Ultrasonic-Assisted Synthesis of Monodisperse Ag Nanoparticles and Their Applications in Surface Enhanced Raman Scattering and Fluorescence Enhancement

Monodisperse Ag nanoparticles with diameters of about 3.4 nm were synthesized by a facile ultrasonic synthetic route at room temperature with the reduction of borane-tert-butylamine in the presence of oleylamine （OAm） and oleic acid （OA）. The reaction parameters of time, the molar ratios of OAm to OA were studied, and it was found that these parameters played important roles in the morphology and size of the products. Meanwhile, surface enhanced Raman spectrum （SERS） property suggested the Ag nanoparticles exhibited high SERS effect on the model molecule Rhodamine 6G. And also, two-photon fluorescence images showed that the silver nanoparticles had high performances in fluorescence enhancement.

Fluorescence Enhancement of Polyamine Derivatives of 1,8-Naphthalimide with Transition Metal Ions

A series of fluorescent chemosensors 1-3 were synthesized to detect transition metal ions. At the room temperature, fluorescence intensities of these chemosensors in acetonitrile without transition metal ions were found to be very weak, due to the process of the efficient intramolecular photoinduced electron transfer （PET）. However, after addition of the transition metal ions, the chemoscnsor 1-3 exhibits obvious fluorescence enhancement. Moreover, the intensity of the fluorescence emission of chemosensors increases significantly in the presence of Zn^2＋ and Cd^2＋. The fluorescent chemosensors with different polyamine as receptors show diverse affinity abilities to the transition metal ions and signal the receptor-metal ion interaction by the intensity change of fluorescence emission.

Fluorescence enhancement and cofluorescence in complexes of terbium(III) with trimellitic acid

The fluorescence of terbium （Ⅲ） was enhanced by about three orders of magnitude in the presence of trimellitic acid （benzene-1, 2, 4-tricarboxylic acid （TLA）） in aqueous solution at pH 6. The fluorescence intensity could be greatly increased when the system of Tb^3＋-TLA was treated with La^3＋ （or Gd^3＋） and TritonX- 100. The addition of La^3＋ （or Gd^3＋） enhanees the fluorescence of the system by about two orders of magnitude due to cofluorescenee, and the TritonX-100 micellar medium plays an important role for stabilization of the system. Both the intermolecular energy transfer mode and intramolecular energy transfer mode are responsible for the mechanism of fluorescence enhancement. In the optimum condi- tions, the fluorescence intensity is a linear function of Tb3~ concentration in the range of 7.8 × 10^-9-3.6 × 10^4 mol/L for the system Tb^3＋-La^3＋-TLA and 1.0 × 10^-8-4.7 × 10^-5 mol/L for the system Tb^3＋-Gd^3＋-TLA, and the limits of detection are 4.6 × 10^-10 mol/L and 6.0 × 10^-10 mol/L, respectively.

On the fluorescence enhancement mechanism of Er^(3+) in germanate glass containing silver particles

The spectral properties of trivalent erbium ions（Er^3＋） are systematically studied in a melt-quenched germanate glass（60 GeO2-20PbO-10BaO-10K2O-0.1Ag2O） containing silver（Ag） particles.Thermal treatment of the material leads to the precipitation of Ag particles as observed by transmission electron microscopy and confirmed by absorption spectrum for the obvious surface plasmon resonance peak of Ag particles.The fluorescence from Er^3＋ in the 10-min-annealed sample with Ag particles is found to be 4.2 times enhanced compared with the unannealed sample excited by 488-nm Ar＋ laser.A comparison is made between a spectral study performed on the unannealed Er^3＋-doped sample and the one annealed for 20 min.The data of absorption cross section and Judd-Ofelt intensity parameters show the agreement between the two samples no matter whether there are Ag particles,indicating that the introduction of Ag particles by post-heat treatment has no effect on the crystal field environment of Er^3＋ ions.The fluorescence enhancement is attributed to the surface plasmon oscillations of Ag particles in germanate glass.

