ABSTRACT
Our work group designed and synthesized a promissory compound N-(2-hydroxyphenyl)-2-propylpentanamide (HO-AAVPA). The HO-AAVPA is a HDAC1 inhibitor and antiproliferative in cancer cell lines. However, HO-AAVPA is poor water solubility and enzymatically metabolized. In this work, the fourth-generation poly(amidoamine) dendrimer (PAMAM-G4) was used as a drug deliver carrier of HO-AAVPA. Moreover, HO-AAVPA and HO-AAVPA-PAMAM complex were submitted to forced degradation studies (heat, acid, base, oxidation and sunlight). Also, the HO-AAVPA-PAMAM-G4 complex was assayed as antiproliferative in a breast cancer cell line (MCF-7). The HO-AAVPA-PAMAM-G4 complex was obtained by docking and experimentally using three pH conditions: acid (pH = 3.0), neutral (pH = 7.0) and basic (pH = 9.0) showing that PAMAM-G4 captureand protect the HO-AAVPA from forced degradation, it is due to sunlight yielded a by-product from HO-AAVPA. In addition, the PAMAM-G4 favored the HO-AAVPA water solubility under basic and neutral pH conditions with significant difference (F(2,18) = 259.9, p < 0.001) between the slopes of the three conditions being the basic condition which solubilizes the greatest amount of HO-AAVPA. Finally, the HO-AAVPA-PAMAM-G4 complex showed better antiproliferative effects on MCF-7 (IC50 = 75.3 µM) than HO-AAVPA (IC50 = 192 µM). These results evidence that PAMAM-G4 complex improve the biological effects of HO-AAVPA.
Subject(s)
Dendrimers , Humans , Dendrimers/pharmacology , MCF-7 Cells , WaterABSTRACT
Although cancer is the leading cause of death among Mexican-Americans, few community-based programs target obesity reduction as a way to reduce the prevalence of obesity-related cancer in underserved populations. Evidence suggests that obesity correlates with 13 types of cancer. The objective is to provide an overview of evaluation and selection of evidence-based content; details of the implementation process; modifications needed to tailor education programs to specific needs of different target audiences; and demonstrate challenges of implementing a community-based prevention program intended to reduce cancer incidence and mortality in Mexican-Americans. We used the Social Cognitive Theory (SCT) to develop a 10-topic menu of educational classes using elements of multiple evidence-based curricula. Outcome measures for physical activity and nutrition were determined using the International Physical Activity Questionnaire (IPAQ) and the Dietary Screener Questionnaire (DSQ). Weight status was determined using weight, body fat, and body mass index (BMI). To date, 2845 adults received wellness education from our program. Multiple delivery models were used to reach a larger audience; they included a 4-week model, 5-week model, employer model, low-income housing, 1- and 2-h sessions, and clinic encounters. Individuals were given education at multiple community locations including senior centers (14%), churches (0.6%), employers (17.6%), low-income housing (8.2%), community centers (16.6%), clinics (11.5%), and schools (32.5%). Our study indicates that our delivery model is feasible and can disseminate evidence-based obesity education. Further investigation is necessary to assess long-term behavioral change and to assess the most effective model for delivery.
Subject(s)
Health Education , Mexican Americans , Neoplasms , Obesity , Adult , Humans , Curriculum , Mexican Americans/education , Mexico , Neoplasms/ethnology , Neoplasms/prevention & control , Obesity/ethnology , United States , Health Education/methods , Health Education/organization & administrationABSTRACT
Most Mexican-Americans do not meet current physical activity recommendations. This paper uses the ORBIT model of obesity intervention development as a framework to outline the process of establishing three employer-based walking challenges in El Paso, Texas, a predominantly Mexican American community. The walking challenges were planned and implemented through the Border Coalition for Fitness and participating partnering organizations. Over 2000 participants and several employers took part in the walking challenges. Results from this ORBIT Phase 1 design intervention suggest that walking challenges are a feasible approach to increase physical activity in Mexican-Americans.
