Repair of spinal cord injury by neural stem cells transfected with brain-derived neurotrophic factor-green fluorescent protein in rats A double effect of stem cells and growth factors?

Brain-derived neurotrophic factor（BDNF）can significantly promote nerve regeneration and repair.High expression of the BDNF-green fluorescent protein（GFP）gene persists for a long time after transfection into neural stem cells.Nevertheless,little is known about the biological characteristics of BDNF-GFP modified nerve stem cells in vivo and their ability to induce BDNF expression or repair spinal cord injury.In the present study,we transplanted BDNF-GFP transgenic neural stem cells into a hemisection model of rats.Rats with BDNF-GFP stem cells exhibited significantly increased BDNF expression and better locomotor function compared with stem cells alone.Cellular therapy with BDNF-GFP transgenic stem cells can improve outcomes better than stem cells alone and may have therapeutic potential for spinal cord injury.

Syntheses, Structures and Fluorescent Property of Two Cd(Ⅱ) 3D Coordination Polymers with Mixed Ligands of Azide and Piperazine Derivatives

Two new coordination polymers, [Cd（N3）2（Baep）l/2]n （1） and [Cd2（N3）4（CH3OH）（Bapp）I/.2]n （2） （Baep = 1,4-bis（2-aminoethyl）piperazine, Bapp = 1,4-bis（3-aminopropyl）piperazine） were synthesized. The crystal of 1 is of monoclinic system, space group P21/c with a = 9.341（7）, b = 11.677（9）, c = 8.195（6） A, fl = 93.925（13）, V= 891.8（11） A3, Z= 4, μ（MoKa） = 2.42 mm-1, Mr = 280.58, Dc = 2.090 g/cm3, the final R = 0.0297 and wR = 0.0720. The crystal of 2 is of triclinic system, space group PI with a = 9.121（5）, b = 9.666（5）, c = 10.250（6） A, a = 72.91（2）, β= 77.10（2）, V = 73.95（2）°, V = 820.0（8）°, Z = 2,μ（MoKa） = 2.62 mm-1, Mr= 522.10, Dc = 2.114 g/cm3, the final R = 0.0251 and wR = 0.0632. Single-crystal X-ray diffraction studies reveal that 1 is a 3D structure based on a dinuclear unit {Cd2（N3）a（Baep）}, in which the Baep ligands formed in situ display two different bridging modes. Compound 2 also has a 3D structure based on a tetranuclear cluster {Cda（N3）8（CH3OH）2（Bapp）}, in which the azido anions exhibit four different bridging modes （μ-1,1, μ-1,3, μ-l,l,1 and μ-1,1,3）. The thermal stability and fluorescent property of 1 and 2 have also been investigated.

Ester-Derivatized Indoles as Fluorescent and Infrared Probes for Hydration Environments

Tryptophan derivatives have long been used as site-specific biological probes. 4-Cyanotrypto- phan emits in the visible region and is the smallest blue fluorescent amino acid probe for bio- logical applications. Other indole or tryptophan analogs may emit at even longer wavelengths than 4-cyanotryptophan. We performed FTIR, UV-Vis, and steady-state and time-resolved fluorescence spectroscopy on six ester-derivatized indoles in different solvents. Methyl indole- 4-carboxylate emits at 450 nrn with a long fluorescence lifetirne, and is a promising candidate for a fluorescent probe. The ester-derivatized indoles could be used as spectroscopic probes to study local protein environments. Our measurements provide a guide for choosing esterderivatized indoles to use in practice and data for computational modeling of the effect of substitution on the electronic transitions of indole.

A Fluorescent Probe based on a Carbazole Derivative for Detecting Brilliant Blue in Food

Here a fluorescent probe based on a carbazole derivative(CNS)was developed to increase the detection range and reduce the detection limit of brilliant blue.Characteristics of CNS are studied.Due to the quenching ability of colorants,CNS shows an excellent current response to brilliant blue(from 1 to 10μM)with a detection limit of 2.7×10^(-8)mol/L(3σ/k)in the conditions of a 1:1 volume ratio of water to tetrahydrofuran.And the stability and reproducibility of CNS in the detection of actual samples indicate great potential for application.

