigeration capacity after the annealing process.     

MCE‐electrochemical detection for following interactions of ssDNA and dsDNA with methylene blue

The interaction between the organic dye, methylene blue and DNA has been studied by MCE with electrochemical detection. Interaction produces two different signals, one corresponding to free methylene blue and other, for the complex methylene blue–DNA. The hybridization between a ssDNA and a complementary sequence, specific to the severe acute respiratory syndrome virus, has been performed and studied in a thermoplastic olefin polymer of amorphous structure CE‐microchip with an end‐channel gold wire detector. Moreover, studies with a longer dsDNA, an expression vector involved in the transitory or stable expression in mammals cells, pFLAG‐CMV4, has also been performed.     

A new route for simple and rapid determination of hydrogen peroxide in RAW264.7 macrophages by microchip electrophoresis

A new method using MCE with LIF detection was developed for the determination of hydrogen peroxide (H₂O₂). Bis(p‐methylbenzenesulfonyl)dichlorofluorescein, a new fluorogenic reagent synthesized by our laboratory was employed as a labeling reagent, the derivatization reaction was performed in 0.10 M HEPES buffer (pH 7.4) for 30 min at 37°C. The detection of H₂O₂ was accomplished in 55 s, using a 40 mM HEPES buffer, 20% mannitol, pH 7.4, on a glass microchip. The RSDs of migration time and peak area were 1.8 and 3.7%, respectively. Method validation showed the linear response ranging from 0.50 to 50 μM with an LOD (S/N=3) of 0.20 μM (19.1 amol). The proposed method was applied to determine H₂O₂ in phorbol myristate acetate‐stimulated RAW264.7 macrophages, the concentration of H₂O₂ was found to be 1.86±0.05 μM; recoveries for macrophage samples were from 96.7 to 97.8%, within‐days and between‐days accuracies were 4.5% (n=5) and 6.8% (n=5), respectively.     

Magnetocaloric effect and multifunctional properties of Ni–Mn-based Heusler alloys

The studies of magnetocaloric properties, phase transitions, and phenomena related to magnetic heterogeneity in the vicinity of the martensitic transition (MT) in Ni–Mn–In and Ni–Mn–Ga off-stoichiometric Heusler alloys are summarized. The crystal structure, magnetocaloric effect (MCE), and magnetotransport properties were studied for the following alloys: Ni₅₀Mn_50−xIn_x, Ni_50−xCo_xMn₃₅In₁₅, Ni₅₀Mn_35−xCo_xIn₁₅, Ni₅₀Mn₃₅In₁₄Z (Z=Al, Ge), Ni₅₀Mn₃₅In_15−xSi_x, Ni_50−xCo_xMn_25+yGa_25−y, and Ni_50–xCo_xMn_32−yFeyGa₁₈. It was found that the magnetic entropy change, ΔS, associated with the inverse MCE in the vicinity of the temperature of the magneto-structural transition, TM, persists in a range of (125-5) J/(kg K) for a magnetic field change ΔH=5 T. The corresponding temperature varies with composition from 143 to 400 K. The MT in Ni₅₀Mn_50−xIn_x (x=13.5) results in a transition between two paramagnetic states. Associated with the paramagnetic austenite-paramagnetic martensite transition ΔS=24 J/(kg K) was detected for ΔH=5 T at T=350 K. The variation in composition of Ni₂MnGa can drastically change the magnetic state of the martensitic phase below and in the vicinity of TM. The presence of the martensitic phase with magnetic moment much smaller than that in the austenitic phase above TM leads to the large inverse MCE in the Ni₄₂Co₈Mn_32−yFeyGa₁₈ system. The adiabatic change of temperature (ΔT_ad) in the vicinity of TC and TM of Ni₅₀Mn₃₅In₁₅ and Ni₅₀Mn₃₅In₁₄Z (Z=Al, Ge) was found to be ΔT_ad=−2 K and 2 K for ΔH=1.8 T, respectively. It was observed that |ΔT_ad|≈1 K for ΔH=1 T for both types of transitions. The results on resistivity, magnetoresistance, Hall resistivity in some In-based alloys are discussed.     

Electrophoretic separations in poly(dimethylsiloxane) microchips using mixtures of ionic,nonionic and zwitterionic surfactants

The use of surfactant mixtures to affect both EOF and separation selectivity in electrophoresis with PDMS substrates is reported, and capacitively coupled contactless conductivity detection is introduced for EOF measurement on PDMS microchips. First, the EOF was measured for two nonionic surfactants (Tween 20 and Triton X‐100), mixed ionic/nonionic surfactant systems (SDS/Tween 20 and SDS/Triton X‐100), and finally for the first time, mixed zwitterionic/nonionic surfactant systems (TDAPS/Tween 20 and TDAPS/Triton X‐100). EOF for the nonionic surfactants decreased with increasing surfactant concentration. The addition of SDS or TDAPS to a nonionic surfactant increased EOF. After establishing the EOF behavior, the separation of model catecholamines was explored to show the impact on separations. Similar analyte resolution with greater peak heights was achieved with mixed surfactant systems containing Tween 20 and TDAPS relative to the single surfactant system. Finally, the detection of catecholamine release from PC12 cells by stimulation with 80 mM K⁺ was performed to demonstrate the usefulness of mixed surfactant systems to provide resolution of biological compounds in complex samples.     

