Chemically modified polysulfones for molecular imprinting. Synthesis and complexation with a fluorescent model template

Polysulfone (PSU) was chemically modified to prepare new molecular imprinted membranes (MIMs). Several amounts of amine and sulfonyl groups were introduced into the PSU chemical structure in order to create interactions with acid or base templates, such as biomolecules or biomacromolecules. A fluorescent dye, Acridine Orange base (AO), was used as a model template and its complexation with the prepared PSUs was monitored by spectroscopic techniques. This study showed an absence of complexation with the native PSU and a strong complexation with the aminated and the sulfonated PSUs. Partially allylated PSU bearing amine or sulfonyl groups were also synthesized. These compounds are expected to be used as precursors for designing new crosslinked molecular imprinting membranes (MIMs), exhibiting high stability of the template memory

Chemically modified polysulfones for molecular imprinting. Synthesis and complexation with a fluorescent model template

Polysulfone (PSU) was chemically modified to prepare new molecular imprinted membranes (MIMs). Several amounts of amine and sulfonyl groups were introduced into the PSU chemical structure in order to create interactions with acid or base templates, such as biomolecules or biomacromolecules. A fluorescent dye, Acridine Orange base (AO), was used as a model template and its complexation with the prepared PSUs was monitored by spectroscopic techniques. This study showed an absence of complexation with the native PSU and a strong complexation with the aminated and the sulfonated PSUs. Partially allylated PSU bearing amine or sulfonyl groups were also synthesized. These compounds are expected to be used as precursors for designing new crosslinked molecular imprinting membranes (MIMs), exhibiting high stability of the template memory

Synthesis of fluorescent alanines by a rhodium catalysed conjugate addition of arylboronic acids to dehydroalanine derivatives

Several arylalanine derivatives containing fluorescent groups were prepared in good yields using a rhodium catalysed conjugate addition of arylboronic acids to N,N-diprotected and N-monoprotected dehydroalanines. The best conditions for these reactions require the use of an excess of aryl boronic acid (4 equiv.), [Rh(COD)2]BF4 as catalyst and CsF as base in dioxane:H2O (10:1) at 110 ºC. These conditions were also applied to several dipeptides with dehydroalanine residues. The photophysical properties of some of the arylalanines were studied in three solvents of different polarity. Due to the absence of the, double bond, the absorption and fluorescence emission of the new compounds are dominated by the photophysical properties of the polycyclic aromatic fluorophores (naphthalene, phenanthrene and pyrene). Considering the relatively high fluorescence quantum yield of these compounds, some of them may be useful as fluorescent markers for peptides and proteins.Thanks are due to the Foundation for Science and Technology (FCT, Portugal), Quadro de Referencia Estrategico Nacional (QREN), and Fundo Europeu de Desenvolvimento Regional/Uniao Europeia (FEDER/EU) for financial support through the research centers, CQ/UM [PEst-C/QUI/UI0686/2011 (FCOMP-01-0124-FEDER-022716)] and CFUM [PEst-C/FIS/UI0607/2011 (F-COMP-01-0124-FEDER-022711)], and project PTDC/QUI/81238/2006 (cofinanced by Fundo Europeu de Desenvolvimento Regional/Programa Operacional Fatores de Competitividade (FEDER/COMPETE), ref. FCOMP-01-0124-FEDER-007467). G. P. acknowledges her PhD grant from Fundacao para a Ciencia e a Tecnologia (FCT), Programa Operacional Potencial Humano/Quadro de Referencia Estrategico Nacional (POPH-QREN), Fundo Social Europeu (FSE) (SFRH/BD/38766/2007)

Pyrenylamino acids : synthesis, photophysical and electrochemical studies

Several beta-pyrenyldehydroamino acids and a pyrenylalanine derivative were synthesized in good to high yields from dehydroamino acids using several types of reactions. A beta-[(pyren-1-yl)methylamino]alanine was prepared treating the methyl ester of N,N-(di-tert-butoxycarbonyl)dehydroalanine with 1-pyrenemethylamine hydrochloride in the presence of an excess of potassium carbonate. The methyl esters of N-(tert-butoxycarbonyl)-beta-(1,2,4-triazol-1-yl) dehydroalanine and dehydroaminobutyric acid were reacted with 1-pyrenemethylamine hydrochloride in the presence of triethylamine to give the E-isomers of the beta-aminomethylpyrene dehydroalanine and dehydroaminobutyric acid derivatives in 84% and 45% yield, respectively. Beta-(Pyren-1-yl) dehydrophenylalanine and dehydroaminobutyric acid derivatives were obtained from the pure stereoisomers of the corresponding beta-bromodehydroamino acids and 1-pyrene boronic acid using Suzuki cross-couplings. This reaction was also applied successfully to beta-bromodehydrodipeptides. The electrochemical behaviour of some of the compounds prepared was studied by cyclic voltammetry. The peak potentials for oxidation and reduction of pyrenylalanine were similar to those referred for pyrene. However, it was found that, when the pyrene ring was conjugated with the dehydroamino acid moiety, the compounds were more difficult to oxidize and easier to reduce than pyrene. The fluorescence properties of four of the pyrenylamino acids synthesized were evaluated in cyclohexane and alcohols. The of methyl ester of N,N-bis(tert-butoxycarbonyl)-beta-[(pyren-1-yl)methylamino] alanine presented high fluorescence quantum yield in cyclohexane and ethanol (0.45 and 0.35, respectively).Fundação para a Ciência e a Tecnologia (FCT)A.S.A - SFRH/BPD/24548/2005Fundo Europeu de Desenvolvimento Regional (FEDER) - POCTI-SFA-3-686, POCI/QUI/59407/200

