A solid-state fluorescence sensing system consisting of chiral (1R,2S)-2-amino-1,2-diphenylethanol and fluorescent 2-anthracenecarboxylic acid

A solid-state fluorescence sensing system was created by using a chiral supramolecular organic fluorophore having a channel-like cavity composed of (1R,2S)-2-amino-1,2-diphenylethanol as a chiral molecule and 2-anthracenecarboxylic acid as a fluorescence molecule.     

A superfluorescent fluorenyl probe with efficient two-photon absorption

The linear photophysical, excited state absorption (ESA), superfluorescence, and two-photon absorption (2PA) properties of 4,4'-(1E,1'E)-2,2'-(7,7'(1E,1'E)2,2'(4,4'-sulfonylbis(4,1-phenylene))bis(ethane-2,1-diyl)bis(9,9-didecy-9H-fluorene7,2-diyl))bis(ethane-2,1-diyl)bis(N,N-diphenylaniline) (1) were investigated in organic and aqueous media with respect to its potential application in biological imaging. The analysis of linear photophysical properties revealed a rather complex nature of the main one-photon absorption band, strong solvatochromic effects in the steady-state fluorescence spectra, single-exponential fluorescence decay, and high fluorescence quantum yields in organic solvents (≈1.0). The ESA spectra of 1 suggested potential for light amplification in nonpolar media while efficient superfluorescence in cyclohexane was demonstrated. The degenerate 2PA spectra of 1 were obtained over a broad spectral range (640-900 nm), using a standard two-photon induced fluorescence method under 1 kHz femtosecond excitation. Two well defined 2PA bands with maximum 2PA cross sections up to 1700 GM in the higher energy, short wavelength band and ≈1200 GM in the lower energy, long wavelength band of 1 were shown. The potential use of 1 in bioimaging was demonstrated via one- and two-photon in vitro fluorescence imaging of HCT 116 cells.     

Direct fluorescence quantification of chromium(VI) in wastewater with organic nanoparticles sensor.

Under ultrasonic irradiation, organic fluorescence nanoparticles have been prepared by a reprecipitation method. Compared with single organic fluorophores, these nanoparticles are brighter, more stable against photobleaching and more water-soluble. They also have high room-temperature fluorescence quantum yields (approximately 20%) and a long fluorescence lifetime (approximately 0.2 micros). Based on the fluorescence quenching of nanoparticles by chromium(VI), a method for the selective determination of chromium(VI) without the separation of chromium(III) in water was developed. Under the optimal conditions, the linear range of the calibration curve was 7.0 x 10(-6) - 1.0 x 10(-4) mol L(-1). The detection limit was 2.8 x 10(-6) mol L(-1). The method is characterized by a short reaction time, stable fluorescence signals, simplicity and high selectivity. The present assay has been applied to the selective quantification of Cr(VI) in wastewater with satisfactory results.     

磷酸缓冲盐和硫酸钠对洋葱假单胞菌脂肪酶的非水相激活

研究了kosmotropic型磷酸缓冲盐和硫酸钠对洋葱假单胞菌脂肪酶(Pseudomonas cepacia lipase, PCL)非水相催化性能的影响.以往磷酸缓冲盐被用来调控体系的pH值,其掺杂量对酶的催化活性无明显影响,而适量硫酸钠的掺杂则可有效提高酶在非水相的催化活性.本文研究发现,通过精确调控冻干过程,磷酸缓冲盐掺杂能够将PCL在有机相中的转酯化活性提高近10倍,达到其水相本征活性的50%,这一激活效果甚至高于硫酸钠掺杂.利用热重方法分析了盐掺杂PCL的含水量和蛋白结构,并将失重结果同其在有机相中的催化活性相关联,发现PCL在磷酸缓冲盐和硫酸钠掺杂下的催化构型与蛋白含水量及其周围盐环境具有不同的依赖关系.利用2-(4’-氨基-2’-羟基苯基)苯并恶唑作为荧光探针,研究了磷酸缓冲盐和硫酸钠掺杂的PCL悬浮于有机相时对荧光探针发射光谱的影响,发现盐掺杂酶制剂的存在能够大大增加荧光探针稳定于极性溶剂的构型含量,这可能与蛋白周围掺杂盐键和的水分子有关.如果用探针分子稳定于极性溶剂和非极性溶剂的构型比值间接表示悬浮酶制剂的极性结构,在正己烷体系中硫酸钠掺杂的PCL具有比磷酸缓冲盐掺杂的PCL大得多的极性,且酶制剂的极性大小与其非水相转酯化活性之间具有相似的变化趋势.上述研究结果表明,掺杂盐对粗PCL酶制剂的激活可能部分归因于掺杂盐键和的水分子在蛋白周围构筑的极性环境.     

