磺基水杨酸的荧光光谱与荧光量子产率

报道了磺基水杨酸 (SSA)的荧光光谱和荧光量子产率。在 pH <2时 ,SSA无荧光 ,随pH升高 ,SSA荧光增强 ,在 pH 5～ 10 5之间 ,SSA有稳定的强荧光 ,最大发射波长为 4 0 2nm ,激发波长为 2 12 ,2 38和2 97nm。在 pH >13的强碱性条件下 ,SSA转变为另一种荧光型体 ,最大激发波长 2 6 1nm ,最大发射波长390nm。SSA浓度较高时 ,荧光激发光谱发生变化 ,但发射光谱不变。在近中性条件下 ,SSA稀溶液的荧光强度与浓度之间存在良好的线性关系 ,线性范围为 5～ 2 5 0ng·mL- 1 ,检测下限为 5ng·mL- 1 。以硫酸奎宁为参比 ,测量了SSA在不同波长下的荧光量子产率 ,在最大激发波长 2 97nm处的荧光量子产率为 0 5 4。     

多光子激发荧光与毛细管电泳联用的实验研究

将多光子激发荧光探测与毛细管电泳技术相结合,研制了多光子激发荧光-毛细管电泳联用装置。这种方法可以高效快速的分离检测复杂样品中多种不同的荧光分子。作者对5HT,FAD,NADH这三种重要的生物分子,不用染料标记,分别用双光子激发和三光子激发,进行了直接的分离、识别和检测。得到的检测限分别是5HT 1.0×10-6 mol·L-1,FAD 7.4×10-７ mol·L-1,NADH 9.8×10-７ mol· L-1。5HT的检测限比紫外吸收低2个数量级;FAD和NADH的检测限比紫外吸收低1个数量级。     

叶绿素A较高激发态的发光

采用激发样品表层和样品中心两种激发方式,在300K和77K温度下研究叶绿素A(Chla)的较高激发行为,观测到峰值位于493、520和580nm三条新的荧光发射带.分别测量它们的荧光激发光谱,证明这三条新的荧光带属于Chla的第二激发单线态向基态的不同振动能级的辐射跃迁发光.最后提出电子跃迁模型,同时进行了讨论.     

利复星与人血清白蛋白作用的荧光光谱研究

用荧光光谱研究了药物利复星(Levofloxacin)与人血清白蛋白(HSA)的作用和影响,测量发现人血清白蛋白的最大激发峰位于286.70 nm处。在向该溶液滴加Levofloxacin时,原有的343.70 nm发射峰强度明显减弱, 且向长波长稍有移位,并出现了位于503.96 nm的新荧光发射峰(利复星的发射峰), 利复星对HSA荧光有猝灭作用。利复星Levofloxacin的503.96 nm荧光的激发峰则位于300.16和336.16 nm。当向该溶液滴加利复星时,300.16和336.16 nm的激发峰仅向长波长方向稍有移动。利复星对HSA的离解常数K_d=3.65×10-5(mol·L-1)。利复星的结合常数为K_S=2.742×104(L·mol-1)。利复星-HSA体系的猝灭过程不是因为分子扩散和碰撞所引起的动态猝灭,而是分子之间结合形成了化合物所引起的静态猝灭。利复星对HSA的能量转移效率为E=0.372, 利复星和人血清白蛋白的色氨酸残基的结合位置为R=1.933 nm。     

铕-樟脑酸-1,10-菲咯啉配合物的合成及发光性质

实验合成了稀土铕 樟脑酸 1,10 菲咯啉二元、三元配合物 ,通过元素分析、1 HNMR、中红外光谱、拉曼光谱 ,确定了配合物的组成为Eu2 (CA) 3·2H2 O ,Eu2 (CA) 3(phen) 2 (CA :樟脑酸根 ,phen :1,10 菲咯啉 ) ,另外 ,又合成了铕、镧混配的上述配合物 ,通过三维荧光光谱确定最佳激发波长为 310nm ,最强荧光波长为6 12nm ,即在 310nm光的激发下 ,发射光谱显示Eu3 的特征发射光谱 ,产生 7条谱带 ,分别是 5D0 7F0 (5 79nm) ,5D0 7F1 (5 94nm) ,5D0 7F2 (6 12 ,6 2 0nm) ,5D0 7F3(6 5 0nm) ,5D0 7F4 (6 89,6 97nm) ,其中7F2 和7F4能级发生了分裂。对荧光强度的研究表明 ,镧的掺入并没有降低铕的荧光强度 ,说明镧对铕的荧光发射有增强作用 ,但发射峰的位置基本不变。     