Fluorescence and cofluorescence enhancement of Tb(Ⅲ) complexes with pyromellitic acid by M (M = Gd, La, Ca, and Sr ions)

Fluorescence and cofluorescence properties of Tb(Ⅲ) solid complexes werestudied using pyromellitic acid (PMA) as ligand and fluorescence inert ions as doping elements. Thecofluorescence enhancement, a result of ligand sensitized fluorescence, was observed in Tb(Ⅲ) solidcomplexes doped with fluorescent inert ions La(Ⅲ), Gd(Ⅲ), Ca(Ⅲ), and Sr(Ⅲ). The effect of thetype and content of doping elements on fluorescence enhancement was studied, and optimum conditionswere determined. The results show that Gd (La, Ca, Sr) has clear cofluorescence effect in solidcomplex Tb-M-PMA system, and in present work, rare earth complex fluorescent powder that emitsbright green fluorescence at ultraviolet excitation was obtained, which had potential application asfluorescent anti-counterfeit ink.

Fluorescence Enhancement of Metal-Capped Perovskite CH3NH3PbI3 Thin Films

We fabricate nano-structural metal films to improve photoluminescence of perovskite films. When the perovskite film is placed on an ammonia-treated alumina film, stronger photoluminescence is found due to local field en- hancement effects. In addition, the oxide spacer layer between the metal （e.g., AI, Ag and Au） substrate and the perovskite film plays an important role. The simulations and experiments imply that the enhancement is related to surface plasmons of nano-structural metals.

Fluorescence enhancement of radix angelica dahurica by binding to single silver sphere

We present a theoretical study of the influence of a single silver sphere on the fluorescence of radix angelica dahurica, which is a kind of traditional Chinese medicine. The enhancement factors of the excitation and the relaxation processes are deduced. The excitation can be enhanced more than 100 times at 315 nm. The enhancement factor of the emission can reach up to 9 at a center wavelength of 400 nm.

Studies on the Fluorescence Enhancement Effect of Eu-La-DBM-DPG-Acetone System

The study of fluorescence enhancement has attracted attention recently. For example, the sensitivity and selectivity of Eu-thenoyltrifluoroacetone （TTA）phenan-throline and Eu-diphacinone-ammonia systems in Triton X-100 micelles are increased by the addition of La;Gd;, Tb;, Lu;or Y;. The mechanism of this fluorescence（?）

Study to mechanism of fluorescence enhancement of Dy3＋-Gd3＋- SSA-CTMAB system by resonance scattering-light spectroscopy

The fluorescence enhancement mechanism of Dy3＋-Gd3＋- SSA-CTMAB system was studied by the resonance light scattering and fluorescence spectrum. In this paper, the influencing factors including the concentration of Gd3＋, ligands, pH value as well as surfactants were studied. As a result, the optimal experimental conditions were obtained. The existence of molecule congeries was proved by scattering-light spectrum.

Determination of Anionic Surfactants in Environmental Water Samples Using Fluorescence Enhancement Method Based on Fe_3O_4@PAA-RB Fluorescent Nanoparticles

[ Objective] The study aims at developing a novel fluorescence enhancement method to determine anionic surfactants. [ Method] Based on Fe3O4 @ PAA-RB fluorescent nanoparticles as fluorescent probes, we have developed a novel fluorescence enhancement method for the determi- nation of an anionic surfactant sodium dodecyl sulfate （SDS） through the gradual optimization of experiment conditions. [ Result] Under the opti- mum conditions, the extent of fluorescence enhancement is directly proportional to SDS concentration varying from 0.5 to 16.0 μmol/L, and the de- tection limit reaches 0.051 μmol/L. The relative standard deviation （RSD） for 4.0 μmol/L SDS is 3.3% （ n =6）. The proposed method has been successfully applied to the determination of SDS in environmental water samples, with recovery of 96.3% -105.5%. E Conclusion] The novel fluo- rescence enhancement method is not only simple and rapid, but also has avoided using tedious solvent-extraction and toxic organic solvents.

Fluorescence enhancement effect and the interaction between donor and acceptor

A new theoretical equation for fluorescence enhancement effect between donor and acceptor has been introduced. By using-it we determined the binding constants and numbers of binding sites of five medicines, including chlorogenic acid, forsythiaside norfloxacin, Ciprofloxacin and fluorenone, to gamma-globulin.