A highly sensitive assay for spectrofluorimetric determination of reduced glutathione using organic nano-probes

In this study, the new nanometer-sized fluorescent particles (1-pyrenemethylamine nanoparticles) have been prepared by reprecipitation method under ultrasonic radiation. These nanoparticles have the potential to overcome problems encountered by organic small molecules by combining the advantages of high photobleaching threshold, high quantum yield, long fluorescence lifetime, good chemical stability, and wide excitation spectral properties. These nanoparticles will be able to be directly used as fluorescent nanoparticles probe without modification. A new fluorimetric method for the determination of reduced glutathione (GSH) has been developed with these nanoparticles. Under optimal conditions, the organic nanoparticles reacted with GSH and o-phthalaldehyde (OPA) to give a highly fluorescent derivative in Na2CO3-HCl buffer (pH=9.0). The fluorescence excitation and emission wavelengths of fluorescent derivative were located at 345 and 400 nm, respectively. The relative fluorescence intensity (RF) was linear in the range of the GSH concentration from 8.0x10(-7) to 1.1x10(-4)moll(-1). Limit of detection of 7.1x10(-8)moll(-1) was achieved for the reduced glutathione. The method was validated and applied to the analysis of three synthetic samples containing reduced glutathione.     

Spectral study on the interaction of cryptophane-A and neutral molecules CHnCl4-n (n=0, 1, 2)

Cryptophane-A was synthesized from vanillin by a three-step method and its spectroscopic properties in different organic solvents were determined. Two absorption bands at about 240-250 and 280-290 nm were observed for cryptophane-A. A fluorescence emission peak was obtained at 320-330 nm using a solution of approximately 10(-5)M cryptophane-A. The interaction of cryptophane-A with chlorinated compounds CH(n)Cl(4 - n) (n=0, 1, 2) in dioxane and ethyl acetate solvents were studied in detail by fluorescence spectroscopy, respectively. The results show that cryptophane-A is well suited for inclusion of CH(2)Cl(2) to form a stable 1:1 complex and the binding constant was estimated to be 19+/-2M(-1). These results were also confirmed by (1)H NMR and CPK models. Larger similar molecules such as CHCl(3) and CCl(4) are unable to enter the cavity of cryptophane-A because of their bigger sizes. However, the fluorescence emission of cryptophane-A can be efficiently quenched by CHCl(3) and CCl(4), following the Stern-Volmer relationship.     

Spectroscopic characterization of intramolecular charge transfer of sodium 4-(N,N-dimethylamino)naphthalene-1-sulfonate

In this paper, a new dual fluorescent N,N-dimethylaminonaphthalene derivative, sodium 4-(N,N-dimethylamino)naphthalene-1-sulfonate (SDMDNS), was reported. It was found that SDMDNS emits dual fluorescence only in highly polar solvent water but not in organic solvents such as methanol, dioxane and acetonitrile. Only a single broad band emission at ca. 420 nm was observed in the short wavelength region in organic solvents. The dual fluorescence of SDMDNS in water was found at 423 and 520 nm, respectively. Introduction of organic solvent as ethanol into aqueous solution of SDMDNS leads to blue shift of the long-wavelength emission, and this was evidently supported by introduction of cyclodextrin or surfactant in the aqueous solution. It indicates that a highly polar solvent was required to bring out dual fluorescence; furthermore, the short wavelength fluorescence is emitted from locally excited (LE) state and the long wavelength fluorescence is emitted from charge transfer (CT) state. The pH dependence of the dual fluorescence of SDMDNS demonstrates that the neutral form of the molecular has a higher ratio of CT band intensity to LE band. Temperature effect on the excited state of SDMDNS was also examined and gave stabilization enthalpy (-DeltaH ) of the CT reaction 8.7 kJ mol(-1).     