HPLC of Amino Acids and Oligopeptides by Pre-Column Fluorescence Derivatization with 9-Acridine Formyl Chloride

A highly sensitive HPLC method for the detection of amino acids and oligopeptides with 9-acridine formyl chloride by pre-column fluorescence derivatization has been developed. Glycine, glycylglycine, histidine, triglycine and glutathione were separated on a reversed-phase C-18 column with methanol-water-triethylamine eluent, derivatization and chromatographic conditions were optimized. The five derivatives were eluted in 28 min with a good reproducibility. Linear range of the calibration graph was 0.08-260 nmol/ml(-1). The relative standard deviations(n=6) are < 5%. Detection limits (signal-to-noise ratio=3) for the five derivatives are 20-40 fmol.

Multi-branched carbazole derivatives for two-photon absorption and two-photon excited fluorescence

Carbazole-core multi-branched chromophores 9-ethyl- 3, 6-bis （ 2- { 4- [ 5- （4-tert-butyl-phenyl） - [ 1, 3, 4 ] oxadiazol-2-yl ] - phenyl }-vinyl） -carbazole（3） and 9-ethyl-3-（ 2- {4-[ 5-（4-tert-butyl- phenyl） -[ 1, 3, 4 ] oxadiazol-2-yl ] -phenyl }-vinyl ） -carbazole （ 2 ） are synthesized through Wittig reaction and characterized by nuclear magnetic resonance（NMR）and infrared（IR）. The two- photon absorption properties of chromophores are investigated. These chromophores exhibit large two-photon absorption crosssections and strong blue two-photon excited fluorescence. The cooperative enhancement of two-photon absorption（TPA） in the multi-branched structures is observed. This enhancement is partly attributed to the electronic coupling between the branches. The electronic push-pull structures in the arm and their cooperative effects help the extended charge transfer for TPA.

1-Pyrenecarboxaldehyde thiosemicarbazone:A novel fluorescent molecular sensor towards mercury(Ⅱ) ion

A novel and simple fluorescent molecular sensor,1-pyrenecarboxaldehyde thiosemicarbazone（Hpytsc）,was synthesized.Its higher sensitivity and selectivity to mercury（Ⅱ） ion were studied through absorption and emission channels.The UV-vis spectra show that the increasing mercury（Ⅱ） ion concentrations result in the decreasing absorption intensity.The fluorescence monomer emission of Hpytsc is enhanced upon binding mercury（Ⅱ） ion,which should be due to the 1：1 complex formation between Hpytsc and metal ion.

One Novel 2D Co(Ⅱ) Polymer with 1,2,3-Triazole Derivative: Crystal Structure, Fluorescence and Hirshfeld Surface Analysis

One new polymer [Co（L）（H2O）2]n（1） was synthesized by 4-（ethoxycarbonyl）-5-methyl-1H-1,2,3-triazole-1-carboxylic acid（Emtc） under the in situ solvent thermal reaction（H2L = 1-（carboxymethyl）-5-methyl-1H-1,2,3-triazole-4-carboxylic acid）. The title complex performs a wave-like 2D framework and the ligand H2L demonstrates the coordination mode as μ4-η-2：η-1η-1：η-1. The crystal structure has been established by single-crystal X-ray diffraction, and characterized by FT-IR. Fluorescent property was investigated in this work. Hirshfeld surface analysis has also been carried out on 1, and obvious main intermolecular interactions are observed.

Synthesis and fluorescence properties of Tb(Ⅲ) complexes with pyridine-2,6-dicarboxylic acid derivatives

