Spectrofluorimetric Determination of Methyl Paraben in Pharmaceutical Preparations by Means of its Dansyl Chloride Derivative

 A spectrofluorimetric method for the determination of methyl paraben based on derivatization with the labelling reagent dansyl chloride (DNS-Cl), is presented. The effect of the reaction variables (pH, DNS-Cl concentration, temperature, reaction time) and instrumental parameters, has been examined. A linear calibration graph in the ng/ml range has been established. The limit of detection is 18 ng/ml with relative standard deviation less than 3%. The proposed method has been satisfactorily applied to determination of the paraben in two pharmaceutical preparations. Received May 25, 1999. Revision October 20, 1999.     

LB膜中聚集体的时间分辨荧光研究

利用吸收，稳态和时间分辨荧光方法研究了苯腙（ＰＤ）和半花菁（ＤＡＥＰ）分子在Ｚ型ＬＢ多层膜中的聚集性质，苯腙和半花菁吸收光谱的红移和兰移，说明它们分别以Ｊ和Ｈ型聚集体形式存在于ＬＢ膜中，苯腙和半花菁ＬＢ膜的荧光发射带分别在５６０ｎｍ和５８４ｎｍ处，亦分别对于它们溶液的荧光谱呈示出红移和兰移的特征，它们的荧光衰减曲线能很好地用双指数模拟拟合，在苯腙和半花菁ＬＢ多层膜中主要存在着荧光寿命分别在ｎｓ和１     

丹磺酰基为核的树枝状化合物的合成和光谱性质研究

通过收敛法合成了二代丹磺酰基为核、活泼羟乙基为外围基团的新型树枝状化合物, 产物进行了IR, ¹H NMR, ¹³C NMR, MS, EA表征. 该合成方法无需复杂的官能团保护与去保护, 后处理简便, 产率高. 对产物的荧光光谱的初步研究结果表明, 随着树枝状产物代数的增加, 荧光强度得到成倍增强.     

稳态荧光探针法研究复配乳化剂的聚集行为

采用荧光探针技术,根据芘的第一振动峰I₁(373 nm)与第三振动峰I₃(384 nm)荧光强度的比值(I₁/I₃)随乳化剂浓度的变化,对十二烷基磺酸钠(AS)与壬基酚聚氧乙烯醚(Oπ-10)复配乳化剂的CMC值进行了测定,并与十二烷基磺酸钠(AS),壬基酚聚氧乙烯醚(Oπ-10)的CMC值进行了比较,结果表明复配乳化剂的CMC介于两者之间.以二苯甲酮为猝灭剂,用稳态荧光法测定了不同比例复配乳化剂的胶束聚集数,实验结果表明,复配乳化剂浓度为4—9倍CMC时,测定的胶束聚集数随复配乳化剂浓度的增大而线性增大;且Oπ-10:AS<2:1时,随着复合乳化剂中Oπ-10比例的增大,复配乳化剂胶束聚集数增大.利用芘的I₁/I₃值,结合胶束微环境的极性变化规律,探讨了复配乳化剂的聚集行为对硅丙乳液聚合物的影响.     

Amphiphilic Fluorescence Resonance Energy-Transfer Dyes: Synthesis,Fluorescence, and Aggregation Behavior in Water

Amphiphilic pyrene/perylene bis-chromophore dyes were synthesized from unsymmetrically substituted perylene bisimide dyes, which were obtained through three synthetic methods. The optical and aggregation behaviors of these functional dyes were studied by means of UV/Vis absorption and fluorescence spectroscopy, dynamic light scattering, and TEM. These dyes are highly fluorescent and cover the whole visible-light region. A donor/acceptor dye displays intramolecular fluorescence resonance energy transfer (FRET), with a high efficiency of up to 96.4 % from pyrene to perylene bisimide chromophores, which leads to a high fluorescence color sensitivity to environmental polarity. Under a λ=365 nm UV lamp, the light-emitting colors of the donor/acceptor dye change from green to yellow with increasing solvent polarity, which demonstrates application potential as a new class of FERT probes. The donor/acceptor dye in water was assembled into hollow vesicles with a narrow size distribution. The bilayer structure of the vesicular wall was directly observed by means of TEM. These vesicular aggregates in water are fluorescent at λ=650–850 nm within the near-infrared region.     

荧光探针法研究新型Gemini表面活性剂在水溶液中的聚集行为

以芘为荧光探针、二苯酮为猝灭剂,用稳态荧光探针法测定了新型Gemini表面活性剂的临界胶团浓度(CMC)、胶团聚集数(N_agg)及胶团微极性.研究了Gemini表面活性剂结构和氯化钠浓度对CMC、N_agg、胶团微极性的影响.结果表明,新型Gemini表面活性剂的CMC比常规表面活性剂的CMC低1—2个数量级.当疏水基碳原子数增加时,CMC依次降低,N_agg增大,胶团微极性减小.当氯化钠浓度增大时,N_agg增大,胶团微极性减小.     

