Glasgow, United Kingdom
Glasgow, United Kingdom

Time filter

Source Type

Soares A.M.S.,University of Minho | Piloto A.M.,University of Minho | Hungerford G.,HORIBA Jobin Yvon IBH Ltd | Costa S.P.G.,University of Minho | Goncalves M.S.T.,University of Minho
European Journal of Organic Chemistry | Year: 2012

In order to develop butyric acid photoactive prodrugs, new heteroaromatic conjugates based on oxygen and nitrogen were synthesised and evaluated under irradiation at 254, 300, 350 and 419 nm. Light-triggered uncaging of butyric acid from the corresponding heterocyclic cages was achieved with complete release of the drug in short times. Naphtho[2,3-d]oxazole, naphtho[1,2-d] oxazole, 3-oxo-3H-benzo[f]benzopyran, 2-oxo-2H-benzo[h]benzopyran and 6-oxo-6H-benzopyrano[6,7-d]oxazole conjugates were readily photolysed, and the best results were obtained for naphtho-oxazoles at 254 and 300 nm and for 3-oxo-3H-benzo[f]benzopyran, 2-oxo-2H-benzo[h]benzopyran and 2-methyl-6-oxo-6H-benzopyrano[6,7-d]oxazole at 350 nm. 3-Oxo-3H-benzo[f] benzopyran also afforded good results at 419 nm. The photophysical processes involved were further elucidated by the use of time-resolved fluorescence techniques. Butyric acid photoactive prodrugs based on oxygen and nitrogen heteroaromatic conjugates were synthesised and evaluated by irradiation at 254, 300, 350 and 419 nm. The photophysical processes involved were further elucidated by the use of time-resolved fluorescence techniques. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Piloto A.M.,University of Minho | Hungerford G.,HORIBA Jobin Yvon IBH Ltd. | Costa S.P.G.,University of Minho | Goncalves M.S.T.,University of Minho
Photochemical and Photobiological Sciences | Year: 2013

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 photochemical reactor. The process was followed by HPLC/UV, resulting in the release of the active molecule in short irradiation times. The results obtained using 419 nm irradiation show promise (35-98 min) for practical purposes. The compounds were further characterised via time-resolved fluorescence to elucidate their photophysical properties and determine the decay kinetics. This journal is © 2013 The Royal Society of Chemistry and Owner Societies.


Piloto A.M.,University of Minho | Hungerford G.,HORIBA Jobin Yvon IBH Ltd | Costa S.P.G.,University of Minho | Goncalves M.S.T.,University of Minho
European Journal of Organic Chemistry | Year: 2013

The photoinduced release of several neurotransmitter amino acids (glycine, alanine, glutamic acid, β-alanine and γ-aminobutyric acid) was accomplished from ester cages based on a new photoremovable protecting group consisting of a coumarin built on the julolidine nucleus, namely a (11-oxo-2,3,5,6,7,11-hexahydro-1H-pyrano[2,3-f]pyrido[3,2,1-ij]quinolin-9-yl) methyl group. Photolysis and steady-state sensitization studies revealed that release of the active molecule occurred in short irradiation times at long wavelengths, with a very promising performance at 419 nm. Given the interest in the development of novel protecting groups that are cleavable with UV A or even visible radiation, it was found that a structural modification in the coumarin ring by assembly of a fused julolidine leads to a promising photolabile protecting group for organic synthesis and also for bioapplications. Photolysis and steady-state sensitization studies of several neurotransmitter amino acids from ester cages based on a new photoremovable protecting group consisting of a coumarin-fused julolidine nucleus, revealed that the release of the active molecule occurred in short irradiation times at long wavelengths, especially at 419 nm. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Adilia Lemos M.,University of Abertay Dundee | Hungerford G.,HORIBA Jobin Yvon IBH Ltd
Photochemistry and Photobiology | Year: 2013