胶束毛细管电泳在线推扫技术分离检测猪肉组织中痕量喹诺酮类药物

利用胶束毛细管电泳法结合在线推扫富集技术对组织中残留的痕量环丙沙星、氧氟沙星和恩诺沙星进行了检测, 弥补了毛细管电泳检测灵敏度低的缺点, 大大减化了操作过程, 为动物食品组织中残留的痕量药物检测提供了一种新的简便可靠的方法.     

A new weakly basic amino‐reactive fluorescent label for use in isoelectric focusing and chip electrophoresis

In this study, we present a novel amino‐reactive fluorescence marker (referred to as UR‐431), which is well suited for electrophoretic techniques. A main feature of this marker is its weakly basic behavior when conjugated to analytes. Labeled primary amines exhibit a positive net charge and accordingly a cathodic mobility below a pH of 2.4. The label features a pH‐independent fluorescence emission and is thus very interesting for electrophoretic applications such as IEF. The absorption maximum of this yellow daylight chromophore is at 431 nm, whereas fluorescence emission peaks at 537 nm (quantum yield≈0.1). The label was successfully conjugated to amines, peptides and proteins and separated via CE and MCE. The on‐chip detection limit of labeled lysine using a mercury‐lamp‐based fluorescence microscope was determined as 12 nM. An important feature of the new label is that it effects only a subtle change of the pI of proteins compared with common anionic labels, e.g. FITC. pI values of proteins were investigated by comparing native proteins and labeled proteins in CIEF. UR‐431 was also applied to sensitive detection of amines and peptides in MCE.     

Magnetocaloric features of complex molecular magnets: The (Cr7Ni)2Cu molecular magnet and beyond

We study the new kind of systems represented by the Cr₇Ni-M-Cr₇Ni (M=Cu⁺²) molecule, which is a promising molecular achievement from the perspective of molecular electronics. By using an effective quantum Hamiltonian, an exact calculation of the magnetic specific heat C_Mag and the magnetocaloric features, namely, the adiabatic change of the entropy ΔS_Mag and temperature ΔT_ad, respectively, are developed. A systematic simulation of the magnetocaloric properties is generated by modifying the effective exchange couplings into the molecular system. Extended discussion of calculated magnetocaloric features and its possible realization by experimental methods, are performed. In addition, comparisons with an exact numerical result and with a Van Vleck transformation, which has important application in similar micromagnetic structures with no exact analytical solution and larger Hilbert space, are presented. Moreover, an expression for the entangling-excitation frequencies of these systems is given as first application of our simplified solution to the effective molecular Hamiltonian.     

芯片毛细管电泳用于人乳头瘤病毒分析的研究进展

人乳头瘤病毒（human papillomavirus,HPV）是一种常见的球形DNA病毒,目前已报道其可以导致6种类型的癌症发生,因此HPV病毒检测方法的研究引起了人们的重视。芯片毛细管电泳（MCE）,作为一种芯片实验设备,结合各种信号放大技术为HPV分型检测提供了简单、快速、高灵敏度和易便携化的检测方法。该文综述了MCE在常规HPV分型检测中的最新研究进展,主要分为MCE技术和MCE结合核酸扩增技术两个部分。综述的第一部分介绍了MCE系统、MCE芯片结构设计和电泳分离方法。典型的MCE系统包含了高压电源、分离芯片、电解液池、进样系统、检测系统等。该文还介绍了近年来应用最广泛的4种芯片通道,包括分离直通道、T型通道、蛇形通道以及双通道,并分别对它们的优缺点进行了比较。第二部分主要介绍芯片电泳在HPV检测中的应用和发展。由于MCE技术的应用,HPV目标物的分离时间,从以前的几个小时缩短到几分钟,极大地提高了分离速度。重点介绍了各种核酸扩增技术结合MCE检测HPV的方法。对聚合酶链式反应（PCR）和MCE结合用于HPV的检测技术、环介导等温扩增（LAMP）技术的HPV检测方法、基于PCR结合限制性片段长度多态性（RFLP）技术用于HPV分型的DNA检测、基于核酸序列扩增（NASBA）技术检测HPV mRNA、巢式PCR等进行了比较分析。其次,对HPV其他检测方法进行了总结,其中包括PCR结合傅里叶变换红外光谱法（FT-IR）、纳米技术、DNA探针结合电化学方法、亚铜粒子氧化还原锌掺杂的二硫化钼量子点结合T7外切酶电化学发光法和基于CRISPR/Cas12a的环介导等温扩增法。在这些非MCE方法中,电化学传感法,如阻抗法、脉冲伏安法和流动生物传感器,由于背景信号低、时间控制能力强,是一种比较理想的方法。最后,虽然近年来MCE技术得到了发展,所开发的设备得到了应用,但目前在MCE技术、方法和应用方面仍然存在一些挑战。MCE技术在HPV分型检测应用中面临的第一个挑战是,MCE本身无法对HPV核酸进行信号放大,从而不能在HPV的高灵敏和高选择性分析中得到很好的应用。第二个挑战是,虽然有一些研究者已经成功地将PCR和MCE集成在一个芯片上,但该技术的广泛应用仍面临困难,目前仍然没有真正集成的PCR-MCE芯片用于HPV检测。第三个挑战是目前MCE技术无法实现小型化、自动化器件的制造。最后,文章就MCE在HPV分型检测中开发更自动化、更快速以及更稳定可靠的检测技术提出了一些观点和见解,希望能对感兴趣的读者提供一些启发。