Transient excited-state absorption and gain spectroscopy of a two-photon absorbing probe with efficient superfluorescent properties

The synthesis, linear photophysical properties, two-photon absorption (2PA), excited-state transient absorption, and gain spectroscopy of a new fluorene derivative tert-butyl 4,4'-(4,4' (1E,1'E)-2,2'-(9,9-bis(2- (2-ethoxyethoxy)ethyl)-9H-fluorene-2,7-diyl)bis(ethene-2,1-diyl)bis(4,1 phenylene)]dipiperazine-1-carboxylate (1) are reported. The steady-state linear absorption and fluorescence spectra, along with excitation anisotropy, fluorescence lifetimes, and photochemical stability of 1 were investigated in a number of organic solvents at room temperature. The 2PA spectra of 1 with a maximum cross-section of ~ 300 GM were obtained with a 1 kHz femtosecond laser system using open-aperture Z-scan and two-photon-induced fluorescence methods. The transient excited-state absorption (ESA) and gain kinetics of 1 were investigated by a femtosecond pump-probe methodology. Fast relaxation processes (~1-2 ps) in the gain and ESA spectra of 1 were revealed in ACN solution, attributable to symmetry-breaking effects in the first excited state. Efficient superfluorescence properties of 1 were observed in a nonpolar solvent under femtosecond excitation. One- and two-photon fluorescence microscopy imaging of HCT 116 cells incubated with probe 1 was accomplished, suggesting the potential of this new probe in two-photon fluorescence microscopy bioimaging.     

一种星型有机低聚物的合成及光电性能

通过多步反应合成了一种新型的具有“双极(bipolar)”性质和发光性能的以N原子为中心的星型有机小分子低聚物——三(4-(5-(4-(5-(4-(二苯胺基)苯基)-1,3,4-噁二唑-2)苯基)-1,3,4-噁二唑-2)苯基)胺. 用¹H NMR, MS和元素分析进行了表征, 研究了化合物的热稳定性和固体粉末的光致发光性质, 并用循环伏安法测定了其电化学性能. 结果表明, 这种合成的同时具备空穴传导和电子输入双重功能基团的星型有机小分子光致发光性能优良(量子效率92%), 热稳定性好, 可以作为制作有机电致发光器件的候选材料.     

Rational design, synthesis, and spectroscopic and photophysical properties of a visible-light-excitable, ratiometric, fluorescent near-neutral pH indicator based on BODIPY

A visible-light-excitable, ratiometric, brightly fluorescent pH indicator for measurements in the pH range 5-7 has been designed and synthesized by conjugatively linking the BODIPY fluorophore at the 3-position to the pH-sensitive ligand imidazole through an ethenyl bridge. The probe is available as cell membrane permeable methyl ester 8-(4-carbomethoxyphenyl)-4,4-difluoro-3-[2-(1H-imidazol-4-yl)ethenyl]-1,5,7-trimethyl-3a,4a-diaza-4-bora-s-indacene (I) and corresponding water-soluble sodium carboxylate, sodium 8-(4-carboxylatophenyl)-4,4-difluoro-3-[2-(1H-imidazol-4-yl)ethenyl]-1,5,7-trimethyl-3a,4a-diaza-4-bora-s-indacene (II). The fluorescence quantum yield Φ(f) of ester I is very high (0.8-1.0) in the organic solvents tested. The fluorescence lifetime (ca. 4 ns) of I in organic solvents with varying polarity/polarizability (from cyclohexane to acetonitrile) is independent of the solvent with a fluorescence rate constant k(f) of 2.4×10(8) s(-1). Probe I is readily loaded in the cytosol of live cells, where its high fluorescence intensity remains nearly constant over an extended time period. Water-soluble indicator II exhibits two acid-base equilibria in aqueous solution, characterized by pK(a) values of 6.0 and 12.6. The Φ(f) value of II in aqueous solution is high: 0.6 for the cationic and anionic forms of the imidazole ligand, and 0.8 for neutral imidazole. On protonation-deprotonation in the near-neutral pH range, UV/Vis absorption and fluorescence spectral shifts along with isosbestic and pseudo-isoemissive points are observed. This dual-excitation and dual-emission pH indicator emits intense green-yellow fluorescence at lower pH and intense orange fluorescence at higher pH. The influence of ionic strength and buffer concentration on the absorbance and steady-state fluorescence of II has also been investigated. The apparent pK(a) of the near-neutral acid-base equilibrium determined by spectrophotometric and fluorometric titration is nearly independent of the added buffer and salt concentration. In aqueous solution in the absence of buffer and in the pH range 5.20-7.45, dual exponential fluorescence decays are obtained with decay time τ(1)=4.3 ns for the cationic and τ(2)=3.3 ns for the neutral form of II. The excited-state proton exchange of II at near-neutral pH becomes reversible on addition of phosphate (H(2)PO(4)(-)/HPO(4)(2-)) buffer, and a pH-dependent change of the fluorescence decay times is induced. Global compartmental analysis of fluorescence decay traces collected as a function of pH and phosphate buffer concentration was used to recover values of the deactivation rate constants of the excited cationic (k(01)=2.4×10(8) s(-1)) and neutral (k(02)=3.0×10(8) s(-1)) forms of II.     