Nanoscale control of Ag nanostructures for plasmonic fluorescence enhancement of near-infrared dyes

Potential utilization of proteins for early detection and diagnosis of various diseases has drawn considerable interest in the development of protein-based detection techniques. Metal induced fluorescence enhancement offers the possibility of increasing the sensitivity of protein detection in clinical applications. We report the use of tunable plasmonic silver nanostructures for the fluorescence enhancement of a near-infrared （NIR） dye （Alexa Fluor 790）. Extensive fluorescence enhan- cement of -2 orders of magnitude is obtained by the nanoscale control of the Ag nanostructure dimensions and interparticle distance. These Ag nanostructures also enhanced fluorescence from a dye with very high quantum yield （7.8 fold for Alexa Fluor 488, quantum efficiency （Qy） = 0.92）. A combination of greatly enhanced excitation and an increased radiative decay rate, leading to an associated enhancement of the quantum efficiency leads to the large enhancement. These results show the potential of Ag nanostructures as metal induced fluorescence enhancement （MIFE） substrates for dyes in the NIR ＂biological window＂ as well as the visible region. Ag nanostructured arrays fabricated by colloidal lithography thus show great potential for NIR dye-based biosensing applications.

Synthesis and fluorescence enhancement behavior of a novel fluorescent aqueous polyurethane emulsion DDAQ-TDI-PU

A novel fluorescent aqueous polyurethane emulsion DDAQ-TDI-PU was synthesized by blocking the anthraquinone moiety of 1,4-diamino-2,3-diphenoxyanthraquinone（DDAQ） into polyurethane chain using 2,4-tolylene diisocyanate（TDI）,poly（propylene glycol） and 2,2-dimethylol propionic acid.The chain structure of DDAQ-TDI-PU was confirmed by means of Fourier transform infrared spectroscopy and UV-vis analysis.Comparing to the UV-vis spectrum of DDAQ,DDAQ-TDI-PU showed a hypsochromic shift from the absorption maxima of 518,558,609 nm to 510,548,586 nm,respectively.It was found that the fluorescence intensity of DDAQ-TDI-PU emulsion was enhanced greatly comparing with that of DDAQ.The fluorescence of DDAQ-TDI-PU was very stable not only for the long term storage but also for the fluorescence quencher.

Detection of Diethyl Ether by a Europium MOF through Fluorescence Enhancement

A new water-stable europium MOF,(Me_(2)NH_(2))[Eu(abtc)(phen)]·2H_(2)O (1),has been synthesized from Eu(NO_(3))_(3)·6H_(2)O with 1,10-phenanthroline (phen) and 3,3′,5,5′-azobenzenetetracarboxylic acid (H_4abtc) ligands under solvothermal conditions and structurally characterized by single-crystal X-ray diffraction analysis,IR,TGA and PXRD.It crystallizes in monoclinic system,C2/c space group,with a=16.278(3),b=14.261(3),c=27.936(5)?,b=103.464(3)°,V=6307(2)A^(3),Z=8,C_(30)H_(26)Eu N_5O_(10),M_(r)=768.5,D_(c)=1.543 g/cm^(3),F(000)=2912,m(Mo Ka)=2.044 mm^(-1),R=0.0315 and w R=0.0663.In the structure of 1,the Eu O_7N_(2) polyhedra are assembled into a 2D layer with rhombic windows and these layers are further condensed to form a 3D framework.It can be used as selective and sensitive fluorescence sensors capable of detecting diethyl ether vapor.

Design and fabrication of a new fluorescence enhancement system of silver nanoparticles-decorated aligned silver nanowires

A new substrate,aligned Ag nanowires decorated with silver nanoparticle composite structure(AgNWs@AgNPs),was fabricated to investigate metalenhanced fluorescence(MEF) and its mechanism.The new composite structure was fabricated via a three-phase interface assembly method followed by SnCl2 sensitization and AgNO3 reduction process.The size and distribution of the nanoparticles on silver nanowires increased with the sensitization and reduction cycles.The formation of AgNPs on the surfaces of AgNWs was confirmed by multiple characterization methods including scanning electron microscopy(SEM),transmission electron microscope(TEM),atomic force microscopy(AFM) and X-ray diffraction(XRD).The results show that the fluorescence intensity of the poly(3-hexylthiophene)(P3HT) on the composite structure was greatly enhanced compared with that on bare glass substrate,and the intensity increased with the increase in particle sizes and density.The mechanism was basedo n the increase in excitation rate and the radiation decay rate.The new type of substrate could serve as a good and efficient MEF substrate for high-performance fluorescence-based devices.