The LB Films of Dansyl Chloride Labeled Octadecylamine and Its Fluorescence Lifetime

IntroductionFluorescent probe labeling 1, 2, microchip and LB (Langmuir-Blodgett) films of DNA and proteins3 are important in molecular electronic and biotechnological applications such as information processing and molecular recognition. As an imitated and simplified model of above complex cases, here we prepare the LB films of dansyl chloride (5-dimethylaminonaphthalene-1-sulfonyl chloride, denoted as DNS) labeled octadecyl amine (AM). A molecule based naphthalene sulfonate is well kno…     

Rational Topological Design for Fluorescence Enhancement upon Aggregation of Distyrylfuran Derivatives

A series of 2,5‐distyrylfuran derivatives bearing pentafluorophenyl‐ and cyanovinyl units have been synthesized for aggregation‐induced emission (AIE). The effect of the type and extent of the supramolecular connections on the AIE of the furan derivatives were examined and correlated with their X‐ray crystal structures. It was found that the simultaneous presence of cyano and perfluorophenyl units strongly enhances the fluorescence upon aggregation. Single‐crystal X‐ray diffraction analysis confirmed that C?H???F, F???F, C?H???nitrile, Ar???Ar_F (Ar=aryl, Ar_F=fluoroaryl), and nitrile???Ar_F intra‐ and intermolecular interactions drive the topology of the molecule and that solid‐state supramolecular contacts favor AIE of the furan derivatives.     

荧光探针法和电子自旋共振技术研究干扰基团对烷基苯磺酸钠聚集行为的影响

利用稳态荧光探针法和电子自旋共振技术测定多烷基苯磺酸钠的临界胶团浓度(cmc)、胶团聚集数(N_agg)、胶团的微极性和微粘度.当干扰基团增加时,烷基苯磺酸钠的临界胶团浓度减少,胶团聚集数减少,胶团微粘度降低,胶团的微极性增强.     

Kinetic Study of the Catalyzed Substitution Reaction of Benzal Chloride and Sodium Iodide in Acetone

The substitution reaction of benzal chloride (PhCHCl₂) and sodium iodide in acetone needs a metal-ion catalyst. Without considering the effects of solubility and the dissociation of salt, salts of Cr(III), Mn(II), Fe(II, III), Co(II), Ni(II), Cu(II)m Zn(II), Cd(II), Hg(I, II), and Sb(III) ions are used to study their catalytic reactivities. It is found that the Fe(II) ion exhibits acceptable catalytic effect. The overall Fe(II)-catalyzed PhCHCl₂-NaI reaction can be described by the following competitive consecutive scheme: PhCHCl₂ → PhCHCII → PhCHI₂. Under suitable conditions, coupling products such as PhCH=CHPh and PhCHClCHClPh are also found. The rate of the first-stage substitution of the PhCHCl₂-NaI reaction increases linearly with the PhCHCl₂ concentration. It increases asymptotically with the FeCl₂ concentration. However, there is an optimum concentration for Nal. The apparent activation energies are 104 ± 4 kJ/mol and 133 ± 4 kJ/mol for the Fe(II)-catalyzed PhCHCl₂-NaI and PhCHCH-NaI reactions, respectively.     

荧光光谱法研究牛血清蛋白在盐酸胍体系中的变性

应用荧光光谱技术,对盐酸胍与牛血清蛋白在30℃水溶液中的结合作用及造成牛血清蛋白变性的过程进行了研究,考察了盐酸胍诱导牛血清蛋白变性时荧光强度和峰位的变化规律,并计算出伸展分数fu,变性平衡常数Ku,伸展吉布斯自由能△Gu,衡量蛋白质对变性剂稳定性的参量△GH2o,衡量蛋白质变性协同性的参量m和变性中点C1/2.研究结...     

壳聚糖在稀溶液中的聚集行为

壳聚糖在稀溶液中的聚集行为;荧光探针;荧光偏振;聚集行为     

Fluorescence Polarization and the Aggregation of Deoxy-Hemoglobin S

Abstract

The fluorescent analogue 8-hydroxy-1,3,6-pyrene-trisulfonate is known to bind to the 2,3-diphosphoglyceric acid binding site of deoxy hemoglobin. We have used this property to monitor temperature dependent changes in concentrated solutions of deoxy hemoglobin S. By monitoring the polarization of fluorescence from the bound fluorophore, we have been able to demonstrate that the polarization of fluorescence goes through a temperature maximum analogous to that which has been observed with temperature versus viscosity measurements when following aggregation of deoxy hemoglobin S. Results of experiments with deoxy hemoglobin A and deoxy hemoglobin S suggest that difference in aggregation may be related more to quantitative differences than to qualitative differences.     