Subject(s)
Mexican Americans , Walking , Exercise , Humans , Obesity , TexasABSTRACT
Brachionus quadridentatus es una especie morfológicamente variable, distribuida por todo el mundo. Su taxonomía es confusa debido a las numerosas variantes infrasubespecíficas descritas en este taxón. Con la taxonomía basada en la morfología, B. quadridentatus tiene tres variantes reconocidas: B. quadridentatus quadridentatus, B. quadridentatus f. brevispinus and B. quadridentatus f. cluniorbicularis. En este estudio, exploramos la diversidad genética entre algunas poblaciones de B. quadridentatus, usando secuencias de los genes COI ADNmt y 18S ARNr. El análisis de delimitación de especies coalescente usando el gen 18S apoya la presencia de al menos tres especies putativas dentro del complejo B. quadridentatus. Estos resultados estuvieron en concordancia con los análisis filogenético y GMYC usando el gen 18S. Sin embargo, se encontró variación en morfología y secuencias del gen COI dentro de cada una de las tres especies putativas. Se encontraron siete linajes delimitados por las secuencias del gen COI usando el método de delimitación ABGD, que además están morfologicamente diferenciadas. Se encontró discordancia mitonuclear entre la filogenia del gen COI y la del gen 18S. La incongruencia entre el marcador mitocondrial y el nuclear puede ser explicada por sorteo incompleto de linaje.
Brachionus quadridentatus is a morphologically variable species of rotifer distributed worldwide. The taxonomy of this species is confused, with numerous infrasubspecific variants described in the taxon: B. quadridentatus quadridentatus, B. quadridentatus f. brevispinus and B. quadridentatus f. cluniorbicularis. In this study, we explored genetic diversity among some populations of B. quadridentatus, using sequences of mitochondrial COI and nuclear 18S genes. The coalescent species delimitation analysis with the 18S gene highly supports the presence of at least three putative species within the B. quadridentatus complex. These results were in agreement with the phylogenetic and GMYC analysis using the 18S gene. However, we also found variation within each of these three putative species in morphology and COI gene sequences. There were seven morphologically differentiated lineages that were recovered as distinct based on COI gene sequences using the ABGD delimitation method. As such, mitonuclear discordance between COI and 18S phylogenies was found. The incongruence between mitochondrial and nuclear markers could be explained by incomplete lineage sorting.
ABSTRACT
Paciente masculino de 3 días con distensión abdominal. sin evacuaciones, ictericia escleral, dilatación de pelvis renal bilateral.
ABSTRACT
ResumenLa laguna de Barra de Navidad es un humedal costero de importancia internacional (sitio RAMSAR) y está incluida entre los 81 sitios prioritarios de manglar de México. Una de las características de mayor valor de la laguna, es la presencia de bosques de mangle en buen estado de conservación. El objetivo de nuestro trabajo, fue medir la producción de hojarasca del manglar y los factores ambientales que pueden influir en su dinámica.El manglar fue dividido en siete zonas y las recolectas de hojarasca se realizaron mensualmente entre noviembre 2011 y octubre 2012, mediante recolectores cuadrados de 0.25 m2 construidos con malla de mosquitero (1 mm) y colocados a 1.3 m del suelo. De forma simultánea, se midieron varias variables abióticas en el agua intersticial recolectada en pozos permanentes en cada zona, mediante un Sistema Multi-Sonda, YSI-556-M. El valor total promedio de producción de hojarasca, según el área de cada zona, fue de 19.12 ± 1.23 gPS/m2.mes (2.29 t/ha.año). Esta baja productividad se atribuye al clima seco de la región y a la poca amplitud de las mareas. Avicennia germinans y Laguncularia racemosa produjeron poco más del 80 % de toda la hojarasca, mientras que Rhizophora mangle sólo contribuyó con el 16 % y Conocarpus erectus< 4%. Existe una correlación significativa entre las variables abióticas del sustrato (principalmente la salinidad y la profundidad del agua intersticial) y la cantidad de hojarasca producida. Se concluye que, existen variaciones espaciales significativas en las variables abióticas del sustrato que se correlacionan con diferencias en la composición por especies del manglar y que, junto con las etapas de los ciclos vitales de esas especies, generan variaciones significativas en la cantidad y composición de la hojarasca producida. La investigación futura se enfocará en la cuantificación de las variaciones espaciales de la estructura del bosque y su relación con la producción de hojarasca.