Turmeric (Curcuma longa L.) is obtained from the rhizome of the Zingberaceae family and has a long history as an ingredient in cooking. It has been used as a dye and recently research has concentrated on its possible health benefits, specifically because of its antioxidant activity. The principal compound that is responsible for this activity is curcumin, which is present with the other curcuminoids; demethoxycurcumin and bisdemethoxycurcumin. Curcumin exhibits fluorescence and its photophysics are markedly affected by the polarity, hydrogen bonding and pH. This provides a means to examine its interaction with proteins, which is important if its potential health role is to be fully investigated. In this work, we monitor the binding kinetics using time-resolved fluorescence measurements, enabled by the use of low dead time electronics coupled with a high repetition rate excitation source and time-resolved emission spectra of the extracted curcuminoids upon interaction with bovine serum albumin. From these measurements the decay-associated spectra of the different lifetime components were obtained, which is consistent with reports of more than one binding site. Monitoring changes in these spectra with increasing temperature also allows for the denaturing of the serum albumin to be inferred. The interaction of turmeric extract with bovine serum albumin was monitored using time-resolved fluorescence techniques. A kinetic time-correlated single-photon counting measurement allowed the binding process of the extract to the serum albumin to be followed and the use of time-resolved emission spectra enabled the binding environment to be elucidated. The results were consistent with the presence of two binding sites. © 2013 The American Society of Photobiology.


Coelho J.,INESC Porto | Azevedo J.,University of Porto | Hungerford G.,HORIBA Jobin Yvon IBH Ltd. | Hussain N.S.,INESC Porto | Hussain N.S.,University of Porto
Optical Materials | Year: 2011

Erbium oxide (0.5-4 mol%) doped lithium boro tellurite (LBT) glasses have been prepared and the NIR emission band at 1.5 μm characterized. By pumping with LED excitation sources at 495 nm and 970 nm, a broader NIR emission transition (4I13/2 → 4Il5/2) was observed. The Judd-Ofelt intensity parameters (Ω2 = 7.36 × 10-20 cm2; Ω4 = 2.79 × 10-20 cm2 and Ω6 = 2.32 × 10 -20 cm2) were derived for the 1 mol% Er3+-doped LBT glass and compared with other tellurite host glasses. The full width at half the maximum (FWHM), stimulated emission cross-sections (σPE) and lifetimes (τmea) for NIR luminescence transitions 4I13/2 → 4I15/2 are reported. For both excitation wavelengths, overall the decay times were found to decrease with increasing erbium content. The present study describes the excitation dependent luminescence properties for this NIR transition. © 2011 Elsevier B.V. All rights reserved.


Damas P.,University of Porto | Coelho J.,INESC Porto | Hungerford G.,HORIBA Jobin Yvon IBH Ltd. | Hussain N.S.,University of Porto | Hussain N.S.,INESC Porto
Materials Research Bulletin | Year: 2012

This paper reports the preparation and structural studies of praseodymium and samarium (0.5, 2 and 4 mol%) oxide doped lithium boro tellurite glasses. These materials were prepared by the quenching technique in a ceramic crucible at 950 °C. Structural characterization was performed by Raman spectroscopy, Scanning Electron Microscopy and Energy Dispersive X-ray spectroscopy techniques. Results from Raman analysis are in good agreement with those reported in the literature, revealing a normal glass structure for the host material. Understanding on how the glasses internal structure changed when the doping concentration increases was also assessed. © 2012 Elsevier Ltd. All rights reserved.


Coelho J.,INESC Porto | Hungerford G.,HORIBA Jobin Yvon IBH Ltd. | Hussain N.S.,INESC Porto | Hussain N.S.,University of Porto
Chemical Physics Letters | Year: 2011

The structural properties of Er3+: silver lead borate glass is assessed by means of SEM, X-ray mapping, EDS and Raman analysis. In order to verify the time dependency of emission spectra, steady-state luminescence spectroscopy (SSLS) and time-resolved emission spectroscopy (TRES) studies have been performed. The stimulated emission cross-sections for the NIR emission transition 4I13/2 → 4I15/2 (1535 nm) at 970 nm excitation are reported. The decay times were obtained by fitting one (τm = 0.301 ms) and two (τm1 = 0.141 ms, τm2 = 0.368 ms) distributions for the NIR transition. Furthermore, by making use of TRES measurements the decay associated spectra were obtained allowing the time dependency for the different emission bands to be elucidated. © 2011 Elsevier B.V. All rights reserved.