Two novel ligands named 4-styrylpyridine-2,6-dicarboxylic acid (4-SPDA) and 4-(4-(2-(2, 6-dicarboxypyridin-4-yl)- vinyl)styryl)pyridine-2,6-dicarboxylic acid(DSPDA) and their complexes with Tb(Ⅲ) were synthesized and characterized by infrared spectrometry, 1H nuclear magnetic resonance, elemental analysis and gas chromatograph-mass spectrometry. The ligand synthetic route was optimized. The fluorescence properties of the complex in solid state, in different kind of solvents and in solutions with different pH values were investigated in detail. The results show that the yields of DSPDA and 4-SPDA reach over 78% by Wittig-Horner reaction and other eight pyridine-2, 6-dicarboxylic acid derivatives with different substituents on pyridine ring, and their complexes with Tb(Ⅲ) are also obtained. The fluorescence intensities of the complexes with electron-donating groups are more intense than those of the complexes with electron-withdrawing groups on pyridine ring; fluorescence intensities of the complexes are the strongest in neutral solution (pH=7), and the less the dipole moment of solvent molecule is, the stronger the fluorescence intensity is. It is found that the two ligands (4-APDA and DSPDA) are the good sensitizers for Tb(Ⅲ) ion.

Study on Fluorescence Property of Sparfloxacin Derivatizing System and its Application

In acid medium, sparfloxacin is oxidized by nitrous acid, then reacts with hydrobromic acid to form a new fluorescence substance, which can emit the strong fluorescence. which is 151 fold more than that of sparfloxacin itself. By this, a new sensitive method for the determination of sparfloxacin in human urine by derivative-synchronous fluorescence is presented with good results.

Synthesis, Fluorescence and Dielectric Properties of Two Novel Compounds Based on Triethylenediamine Derivatives

Two compounds C_8H_(18)N_2Br_3Mn_(0.5)(1) and C_(12)H_(26)N_2Cl_4Mn(2) based on triethylenediamine derivatives were synthesized by solution method and were characterized by elemental analysis, infrared spectroscopy, single-crystal X-ray structure analysis, fluorescence test, circular dichroism(CD) analysis and dielectric measurement, respectively. According to single-crystal X-ray determination, compound 1 crystallizes in the cubic system, space group Pa3 with a = b = c = 13.7246(5) ?, Z = 24, V = 2585.2(3) ?~3; and compound 2 crystallizes in the orthorhombic system, space group P212121 with a = 7.9716(13), b = 15.309(3), c = 15.804(3) ?, Z = 4 and V = 1928.7(6) ?3. Fluorescent analysis of compound 1 showed an intense emission band at 670 nm when the exciting radiation was set at 378 nm and fluorescent analysis of compound 2 showed an intense emission band at 515 nm when the exciting radiation was set at 363 nm. Dielectric constants of compounds 1 and 2 were measured at different frequencies with temperature variation.

Synthesis, Characterization and Fluorescence of Rare earth Nitrate Complexes with Triaza-crown Ether Derivative

Four new complexes of rare earths with a triaza crown ether (L) derived from N 3O 2 macro cycle 1,12,15 triaza 3, 4: 9,10 dibenzo 5, 8 dioxacycloheptadecane were synthesized and characterized by elemental analysis, IR, molar conductance, TG DTA analysis and fluorescence spectra. The composition of the complexes determined as [RE(NO 3) 3L·3H 2O]·H 2O (RE=Sm, Eu, Tb and Dy). It is found that Sm 3+ , Eu 3+ , Tb 3+ and Dy 3+ complexes all show strong fluorescence emission in the solid state. Among these complexes, Tb 3+ complex has the strongest luminescence intensity. It shows that the ligand L triplet state energy matches 5D 4 energy level of Tb 3+ . In the Eu 3+ complex, η ( 5D 0→ 7F 2/ 5D 0→ 7F 1) is 2.6, which indicates that Eu 3+ locates at the asymmetric coordination field.

Syntheses, Crystal Structures and Fluorescence Properties of Two Triazolyl Derivatives with Biphenyl Links

Two novel triazolyl derivatives with biphenyl links, namely 4,4-bis（1,2,4-triazol-1-ylmethyl）biphenylene 1 and 4,4-bis（3,5-dimethyl-1,2,4-triazol-1-ylmethyl）biphenylene 2, have been synthesized and structurally characterized by single-crystal X-ray diffraction. Compounds 1·H2O·HCl and 2·2H2O·2HCl crystallize in the monoclinic system with space group C2/c and P21/c, respectively. The dihedral angles of the two phenyl rings are 30.26（6）° in 1·H2O·HCl, while co-planar （0.00（7）°） in 2·2H2O·2HCl. In 1·H2O·HCl, the N-H…O hydrogen bonds link 1 to form chain-like structures which are further connected by O-H…Cl, C-H…Cl, C-H…O and π-π supramolecular interactions. The hydrogen bonds of O-H…Cl in 2·2H2O·2HCl provide distinguishing P/M helical chains along the b axis, and these chains are further connected by N-H…O hydrogen bonds to generate a 2D structure. Compounds 1 and 2 in methanol solution show much stronger emission bands at 319 nm than biphenyl at 316 nm under excitation at 260 nm.

