卤代荧光素荧光猝灭法测定肾上腺色腙

在pH=6.6 的缓冲介质中, 肾上腺色腙(CBZC)与二氯荧光素(DCF)、二溴荧光素(DBF) 和二碘荧光素(DIF)通过静电引力、芳基堆积作用和范德华力形成摩尔比为2: 1的复合物, 引起上述二卤代荧光素的荧光发生猝灭, 最大猝灭波长分别位于533, 536和560 nm. 其荧光猝灭值(ΔF)在一定范围内与肾上腺色腙浓度成正比, 荧光猝灭反应具有较高的灵敏度, 对CBZC的检出限分别为3.3 ng/mL(CBZC-DCF体系), 5.7 ng/mL(CBZC-DBF体系)和129.6 ng/mL(CBZC-DIF体系). 考察了共存物质的影响、荧光猝灭反应的适宜条件和影响因素, 结果表明, 该方法具有良好的选择性, 可用于CBZC的血药和尿药浓度的快速检测. 从温度的影响、荧光寿命以及Stern-Volmer图判断该反应为静态猝灭反应.     

液膜分离富集二甲氧基羟基苯基荧光酮荧光猝灭法测定微量钼的研究

研究了在pH5．0～6．4的HAC-NaAC缓冲介质中和CTMAB存在下,Mo(Ⅳ)对二甲氧基羟基苯基荧光酮(DMH-PF)的荧光猝灭效应,建立了荧光猝灭法测定微量Mo(Ⅳ)的新体系,DMH-PF最大激发波长为λex=514nm、最大发射波长为λem=547nm,DMH-PF与Mo(Ⅵ）形成1：2配合物使荧光猝灭,荧光猝灭量与Mo(Ⅵ)在0～0．072mg／L范围内呈线性关系,方法的检出限为0．0022mg／L,体系稳定,灵敏度高,采用液膜分离富集钼,可应用于合金钢和石墨中微量钼的测定。     

联噻唑衍生物荧光猝灭汞离子传感器的研究

合成了一种新的荧光体4,4'-叔丁基-2,2'-联噻唑(DtBBT),并将其PVC敏感膜用于Hg(Ⅱ)的检测.实验表明,Hg(Ⅱ)对DtBBT的荧光具有猝灭作用,当HS(Ⅱ)浓度为1.0×10-9～1.0×10-5mol/L时,体系荧光猝灭度与Hg(Ⅱ)的浓度呈线性关系,据此建立了测定痕量Hg(Ⅱ)的高灵敏、高选择性方法,并用于河水中Hg(Ⅱ)的测定,获得了满意的结果.     

荧光光谱法研究亚甲蓝与三种芳香族氨基酸的相互作用

本文运用荧光光谱法研究亚甲蓝(MB)分别与色氨酸(Trp)、酪氨酸(Tyr)和苯丙氨酸(Phe)三种芳香族氨基酸的相互作用。在pH 7.4 Tris-HCl缓冲溶液中,MB引起上述三种氨基酸明显的荧光猝灭现象,最大荧光猝灭波长分别位于346、303和282nm。其荧光猝灭值(F0-F)在一定范围内与MB成正比,用于测定MB具有高灵敏度。通过Stern-Volmer作图及温度的影响,表明MB与三种芳香族氨基酸之间以摩尔比1∶1形成基态复合物,均产生显著的静态猝灭,相互作用力较强,其中MB主要通过疏水作用与Trp结合,与Tyr和Phe之间的结合过程以静电作用力为主。     

