铁氰化钾-钙黄绿素体系后化学发光反应测定氨基比林

研究发现,氨基比林在铁氰化钾-钙黄绿素化学发光反应体系中的后化学发光反应。优化了反应条件,建立了一种利用后化学发光反应测定氨基比林的流动注射化学发光方法。方法的检出限为20μg/L;相对标准偏差为2.0%(2.0mg/L氨基比林,n=11);线性范围为1.0×10-4~1.0×10-2g/L。此法已用于复方氨林巴比妥注射液中氨基比林含量的测定,结果与药品标准方法测定值一致。     

烟草脱外壁花粉与完整花粉电激导入效果的比较研究

利用膜不通透的荧光染料钙黄素作为指示剂，比较了烟草脱外壁花粉与完整的未萌发花粉和萌发花粉电激导入的效果．研究了电激过程中的电场强度、脉冲持续时间、电激液的介质成分和浓度对三者的导入率及电激后花粉萌发率的影响．结果表明，从未萌发花粉、萌发花粉到脱外壁花粉，导入率逐渐升高，证实了脱外壁花粉由于摆脱了外壁的阻碍而有利于外源物质的电激导入．但电激后花粉萌发率的变化规律相反．荧光指示剂的应用便于优化选择适宜电激参数，为外源基因的导入实验提供了参考依据．     

胆汁中微量钙的分光光度测定

阐述了应用分光光度法测定胆汁中微量钙的方法．方法基于在强碱性溶液中钙与钙黄绿 素（荧光素－３，３’－双甲氨基－二乙酸）间形成一种配合物，于钙黄绿素溶液中加入钙后在波长５０９ｎｍ 处测量钙黄绿素溶液吸光度减少值．方法简便、快速，测定范围为 ０．２～２．５μｍ Ｃａ／ｍＬ，相对标 准偏差为±２％左右．胆汁中的镁、锌和胆绿素不干扰测定．本法可用于临床分析中钙的测定．     

Spectrofluorimetric Study of the Complexes Between Calcein and Lanthanide(III) Ions

ABSTRACT

The equilibrium of calcein, an H6L type fluorescent ligand, with lanthanide(III) ions, Ln(III), was studied spectrofluorimetrically in aqueous solution at constant ionic strength =0.1 (KC1), pH 8.0 and 25.0±0.1°C. Application of the mole ratio and continuous variation methods reveals the formation of 1:1 complexes. The conditional stability constants (β') were calculated from the analysis of the observed fluorescence vs. [Ln(III)]/[calcein] mole ratio data by using an iterative non-linear least-squares computer program. The values obtained for β' are in the range 5.24×10⁶-5.77×10⁷ The thermodynamic stability constant (β) were estimated by calculating the sidereaction coefficients (α) fro lanthanides and calcein. The β values obtained were from 3.2×10¹² to 3.6×10¹³     

钙黄绿素荧光猝灭法测定辛硫磷

中性介质中,生物小分子钙黄绿素与阳离子表面活性剂CTMAB缔合,体系荧光强度降低,而当加入辛硫磷后荧光强度继续降低并且降低的程度与加入辛硫磷的量在一定浓度范围内成线性.据此建立了一种测定辛硫磷的新方法,该法的线性范围为0～5.6mg/L,检测限为0.039mg/L.     

利用聚钙黄绿素薄膜修饰电极测定黄嘌呤

利用循环伏安法,制备出具有良好催化活性的聚钙黄绿素薄膜修饰电极(PCALE).利用PCALE对黄嘌呤(Xa)的电催化作用,建立了对黄嘌呤含量定量分析的电分析方法.在0.02 mol/L PBS(pH=6.8)+0.2 mol/L KNO3体系中,黄嘌呤的浓度在5.0×10-6~1.0×10-4 mol/L范围内与峰电流呈良好的线性关系,线性回归方程和线性相关系数分别为:ip=-0.010 5C-2.09,γ=0.998 9,检出限可达2×10-7 mol/L.利用该法对尿液中的黄嘌呤进行定量分析,得到满意结果.5次样品分析结果的相对标准偏差小于2%.     

