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Acridinyl methyl esters as photoactive precursors in the release of neurotransm...
Piloto, Ana M.; Hungerford, Graham; Costa, Susana P. G.; Gonçalves, M. Sameiro T.An investigation of the use of an azaheterocycle, acridine, as an alternative photochemically removable protecting group for the carboxylic function of neurotransmitter amino acids was carried out. 9-Bromomethylacridine was used in the reaction with glycine, alanine, glutamic acid, β-alanine and γ-aminobutyric acid, to obtain model ester derivatives, which were irradiated at different wavelengths in a photochem...
Photolysis at long wavelengths of amino acid ester derivatives based on 4-methy...
Piloto, Ana M.; Soares, Ana M. S.; Hungerford, Graham; Costa, Susana P. G.; Gonçalves, M. Sameiro T.Ester derivatives of fused 4-methyl-6-methoxy-2-oxo-2H- naphtho[1,2-b]pyran, using valine and phenylalanine as model bifunctional molecules were synthesised, to assess its applicability as a photocleavable protecting group, for solution phase organic synthesis and in caging applications, at longer wavelengths. The behaviour of the corresponding derivatives towards photolysis was evaluated by irradiation in mixt...
Fluorescence probe techniques to monitor protein adsorption-induced conformatio...
Benesch, Johan; Hungerford, Graham; Suhling, Klaus; Tregidgo, Carolyn; Mano, J. F.; Reis, R. L.The study of protein adsorption and any associated conformational changes on interaction with biomaterials is of great importance in the area of implants and tissue constructs. This study aimed to evaluate some fluorescent techniques to probe protein conformation on a selection of biodegradable polymers currently under investigation for biomedical applications. Because of the fluorescence emanating from the pol...
Effect of the labelling ratio on the photophysics of fluorescein isothiocyanate...
Hungerford, Graham; Benesch, Johan; Mano, J. F.; Reis, R. L.The non-linearity of the fluorescence emission on increasing the probe to protein ratio has long been regarded as problematic and has lead to the development of dyes to overcome this effect. One of the causes of this non-linear response can be ascribed to the overlap of the label’s own absorption and emission spectra. At higher labelling ratios, this affords the possibility of a reasonably efficient energy migr...
Interaction of DODAB with neutral phospholipids and cholesterol studied using f...
Hungerford, Graham; Baptista, Adelina L. F.; Coutinho, Paulo J. G.; Castanheira, Elisabete M. S.; Oliveira, M. ElisabeteLiposomes composed of cationic lipids and neutral phospholipids have been used as vehicles for cellular delivery of DNA and drug delivery. The aim of this study is to get a better understanding of phospholipid–cationic lipid interactions that is essential for the development of this potential. We have studied the interaction between cationic lipid liposomes primarily composed of dioctadecyldimethylammonium brom...
Domain formation in DODAB–cholesterol mixed systems monitored via nile red anis...
Hungerford, Graham; Castanheira, Elisabete M. S.; Baptista, Adelina L. F.; Coutinho, Paulo J. G.; Oliveira, M. ElisabeteThe effect of the cholesterol (Ch) on liposomes composed of the cationic lipid dioctadecyldimethylammonium bromide (DODAB) was assessed by studying both the steady-state and time-resolved fluorescence anisotropy of the dye Nile Red. The information obtained combined with analysis of the steady-state emission and luorescence lifetime of Nile Red (NR) for different cholesterol concentrations (5–50%) elucidated t...
Fluorescence studies of the interaction of pyrenylmethyl tributylphosphonium br...
Oliveira, M. Elisabete; Baptista, Adelina L. F.; Coutinho, Paulo J. G.; Castanheira, Elisabete M. S.; Hungerford, GrahamThe interaction between pyren-1-ylmethyl tri-n-butylphosphonium bromide (PMTP), a water-soluble cationic pyrene derivative and the double-strand polynucleotides Poly[dA-dT], Poly[dA].Poly[dT], Poly[dG-dC] and Poly[dG]. Poly[dC] was studied using UV-Vis absorption and fluorescence spectroscopy. The PMTP probe interacts with polynucleotides through both weak and intercalative binding, evidenced through changes in...
Synthesis and characterization of a sol-gel derived ureasilicate hybrid organic...
Boev, Victor I.; Silva, C. J. R.; Hungerford, Graham; Gomes, M. J. M.A hybrid organic-inorganic material filled with in situ generated inorganic particles has been synthesised by the homogeneous precipitation of CdS from aqueous solutions of Cd(NO3)2 and CH3CSNH2 . These highly transparent, homogeneous and flexible CdS doped xerogels were prepared by the sol-gel technique using, as precursors, organically modified silicon alkoxide (3-isocyanatepropyltriethoxysilane) and a di-ami...
Monitoring Ternary Systems of C12E5/Water/Tetradecane via the Fluorescence of S...
Hungerford, Graham; Castanheira, Elisabete M. S.; Oliveira, M. Elisabete C. D. Real; Miguel, M. da Graça; Burrows, Hugh D.In this work ternary systems of the nonionic surfactant C12E5 (C12H25(OCH2CH2)5OH), tetradecane, and water were probed by the use of steady state and time-resolved fluorescence. Microemulsions, which were rich in oil, rich in water, and also both continuous in oil and water, were monitored via the application of solvatochromic fluorescent probes. The hydrophobic laser dye Nile Red was used to report from the si...
Monitoring the Phase Transition of C12E5/Water/Alkane Microemulsions Through Ex...
Oliveira, M. E. C. D. Real; Hungerford, Graham; Castanheira, E. M. S.; Miguel, M. da G.; Burrows, H. D.The phase transition of microemulsions involving the nonionic surfactant C12E5 [C12H25(OCH2-CH2)5OH], water, and alkanes (heptane, decane and tetradecane) has been investigated through the excimer formation of pyrene. On going to the microemulsion bicontinuous phase, by changing either composition or temperature, pronounced changes in the pyrene excimer-to-monomer fluorescence intensity ratio, IE/IM, are observ...
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