肌红蛋白与生物碱相互作用的光谱性质研究

用分子荧光光谱法和紫外可见分光光度法研究了肌红蛋白（myoglobin,Mb）与咖啡因、茶碱相互作用的光谱性质变化。据Stern-Volmer图得到猝灭常数,由紫外-可见吸收光谱判断均为静态猝灭,通过热力学常数得出其相互作用力为静电作用,依据Foerster偶极-偶极无辐射能量转移理论计算出Mb与生物碱间的距离,并用同步荧光光谱技术考察了生物碱对Mb构象的影响。     

荧光法研究司帕沙星与白蛋白的作用

本文用荧光光谱法、分光光度法研究了水溶液中喹诺酮类药物司帕沙星与牛血清白蛋白 (BSA)、鸡蛋白 (CEA)的相互作用 ,求得它们间的结合常数为K鸡 =8 2 9× 10 6,K牛 =4 41× 10 7;结合位点数分别为n鸡=0 5 88,n牛 =0 793,并根据F rster非辐射能量转移机制 ,测定了司帕沙星与两种血清白蛋白相互结合时其给体 受体间距离 (R鸡 =1 99nm ,R牛 =2 0 9nm)和能量转移效率 (E鸡 =0 76 6 ,E牛 =0 714)。实验表明 ,随着温度升高 ,BSA及CEA的猝灭曲线斜率降低 ,证实了司帕沙星与BSA和CEA的相互结合作用为单一的静态猝灭过程 ,其作用机制属能量转移机制。通过两种血清白蛋白与抗菌药物司帕沙星结合反应 ,探讨了药物司帕沙星在生物体内与蛋白质的相互作用的生物学效应及其作用机理。     

Fluorescence quenching of 2,2″ dimethyl-p-terphenyl by carbon tetrachloride in different solvents and temperatures

The fluorescence quenching of 2,2″-dimethyl-p-terphenyl (DMT) by carbon tetrachloride by steady state in different solvents, and by transient method in benzene has been carried out at room temperature. The Stern-Volmer (SV) plot has been found to be non-linear with a positive deviation for all the solvents studied. In order to interpret these results we have invoked the ground state complex and sphere of action static quenching models. Using these models various rate parameters have been determined. The magnitudes of these parameters imply that sphere of action static quenching model agrees well with the experimental results. Hence the positive deviation in the SV plots is attributed to the static and dynamic quenching. Further, from the studies of temperature dependence of rate parameters and lifetime measurements, it could be explained that the positive deviation is due to the presence of a small static quenching component in the overall dynamic quenching. With the use of finite sink approximation model, it was possible to check whether these bimolecular reactions as diffusion limited and to estimate independently distance parameter R′ and mutual diffusion coefficient D. Finally an effort has been made to correlate the values of R′ and D with the values of the encounter distance R and the mutual diffusion coefficient D determined using the Edward's empirical relation and Stokes-Einstein relation.     

Study on the Interaction Mechanism of Lysozyme and Bromophenol Blue by Fluorescence Spectroscopy

The interaction of lysozyme with bromophenol blue (BPB) in acetate buffer (pH 6.0) was studied by fluorescence quenching method for the first time. It was found that BPB could conspicuously quench the fluorescence of lysozyme by the static quenching process, possibly due to the binding on the active site near Trp62. The binding parameters including the binding constant and the number of binding site were calculated. The thermodynamic parameters ΔH°, ΔS° and ΔG° at different temperatures were obtained. The formation of lysozyme–BPB complex depended on the cooperation of the hydrophobic and electrostatic forces. And the binding average distance between lysozyme and BPB was determined. The effect of common metal ions on the binding constant of lysozyme–BPB was also examined.     

Yb∶YAG晶体的荧光特性研究

测量了不同掺杂浓度Yb∶YAG晶体氧化和还原气氛退火前后的色心吸收光谱、荧光光谱和荧光寿命.研究了色心对Yb∶YAG晶体的荧光强度和荧光寿命的影响.结果表明,只有当Yb的掺杂浓度大于10 at.%时,色心吸收的加强对发光强度和荧光寿命有明显猝灭作用.     