AbstractBarra de Navidad lagoon is a coastal wetland of international importance (Ramsar site) and it is included among the 81 Mexican mangrove priority sites. One of the most valued characteristics of this lagoon is the presence of mangrove forest in a good conservation state. The goal of our research was the measurement of mangrove litter production and environmental factors influencing its dynamics. The mangrove area was divided into seven zones and litterfall was monthly sampled from November 2011 to October 2012 using 0.25 m2 square collectors made with mosquito mesh (1 mm) and positioned at 1.3 m above the ground. Abiotic variables of the interstitial water were measured simultaneously at each zone in permanent plots using a multi-parameter probe, YSI-556-M. Total mean value of litterfall production, weighted by zone surface, was 19.12 ± 1.23 gPS/m2.mo (2.29 t/ha.year). This low productivity is a consequence of the region's dry climate and low tide range. The species Avicennia germinans and Laguncularia racemosa produced more than 80 % of total litterfall, while Rhizophora mangle contributed only 16 % and Conocarpus erectus < 4 %. A significant correlation between litterfall production and abiotic variables was found (e.g. salinity and interstitial water depth). We concluded that there are significant spatial variations in soil abiotic variables which are correlated with differences in mangrove species composition, and produce, together with the life cycles stages of those species, significant variations in the quantity and composition of litterfall. Future research will be focused on quantifying spatial variations in forest structure and their relationship with litterfall production.
Subject(s)
Rhizophoraceae , Seasons , Population Dynamics , Population Density , Spatio-Temporal Analysis , MexicoABSTRACT
Barra de Navidad lagoon is a coastal wetland of international importance (Ramsar site) and it is included among the 81 Mexican mangrove priority sites. One of the most valued characteristics of this lagoon is the presence of mangrove forest in a good conservation state. The goal of our research was the measurement of mangrove litter production and environmental factors influencing its dynamics. The mangrove area was divided into seven zones and litterfall was monthly sampled from November 2011 to October 2012 using 0.25 m(2) square collectors made with mosquito mesh (1 mm) and positioned at 1.3 m above the ground. Abiotic variables of the interstitial water were measured simultaneously at each zone in permanent plots using a multi-parameter probe, YSI-556-M. Total mean value of litterfall production, weighted by zone surface, was 19.12 ± 1.23 gPS/m(2).mo (2.29 t/ha.year). This low productivity is a consequence of the region's dry climate and low tide range. The species Avicennia germinans and Laguncularia racemosa produced more than 80 % of total litterfall, while Rhizophora mangle contributed only 16 % and Conocarpus erectus < 4 %. A significant correlation between litterfall production and abiotic variables was found (e.g. salinity and interstitial water depth). We concluded that there are significant spatial variations in soil abiotic variables which are correlated with differences in mangrove species composition, and produce, together with the life cycles stages of those species, significant variations in the quantity and composition of litterfall. Future research will be focused on quantifying spatial variations in forest structure and their relationship with litterfall production.
Subject(s)
Rhizophoraceae , Mexico , Population Density , Population Dynamics , Seasons , Spatio-Temporal AnalysisABSTRACT
Observation of the activation and inhibition of angiogenesis processes is important in the progression of cancer. Application of targeting peptides, such as a small peptide that contains adjacent L-arginine (R), glycine (G) and L-aspartic acid (D) residues can afford high selectivity and deep penetration in vessel imaging. To facilitate deep tissue vasculature imaging, probes that can be excited via two-photon absorption (2PA) in the near-infrared (NIR) and subsequently emit in the NIR are essential. In this study, the enhancement of tissue image quality with RGD conjugates was investigated with new NIR-emitting pyranyl fluorophore derivatives in two-photon fluorescence microscopy. Linear and nonlinear photophysical properties of the new probes were comprehensively characterized; significantly the probes exhibited good 2PA over a broad spectral range from 700-1100 nm. Cell and tissue images were then acquired and examined, revealing deep penetration and high contrast with the new pyranyl RGD-conjugates up to 350 µm in tumor tissue.