Photochemical-fluorimetric method for the determination of total chlorophenoxyacid herbicides

A room temperature photochemically-induced fluorescence (RTPF) method is proposed for the quantitative analysis of seven widely-used chlorophenoxyacid herbicides. The influence of organic solvent, pH (in aqueous solutions), methanol percentage, and UV irradiation time on the excitation and emission wavelengths and fluorescence intensity was investigated. It was found that the largest fluorescence signals were obtained in a mixture of methanol and pH 5 buffer (50/50, v/v), while organic solvents and water produced generally lower signals. The tri- and bichlorinated phenoxyacid herbicides were photolysed significantly more slowly than the monochlorinated derivatives, and the derivatives of 2-propionic acid were photodegraded more quickly than the corresponding derivatives of acetic and butyric acid. Selected UV irradiation times were found to be 15 min for all herbicides under study. Linear calibration graphs were established over about one to two orders of magnitude in the interval 0.1-10 mug ml(-1). The RTPF limits of detection were between 36 ng ml(-1) and 179 ng ml(-1), according to the compound. Analytical application of RTPF to river water samples containing chlorophenoxyacid herbicides is discussed.     

Sensitive determination of nucleic acids using organic nanoparticle fluorescence probes

This paper describes the preparation of organic nanoparticles by reprecipitation method under sonication and vigorous stirring. Transmission electron microscopy (TEM) was used to characterize the size and size distribution of the luminescent nanoparticles. Their average diameter was about 25 nm with a size variation of +/-18%. The fluorescence decay lifetime of the nanoparticles also was determined on a self-equipped fluorospectrometer with laser light source. The lifetime (approximately 0.09 micros) of nanoparticles is about three times long as that of the monomer. The nanoparticles were in abundant of hydrophilic groups, which increased their miscibility in aqueous solution. These organic nanoparticles have high photochemical stability, excellent resistance to chemical degradation and photodegradation, and a good fluorescence quantum yield (25%). The fluorescence can be efficiently quenched by nucleic acids. Based on the fluorescence quenching of nanoparticles, a fluorescence quenching method was developed for determination of microamounts of nucleic acids by using the nanoparticles as a new fluorescent probe. Under optimal conditions, maximum fluorescence quenching is produced, with maximum excitation and emission wavelengths of 345 and 402 nm, respectively. Under optimal conditions, the calibration graphs are linear over the range 0.4-19.0 microgml(-1) for calf thymus DNA (ct-DNA) and 0.3-19.0 microgml(-1) for fish sperm DNA (fs-DNA). The corresponding detection limits are 0.25 microgml(-1) for ct-DNA and 0.17 microgml(-1) for fs-DNA. The relative standard deviation of six replicate measurements is 1.3-2.1%. The method is simple, rapid and sensitive with wide linear range. The recovery and relative standard deviation are very satisfactory.     

两个新的苯并噻唑衍生物的合成与光物理性质

以苯并噻唑、苯乙酰基和吡啶阳离子为电子受体,二乙烯基苯为共轭桥,合成了两个新的A-π-A′型苯并噻唑衍生物:4-(2-苯并噻唑)-乙烯基查尔酮(1)和4-{4-[2-(苯并噻唑)乙烯基]苯乙烯基}-N-甲基吡啶碘盐(2).研究了它们在溶液和固体基质中的光物理性质.研究发现:染料2由于具有较强的极性和较好的平面性,从而具有较长的吸收、发射峰和较强的荧光发射.有机染料在聚甲基丙烯酸甲酯/溶胶-凝胶复合玻璃中的发光行为与聚甲基丙烯酸甲酯和溶胶-凝胶玻璃二者的基质性质有关,同时由于固体基质中分子发生聚集的可能性降低,荧光强度相对于同浓度溶液增强,稳定性提高.     