发粉红色荧光的含铽络合物光谱表征

本文报道合成了可发出粉红色荧光的含铽络合物２－萘甲酸－邻菲罗啉－铽，并对其进行了荧光光谱及红外光谱研究，结果表明，由于２－萘甲酸，邻菲罗啉配体的混配作用，使铽离子的＾５Ｄ４－＾７Ｆ３跃迁产生较强的６１５ｎｍ发射峰，其发射强度大于由＾５Ｄ４－＾７Ｆ５跃迁产生的５４５ｎｍ发射峰，因而络合行发出粉红色荧光。     

Fluorescence Study of DNA–Dye Complexes Using One-Photon and Two-Photon Picosecond Excitation

Preliminary results of investigation of one-photon- and two-photon-induced fluorescence of acridine orange (AO), epirubicin (ER), hypericin (HYP), and ethidium bromide (EB) in complexes with DNA are presented. A spectrofluorometer based on a picosecond Nd:YAG laser was used for investigations of two-photon (1064-nm, 1-mJ, 40-ps) and one-photon (532- and 355-nm) dye excitation. The spectra of two-photon-induced fluorescence of dyes and their complexes with DNA as well as the kinetics of dyes' fluorescence intensification during their interactions with DNA in dependence on the biomacromolecule concentration were obtained. The intensities of AO, HYP, and EB fluorescence were increased 2.4, 3.2, and 8 times, respectively, after binding with DNA at two-photon excitation, while at one-photon excitation the corresponding values were 2.5, 3.7, and 10 times. The difference in fluorescence enhancement during DNA–dye complex formation at linear and nonlinear excitation may possibly be associated with the fact that the cross sections of one-photon and two-photon absorption, in general, change unequally during the binding of dyes to organic molecules and bathocromic shift of the electronic transitions. It was shown that the peak of AO fluorescence shifted to a longer wavelength on 10 nm after two-photon excitation at 1064 nm in comparison with one-photon excitation at 532 nm.     

Temperature and excitation wavelength dependencies of 3-pentanone absorption and fluorescence for PLIF applications

The temperature and excitation wavelength dependencies of 3-pentanone absorption and fluorescence were studied in support of planar laser-induced fluorescence (PLIF) imaging of temperature and mixture fraction in flows of practical interest. The temperature dependencies (300–875 K) of absorption and fluorescence were measured for gaseous 3-pentanoneat atmospheric pressure in a nitrogen bath gas using 248, 266, and 308 nm excitation. The results indicate that the fluorescence signal per unit mole fraction using 248 nm excitation is highly temperature-sensitive below 600 K, while the signal from 308 nm excitation is not temperature sensitive below 500 K. For quantitative measurements over a broad range of temperatures, one must choose excitation schemes carefully to balance the trade-off between measurement sensitivity and the amount of signal at the expected conditions. As an example of such a choice and to show the capabilities of ketone PLIF techniques, we include temperature and mixture fraction images of a 300–650 K heated air jet using near-simultaneous 308 and 266 nm excitation. Received: 29 May 2002 / Revised version: 5 November 2002 / Published online: 26 February 2003 RID="*" ID="*"Corresponding author. Fax: +1-650/723-1748, E-mail: jkoch@stanford.edu RID="**" ID="**"E-mail: hanson@me.stanford.edu     