邻菲罗啉荧光猝灭法测定镍

本文基于镍对邻菲罗啉的荧光具有猝灭的特性 ,拟定了一种测定痕量镍的方法。该方法的激发波长为 2 72nm ,发射波长为 3 66nm ,线性范围为 1 0 0～ 1 2 0ng·mL- 1 ,相关系数为 0 9996,检测限为 7 6ng·mL- 1 ,对于 4 0ng·mL- 1 的镍测定 1 0次的相对标准偏差为 1 2 %。用该方法测定了工业废水中的痕量镍 ,结果令人满意。     

Fluorescence yield in rare-earth-doped sol-gel silicate glasses

We have used trivalent terbium to investigate the mechanism behind fluorescence enhancement by Al³⁺ co-doping. Our results indicate that rare-earth (RE) ions cluster together in aluminum-rich regions of the glass, and behave as if they were dispersed uniformly throughout these regions when the ratio of Al to RE is ∼10 or greater. We also studied the effects of adding chemical drying agents to the precursor solution for the synthesis of sol-gel-derived silicate glasses. Such glasses can be treated at significantly higher annealing temperatures without degradation of optical quality, and have the density of melt glass. Fluorescence yield from doped RE ions improves markedly with the addition of the drying agents, and the denser glasses are not subject to rehydration.     

荧光猝灭法对肉桂酸与人血清白蛋白间的相互作用的研究

白蛋白是血液循环系统中最丰富的一种蛋白质,能与许多物质结合,并起着运输蛋白的作用。文章利用荧光光谱法研究了中药有效成分肉桂酸与人血清蛋白间的非共价结合特性。研究表明,在pH7.4作用液、286nm激发波长条件下,肉桂酸对人血清白蛋白的荧光发射有较强猝灭作用。当作用温度为37和47℃时,肉桂酸与人血清蛋白间的结合常数K分别为1.2767×103和3.4041×103L.mol-1,结合位点数n分别为0.7586和0.8356,表明温度升高有利于两者的结合;同时,根据不同作用温度时非共价结合复合物的热力学参数变化,证明肉桂酸与人血清白蛋白分子间的结合力主要是疏水作用。研究结果为进一步研究肉桂酸的药理作用,尤其是对血浆蛋白构像的影响提供了重要信息。     

邻菲咯啉荧光熄灭法测定铜

研究了在pH 6 2 5～ 7 5 5KH2 PO4 Na2 HPO4 缓冲介质中 ,铜与邻菲咯啉形成配合物而使荧光熄灭的实验条件 ,建立了荧光熄灭法测定微量铜的新方法。该方法的λex =2 6 6nm ,λem =36 8nm ,铜含量在 8～ 30 0ng·mL- 1 范围内 ,有良好的线性关系 ,相关系数r=0 9996 ,检出下限为 10 4ng·mL- 1 。用本法经巯基棉分离测定了环境水样中的微量铜。     

血啉甲醚的时间分辨荧光光谱研究

实验研究了用于肿瘤光动力学诊断的第二代新型光敏剂血啉甲醚(HMME)分别在不同血型人血清和生理盐水环境中的时间分辨光谱,同时还研究了在不同荧光发射峰处的荧光寿命以及光敏剂浓度对荧光寿命的影响。结果表明:HMME在625和690nm处的荧光寿命基本相同,无显著差异。HMME在生理盐水和人血清环境中的荧光寿命具有显著差异,分别为14.6和16.6ns,同时实验结果还表明光敏剂浓度对荧光寿命没有影响。结论对于开展肿瘤的时间分辨药物荧光光谱诊断与成像技术具有重要的指导意义。     

C60-糖皮质激素荧光特性研究

C60及其衍生物的荧光特性的研究是富勒烯科学领域的一个重要分支.研究了C60-糖皮质激素类衍生物的荧光性质,发现室温下用350 nm波长的光激发,C60-糖皮质激素类衍生物在447 nm处有荧光发射.由于C60分子中60个碳原子是等价的,属Ih群,呈高度对称性,因而同样条件下难以观测到荧光.而C60-糖皮质激素类衍生物在形成的过程中分子结构的对称性发生了改变,使得这类化合物可以在一定波长光的激发下发射荧光.此外,通过对系列浓度(10～130 μmol·L-1)的C60-糖皮质激素氯仿溶液的荧光测定,发现这类化合物存在荧光浓度自猝灭现象,10～64 μmol·L-1浓度范围内,荧光强度随浓度的增大而逐渐增大,大于64 μmol·L-1时荧光强度随浓度的增大而逐渐降低.     