Strong blue-fluorescence-emitted stable monolayers formed in organic solvents by a coordination polymer with long-chained bis-Schiff base

The coordination polymer, P(ZnL) (L=N,N'-bis[2-hydroxy-4-(dodecyloxy)benzaldehyde)]-ethylenedimine), forms a novel uniform lamellar superstructure in organic liquids, which exhibits intense fluorescence in organic dispersions as well as in the corresponding cast films.     

Fluorescence lifetimes and spectral properties of protochlorophyllide in organic solvents in relation to the respective parameters in vivo

In this work, absorption and fluorescence spectra of protochlorophyllide (Pchlide), as well as its fluorescence lifetime, were investigated in organic solvents having different physical properties. The obtained Pchlide spectral features are discussed in relation to the parameters describing solvent properties (refractive index and dielectric constant) and taking into account the specific solvent-Pchlide interaction. The correlation of Pchlide Qy and Soret absorption bands with solvent polarizability function ((n2 - 1)/(n2 + 2)) has been found; however, the dispersion of the observed points was rather high. A small Stokes shift of a magnitude between 50 and 300 cm(-1) was found, which indicates low sensitivity of Pchlide to nonspecific solvation. The fluorescence decay of Pchlide was single exponential in all the investigated solvents, with the lifetime value ranging from 5.2 ns for dioxane to 3.5 ns for methanol. Dependence of the obtained fluorescence lifetimes on the solvent orientation polarizability, a parameter being the function of both refractive index and dielectric constant, was discussed. In water-methanol mixtures, a further decrease of the fluorescence lifetime was observed, giving values of 2.9 ns for 25% methanol. Double-exponential decay of Pchlide fluorescence was found for Pchlide in a solution of 15% methanol with the lifetimes of 4.5 +/- 0.5 ns and 1.2 +/- 0.3 ns and in pure water with the lifetimes of 2.5 +/- 0.5 ns and 0.4 +/- 0.1 ns. The obtained results are discussed in relation to spectroscopic properties of Pchlide in vivo.     

Application of liquid-liquid-liquid microextraction and high-performance liquid chromatography for the determination of alkylphenols and bisphenol-A in water

A method termed liquid-liquid-liquid microextraction (LLLME) was utilized to extract 4-t-butylphenol, 4-t-octylphenol, 4-n-nonylphenol, and bisphenol-A from water. The extracted target analytes were separated and quantified by high-performance liquid chromatography using a fluorescence detector. In LLLME, the donor phase (i.e. water sample) was made weakly acidic by adding monobasic potassium phosphate (KH(2) PO(4)); the organic phase adopted was 4-chlorotoluene; the acceptor phase (i.e. enriched extract) was 0.2 M tetraethylammonium hydroxide dissolved in ethylene glycol. This study solves a problem associated with the surface activity of long-chain alkylphenolate ions, permitting LLLME to extract long-chain alkylphenols. Experimental conditions such as acceptor phase composition, organic phase identity, acceptor phase volume, sample agitation, extraction time, and salt addition were optimized. The relative standard deviation (RSD, 2.0-5.8%), coefficient of determination (r(2) 0.9977-0.9999), and detection limit (0.017-0.0048 ng/mL) of the proposed method were achieved under the selected optimized conditions. The method was successfully applied to analyses of lake and tap water samples, and the relative recoveries of target analytes from the spiked lake and tap water samples were 92.8-106.3 and 93.6-105.6%, respectively. The results obtained with the proposed method confirm this microextraction technique to be reliable for the monitoring of alkylphenols and bisphenol-A in water samples.     