运用偏振荧光的手段研究氧化胁迫对小麦叶绿体荧光的影响

采集抽穗期小麦旗叶,采用1mmol.L-1 H2O2、干旱、黑暗处理24h诱导产生氧化损伤模型,然后运用偏振荧光的手段检测了叶绿体的荧光发射谱和荧光激发谱,结果发现,无论选择436nm激发叶绿素a(Chla)分子,或固定475nm激发叶绿素b(Chlb)分子,氧化胁迫后光系统Ⅱ反应中心P680与光系统Ⅰ反应中心P700的荧光发射峰峰面积比值A684/A720呈上升趋势;通过比较偏振荧光激发谱上E436/E475和E475/E600比值,发现随着氧化胁迫的进行,Chla对于反应中心能量传递的相对贡献大于Chlb;此外,类胡萝卜素向Chlb能量传递效率在各个偏振方向上均有所提高;通过计算偏振度及粘度,发现氧化胁迫处理促使680nm处荧光偏振度提高,内囊体膜微环境粘度增加。上述结果为研究氧化胁迫提供了一种简单、易行的方法。     

Activation Energy of Light Induced Isomerization of Resveratrol

Isomerization of trans-stilbenes is known to be induced by light. The two isomers have distinct absorption, fluorescence excitation and emission spectra. Resveratrol, 3,4',5-trihydroxystilbene, is a member of the stilbene family. The interest of the scientific community in resveratrol has increased over the last years due to its biomedical properties. Whereas there is a growing confidence that trans-resveratrol is non-toxic, very little is known about the pharmacology of cis-resveratrol. Of this very reason there is considerable interest in knowing the energetics of the trans-cis conversion. Cis-resveratrol is characterized by a large fluorescence quantum yield when compared to trans-resveratrol. In the present paper we report a detailed analysis of the spectral changes induced in trans-resveratrol upon 260?nm excitation for different time periods. Spectral changes have been monitored with UV-visible absorption and steady-state fluorescence spectroscopy at pH?4 at 20, 25, 30, 35, 40, 45 and 50?°C. Continuous 260?nm excitation induces a blue shift in the absorption and fluorescence excitation spectra of resveratrol and a 14?nm blue shift in its fluorescence emission. The photoisomerization yield is reported as a function of 260?nm excitation time. 330?min continuous excitation led to ~60% isomerization yield. The kinetics of trans-cis isomerization has been monitored following the increase in fluorescence quantum yield upon continuous 260?nm excitation of trans-resveratrol. The study was carried out at the above mentioned temperatures in order to obtain the Arrhenius activation energy of photoisomerization. Activation energy and pre-exponential factor were 3.7?±?0.3?kcal.mol(-1) and 10.6?±?1.6 s(-1), respectively. The activation energy is comparable with previously reported values for the photoisomerization of other stilbenes.     

赤藓红荧光激发光谱突变的研究

实验测量了10,20,30,40,50和60μg·mL-1六种浓度赤藓红溶液的荧光激发光谱和吸收光谱.发现在浓度为10和20μg·mL-1时,其荧光激发光谱在530 nm处会出现一个明显的激发峰,而当溶液浓度超过30μg·mL-1后,荧光激发光谱线型会发生突变,530 nm处成为谷值位置,并在530 nm两侧出现两个新...     

Experimental evidence of excited multicharged atomic fragments coming from laser-induced coulomb explosion of molecules

Direct experimental evidence is presented for the production of excited multicharged atomic fragments in the laser-induced Coulomb explosion of molecules. The comparison of the fluorescence signals of several atomic and molecular species shows that the excited fragments come from transient excited multicharged molecules. The atomic fluorescence spectra recorded with NH3, N2, and N2O, in the 50-120 nm wavelength range, show that the excitation increases noticeably from NH3 to N2O. This effect is interpreted in terms of the initial electronic configuration, which favors a stronger excitation when the electronic density is more delocalized on the molecular nuclear structure.     