金属离子铜(Ⅱ)、铅(Ⅱ)和镍(Ⅱ)存在时苋菜红与牛血清白蛋白作用的荧光光谱研究

用荧光光谱法研究了在铜(Ⅱ)、铅(Ⅱ)及镍(Ⅱ)存在时对苋菜红(AT)与牛血清白蛋白(BSA)结合反应的荧光光谱特性的影响。试验在pH 7.43的B-R缓冲溶液中进行,荧光测定的激发波长(λex)为280nm和发射波长(λem)为350nm。试验发现:1由于与AT的结合,使BSA的内源性荧光发生猝灭现象,荧光的猝灭程序随AT的浓度增加而加强;2上述3种离子的加入,使AT-BSA体系的荧光猝灭有不同程度的增强;3 3种离子均能与AT竞争参与和BSA的结合,产生以生成不发光基态配合物为主的静态荧光猝灭,加强了AT对BSA的猝灭作用,但并不改变其反应的类型,在猝灭反应中同时有非辐射能量转移;4在3种离子中铅(Ⅱ)与BSA的结合能力更强。     

荧光红-曙红Y能量转移荧光猝灭法测定痕量铜(Ⅱ)的研究

探讨了荧光红与曙红Y之间的荧光能量转移,研究了Cu(Ⅱ)-荧光红-曙红Y-邻菲罗啉能量转移荧光猝灭体系的最佳条件,建立了荧光分析测定痕量铜的新方法.实验结果表明,在λex/λem=404.7 nm/545 nm,乳化剂0P存在下,荧光红的荧光光谱(λem=524 nm)和曙红Y的吸收光谱(λmax=520 nm)能有效重叠.当荧光红和曙红Y单独存在时,其最大发射波长分别为524 nm和545 nm;当荧光红和曙红Y同时存在时,曙红Y的最大发射波长不变,但其荧光强度明显增大,可见,荧光红和曙红Y分别作为能量给予体和能量接受体发生能量转移,使曙红Y荧光光谱灵敏度增大.在pH 6.5～7.6的KH2PO4-NaOH缓冲溶液中,Cu(Ⅱ)与曙红Y和邻菲罗啉形成配合物使曙红Y的荧光猝灭,加入荧光红后,体系的荧光猝灭值大大增加.利用荧光红-曙红Y能量转移荧光猝灭法测定痕量铜,提高了测定铜的灵敏度和选择性.铜含量在0～250μg/L范围内与曙红Y的荧光猝灭程度成良好的线性关系.方法的检出限为0.082μg/L;测定100μg/L铜溶液,其相对标准偏差为4.6%;样品加标回收率为101%～107.7%.方法已应用于人发、茶叶中痕量铜的测定.     

硅掺杂碳量子点荧光猝灭法测定水样中铜(Ⅱ)

3-氨丙基三甲氧基硅烷(APTMS)与戊二醛(GA)混合前驱物合成的硅掺杂碳量子点(SDCQDs),其最大吸收、激发和发射波长分别为259,245,395 nm,量子产率为13.60%,XPS谱图表明碳量子点掺杂Si,且富含甲亚胺基团和硅氧键。Cu~(2+)对碳量子点荧光产生猝灭作用,依据Cu~(2+)浓度与碳量子点荧光强度猝灭率的相关性,建立碳量子点荧光探针测定水样中Cu~(2+)的分析方法,其它金属离子对Cu~(2+)干扰程度较小,回收率为91.4%~100.8%,检出限为0.13μmol/L,相对标准偏差为0.20%~0.92%。     

农药敌磺钠与吖黄素的荧光猝灭反应及其分析应用

在pH=5.4的Britton-Robinson(BR)缓冲溶液中,农药敌磺钠(FM)与吖黄素(AF)相互作用,形成离子缔合物,导致吖黄素溶液的荧光猝灭。 当分别于最大激发波长和最大发射波长(λex/λem)451 nm/508 nm测量时,荧光猝灭值(ΔF)与敌磺钠浓度在0.16~5.0 mg/L范围内呈良好的线性关系,检出限为0.048 mg/L。 据此建立了一种测定敌磺钠的荧光分析新方法。 该方法操作简单、灵敏度高、选择性好,用于敌磺钠农药以及土壤中敌磺钠残留检测,结果满意。 还研究了反应体系的荧光特性,并结合量子化学AM1计算对荧光猝灭机理进行了讨论。     