纳米银胶中PVP和Alq3的荧光猝灭研究

本文通过湿法化学还原法合成了平均粒径为4.42nm、标准差为0.98nm的球形银纳米颗粒,并研究了在不同反应时间后获得的银纳米颗粒对PVP和Alq3的荧光猝灭效应。通过深入研究发现,PVP的荧光猝灭效应主要由于其分子链上的酮基与Ag颗粒之间发生了静电吸附,进而导致处在激发态的PVP分子与银颗粒之间产生电子或者能量转移(即非辐射弛豫),猝灭了PVP的荧光发光;而Alq3的荧光猝灭效应则主要归因于银纳米颗粒的欧姆损耗。通过采用时域有限差分法进行模拟发现,溶液中随机分布的银纳米颗粒,不仅能够吸收激发电磁波,削弱激发场强度,而且能够吸收荧光分子辐射的电磁波,进而猝灭了Alq3分子的荧光效应。这些研究成果将有利于了解金属纳米颗粒与PVP及Alq3分子荧光发光之间的关系,为调控荧光发光提供指导。     

基于荧光分析技术的大鼠肠灌流液中H_2S含量测定

荧光素汞在碱性条件下具有很强的荧光,H2S能与荧光素汞结合,使其荧光猝灭,据此建立了一种荧光法测定大鼠肠灌流液中H2S含量的方法。在0.1mol·L-1 NaOH溶液中,以Na2S作为H2S供体,荧光素汞浓度为5.0×10-5 mol·L-1,Na2S浓度为1.0×10-5 mol·L-1时,以498nm为激发波长,在522nm处测定此二元体系的荧光强度。结果表明,在4.0×10-7~2.0×10-6 mol·L-1范围内,H2S浓度与荧光强度的下降程度呈良好的负相关性,r=0.998 0,精密度实验RSD=4.59%(n=7),检出限3.5×10-8 mol·L-1,样品中H2S含量分别为1.01×10-6和1.15×10-6 mol·L-1,加标回收率为95.8%~101.0%。该方法操作简单,灵敏度高,稳定性好,可准确测定肠灌流液中H2S含量,为内源性H2S的测定提供了依据。     

对NFDA1和芘荧光猝灭性质的比较研究

对Bei和芘在电子给体化合物,N,N－二甲苯胺（DMA）和电子受体化合物对苯二甲酸二甲酯（DMTP）作用下的荧光猝灭进行了研究。结果表明芘与DMA和DMTP在室温下均可形成激基化合物（exciplex),而Ben仅仅与DMA形成exciplex。荧光猝灭的数据符合Stern-Volmer方程：F0／F＝1＋KSV[Q],芘的Stern-Volmer常数KSV大于Bei.Bei和芘在荧光猝灭方面的差别是由于Bei分子并不是一个典型的大共轭体系,分子的共平面性不如芘那样典型。     

Fluorescence Study on the Interaction of Bovine Serum Albumin with P-Aminoazobenzene

In this paper, the interaction between p-aminoazobenzene (PAAB) and BSA was investigated mainly by fluorescence quenching spectra, circular dichroism (CD) and three-dimensional fluorescence spectra under simulative physiological conditions. It was proved that the fluorescence quenching of BSA by PAAB was mainly a result of the formation of a PAAB-BSA complex. The modified Stern-Volmer quenching constant K _a and the corresponding thermodynamic parameters ΔH, ΔG and ΔS at different temperatures were calculated. The results indicated that van der Waals interactions and hydrogen bonds were the predominant intermolecular forces in stabilizing the complex. The distance r?=?4.33 nm between the donor (BSA) and acceptor (PAAB) was obtained according to Förster’s non-radioactive energy transfer theory. The synchronous fluorescence, CD and three-dimensional fluorescence spectral results showed that the hydrophobicity of amino acid residues increased and the losing of α-helix content (from 63.57 to 51.83%) in the presence of PAAB. These revealed that the microenvironment and conformation of BSA were changed in the binding reaction.     