Subject(s)
Fluorescent Dyes/chemistry , Nanoparticles/chemistry , Neoplasms/blood supply , Oligopeptides/chemistry , Animals , Carcinoma, Lewis Lung/blood supply , Carcinoma, Lewis Lung/diagnosis , Carcinoma, Lewis Lung/metabolism , Fluorescent Dyes/metabolism , Humans , Infrared Rays , Integrins/metabolism , Mice , Mice, Inbred C57BL , Microscopy, Fluorescence, Multiphoton , Nanoparticles/metabolism , Neoplasms/diagnosis , Neoplasms/metabolism , Oligopeptides/metabolism , Optical Imaging , PhotonsABSTRACT
The synthesis, linear photophysical characterization, and nonlinear optical properties of two new symmetrical fluorene-containing quinolizinium derivatives, 2,8-bis((E)-2-(7-(diphenylamino)-9,9-dihexyl-9H-fluoren-2-yl)vinyl)quinolizinium hexafluorophosphate (1) and 2,8-bis((E)-2-(7-((7-(diphenylamino)-9,9-dihexyl-9H-fluoren-2-yl)ethynyl)-9,9-dihexyl-9H-fluoren-2yl)vinyl)quinolizinium hexafluorophosphate (2), are reported. The nature of the dual-band steady-state fluorescence emission of 1 and 2 was determined, and violation of Kasha's rule along with a strong dependence on solvent polarity were shown. A relatively complex structure of two-photon absorption (2PA) spectra of 1 and 2, with maximum cross sections of â¼400-600 GM, was determined using the open aperture Z-scan method. Different types of fast relaxation processes with characteristic times of 0.3-0.5 ps and 1.5-2 ps were observed in the excited states of the new compounds via femtosecond transient absorption pump-probe spectroscopy. To better understand the photophysical behavior of 1 and 2, a quantum-mechanical study was undertaken using TD-DFT and ZINDO/S methods. Simulated linear absorption spectra were found to be in good agreement with experimental data, while 2PA cross sections were overestimated. Although the new dyes were highly fluorescent in nonpolar solvents, they were essentially nonfluorescent in polar media. Significantly, the quinolizinium dyes exhibited fluorescence turn-on behavior upon binding to bovine serum album (BSA) protein, exhibiting over 4-fold fluorescence enhancement, which was a finding that was leveraged to demonstrate cell membrane fluorescence imaging of HeLa cells.
Subject(s)
Cell Membrane/chemistry , Fluorenes/chemistry , Fluorescent Dyes/chemistry , Quinolizines/chemistry , Cations/chemistry , Cells/chemistry , Fluorescence , Fluorescent Dyes/chemical synthesis , HeLa Cells , Humans , Spectrometry, FluorescenceABSTRACT
The great complexity of many human pathologies, such as cancer, diabetes, and neurodegenerative diseases, requires new tools for studies of biological processes on the whole organism level. The discovery of novel biocompatible reactions has tremendously advanced our understanding of basic biology; however, no efficient tools exist for real-time non-invasive imaging of many human proteases that play very important roles in multiple human disorders. We recently reported that the "split luciferin" biocompatible reaction represents a valuable tool for evaluation of protease activity directly in living animals using bioluminescence imaging (BLI). Since BLI is the most sensitive in vivo imaging modality known to date, this method can be widely applied for the evaluation of the activity of multiple proteases, as well as identification of their new peptide-specific substrates. In this unit, we describe several applications of this "split luciferin" reaction for quantification of protease activities in test tube assays and living animals.