荧光光度法测定纤维用亚麻原茎中微量铜

在KH2PO4-Na2HPO4介质中,乳化剂OP存在下,铜(Ⅱ)与水杨基荧光酮(SAF)形成配合物使荧光猝灭,由此建立了测定微量铜的荧光猝灭新方法.该体系的最大激发波长λex＝365 nm,最大发射波长λem＝526 nm.研究表明,该法Cu(Ⅱ)的含量在0.0～5.0 μg/25mL范围内与荧光猝灭程度(△F)呈线性关系,相关系数R2＝0.9993,检出限为1.28 μg/L.方法灵敏度高,选择性好,用于测定纤维用亚麻原茎中微量铜的测定,回收率在99.8％～101.5％之间.     

新型水溶性萘啶基荧光材料的制备及性能研究

本文制备得到一种新型萘啶基的水溶性光致发光聚合物:聚丙烯酸(PAA)-2-苄氨基-7-甲基-1,8-萘啶,PAA₅-PAMN₂(PAMN是2-phenmethy-lamino-7-methyl-1,8-naphthyridine的缩写),经光谱分析和密度泛函理论计算,研究了化合物的结构和组成.这种聚合物在酸性和碱性条件下呈现最大的吸收波长分别为364和342 nm.Zn(OAc)₂的加入致使PAA₅-PAMN₂水溶液的荧光猝灭,而当OAc^-改变为NO₃^-时,在荧光强度不断降低的同时,由于NO₃^-离子的配位使最大发射波长从410 nm蓝移到400 nm.Na⁺+离子对其没有明显的荧光猝灭效应.     

Gas permeation behavior of PS/PPO blends

Miscible blends of polystyrene (PS) and poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) were prepared by a solution casting method to examine the permeation characteristics for oxygen and nitrogen. Gas permeation characteristics of PS/PPO membranes prepared using two different methods, slowly cooled and quenched, after being treated at various annealing temperatures were examined with respect to the controlled free volume. A variety of compositions of PS/PPO membranes provided varying permeability coefficients and ideal separation factors. This indicates that the present miscible blends gave rise to a decrease in the free volume by the physical interaction between two polymer components. For the slowly cooled PS/PPO membranes, the permeability coefficient decreased but the ideal separation factor increased with decreasing annealing temperatures due to the fast macromolecular relaxation or the efficient packing effect of macromolecular chains. On the other hand, the permeability coefficient of the quenched PS/PPO membranes increased with increasing annealing temperatures, as the quenching from higher annealing temperatures led to the existence of more free volume.     

Investigation on the Luminescence Performance of Four Quinolones

Abstract

In this paper we report on the low temperature phosphorescence (LTP), the low temperature fluorescence (LTF), the paper substrate room temperature phosphorescence (PS‐RTP), and the room fluorescence (RTF) properties of ciprofloxacin (CPFX), lomefloxacin (LMX), fleroxacin (FLX), and ofloxacin (OFLX), which were investigated and compared. Some rules were discovered: their maximal excitation wavelength and emission wavelength are in the range of 280–295 nm and 428–500 nm, respectively, except OFLX, and the difference in molecular structure may be responsible for it. The pH experiments show that all their emissions are strongest in acid, followed by neutral, and weakest in alkali medium. The PS‐RTP characters of lifetime and polarization were also investigated and compared. It was found that the lifetimes of PS‐RTP were all in the level of 0.1 s. These quinolones belong to long‐life phosphorescence and their PS‐RTP spectra are incompletely polarized.     

EFFECT OF PLASTICIZER ON THE MICROSTRUCTURE OF PS/PVC BLENDS

In this work, controlling of the particle size of PVC in PS/PVC blends was studied. Itis shown that viscosity ratio and particle size can be changed by adding a third composition,such as plasticizers, and the distribution of the third composition in two phases plays avery important role in controlling viscosity ratio and particle size. When DOP was used asthe plasticizer of PVC in PS/PVC blends, the particle size of PVC could not be reduceddue to the transference of DOP into PS phase. When polycaprolactone (PCL) was usedas the plasticizer of PVC in the same blends, the particle size of PVC could be descreasedobviously because PCL does not migrate to PS phase.     