Lemos M.A.,University of Abertay Dundee | Aliyu M.M.,University of Abertay Dundee | Hungerford G.,HORIBA Jobin Yvon IBH Ltd
Food Chemistry | Year: 2014

Tubers rich in phytochemicals can exhibit a potential health benefit. This work aims at studying the relative effect of different domestic cooking techniques by monitoring the level of total phenolic compounds (TP), total anthocyanins (TA) and anti-oxidant activity (AOA) on a variety of pigmented potatoes. Raw purple potatoes are a good source of anthocyanins (219 mg/kg FW) and the level of these compounds increased using different cooking techniques, with the exception of baking. However, the levels of phenolic compounds (originally 209 mg GAE/100 g FW) decreased in the cooked potatoes. Although potatoes contain different antioxidants in this work the antioxidant activity seems to be related to the levels of phenolic compounds present in the pigmented potato. The fact that some of the compounds present fluoresce enabled both steady state and time-resolved fluorescence techniques to be assessed as a non destructive means of monitoring. This elucidated the presence of different components (via spectral deconvolution and time-resolved emission spectra). Their relative contribution to the fluorescence emission was found to be affected by the different cooking process, with a longer wavelength emission appearing to relate to reflect the presence of anthocyanins. © 2014 Elsevier Ltd. All rights reserved.


Holmes-Smith A.S.,Glasgow Caledonian University | McDowell G.R.,Glasgow Caledonian University | Toury M.,HORIBA Jobin Yvon IBH Ltd. | McLoskey D.,HORIBA Jobin Yvon IBH Ltd. | Hungerford G.,HORIBA Jobin Yvon IBH Ltd.
ChemPhysChem | Year: 2012

The efficiency of Förster resonance energy transfer (FRET) can be enhanced in the presence of a metal. Herein, we demonstrate the increased efficiency for a novel model sensor system where FRET is shown to occur between Rhodamine 6G in the bulk sol-gel matrix and Texas Red, which is held a fixed distance away by covalent attachment onto a silane spacer. Silver colloids are formed using light to initiate the reduction of a silver salt, which can be achieved at controlled locations within the film. Both the fluorescence intensity and lifetime maps and analysis indicate that an enhanced FRET efficiency has been achieved in the presence of silver nanoparticles. An increase in efficiency of 1.2-1.5 times is demonstrated depending on the spacer used. The novelty of our approach lies in the method of silver-nanoparticle formation, which allows for the accurate positioning of the silver nanoparticles and hence selective fluorescence enhancement within a biocompatible host material. Our work gives a practical demonstration of metal-enhanced FRET and demonstrates the ability of such systems to be developed for molecular-recognition applications that could find use in lab-on-a-chip technologies. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Lemos M.A.,University of Abertay Dundee | Aliyu M.M.,University of Abertay Dundee | Hungerford G.,HORIBA Jobin Yvon IBH Ltd
Innovative Food Science and Emerging Technologies | Year: 2012

Anthocyanins are water soluble phenolic compounds present in fruit and vegetables which are responsible for the bright red, blue and purple colours of these food products. They are also responsible for the characteristic autumn leaf colouration in some trees. These are versatile compounds, as well as having application in the food industry, they have also found usage to sensitise titanium dioxide in research related to dye sensitised solar cells. This has prompted investigation into their photophysical properties in order to elucidate their charge transfer mediation behaviour. Recently anthocyanins are becoming of high interest both from a health point of view and because of their potential usage as food colouring agents. However, anthocyanins are very unstable compounds and their stability can be affected by several factors such as temperature, pH, oxygen and light. Here we show the effect of the microwave process (which is a promising method for anthocyanin extraction) on the location and form of anthocyanin in Purple Majesty potato (novel variety of purple potato rich in anthocyanins, the major one of which is petanin), when compared with the raw potato using time-resolved fluorescence techniques, both on extracted anthocyanin and in-situ on potato slices using fluorescence lifetime imaging. Industrial relevance: Anthocyanins can be extracted from plant based food and have potential application in Food Industry because of their anti-microbial and anti-oxidant properties. This group of compounds also present strong (principally) red and purple colourations in plant matter, which make them interesting to use as food colorants by the Food Industry. However, anthocyanins can have different structures (forms) which are dependent of the environmental conditions (mainly pH/complexation/concentration) which can affect their properties. Considering that these compounds can be extracted from plants it is important to easily observe their location in the cell and to elucidate their properties. Because of this requirement we show, in this paper, that it is possible to use time-resolved fluorescence, using microscopy and time-resolved emission spectra, which we believe add novelty to obtain pertinent information from extracted (unpurified) anthocyanin and in-situ within the potato tuber cells. This shows the potential of these techniques in elucidating data in this study and with future application in food industry. © 2012 Elsevier Ltd.

Loading HORIBA Jobin Yvon IBH Ltd. collaborators
Loading HORIBA Jobin Yvon IBH Ltd. collaborators