色氨酸和酪氨酸的三维荧光光谱特征参量提取

氨基酸是维持生命活动的重要物质,而色氨酸和酪氨酸又是天然氨基酸中重要的发光组分,应用荧光光谱法对其进行测量和分辨具有重要的意义。文章用美国Pekin-Elmer LS55型荧光分光光度计,对色氨酸和酪氨酸的三维荧光光谱进行了测量。将测量的数据用激发-发射-荧光强度的三维坐标表示,得到三维荧光谱图,但色氨酸和酪氨酸存在共性峰,通过波峰位置简单地来辨别两种混叠的物质很有难度。以数理统计概念为基础,提取该三维荧光光谱的特征参数,得到两种物质荧光光谱中最相关的信息,可以解决两种物质光谱混叠的分辨问题。结果表明,色氨酸和酪氨酸的三维荧光光谱平均值、标准差、原点矩、混合中心矩等参数差值百分比分别为330.37%, 102.86%, 329.16%, 329.63%,区别较大;而边际分布、相关系数值差值百分比仅为10.61%和2.40%。因而平均值、标准差、原点矩、混合中心矩可作为敏感特征参数,用其分辨谱图混叠的色氨酸和酪氨酸是可行的。这种“数学预提取”的三维光谱分析法可以找出组分之间的敏感特征参量,能够取代传统的三维荧光光谱分析法。     

曲通X-100的荧光光谱与荧光量子产率

报道了曲通X-100(TX)水溶液的荧光光谱与荧光量子产率。实验发现,在强酸性条件下,TX没有荧光,当pH ＞1时,TX有稳定的强荧光,荧光激发波长为229和275 nm,发射波长为302 nm。TX水溶液可产生共振荧光,共振荧光峰位于285 nm。在0.1～90 mg·L-1浓度范围内,TX荧光强度与浓度之间存在线性关系,检测限为0.1 mg·L-1。以L-色氨酸为参比,测得在激发波长280 nm处TX水溶液的荧光量子产率为0.121。     

Local fluorescence spectroscopy and detection of malignancies using laser excitation at various wavelengths

Comparative study of the sensitivity of the local fluorescence spectroscopy in the detection of malignancies with a size of 1–7 mm is performed for various fluorescence excitation wavelengths of the injected photosensitizing agent. Several algorithms for the calculation of the fluorescence contrast of malignant lesion against the adjacent uninvolved tissue are analyzed using the Sarcoma 37 experimental tumor model. The photosensitizers from the Porphyrin (e.g. the 5-ALA-induced Protoporphyrin IX) and Chlorin (e.g. Chlorin e6) families are selected as the fluorescent marker of tissues. Three laser sources with radiation wavelengths of 408, 532, and 635 nm which fall in the absorption bands of Porphyrins and Chlorines are used for the tissue fluorescence excitation.     

银纳米敏化铽-诺氟沙星荧光和二级散射的研究与应用

铽(Ⅲ)(Tb3+)与诺氟沙星能生成二元配合物,在272 nm紫外光照射下配合物中的配体诺氟沙星能吸收能量并将其能量转移给稀土铽(Ⅲ)离子,产生铽(Ⅲ)离子的特征荧光峰,最大峰位于545 nm。而配合物的二级散射峰也恰好在545 nm。当一定浓度和一定大小颗粒的银纳米粒子加入到二元体系中时,不仅增强了铽(Ⅲ)与诺氟沙星配合物分子间的能量传递,同时也增大了体系的二级散射光强度,使得体系在545 nm处的总发射光强度大大增加,且体系的发光强度与诺氟沙星的浓度在一定浓度范围内成正比。 据此建立了一种新的诺氟沙星的分析方法。实验研究了银纳米粒子-铽(Ⅲ)-诺氟沙星体系测定诺氟沙星的最佳实验条件,线性范围为6.0×10-9～1.0×10-5 mol·L-1,检出限为4.4×10-9 mol·L-1。由于产生的发射光谱是长波区的锐线光谱,该方法干扰少、灵敏度高、选择性好, 用于测定胶囊和眼药水中诺氟沙星的含量,其回收率在93.2%～102.0%。     

Derivative fluorimetry analysis of new cluster structures formed by ethanol and Water molecules