荧光光谱法研究PS分子链在不同溶剂中的荧光特性

利用荧光光谱法研究了溶剂和浓度对聚苯乙烯（PS）荧光特性的影响. 研究表明,PS在四氢呋喃溶液中的荧光发射波长为345 nm,其荧光强度达到最大时的饱和浓度为0.1 mg/mL;PS在甲苯溶液中的荧光发射波长为310 nm,其荧光强度达到最大时的饱和浓度为0.075 mg/mL. 造成这种现象的原因在于:四氢呋喃不具荧光性,不与PS分子链中的苯环发生相互作用,而甲苯溶剂自身具有苯环结构,PS和甲苯生色团荧光频率接近,同时PS分子链上苯环与甲苯上的苯环的间距非常小,相邻苯环上的π电子可以互相重叠,形成T型构造的苯环二聚体,使体系的荧光发射峰蓝移至310 nm. 另外,随着PS在溶液中浓度的增大,开始呈线性增加,当浓度大于饱和浓度C*后,随后其荧光强度呈现非线性下降,这主要是PS在溶剂中形成了二聚体.     

氮掺杂鸡毛碳点荧光关开探针用于测定百草枯

以鸡毛和乙二胺为碳源和氮源,通过一步水热法合成强荧光性能的氮掺杂碳量子点(N-CQDs),并优化其制备和掺杂条件。该碳量子点具有良好的光学、结构性质和稳定性,平均粒径7.89 nm,荧光量子产率为14%。最大激发波长为320 nm,最大发射波长为386 nm。Hg²⁺存在条件下N-CQDs溶液的荧光被猝灭(关),添加百草枯后猝灭的荧光被恢复(开)。通过N-CQDs/Hg²⁺体系设计了荧光"关-开"方法,在最佳条件下,百草枯在0.05~1.0μg/mL范围内具有良好的线性,线性方程为ΔF=92.41X+123.31(R²=0.9989),检出限为16μg/L,加标回收率为95.3%~104.4%,RSD<3.8%。以鸡毛为原料制备的高选择性和灵敏性的荧光"关-开"探针方法可有效检测实际样品中的百草枯。     

SPECTRAL ANALYSES OF LOW LEVEL CHEMILUMINESCENCE OF A SHORT LIFETIME USING A HIGHLY SENSITIVE POLYCHROMATIC SPECTROMETER INCORPORATING A TWO DIMENSIONAL PHOTON-COUNTING TYPE DETECTOR

Abstract— Spectral analyses of low level chemiluminescence were carried out by using a newly developed polychromatic spectrometer in which a diffracted photon emission was detected simultaneously using a two dimensional photon-counting device. The spectrometer was sensitive in the 400–800 nm wavelength range. Low level chemiluminescence generated in a 1 nM luminol solution could be detected as a spectrum, showing a peak at 430 nm. Short lifetime photon emission from singlet oxygen showed only two peaks at around 630 and 700 nm in this highly time-resolved spectroscopy. Lipid peroxidation of linoleic acid by the lipoxygenase emitted a low intensity peak centered at 440 nm, but singlet oxygen emission arising from the decomposition of lipid peroxide was not observed. An injured cotyledon of a soybean seedling gave a broad emission centered at 725 nm in the absence of hydrogen peroxide, while in its presence a different emission peak appeared at a shorter wavelength (515 nm). Oxygenated, fluorescent components in the soybean seedling may be the emitting species. Singlet oxygen and triplet carbonyl groups were shown to be unlikely sources of the emission.     