Fluorescence enhancement of Tb(Ⅲ) complex with a new β-diketone ligand by 1,10-phenanthroline

A novel β-diketone, 1-（3,4,5-trisbenzyloxy）benzoyl-5-benzoyl acetylacetone （TBAA）, and its corresponding binary Tb（Ⅲ） complex Tb（TBAA）3·2H2O and ternary complex Tb（TBAA）3Phen with 1,10-phenanthroline （Phen） were prepared. The ligand was characterized based on elemental analysis, FT-IR, and 1H NMR. The complexes were characterized with elemental analysis, FT-IR and thermogravimetry and derivative thermogravimetry （TG-DTG）. Photoluminescence measurements indicated that the energy absorbed by the organic ligand was efficiently transferred to the central Tb3＋ ions, and the complex showed intense and characteristic emissions due to the 5D4→7FJ transitions of the central Tb3＋ ions. Both complexes showed longer fluorescence lifetimes. After the introduction of the second ligand Phen group, the relative emission intensities and fluorescence lifetimes of the ternary complex Tb（TBAA）3Phen enhanced more obviously than that of the binary complex Tb（TBAA）3·2H2O. This indicated that the presence of the ligand TBAA and the second ligand Phen could sensitize fluorescence intensities of Tb（Ⅲ） ions, and the introduction of Phen group resulted in the enhancement of the fluorescence properties of the Tb（Ⅲ） ternary rare earth complex.

Study of the Interaction of Cephalosporin Class Medicine with Albumin by Fluorescence Enhancement and Fluorescence Quenching Theories

The interaction of 7 kinds of cephalosporin-medicine with HSA and BSA was studied and compared using fluorescence enhancement and fluorescence quenching method, then deeply analyzed. The binding characteristics of medicine with albumin and usual characteristic constants such as dissociation constant, quenching constant, quenching efficiency, energy-transfer efficiency and the distance between donor and accepter were also deeply analyzed.

Fluorescence enhancement and cytotoxicity reduction of bis-viologen biphenyl by complexation of cucurbit[7]uril

The effect of cucurbit[7]uril(CB[7]) on fluorescence properties and biocompatibility of the bis-viologen biphenyl molecule(BPV22+) was investigated by using 1 H NMR spectroscopy,fluorescence emission titration,and in vitro cytotoxicity experiments.CB[7] can be combined with BPV22+ in a stoichiometric ratio of 1:1 and 2:1.After the formation of host-guest complex,the fluorescence emission intensity of BPV22+ increased significantly,and the emission spectrum blue shifted.Meanwhile,the host-guest complexes showed better biocompatibility than BPV22+ in cell cytotoxicity studies.Results of this paper lay a foundation for the development of host-guest type of fluo rescent probes,biological imaging and so forth.

Fluorescence Enhancement of Samarium－Thenoyl－trifluoroacetone－Cetyltrimethylammonium Bromide－Triton X－100 by Scandium

fluorescence enhancement phenomenon shown by adding scandium ion to thesamarium-thenoyltrifluoroacetone (TTA)-cetyltrimethylammonium bromide(CTMAB)-Triton X-100(TX-100) system was observed and the effect of the condi-tions on the system was studied in detail. The excitation and emission wavelengthswere 370 nm, 565 nm, 603 nm and 645 nm, respectively. The optimum conditionsforming Sm-Sc-TTA-CTMAB-TX-100 system were that the concentration of Sc￣(3+)was equal to 5.0× 10￣(-5) mol/L, pH was 7. 7. Under these conditions, the fluores-cence intensity can be increased about 10 times higher than that of the system con-taining no Sc￣(3+) , and it was a linear function of the concentration of samariumn therange of 1. 0 × 10￣(-9)-4. 0 × 10￣(-7) mol/L. The detection limit was 6. 0 ×10￣(-10) mol/L.This system was used for the spectrofluorimetric determination of samarium withsatisfactory results. The nature of enhanced fluorescence was explained using in-tramolecular and intermolecular energy transfer theory.

Fluorescence enhancement of acridine orange in a water solution by Au nanoparticles

The surface enhanced fluorescence effect of acridine orange fluorophore in the proximity of Au nanoparticles has been investigated experimentally in the system of aqueous solution.Significant enhancement of the fluorescence intensity was observed when the system was excited with 532 nm or 442 nm CW lasers.The influence of the distances between neighboring Au particles as well as that between the fluorophore molecules and the Au surface were explored experimentally.The results demonstrated that a compact distribution of metallic particles was able to produce stronger fluorescence enhancement.Proper separation between the fluorophore molecules and the metal surface was favorable for a better enhancement.