The ultraviolet （UV） light excited fluorescence spectra of ethanol-water mixture with different concentrations are investigated by derivative fluorimetry. It is found that there are 8 types of luminescent cluster molecules, formed by ethanol and water molecules in different ways, existing in the solution. The peak wavelengths of all these clusters＇ fluorescence spectra are measured and their contents are obtained by measuring the peak values in the second derivative fluorescence spectra. The spectra corresponding to the 8 types of clusters are obtained by Gaussian decomposition. It is found that two kinds of cluster molecules whose peak wavelengths are 330 and 345 nm have an optimal excitation wavelength located at （236 4- 3） nm. This research contributes to the study of ethanol-water cluster structures and their physical and chemical characteristics.     

某些稠环芳香碳氢化合物的荧光寿命测量

应用时间相关单光子计算仪器,测量了八个对荧光光谱学和生物化学重要的稠环芳烃.所有溶液在测量前均通高纯氮除氧,对所有化合物都使用337nm激发波长,对荧蒽还在351nm激发,以验证上述两组作者所给数值之间的分歧.我们的实验对于荧蒽在337nm激发给出荧光寿命39ns,在351nm激发给出36ns,表明两个激发波长不应导致寿命数值的实质性差异.我们对其余稠环芳烃所测得的寿命值或者与文献相符,或者看起来是合理的.     

常用合成食品色素荧光光谱研究

分析合成食品色素的分子结构特点,根据荧光与分子结构的关系,理论上推断合成食品色素是荧光物质。应用SP-2558多功能光谱测量系统,测得胭脂红、苋菜红、柠檬黄、日落黄、亮蓝等五种最常用的合成食品色素标准溶液的三维荧光光谱。结果表明,胭脂红在波长330～430 nm的光激发下,产生较强荧光,荧光峰值波长为621 nm,最佳激发波长为376 nm;苋菜红在波长300～440 nm的光激发下,产生较强荧光,荧光峰值波长为643 nm,最佳激发波长为370 nm;柠檬黄在波长280～380 nm的光激发下,产生很强荧光,荧光峰值波长为565 nm,最佳激发波长为315 nm;日落黄在波长310～410 nm的光激发下,产生较强荧光,荧光峰值波长为592 nm,最佳激发波长为348 nm;亮蓝在波长320～390 nm的光激发下,产生较强荧光,荧光峰值波长为456 nm,最佳激发波长为350 nm。进而对这五种合成食品色素的荧光光谱进行了分析讨论。结果可为食品色素检测和食品安全提供帮助。     

环丙沙星的光谱性质、质子化作用与荧光量子产率

研究了环丙沙星(ciprofloxacin, CIP)在不同pH条件下的荧光光谱、紫外吸收光谱和质子化作用,测量了CIP在中性条件下的荧光量子产率。在H+浓度大于1 mol·L-1的HCl介质中,CIP分子(简写为HL)可以结合3个质子而以H₄L3+形式存在,有微弱的荧光,最大荧光发射波长(λ_ｍａｘ)为456 nm。在pH 0～2的酸性条件下,CIP主要以H₃L2+形式存在,λ_ｍａｘ为450 nm,荧光较弱,荧光强度随pH的升高而上升。在pH 2～4时,CIP主要以H₂L+形式存在,具有强荧光,λ_ｍａｘ仍为450 nm。当pH＞4时,λ_ｍａｘ逐步蓝移到414 nm,荧光强度随pH的升高而稍有降低,同时紫外吸收光谱也有明显变化,表明H₂L+随pH升高而失去质子,以双极离子HL形式存在。当pH＞8时,荧光强度随pH升高而减弱至消失,表明HL逐步失去质子,转化为无荧光的阴离子L-。在分子形态变化过程中,最大荧光激发波长始终在275 nm附近,但最大荧光发射波长有较大变化。在pH 7.0的缓冲溶液中,以硫酸奎宁为参比,测得CIP在最大荧光激发波长275 nm处的荧光量子产率为0.12。