Intramolecular charge transfer dual fluorescence of p-dimethylaminobenzoates

A series of ester, p-N,N-dimethylaminobenzoates ((CH3)2NC6H4COOR, R=n-CnH2n+1, n=1,2,...8), were synthesized and their fluorescence spectra were recorded. Intramolecular charge transfer (CT) dual fluorescence was found in common organic solvent or in water with cetyltrimethylammonium bromide (CTAB) micelle. The fluorescence intensity ratio of CT band to normal band (ICT/ILE) was decreased dramatically with the increasing of carbon number of R group when the carbon number of R group were 1-3, but the dependence was not obvious when the carbon number of R group were 4-8. Oppositely, the ICT/ILE was increased with increasing of carbon number of R group in water with CTAB micelle.     

基于杂交链式反应和共价有机框架的新型荧光传感器用于ctDNA的高灵敏和选择性检测

共价有机框架是近年来发展起来的一种高度结晶的多孔聚合物,由有机单元连接形成。由于其优异的孔隙率,模块性,结晶性和生物相容性,在传感领域显示出良好的应用前景。本文开发了一种基于杂交链式反应 (HCR) 和共价有机框架的新型荧光传感平台,用于高灵敏的检测循环肿瘤DNA (ctDNA)。ctDNA可以作为HCR的激活剂,通过触发发夹1 (H1) 和发夹2 (H2) 的自主交叉打开,激活HCR形成延伸的有缺口的双链DNA,导致荧光信号的变化,从而实现ctDNA的定量检测。HCR产物和荧光信号分别采用琼脂糖凝胶电泳和荧光光谱进行表征。ctDNA浓度在0-10 nM范围内,ctDNA的浓度与荧光信号呈良好的线性关系,检测限为1.3 nM。该方法对ctDNA具有满意的选择性,并在人类血清样品中显示出良好的性能。该荧光传感平台为ctDNA的检测提供了新思路,在癌症早期诊断中显示出潜在的应用前景。     

Investigations into the synthesis and fluorescence properties of Tb(III) complexes of a novel bis-beta-diketone-type ligand and a novel bispyrazole ligand

A novel bis-beta-diketone organic ligand, 1,1'-(2,6-bispyridyl)bis-3-(p-methoxyphenyl)-1,3-propanedione (L1) and its derivatives, a novel bispyrazole ligand, 2,6-bis(5-(4-methoxyphenyl)-1H-pyrazol-3-yl)pyridine (L2) were designed and synthesized and their complexes with Tb(III) ion were successfully prepared. The ligands and the corresponding metal complexes were characterized by elemental analysis, infrared, proton nuclear magnetic resonance spectroscopy and TG-DTA. Analysis of the IR spectra suggested that the lanthanide metal ion Tb(III) coordinated to the ligands via the nitrogen atom of the pyridine ring and the carbonyl oxygen atoms for ligand L1 and the nitrogen atom of the pyrazole ring for ligand L2. The fluorescence properties of the two complexes in solid state were investigated and it was discovered that the Tb(III) ions could be sensitized by both the ligand (L1) and ligand (L2) to some extent. In particular, the complex of ligand (L2) is a better green luminescent material that could be used as a candidate material in organic light-emitting devices (OLEDs) since it could be much better sensitized by the ligand (L2), and the fluorescence intensity of Tb(III) complex of L2 are almost as twice strong as L1's.     

Effect of the Pretreatment of Lipase with Organic Solvents on its Conformation and Activity in Reverse Micelles

The activity and conformation of Chromobacterium viscosum lipase-pretreated with various organic solvents were investigated. The pretreatment of lipase led to a substantial increase of enzyme activity in AOT (sodium bis [2-ethyl -1-hexyl] sulfosuccinate)/isooctane/water reverse micelles. Among the organic solvents used, n-hexane was found to be most effective. It was observed that higher hexane content with shorter agitation time and vice versa had almost the same effect on the initial activity of lipase. The kinetic study showed that the Michaelis constant (K _m) and the substrate adsorption equilibrium constant (K _ad) were reduced by the pretreatment of lipase with hexane, whereas the change in the maximum reaction rate (V _max) was insignificant. The two spectroscopic techniques (Fluorescence spectra of lipase encapsulated in RMs and Fourier transform infrared [FTIR] spectra of lipase powders) were performed to detect possible conformational changes in the enzyme caused by the pretreatment. A correlation between the maximum fluorescence intensity and the activity of treated lipase was found as a function of agitation time. The FTIR spectrum of lipase showed a new shape peak corresponding to 1,500 cm⁻¹ as a result of pretreatment with organic solvents.