Wavelength Shifters for Water Cherenkov Detectors

The light yield of a water-based Cherenkov detector can be significantly improved by adding a wavelength shifter. Wavelength shifter (WLS) molecules absorb ultraviolet photons and re-emit them at longer wavelengths where typical photomultiplier tubes are more sensitive. In this study, several wavelength shifter compounds are tested for possible deployment in the Sudbury Neutrino Observatory (SNO). Test results on optical properties and chemical compatibility for a few WLS candidates are reported; together with timing and gain measurements. A Monte Carlo simulation of the SNO detector response is used to estimate the total light gain with WLS. Finally, a cosmic ray Cherenkov detector was built to investigate the optical properties of WLS.Comment: 13 pages, 3 figure

Fluorescent probes based on side-chain chlorinated benzo[a]phenoxazinium chlorides: studies of interaction with DNA

The interaction of DNA with six water soluble benzo[a]phenoxazinium chlorides mono- or di-substituted with 3-chloropropyl groups at the O and N of 2- and 9-positions, along with methyl, hydroxyl and amine terminal groups at 5-positions, was investigated by photophysical techniques. The results indicated that almost all compounds intercalated in DNA base pairs at phosphate to dye ratio higher than 5. At lower values of this ratio, electrostatic binding mode with DNA was observed. Groove binding was detected mainly for the benzo[a]phenoxazinium dye with NH2.HBr terminal. The set of six benzo[a]phenoxazinium chlorides proved successful to label the migrating DNA in agarose gel electrophoresis assays. These finding proves the ability of these benzo[a]phenoxazinium dyes to strongly interact with DNA.Thanks are due to Fundação para a Ciência e a Tecnologia (FCT, Portugal) and FEDER (European Fund for Regional Development)/COMPETE-QREN-EU for financial support to Research Centres CQ/UM [PEst-C/QUI/UI0686/2013 (FCOMP-01-0124-FEDER-037302)] and CFUM [PEst-C/FIS/UI0607/2013 (F-COMP-01-0124-FEDER-022711)]. The Postdoctoral grant to B. R. Raju (SFRH/BPD/62881/2009) is also acknowledged to FCT, POPHQREN, FSE

Synthesis and photophysical studies of a pyrenylindole and a phenalenoindole obtained from dehydroamino acid derivatives : application as fluorescent probes for biological systems

Two pyrenyl-dehydroamino acid derivatives were cyclized by a metal-assisted C–N intramolecular cyclization developed in our research group, to give a pyrenylindole and a phenalenoindole. The pyrenylindole was inserted into a peptide by solid-phase coupling, with use of a 2-chlorotrityl chloride resin and a Fmoc strategy. The photophysical properties of the pyrenylindole and phenalenoindole in several solvents were studied and showed that these compounds can be used as fluorescence probes. The results obtained with the peptide labelled with the pyrenylindole moiety show potential for use of this compound as a fluorescence label avoiding the aggregation propensity of pyrene compounds. Photophysical studies of the pyrenylindole and of the phenalenoindole in lipid membranes were also carried out. Steady-state fluorescence anisotropy measurements revealed that both compounds adopt locations inside the lipid bilayers and are able to report the transition between the gel and liquid-crystalline phases. The results point to potential use of these compounds as fluorescent probes for biological systems.Fundação para a Ciência e a Tecnologia (FCT) - (SFRH/BPD/24548/2005), (SFRH/BD/38766/2007)Fundo Europeu de Desenvolvimento Regional (FEDER) - Project PTDC/QUI/81238/200

Magnetoliposomes as carriers for promising antitumor thieno[3,2-b]pyridin-7-arylamines: photophysical and biological studies

Magnetoliposomes containing superparamagnetic manganese ferrite nanoparticles were tested as nanocarriers for two new promising antitumor drugs, a N-(3-methoxyphenyl)thieno[3,2-b]pyridin-7-amine (1) and a N-(2-methoxy-phenyl)thieno[3,2-b]pyridin-7-amine (2). The fluorescence emission of both compounds was studied in different polar and non-polar media, evidencing a strong intramolecular charge transfer character of the excited state of both compounds. These in vitro potent antitumor thienopyridine derivatives were successfully incorporated in both aqueous and solid magnetoliposomes, with encapsulation efficiencies higher than 75%. The magnetic properties of magnetoliposomes containing manganese ferrite nanoparticles were measured for the first time, proving a superparamagnetic behaviour. Growth inhibition assays on several human tumor cell lines showed very low GI50 values for drug-loaded aqueous magnetoliposomes, comparing in most cell lines with the ones previously obtained using the neat compounds. These results are important for future drug delivery applications using magnetoliposomes in oncology, through a dual therapeutic approach (simultaneous chemotherapy and magnetic hyperthermia).This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding of CF-UM-UP (UID/FIS/04650/2013), CQUM (UID/QUI/00686/2013 and 2016) and CIMO (UID/AGR/00690/2013), the latter also supported by FEDER -Program PT2020. FCT, POPH-QREN and FSE are acknowledged for the PhD grant of A. R. O. Rodrigues (SFRH/BD/90949/2012), the postdoc grant of R. C. Calhelha (SFRH/BPD/68344/2010) and for financial support to MAP-Fis PhD Programme.info:eu-repo/semantics/publishedVersio