Study on State of Terbium Ion in Liposome by One order Derivative Fluorescence Quenching Method

The state of Tb3+ is investigated in liposome. When the concentration of PC is below CMC (critical micell concentration), most of Tb3+ is associated with PC, the binding constant is about 3.35×103 L/mol. When the concentration of PC is beyond CMC, most of Tb3+ is dimerized, the dimerization constant is about 3.92×104L/mol. In PC?CH?H2O system, the binding constant of Tb3+?CH complex 2.93×104L/mol is obtained.

Synthesis and pH Sensitive Fluorescent Performance of 2'-Chloroseminaphthofluorescein with Dual Bands

A novel unsymmetrical fluorescein derivative substituted by chlorine and naphthol, 2 '-chloroseminaphthofluorescein, was prepared by the two-step synthetic method. This method can effectively control the reactive process,so the pure unsymmetrical fluorescein derivative can be obtained in high yield. The new fluorophore exhibited dual absorption bands,dual excitation bands and dual emission bands with long-wavelength,selectively exciting the acidic and basic forms of the fluorophore. Compared with the similar symmetrical fluorescein derivatives such as 2 ', 7 '-dichlorofluorescein and dinaphtofluorescein, this fluorophore was found to have larger Stokes shift,especially in the basic form. Based on the properties above,this unsymmetrical fluorescein derivative is expected as a good fluorescent probe to be used where the interference exists due to the presence of endogenous fluorescers.

Synthesis of Porphyrin-Appended Pyridine as a Fluorescent Chemosensor for Cd（Ⅱ） and Hg（Ⅱ）

In this research, specific molecular sensors are classified according to the type of receptor-cation interaction, that is ligand-metal interactions. Receptors are based on a multidentate protoporphyrin-appended pyridine platform, which leaves at least a vacant coordination site for the incoming metal ions. A protoporphyrin-appended pyridine, 2,5-pyridine dicarboxyamidyl-8,13-bis（vinyl）-3,7,18,17-tetramethyl-21 H, 23 H-porphyrin（P-PTP）, was designed and synthesized. Its application as potential fluoroionophore for recognition of cadmium and mercury ions is reported. P-PTP shows chelation-enhanced fluorescence effect with Cd（Ⅱ） and Hg（Ⅱ） via the interruption of photoinduced electron transfer （PET） process, which has been utilized as the basis of the fabrication of the metal ions-sensitive fluorescent chemosensor. The analytical performance characteristics of the proposed Cd（Ⅱ）- and Hg（Ⅱ）- sensitive chemosensors were investigated. It shows a linear response toward Cd（Ⅱ） and Hg（Ⅱ） in the concentration range of 1.0×10-3 to 1.0×10-7 M with a limit of detection of 1.0×10-7 M and 0.5×10-7M for Cd（Ⅱ） and Hg（Ⅱ）, respectively. The chemosensor shows good selectivity for Cd（Ⅱ） over a large number of other transition metal ions, i.e., Cu（Ⅱ）, Zn（Ⅱ） and mixed metal ions.

STUDIES ON FLUORESCENCE SPECTRA OF SAMARIUM EUROPIUM TERBIUM AND DYSPROSIUM WITH BENZOYL UREA DERIVATIVES AND PHENANTHROLINE

Rare earth chelates of benzoyl urea derivatives were prepared in ethanol and fluorescence spectra of these chelates were studied in detail. A composition of [RE(BU)_3Phen] (NO_3)_3 was obtained. Correlation between chemical properties of ligands, chelates and spectroscopy was discussed. Intramolecular energy transfer in rare earth chelates was explained.