Photophysical study on daunorubicin by fluorescence spectroscopy

Steady-state fluorescence and time-resolved fluorescence intensity decays of daunorubicin have been studied in polar solvents and in aqueous solution by a time-correlated single-photon counting technique. Daunorubicin, quinizarin, and 2,3-dimethylquinizarin show bi-exponential decay. The decay of daunorubicin becomes tri-exponential in the presence of adenosine 5′ monophosphate. The quenching of the fluorescence of daunorubicin by adenosine 5′ monophosphate exhibits downward deviation from the Stern-Volmer linearity, suggesting the existence of fluorophore in two conformers in the ground state differing only in the extent of hydrogen bonding.     

Interaction of Thyroxine with 7 Hydroxycoumarin: A Fluorescence Quenching Study

The interaction between thyroxine hormone and 7 hydroxycoumarin (7HC) was investigated using fluorescence quenching method. The experimental results showed that thyroxine could quench the fluorescence of 7HC by forming the 7HC–thyroxine complex with static quenching. The apparent binding constants (K) between 7HC and thyroxine were determined to be 1.51 × 10⁴ (297 K) and 9.06 × 10³ (310 K). The binding sites (n) 0.98 ± 0.1. The thermodynamic parameters showed that the interaction between 7HC and thyroxine was driven mainly by hydrogen bonding interactions and van der Waals force. Calibration for thyroxine, based on quenching titration data, was linear in the concentration range 2.0 × 10⁻⁸ to 3.0 × 10⁻⁷ mol/l. The relative standard deviation was 2.58% for 2.0 × 10⁻⁷ mol/l thyroxine (n = 4) and the 3σ limit of detection was 3.42 × 10⁻⁸ mol/l in cationic surfactant CTAB medium.     

荧光猝灭法测定对羟基苯丙酮酸

对羟基苯丙酮酸在一定条件下对色氨酸的自体荧光有显著的猝灭作用。在pH为 11 0 1的NH4 Cl NH3 缓冲介质中 ,对羟基苯丙酮酸的含量在 0～ 15 μg·mL-1范围内与荧光强度的猝灭程度呈良好的线性关系 ,方法检测限为 0 37μg·mL-1,平行测定含 10 μg·mL-1的对羟基苯丙酮酸 2 0次 ,方法的相对标准偏差为 1 2 %。本方法有较高的灵敏度和较好的选择性 ,可用于血清中的对羟基苯丙酮酸含量的测定 ,结果满意     

PAR-吖啶黄能量转移荧光猝灭法测定痕量铁(Ⅱ)的研究

对 4 (2 吡啶偶氮 ) 间苯二酚 (PAR)与吖啶黄间荧光能量转移进行了探讨 ,研究了其能量转移的最佳条件 ,并应用该体系测定痕量铁 (Ⅱ ) ,由此建立了能量转移荧光测定痕量铁的新方法。在λex/em =46 5nm/5 0 5nm ,十二烷基硫酸钠 (SDS)作用下 ,pH =9 2时 ,吖啶黄与PAR 铁 (Ⅱ )络合物间能发生有效能量转移 ,使吖啶黄的荧光猝灭。铁的量在 0～ 10 μg·L-1范围内呈良好的线性关系。最低检出限 0 0 6 μg·L-1。该方法用于水样、发样中痕量铁的测定 ,结果满意。     

茜素红S荧光猝灭法测定壳聚糖含量

在pH 5.0的NaAc-HAc缓冲液中壳聚糖对茜素红S的荧光强度具有明显的猝灭作用,且猝灭程度F0/F与加入的壳聚糖浓度成线性关系,据此建立一种测定壳聚糖含量的荧光猝灭法。确定了最佳测定条件,线性回归方程为F0/F=-0.438 37 0.436 27c(mg·L-1),线性范围为0-16.667 mg·L-1,r=0.996,检测限为0.473 mg·L-1;平均回收率为100.60％,测定了样品中壳聚糖的含量,并考察了干扰因素对测定的影响。采用该方法可测定复杂样品中微量壳聚糖含量。