催化褪色光度法测定痕量铅

基于十二烷基磺酸钠存在下,Pb2+能显著地催化NaIO4氧化钙黄绿素(R)的褪色反应,因而提出了一种高灵敏十二烷基磺酸钠活化Pb2+催化NaIO4氧化R测定痕量铅的新方法.铅含量在0.040-2.00μg/L范围内与△A值符合比尔定律,工作曲线的回归方程为ΔA=0.01122+0.04528 C Pb2+(μg/L),相关系数为r=0.9970,检出限为3.7×10-11g/mL.该方法准确、灵敏、操作简便,选择性好,成功用于水样及发样中的铅含量的测定.     

Selective Dequenching by Photobleaching Increases Fluorescence Probe Visibility

Self-quenching properties of fluorescent dyes have been developed to improve the sensitivity of fluorescent measurement. Photobleaching of Calcein at a concentration greater than the critical, self-quenching concentration actually increased fluorescence, whereas at lower concentrations photobleaching decreased fluorescence, enhancing signal to noise by almost 4000. The photobleaching-dequenching principle has been demonstrated in giant liposomes encapsulating Calcein at higher quenched concentrations. Upon photobleaching background fluorescence was reduced and the liposome fluorescence increased. Liposomes invisible in the presence of background fluorescence became visible upon photobleaching. Fluorescent lifetime was unaffected by photobleaching, whereas the lifetime decreased significantly upon dilution, allowing distinction between photobleached fluorescence particularly upon dequenching. The principle may be suited to improving fluorescence imaging and resolving fluorescent probes in particle-based assays.     

Measurement of Cell Volume Changes by Fluorescence Self-Quenching

At high concentrations, certain fluorophores undergo self-quenching, i.e., fluorescence intensity decreases with increasing fluorophore concentration. Accordingly, the self-quenching properties can be used for measuring water volume changes in lipid vesicles. In cells, quantitative determination of water transport using fluorescence self-quenching has been complicated by the requirement of relatively high (mM) and often toxic loading concentrations. Here we report a simple method that uses low (M) loading concentrations of calcein-acetoxymethyl ester (calcein-AM) to obtain intracellular concentrations of the fluorophore calcein suitable for measurement of changes in cell water volume by self-quenching. The relationship between calcein fluorescence intensity, when excited at 490 nm (its excitation maximum), and calcein concentration was investigated in vitro and in various cultured cell types. The relationship was bell-shaped, with the negative slope in the concentration range where the fluorophore undergoes fluorescence self-quenching. In cultured retinal pigment epithelial cells, calcein fluorescence and extracellular osmolarity were linearly related. A 25-mOsm hypertonic challenge corresponded to a decrease in calcein fluorescence with high signal-to-noise ratio (>15). Similar results were obtained with the fluorophore BCECF when excited at its isosbestic wavelength (436 nm). The present results demonstrate the usefulness of fluorescence self-quenching to measure rapid changes in cell water volume.     

Encapsulation and Releasing of Calcein by Spontaneously Formed Zwitterionic/Anionic Vesicle without Separation

The encapsulation and releasing of fluorescence dye calcein by spontaneously formed vesicle, from the mixtures of anionic surfactant (sodium dodecyl benzene sulfonate) and zwitterionic surfactant (Lauryl sulfonate betaine), was characterized with a simple but sensitive and accurate fluorescence method, using cobalt chloride as a quenching agent. Different from the separation method, the whole process proceeded in the same solution without removing the free calcein. After cobalt chloride quenching the outer calcein, the releasing of the calcein from the vesicle to bulk solution starts and finally reaches a steady value depending on the equilibrium between the osmotic pressure and resistance of membrane. The entrapment quantity of the SDBS/LSB vesicles to the calcein could then be deduced according to the difference of fluorescence intensity before and after the quenching, which varies with the mixing ratios of the two kinds of surfactants. The addition of additives such as salt and especially the polymer (polyvinylpyrrolidone) reduces the releasing velocity by strengthening the bilayers, and increases the encapsulation quantity, even 3times at the most.