Subject(s)
Benzothiazoles/chemistry , Fluorescent Dyes/chemistry , Molecular Imaging/methods , Peptide Hydrolases/chemistry , Animals , Animals, Genetically Modified , Caspase 3/chemistry , Caspase 3/metabolism , Caspase 7/chemistry , Caspase 7/metabolism , Disease Models, Animal , Luminescence , Mice , Peptide Hydrolases/metabolism , Thrombin/chemistry , Thrombin/metabolismABSTRACT
A fluorene-based donor-acceptor ligand was successfully employed to sensitize visible and near-IR emitting lanthanide centers. The ligand construct is based on a donor-π-acceptor architecture with diphenylamino acting as the donor and a fluorenyl π bridge derivatized with a trifluoroacetonate moiety acting as both a strong acceptor and the classic bidentate scaffold for complexing metals. (1)H NMR analysis in the polar solvents THF and CDCl3 revealed the enolic form of the diketone dominant in solution equilibria at room temperature. This preferred cis-enol form binds strongly to the lanthanide(III) ions (Ln = Eu, Sm, Dy, Tb, Yb, Nd, Er, and Gd) in the presence of phenanthroline affording the resulting ternary tris(diketonates) complexes with 1,10-phenanthroline. Detailed characterization of these complexes was conducted, with particular emphasis on linear and nonlinear photophysical properties. Steady-state and time-resolved emission spectroscopy and overall photoluminescence quantum yield (PLQY) measurements were performed on all the complexes. Sizeable visible and near-IR efficiency for europium (room temperature, visible), samarium (low temperature, visible) and ytterbium, neodymium and erbium (room temperature, near-IR) was displayed, with long luminescent lifetimes for the europium and samarium complexes of 85 and 70 µs, respectively Measurement of the luminescence decay for the Yb complex at 976 nm, Nd complex at 874 nm, and Er complex at 1335 nm yielded mono-exponential decay curves, with lifetimes of ~13 µs, ~1.6 µs, and ~2.5 µs, respectively, inferring that the emission was generated by a single species. In addition, fluorescence anisotropy and two-photon absorption (2PA) spectra (via Z-scan) were obtained for the ligand and europium complex, revealing a maximum 2PA cross section of 340 GM for the latter upon excitation at 760 nm. A quadratic relationship was found by varying laser excitation power vs. luminescence intensity of the europium complex, confirming sensitization via two-photon excitation.
Subject(s)
Coordination Complexes/chemistry , Fluorenes/chemistry , Ketones/chemistry , Lanthanoid Series Elements/chemistry , Ligands , Luminescence , Spectrometry, FluorescenceABSTRACT
Honduras is one of the 17 priority countries included in the International Federation of Gynecology and Obstetrics (FIGO) Initiative for the Prevention of Unsafe Abortion and its Consequences. The priority category enables the country to request emergency funding to acquire services or commodities that could contribute toward achieving the objectives laid out in its plan of action. These objectives include improving postabortion care by increasing the use of manual vacuum aspiration (MVA) as an outpatient procedure with minimal human and material resources. Since the Ministry of Health lacked funding, use of the emergency fund was approved for the purchase and distribution of MVA kits nationwide to ensure continuity and the hope of increasing MVA use. Eleven hospitals participating in this initiative provided data for analysis of the outcome. These data show no increase in MVA use; however, as discussed in the article, further investigation provided valuable information on the reasons behind these results.
Subject(s)
Abortion, Induced/methods , Aftercare/methods , Vacuum Curettage/methods , Ambulatory Care/methods , Female , Honduras , Humans , International Agencies/organization & administration , Pregnancy , Public Health/methodsABSTRACT
[This corrects the article DOI: 10.1371/journal.pone.0067559.].