Design,synthesis and biological evaluation of fluorescent derivatives of ursolic acid in living cells

Ursolic acid(UA)is a naturally occurring ursane triterpenoid,which exhibits a wide range of unique biological activities.To clarify its mechanism of action(MOA),a series of fluorescent derivatives of UA(5a-c)were designed and synthesized by conjugation with 7-nitrobenzo-2-oxa-1,3-diazole(NBD)fluorophore.Among them,5c exhibited similar anti-proliferative activity with UA against HCT116 cells(half maximal inhibitory concentration(IC_(50))=9.21±0.50μmol/L).Cell imaging experiment indicated that 5c was rapidly taken up in HCT116 cells in a dose and time-dependent manner.Then,5c was found to localize in endoplasmic reticulum(ER),lysosomes,and mitochondria,but not in nucleus of HCT116 cells by confocal microscopy studies.Preliminary MOA proved that UA induced autophagy with a unique intracellular distribution mechanism involving ER and lysosome.In all,our work provides new clues for revealing the molecular mechanism of UA as an antitumor agent.

Photo-induced Ag modulating carbon dots:Greatly improved fluorescent properties and derived sensing application

Carbon dots(CDs)have been attracted much attention and widely studied due to their excellent fluorescence(FL)properties,better biocompatibility and outstanding photo/chemical stability.However,the disadvantage of lower quantum yield(QY)still limits its wide application.Herein,we reported a novel and convenient strategy to prepare photo-induced Ag/CDs(p-Ag/CDs)by irradiating the mixed Ag+and hydrophobic CDs(h-CDs)acetone solution with ultraviolet(UV)light.The obtained p-Ag/CDs exhibit a greatly enhanced FL emission together with a blue shift(460 nm)than h-CDs(520 nm).The QY of p-Ag/CDs is measured to be 51.1%,which is 10.4 times higher than that of h-CDs(4.9%),indicating that photo-induced Ag modulation can effectively improve the optical properties of CDs.The mechanisms for the FL enhancement and blue shift of h-CDs are studied in detail.The results prove that the greatly enhanced FL emission is from the generated Ag nanoparticles(AgNPs)by UV light irradiation based on metal-enhanced fluorescence(MEF),and the increased oxygen-contained groups in this process lead to the blue shift in CDs fluorescence.Interestingly,the p-Ag/CDs exhibit higher sensitivity and selectivity for sulfide ions(S2-)detection than that of h-CDs,which have a lower response to S2-.This work not only offers a novel strategy to improve the FL properties of materials but also endows them with new functions and broadens their application fields.

Spectroscopic analysis on the binding interaction of biologically active pyrimidine derivative with bovine serum albumin

A biologically active antibacterial reagent, 2-amino-6-hydroxy-4-（4-N, N-dimethylaminophenyl）-pyr- imidine-5-carbonitrile （AHDMAPPC）, was synthesized. It was employed to investigate the binding in- teraction with the bovine serum albumin （BSA） in detail using different spectroscopic methods. It ex- hibited antibacterial activity against Escherichia cali and Staphylococcus aureus which are common food poisoning bacteria. The experimental results showed that the fluorescence quenching of model carrier protein BSA by AHDMAPPC was due to static quenching. The site binding constants and number of binding sites （n ≈ 1） were determined at three different temperatures based on fluorescence quenching results. The thermodynamic parameters, enthalpy change （AH）, free energy （AG） and entropy change （AS） for the reaction were calculated to be 15.15 kJ/mol, -36.11 kJ/mol and 51.26J/mol K according to van＇t Hoff equation, respectively. The results indicated that the reaction was an endothermic and spontaneous process, and hydrophobic interactions played a major role in the binding between drug and BSA. The distance between donor and acceptor is 2.79 nm according to Forster＇s theory. The alterations of the BSA secondary structure in the presence of AHDMAPPC were confirmed by UV-visible, synchronous fluorescence, circular dichroism （CD） and three-dimensional fluorescence spectra. All these results in- dicated that AHDMAPPC can bind to BSA and be effectively transported and eliminated in the body. It can be a useful guideline for further drug design.