Theoretical study of determining orientation and alignment of symmetric top molecule using laser-induced fluorescence

General expressions used for extracting the orientation and alignment parameters of a symmetric top molecule from laser-induced fluorescence (LIF) intensity are derived by employing the density matrix approach. The molecular orientation and alignment are described by molecular state multipoles. Excitation and detection are circularly and linearly polarized lights, respectively. In general cases, the LIF intensity is a complex function of the initial molecular state multipoles, the dynamic factors and the excitation-detection geometrical factors. It contains a population, ten orientation and fourteen alignment multipoles. The problem of how to extract the initial molecular state multipoles from the resolved LIF intensity is discussed.

Homogeneous time-resolved fluoroimmunoassay of bensulfuron-methyl by using terbium fluorescence energy transfer

A sensitive homogenous time-resolved fluoroimmunoassay (TR-FIA) method for bensulfuron-methyl (BSM) based on fluorescence resonance energy transfer (FRET) from a Tb3+ fluorescent chelate with N,N,N',N'-[2,6-bis(3'-aminomethyl-1'-pyrazoly)-4-phenylpyridine] tetrakis(acetic acid) (BPTA-Tb3+) to organic dye, Cy3 or Cy3.5 has been developed. New method combined the use of BPTA-Tb3+ labeled streptavidin, Cy3 or Cy3.5 labeled anti-BSM monoclonal antibody and biotinylated BSM-BSA conjugate (BSA is bovine serum albumin) for competitive-type immunoassay. After BPTA-Tb3+ labeled streptavidin was reacted with a competitive immune reaction solution containing biotinylated BSM-BSA, BSM sample and Cy3 or Cy3.5 labeled anti-BSM monoclonal antibody, the sensitized and long-lived emission of Cy3 or Cy3.5 derived from FRET was measured, and thus the concentration of BSM in sample was calculated. The present method has the advantages of rapidity, simplicity and high sensitivity since the B/F (bound reagent/free reagent) separation steps and the solid-phase carrier are not necessary. The method gives the detection limit of 2.10 ng ml(-1). The coefficient variations of the method are less than 1.5% and the recoveries are in the range of 95-105% for BSM water sample measurement. (C) 2001 Elsevier Science B.V. All rights reserved.

Rapid authentication of ginseng species using microchip electrophoresis with laser-induced fluorescence detection

Ginseng is one of the most expensive Chinese herbal medicines and the effectiveness of ginseng depends strongly on its botanical sources and the use of different parts of the plants. In this study, a microchip electrophoresis method coupled with the polymerase chain reaction (PCR)-short tandem repeats (STR) technique was developed for rapid authentication of ginseng species. A low viscosity hydroxypropyl methylcellulose (HPMC) solution was used as the sieving matrix for separation of the amplified STR fragments. The allele sizing of the amplified PCR products could be detected within 240 s or less. Good reproducibility and accuracy of the fragment size were obtained with the relative standard deviation for the allele sizes less than 1.0% (n = 11). At two microsatellite loci (CT 12, CA 33), American ginseng had a different allele pattern on the electropherograms compared with that of the Oriental ginseng. Moreover, cultivated and wild American ginseng can be distinguished on the basis of allele sizing. This work establishes the feasibility of fast genetic authentication of ginseng species by use of microchip electrophoresis.

A collinear light-emitting diode-induced fluorescence detector for capillary electrophoresis

A novel fluorescence detector based on collinear scheme using a brightness light-emitting diode emitting at 470 nm as excitation source is described. The detector is assembled by all-solid-state optical-electronic components and Coupled with capillary electrophoresis using on-column detection mode. Fluorescein isothiocyanate (FITC) and FITC-labeled amino acids and small molecule peptide as test analyte were used to evaluate the detector. The concentration limit of detection for FITC-labeled phenylalanine was 10 nM at a signal-to-noise ratio (S/N) of 3. The system exhibited good linear responses in the range of 1 x 10(-7) to 2 x 10(-5) M (R-2 = 0.999). (c) 2004 Elsevier B.V. All rights reserved.

Simultaneous light emitting diode-induced fluorescence and contactless conductivity detection for capillary electrophoresis

A combined detection system of simultaneous contactless conductometric and fluorescent detection for capillary electrophoresis (CE) has been designed and evaluated. The two processes share a common detection cell. A blue light-emitting diode (LED) was used as the excitation source and an optical fiber was used to collect the emitting fluorescence for fluorescent detection (FD). Inorganic ions, fluorescein isothiocyanate (FITC)-labeled amino acids and small molecule peptides were separated and detected by the combined detector, and the detection limits (LODs) of sub-μ M level were achieved.

The surface sites of sulfated zirconia studied in situ by laser-induced fluorescence spectroscopy

The surface sites of sulfated zirconia were investigated in situ by laser-induced fluorescence spectroscopy using aniline as the probe molecule. Different from the cases for many other oxides, the aniline adsorbed on the unique active sites of sulfated zirconia at r.t. is changed into another species, which emits a characteristic fluorescence band at 422 nm. The results illustrate that the sulfate groups in sulfated zirconia are favorable for the generation of these unique active sites, which also rarely exist on pure zirconia composed of tetragonal and monoclinic phases but do not exist on pure zirconia composed of monoclinic phase. (C) 2004 Elsevier B.V. All rights reserved.

Colorimetric and ratiometric fluorescence sensing of fluoride: Tuning selectivity in proton transfer

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Theranostic applications of fluorescent liquid crystalline nanoparticles

Lipid liquid crystalline nanoparticles can find application as nanocarriers in several fields of the daily life but, very likely, the pharmaceutical arena is the most relevant. Indeed, several problems encountered in drugs administration (e.g. critical sideeffects from antitumor drugs) require alternative, less invasive, but simultaneously efficient therapeutic routes to be explored. Novel fields of personalized nanomedicine are developing in this direction. One of the most interesting is theranostic, which calls for the design of platforms capable of combining therapeutic and diagnostic functionalities. In this optic, we explored the potential of monoolein-based cubosomes and hexosomes as nanocarriers for theranostic purposes. Our work focussed on the design of lipid nanoparticles able to deliver antineoplastic drugs and imaging probes for fluorescent optical in vitro and in vivo imaging. We developed cubosome formulations loaded with antineoplastic drugs and useful for the fluorescence imaging of cells. Such formulations were also actively targeted to cancer cells and coupled with a NIR-emitting fluorophore, which was the promise for in vivo applications. We also investigated hexosomes with encouraging results encapsulating in their lipid matrix a BODIPY derivative with solvatochromic properties, helpful for the understanding of the dye localization. Importantly, we reported (manuscript submitted) the first proof-of-principle for in vivo fluorescence optical imaging application using monoolein-based cubosomes in a healthy mouse animal model. Finally, since relatively little is known about the interaction of cubosomes with biological systems, their effects on lipid droplets, mitochondria and lipid profile of HeLa cells were deeply studied. This thesis is divided in two main parts. The introduction section reports on the essential background of the research field, and it is followed by the publications (published or submitted) resulting from these three years of work.