ABSTRACT
The design, synthesis, and photophysical properties of a new fluorene-based fluorescent chemosensor, 4-((E)-2-(2-(benzo[d]thiazol-2-yl)-9,9-diethyl-9H-fluoren-7-yl)vinyl)-N,N-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)benzenamine (AXF-Al), is described for the detection of Al3+. AXF-Al exhibited absorption at 382 nm and strong fluorescence emission at 542 nm (fluorescence quantum yield, Φ F, of 0.80). The capture of Al3+ by the pyrazolyl aniline receptor resulted in nominal change in the linear absorption (372 nm) but a large hypsochromic shift of 161 nm in the fluorescence spectrum (542 to 433 nm, Φ F = 0.88), from which Al3+ was detected both ratiometrically and colorimetrically. The addition of other metal ions, namely Mg2+, Ca2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg 2+ and Pb2+, produced only minimal changes in the optical properties of this probe. The emission band of this probe was also accessed by two-photon excitation in the near-IR, as two-photon absorption (2PA) is important for potential applications in two-photon fluorescence microscopy (2PFM) imaging. The 2PA cross section of the free fluorenyl ligand AXF-Al was 220 GM at 810 nm and 235 GM at 810 nm for the Al-ligand complex, practically useful properties for 2PFM.
ABSTRACT
Deep imaging within tissue (over 300 µm) at micrometer resolution has become possible with the advent of two-photon fluorescence microscopy (2PFM). The advantages of 2PFM have been used to interrogate endogenous and exogenous fluorophores in the skin. Herein, we employed the integrin (cell-adhesion proteins expressed by invading angiogenic blood vessels) targeting characteristics of a two-photon absorbing fluorescent probe to image new vasculature and fibroblasts up to ≈ 1600 µm within wound (neodermis)/granulation tissue in lesions made on the skin of mice. Reconstruction revealed three dimensional (3D) architecture of the vascular plexus forming at the regenerating wound tissue and the presence of a fibroblast bed surrounding the capillaries. Biologically crucial events, such as angiogenesis for wound healing, may be illustrated and analyzed in 3D on the whole organ level, providing novel tools for biomedical applications.
Subject(s)
Capillaries/ultrastructure , Granulation Tissue/ultrastructure , Imaging, Three-Dimensional/methods , Skin/blood supply , Skin/ultrastructure , Animals , Capillaries/injuries , Fibroblasts/cytology , Fibroblasts/physiology , Fluorescent Dyes , Granulation Tissue/injuries , Imaging, Three-Dimensional/instrumentation , Integrins/metabolism , Male , Mice , Mice, Inbred BALB C , Microscopy, Fluorescence, Multiphoton , Neovascularization, Physiologic , Skin/injuries , Wound Healing/physiology , Wounds, Penetrating/pathologyABSTRACT
A new series of unsymmetrical diphenylaminofluorene-based chromophores with various strong π-electron acceptors were synthesized and fully characterized. The systematic alteration of the structural design facilitated the investigation of effects such as molecular symmetry and strength of electron-donating and/or -withdrawing termini have on optical nonlinearity. In order to determine the electronic and geometrical properties of the novel compounds, a thorough investigation was carried out by a combination of linear and nonlinear spectroscopic techniques, single-crystal X-ray diffraction, and quantum chemical calculations. Finally, on the basis of two-photon absorption (2PA) cross sections, the general trend for π-electron accepting ability, i.e., ability to accept charge transfer from diphenylamine was: 2-pyran-4-ylidene malononitrile (pyranone) > dicyanovinyl > bis(dicyanomethylidene)indane >1-(thiophen-2-yl)propenone > dicyanoethylenyl >3-(thiophen-2-yl)propenone. An analogue with the 2-pyran-4-ylidene malononitrile acceptor group exhibited a nearly 3-fold enhancement of the 2PA cross section (1650 GM at 840 nm), relative to other members of the series.
Subject(s)
Nitriles/chemistry , Nitriles/chemical synthesis , Pyrans/chemistry , Pyrans/chemical synthesis , Absorption , Crystallography, X-Ray , Photons , Quantum Theory , Spectrometry, Fluorescence , X-Ray DiffractionABSTRACT
We report the use of small molecule and block copolymer RGD peptide conjugates for deep ex vivo imaging of tumor vasculature in "whole" excised tumors using two-photon fluorescence microscopy (2PFM). The fluorescent probes were administered to mice via tail-vein injection, after which the tumors were excised, fixed, and imaged without further sample preparation. Both RGD conjugates demonstrated specific targeting to tumor blood vessels, and this selectivity imparted excellent contrast in 2PFM micrographs that captured high-resolution 3-D images of the tumor vasculature up to depths of 830 µm in Lewis Lung Carcinoma (LLC) tumors. 2PFM ex vivo fluorescence micrographs clearly revealed tumor vessels, while differences in the sensitivity of tumor vessel imaging were apparent between the small molecule and block copolymer conjugates. Both the small molecule and polymer-based two-photon absorbing probe conjugate are valuable for deep tissue tumor microvasculature imaging.