Phenoxazine-Dibenzothiophene Sulfoximine Emitters Featuring Both Thermally Activated Delayed Fluorescence and Aggregation Induced Emission

In this work, we demonstrate dibenzothiophene sulfoximine derivatives as building blocks for constructing emitters featuring both thermally activated delayed fluorescent (TADF) and aggregation-induced emission (AIE) properties, with multiple advantages including high chemical and thermal stability, facile functionalization, as well as tunable electron-accepting ability. A series of phenoxazine-dibenzothiophene sulfoximine structured TADF emitters were successfully synthesized and their photophysical and electroluminescent properties were evaluated. The electroluminescence devices based on these emitters displayed diverse emissions from yellow to orange and reached external quantum efficiencies (EQEs) of 5.8% with 16.7% efficiency roll-off at a high brightness of 1000 cd·m⁻².     

激光光散射与荧光光谱法研究大豆苷与牛血清白蛋白作用及聚集态

荧光光谱法和动态光散射法研究大豆苷与牛血清白蛋白在生理条件下的相互作用. 研究表明, 大豆苷与牛血清白蛋白能形成2∶l复合物, 荧光猝灭属于静态猝灭过程; 大豆苷与牛血清白蛋白分子间主要的结合作用力为疏水作用; 310 K下, 两者结合常数和结合位点数分别为7.4×l04 L&#8226;mol―1和1.75; 大豆苷使牛血清白蛋白的构象发生了变化; 动态光散射数据探讨了牛血清白蛋白与大豆苷分子产生聚集与之相互作用, 进一步证实了牛血清白蛋白在大豆苷水溶液中的构象变化. 实验结果为进一步研究大豆苷对心血管疾病的药理作用, 特别是对血浆蛋白构象的影响提供了重要依据.     

Polymorph‐Dependent Thermally Activated Delayed Fluorescence Emitters: Understanding TADF from a Perspective of Aggregation State

Current research on thermally activated fluorescence (TADF) emitters is mainly based on the molecular levels, while the aggregation states of TADF emitters are to be explored deeply. Now two multifunctional emitters are reported with simultaneous TADF, aggregation induced emission (AIE), and multicolor mechanochromic luminescence (MCL) features. Both emitters also show polymorph‐dependent TADF emission. Crystal structure analysis reveals that the polymorphism is ascribed to the mutable conformations in different aggregation states. This work brings new insight to TADF emitters from a perspective of aggregation states.     

PAMAM structure-based multifunctional fluorescent conjugates for improved fluorescent labelling of biomacromolecules

Fluorescent probes are of increasing interest in medicinal and biological applications for the elucidation of the structures and functions of healthy as well as tumour cells. The quality of these investigations is determined by the intensity of the fluorescence signal. High dye/carrier ratios give strong signals. However, these are achieved by the occupation of a high number of derivatisation sites and therefore are accompanied by strong structural alterations of the carrier. Hence, polyvalent substances containing a high number of fluorescent dyes would be favourable because they would allow the introduction of many dyes at one position of the compound to be labelled.A large number of different dyes have been investigated to determine the efficiency of coupling to a dendrimer scaffold and the fluorescence properties of the oligomeric dyes, but compounds that fulfil the requirements of both strong fluorescence signals and reactivities are rare. Herein we describe the synthesis and characterisation of dye oligomers containing dansyl-, 7-nitro-2,1,3-benzoxadiazol-4-yl- (NBD), coumarin-343, 5(6)-carboxyfluorescein and sulforhodamine B2 moieties based on polyamidoamine (PAMAM) dendrimers. The PAMAM dendrimers were synthesised by an improved protocol that yielded highly homogeneous scaffolds with up to 128 conjugation sites. When comparing the fluorescent properties of the dye oligomers it was found that only the dansylated dendrimers met the requirements of enhanced fluorescence signals. The dendrimer containing 16 fluorescent dyes was conjugated to the anti-epidermal-growth-factor receptor (EGFR) antibody hMAb425 as a model compound to show the applicability of the dye multimer compounds. This conjugate revealed a preserved immunoreactivity of 54%.We demonstrate the applicability of the dye oligomers to the efficient and applicable labelling of proteins and other large molecules that enables high dye concentrations and therefore high contrasts in fluorescence applications.