免疫检测及核酸分析中的电化学方法

文介绍电化学方法在免疫检测及核酸分析中的应用. 鉴于有关方面的文献综述已有多篇,这里着重于已经商品化和临床应用的电化学分析技术. 希望从这些成功地应用于体外诊断的方法中得到一些启示,并提出作者个人对于该领域研究前景的看法.     

The analysis of nitrogen rotational and vibrational bands in a helium microhollow gas discharge

Emission spectroscopy is applied to measure the gas temperature T _g and the vibrational distribution of N₂ (C ³Π_u) and N₂ ⁺(B ²Σ_u ⁺) excited states from a helium microhollow gas discharge (MHGD) at atmospheric pressure. The rotational temperature T _rot of N₂ ⁺ is determined from relative intensity of the R‐branch lines of the N₂ ⁺(B ²Σ_u ⁺–X ²Σ_g ⁺) bands at 427.81 and 419.91 nm and the well‐known Boltzmann plot (BP). Using the same diagnostic technique, the rotationally resolved N₂(C ³Π_u–B ³Π_g) band at 380.49 nm is used to measure T _rot. Under our experimental conditions, T _g is equal to T _rot = 550–650 K for nitrogen molecules and shows a slight increase with the discharge current in the current range 3–10 mA. From the intensity ratio of two consecutive vibrational bands of the same sequence, the N₂(C ³Π_u) and N₂ ⁺(B ²Σ_u ⁺) vibrational temperature T _vib = 3,700–4,000 K is determined. It has been found that N₂ ⁺(B ²Σ_u ⁺) ions have non‐Boltzmann distribution in the helium MHGD, while N₂(C ³Π_u) molecules are populated according to the Boltzmann distribution. Following the Franck–Condon principle, the vibrational distribution of the ground state of N₂(X ¹Σ_g ⁺) molecules has been determined from the N₂(C ³Π_u) distribution using the inversion matrix of elements q _XC(ν ,ν ′).     

Areal homogeneity verification of plasma generated by diffuse coplanar surface barrier discharge in ambient air at atmospheric pressure

This paper deals with an optical emission spectroscopy study of a diffuse coplanar surface barrier discharge (DCSBD ) in air at atmospheric pressure. The main aim of this study was to verify the areal homogeneity of the generated plasma, which is important for many applications like treatment of nonwoven fabrics, glass, metals, polymers, foils, and so on. Optical emission spectra of DCSBD plasma in air were measured for three different frequencies (15, 30, and 50 kHz ) of the applied voltage. Comparison of the calculated rotational and vibrational temperatures was carried out, and areal homogeneity of plasma was proved. Electrical parameters of discharge such as the plasma power using the area of the Lissajous figures and energy transfer efficiency to the discharge were also investigated. The effective thickness of plasma layer as a function of the input power was measured.     

The effect of improved satellite line shapes on the argon Heβ spectral feature

The effect of the interference term in the electron broadening of the Li-like satellites to the Ar Heβ line has been investigated in the standard Stark broadening theory. Although the interference term has negligible or small effect on satellite lines with spectator electrons in n = 2 and n = 3 shells, it shows significant narrowing for lines with n = 4 spectator electrons. Nevertheless, the improved n = 4 satellite line shape makes a small difference in the emergent intensity distribution of the composite spectral feature. Accordingly, this change in line shape does not affect previous diagnosis of plasma conditions in Ar-doped ICF implosion cores.     

Emission spectrum from an Al/Mg tracer in the blow-off region of a radiatively ablated capsule

A study of X-ray emissions from Al/Mg tracers buried at two different depths in a plastic shell is presented. The X-rays originating from the K-shell transitions of the Al/Mg ions begin to irradiate after the ablative heating wave has passed through the trace layer and are recorded with a streaked crystal spectrometer. Only emissions from the capsule with the trace layer buried at a smaller depth are observed. Hydrodynamic simulations and a collisional—radiative model including detailed atomic physics are used to investigate the measured spectrum. It is found that the effects of the radiative heating play important roles in the formation of the K-shell emission. The time correlation between the simulations and the measurements is obtained by comparing the measured time profile of the He α emission with the calculated one. The line ratio of Ly α to He α is also calculated and is found to be in fairly good agreement with the experimental data. Finally, the relation between the time profile of the He α emission and the ablation velocity is also discussed.     

Characteristics of the preplasma formation using an uncompressed picosecond-long laser pulse with a large spot size on Al and mylar targets

A preplasma plays a very important role in laser-driven proton acceleration, where it can increase the proton energy significantly. In this research, we generated a nearly planar preplasma intentionally by sending an uncompressed picosecond-long Ti:sapphire laser pulse with a large spot size onto a thin foil target (Al and mylar) and investigated the characteristics of the preplasma by using a space-time-resolved Nomarski interferometer. In this paper, a simple analytical approach employing the one-dimensional collisional plasma concept was also developed and its result is compared with the experimental results. This work reveals the detailed characteristics of the behavior of the planar preplasma, which is very important in laser-driven proton acceleration, X-ray laser, etc., employing laser-solid interactions.     

Strong rotating flow in stationary droplets in low power budget using wire electrode configuration

We explore a simple strategy of generating strong rotating flow in a stationary surface‐droplet, using an intricate interplay of local electrical and thermal fields. Wire electrodes are employed to generate on‐spot heating without necessitating any elaborate micro‐fabrication, which causes strong local gradients in electrical properties to induce mobile charges into the droplet. Applying a low voltage (～10 V), strong rotational velocity of the order of mm/s can be achieved in the system, within the standard operating ranges of operating and geometrical parameters. Further, altering the diameter of the electrode, vortices can be tuned locally or globally in low power budget, without incurring any droplet oscillations. These results may turn out to be of immense consequence in enhancing micromixing in a plethora of droplet based applications ranging from thermal management to medical diagnostics to be potentially employed in resource‐limited settings.     

Analysis of thrombin‐antithrombin complex formation using microchip electrophoresis and mass spectrometry

Preterm birth (PTB) related health problems take over one million lives each year, and currently, no clinical analysis is available to determine if a fetus is at risk for PTB. Here, we describe the preparation of a key PTB risk biomarker, thrombin‐antithrombin (TAT), and characterize it using dot blots, MS, and microchip electrophoresis (µCE). The pH for fluorescently labeling TAT was also optimized using spectrofluorometry and spectrophotometry. The LOD of TAT was measured in µCE. Lastly, TAT was combined with six other PTB risk biomarkers and separated in µCE. The ability to make and characterize TAT is an important step toward the development of an integrated microfluidic diagnostic for PTB risk.