Photoluminescence from water-soluble BSA-protected gold nanoparticles

The photoluminescence from water-soluble gold nanoparticles, each composed of a 5.1 nm gold core and a bovine serum albumin (BSA)-protected layer, has been observed. The maximal excitation and the maximal emission wavelength are at 320 and 404 nm, respectively. The photoluminescence quantum yield is estimated as 0.053+/-0.0070, at room temperature. The mechanism of the luminescence is hypothesized to be associated with interband transitions between the filled 5d(10) band and 6(sp)(1) conduction band. The photoluminescence is sensitive to pH, organic solvents and metal ions. These observations suggest that this nanoparticles are a viable alternative to organic fluorophores or semiconductor nanoparticles for biological labeling and imaging.     

Poly(N,N-dimethylaminoethyl methacrylate) grafted poly(vinyl chloride)s synthesized via ATRP process and their membranes for dye separation

To functionalize poly(vinyl chloride)(PVC) for various applications, monomers containing tertiary amine group are incorporated into PVC via atom transfer radical polymerization(ATRP) initiated by the labile chlorines in their backbones. The kinetics of synthesis was carefully investigated, and it is proven that the grafting polymerization process can be effectively controlled by regulating the reaction time. The membranes are fabricated using PVC and copolymers by non-solvent induced phase separation(NIPS) process. The hydrophilicity and pore structure of copolymer membranes were enhanced as well, these membranes are endowed with positive charge. When PDMA%(i.e., the PDMA weight percentage in copolymer) is 31.1%, the flux and Victoria blue B rejection are 26.0 L?m?2?h?1(0.5 MPa) and 91.2%, respectively. Thus, the newly synthesized polymer is proven to be a promising material for dye separation with positive charges.     

INVARIABLE TRAPPING TIMES IN PHOTOSYSTEM I UPON EXCITATION OF MINOR LONG-WAVELENGTH-ABSORBING PIGMENTS

The primary charge separation in photosystem (PS) I was measured on stacked pea thylakoids using the light-gradient photovoltage technique. Upon 532 nm excitation with picosecond flashes, a trapping time of 80 ± 10 ps for PS I was found, which is in close agreement with literature data. In the wavelength range between 700 nm and 717 nm the trapping time was essentially the same although there was an indication for a slight decrease. To further analyze the data we performed a spectral decomposition of PS I with Chi a and b solvent spectra. This procedure yielded bands at around 682 nm, 690 nm, 705 nm and 715 nm. According to this decomposition, a selective excitation of long-wavelength antenna pigments at wavelengths Λ > 710 nm is possible, because the direct excitation of the main 682 nm band is small compared to the excitation of the two most red-shifted bands. The invariability of the trapping time of the excitation wavelength suggests thermal equilibration of the excitation energy among all antenna pigments according to their excited state energy levels and their abundance. Hence, we conclude that trapping in PS I is essentially rate-limited by the primary charge separation much as it is the case in PS II. Then, according to our spectral decomposition in a time constant of2–3 ps is predicted for the primary charge separation in PS I.     

Interface thickness of the incompatible polymer system PS/PnBMA as measured by neutron reflectometry and ellipsometry

The techniques of neutron reflectometry and spectroscopic ellipsometry are compared as methods to measure the interface width between immiscible polymers. The interface thickness of the incompatible polymer system of polystyrene (PS) and polyn-butyl methacrylate) (PnBMA) is determined by neutron reflectrometry to (6.4±0.2) nm and (8.6±0.2) nm at temperatures of 120 and 156°C, respectively. Some emphasis is put on the measurement of those values also by spectroscopic ellipsometry using the same materials. A special sample geometry is chosen for ellipsometric measurements to compensate for thickness changes of films during annealing, and the dispersions of PS and PnBMA films are determined. With respect to the determination of the interface widths, however, it turns out that in the available wavelength range of 280 to 700 nm spectroscopic ellipsometry is not sensitive enough to measure the thin interface width between PS and PnBMA films. Neutron reflectivity results obtained for PS/PnBMA are discussed with respect to the Flory-Huggins segment interaction parameter calculated within the approximations of meanfield theory.