Gokhan Yahioglu
Imperial College London
Fluorescence anisotropyAnalytical chemistryCancerBiophysicsViscosityMicroviscosityPathologyAntibodyNanotechnologyLight-emitting diodeChemistryMaterials scienceConjugateIn vitroMUC1PorphyrinDrugPhotodynamic therapyCancer researchFluorescence-lifetime imaging microscopyMedicinePhotochemistryFluorescence
65Publications
24H-index
2,097Citations
Publications 62
Newest
#1James A. Levitt ('KCL': King's College London)H-Index: 21
#2Pei-Hua Chung ('KCL': King's College London)H-Index: 11
Last. Klaus Suhling ('KCL': King's College London)H-Index: 41
view all 7 authors...
We present polarization-resolved fluorescence measurements of fluorescent molecular rotors 9-(2-carboxy-2-cyanovinyl)julolidine (CCVJ), 9-(2,2-dicyanovinyl)julolidine (DCVJ), and a meso-substituted boron dipyrromethene (BODIPY-C 12 ). The photophysical properties of these molecules are highly dependent on the viscosity of the surrounding solvent. The relationship between their quantum yields and the viscosity of the surrounding medium is given by an equation first described and presented by Fors...
73 CitationsSource
#1Pei-Hua Chung ('KCL': King's College London)H-Index: 11
#2James A. Levitt ('KCL': King's College London)H-Index: 21
Last. Klaus Suhling ('KCL': King's College London)H-Index: 41
view all 5 authors...
ABSTRACT Meso-substituted boron-dipyrromethene (BODIPY-C 12 ) was used to monitor the viscosity in cells via fluorescence lifetime imaging (FLIM), and time-resolved fluorescence anisotropy measurements. Our results show that meso-substituted BODIPY-C 12 senses the viscosity in HeLa cells and is insensitive to the surrounding polarity. The relationship between the fluorescence lifetime and the rotational correlation time of the dye in homogeneous solutions agree with the combination of the Forste...
Source
#1James A. Levitt ('KCL': King's College London)H-Index: 21
#2Marina K. Kuimova (Imperial College London)H-Index: 38
Last. David Phillips (Imperial College London)H-Index: 59
view all 6 authors...
Fluorescence liftime imaging (FLIM) of modified hydrophobic bodipy dyes that act as fluorescent molecular rotors shows that the fluorescence lifetime of these probes is a function of the microviscosity of their environment. Incubating cells with these dyes, we find a punctate and continuous distribution of the dye in cells. The viscosity value obtained in what appears to be endocytotic vesicles in living cells is around 100 times higher than that of water and of cellular cytoplasm.Time-resolved ...
4 CitationsSource
#1Ioanna Stamati (Imperial College London)H-Index: 5
#2Marina K. Kuimova (Imperial College London)H-Index: 38
Last. Mahendra Deonarain (Imperial College London)H-Index: 19
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Photodynamic Therapy (PDT) is a minimally invasive procedure used for treating a range of neoplastic diseases, which utilises combined action of light and a PDT drug called a photosensitiser. The efficiency of this treatment depends crucially on the properties of the photosensitiser used, namely on its efficient uptake by cells or by the surrounding vasculature, intracellular localisation, minimal dark toxicity and substantial phototoxicity. In this report we compare the spectroscopic properties...
27 CitationsSource
#1Graham HungerfordH-Index: 22
#2Archie AllisonH-Index: 3
Last. Klaus SuhlingH-Index: 41
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The sol-to-gel transition was monitored via the use of time-resolved recording of the fluorescence emission of viscosity-sensitive probes. Two dyes were chosen for the study, water-soluble DASPMI and a hydrophobic BODIPY, and steady-state, time-resolved and time-tagged fluorescence measurements were performed. These techniques, coupled with the probes different solubility, allowed complementary fluorescence lifetime and intensity data to be obtained from the dyes introduced into the matrix-formi...
67 CitationsSource
#1James A. LevittH-Index: 21
#2Marina K. KuimovaH-Index: 38
Last. David PhillipsH-Index: 59
view all 6 authors...
We report intracellular fluorescence lifetime imaging (FLIM) and fluorescence anisotropy measurements of two meso-substituted fluorophores based on the boron−dipyrrin (BODIPY) structure. Both dyes incorporate hydrophobic groups, which render them membrane-soluble. We have obtained values for quantum yields, radiative and nonradiative rate constants, fluorescence lifetimes, and time-resolved anisotropy data for the dyes in homogeneous methanol/glycerol solutions of varying viscosities from 0.6 to...
208 CitationsSource
#1Gemma C. Shearman (Imperial College London)H-Index: 13
#2Gokhan Yahioglu (Imperial College London)H-Index: 24
Last. John M. Seddon (Imperial College London)H-Index: 50
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A homologous series of three octakis-alkyl-substituted porphyrin (OAP) derivatives with alkyl chain lengths of C8, C10 and C12 has been synthesised. For each compound, both the free-base (i.e. two H-atoms) and the fourfold coordinated zinc complex were investigated, where the latter for each chain length was found to exhibit liquid-crystalline mesophase behaviour. At low temperatures all three metal coordinated compounds formed a solid S phase with a structure based on a square packing of column...
23 CitationsSource
#1Marina K. Kuimova (Imperial College London)H-Index: 38
#2Gokhan YahiogluH-Index: 24
Last. Peter R. OgilbyH-Index: 58
view all 3 authors...
Singlet molecular oxygen, O2(a1Δg), can be created in a single cell from ground-state oxygen, O2(X3Σg−), upon focused laser irradiation of an intracellular sensitizer. This cytotoxic species can subsequently be detected by its 1270 nm phosphorescence (a1Δg → X3Σg−) with subcellular spatial resolution. The singlet oxygen lifetime determines its diffusion distance and hence the intracellular volume element in which singlet-oxygen-initiated perturbation of the cell occurs. In this study, the time-r...
188 CitationsSource
#1Marina K. Kuimova (Imperial College London)H-Index: 38
#2Gokhan YahiogluH-Index: 24
Last. Klaus SuhlingH-Index: 41
view all 4 authors...
The fluorescence intensity and lifetime of the 4,4′-difluoro-4-bora-5-(p-oxoalkyl)phenyl-3a,4a-diaza-s-indacene (1) show a strong correlation with the viscosity of the medium due to the viscosity-dependent twisting of the 5-phenyl group, which gives access to the dark nonemissive excited state. We propose a sensitive and versatile method for measuring the local microviscosity in biological systems, based on the determination of the fluorescence lifetime of 1. Fluorescence lifetime imaging (FLIM)...
544 CitationsSource
#1Manpreet Bhatti (Imperial College London)H-Index: 10
#1Manpreet S. Bhatti (Imperial College London)H-Index: 15
Last. Mahendra Deonarain (Imperial College London)H-Index: 19
view all 6 authors...
Current photodynamic therapy (PDT) of cancer is limited by inefficiencies involved in specifically targeting photosensitizers to tumors. Although antibodies are being explored as targeting vehicles, they present significant challenges, particularly in terms of pharmacokinetics and drug-coupling. We describe here a novel and effective system to covalently attach multiple photosensitizer molecules (both preclinical, pyropheophorbide-a and clinically approved, verteporfin photosensitizers) to singl...
100 CitationsSource