Subject(s)
Carcinoma, Lewis Lung/pathology , Fluorescent Dyes/chemistry , Microscopy, Fluorescence/methods , Neoplasms/blood supply , Neoplasms/pathology , Oligopeptides/chemistry , Animals , Carcinoma, Lewis Lung/blood supply , Cell Line, Tumor , Male , Mice , Mice, Inbred C57BL , Microscopy, ConfocalABSTRACT
The synthesis, comprehensive linear photophysical characterization, two-photon absorption (2PA), steady-state and time-resolved stimulated emission depletion properties of a new fluorene derivative, (E)-1-(2-(di-p-tolylamino)-9,9-diethyl-9H-fluoren-7-yl)-3-(thiophen-2-yl)prop-2-en-1-one (1), are reported. The primary linear spectral properties, including excitation anisotropy, fluorescence lifetimes, and photostability, were investigated in a number of aprotic solvents at room temperature. The degenerate 2PA spectra of 1 were obtained with open-aperture Z-scan and two-photon induced fluorescence methods, using a 1 kHz femtosecond laser system, and maximum 2PA cross-sections of â¼400-600 GM were obtained. The nature of the electronic absorption processes in 1 was investigated by DFT-based quantum chemical methods implemented in the Gaussian 09 program. The one- and two-photon stimulated emission spectra of 1 were measured over a broad spectral range using a femtosecond pump-probe-based fluorescence quenching technique, while a new methodology for time-resolved fluorescence emission spectroscopy is proposed. An effective application of 1 in fluorescence bioimaging was demonstrated by means of one- and two-photon fluorescence microscopy images of HCT 116 cells containing dye encapsulated micelles.
Subject(s)
Diphenylamine/chemistry , Fluorenes/chemical synthesis , Fluorescent Dyes/chemical synthesis , Absorption , Fluorenes/chemistry , Fluorescent Dyes/chemistry , HCT116 Cells , Humans , Micelles , Molecular Structure , PhotonsABSTRACT
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.
ABSTRACT
A novel axially chiral binaphthyl fluorene based salen ligand, AFX-155 [2,2'-(1E,1'E)-(R)-1,1'-binaphthyl-2,2'-diylbis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-ylidene)bis(4-((7-(diphenylamino)-9,9-dihexyl-9H-fluoren-2-l)ethynyl)phenol)], with potential applications in homogeneous catalysis, biophotonics, and sensing was synthesized. A full comparative theoretical-experimental analysis of the UV-vis and electronic circular dichroism (ECD) spectra of the 10 primary isomers, comprising stereoisomers and optical isomers, revealed the presence of the unique structure in tetrahydrofuran (THF) solution, the trans-R-intra//trans-R-extra. A proposed route of attack of the (R)-(+)-2,2'-diamino-1,1'-binapthalene onto a salicaldehyde 5-(2-(2-(diphenylamino)-9,9-dihexyl-9H-fluoren-7-yl)ethynyl)-2-hydroxybenzaldehyde followed by a consecutive attack of the resulting species onto another salicaldehyde, both via Burgi:Dunitz trajectory, validates the unambiguous formation of the established isomer. Steric hindrances seem to be the determinant factor that defines the 3D structural conformation of this particular stereoisomer of AFX-155 with triple axial chirality. The determination of every optimal structure and the dominant conformers of AFX-155 were calculated evaluating, in CONFLEX, their steric energies using force fields at MMFF94S (2006-11-24HGTEMP) level in gas phase. The geometry of the conformers was optimized in THF (using PCM) using Gaussian 09 at the DFT/B3LYP level of theory and 6-31G* basis set. The first 100 electronic excited states were calculated using the same level of theory and basis set.
