Olaf J Rolinski

Scottish Universities Physics Alliance, Glasgow, Scotland, United Kingdom

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Publications (45)106.79 Total impact

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    ABSTRACT: The fluorescence decay of beta-amyloid's (Aβ) intrinsic fluorophore tyrosine has been used for sensing the oligomer formation of dye-labelled Aβ monomers and the results compared with previously studied oligomerization of the non-labelled Aβ peptides. It has been demonstrated that two different sized, covalently bound probes 7-diethylaminocoumarin-3-carbonyl and Hilyte Fluor 488 (HLF), alter the rate and character of oligomerization to different extents. The ability of HLF to inhibit formation of highly ordered structures containing beta-sheets was also shown. The implications of our findings for using fluorescence methods in amyloidosis research are discussed and the advantages of this auto-fluorescence approach highlighted.
    01/2014; 104(6).
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    ABSTRACT: The development of Alzheimer's disease is associated with the aggregation of the beta-amyloid peptides Aβ1−40 and Aβ1−42. It is believed that the small oligomers formed during the early stages of the aggregation are neurotoxic and involved in the process of neurodegeneration. In this paper we use fluorescence decay measurements of beta-amyloid intrinsic fluorophore tyrosine (Tyr) and molecular dynamics (MD) simulations to study the early stages of oligomer formation for the Aβ1−40 and Aβ1−42 peptides in vitro. We demonstrate that the lifetime distributions of the amyloid fluorescence decay efficiently describe changes in the complex Tyr photophysics during the peptide aggregation and highlight the differences in aggregation performance of the two amyloids. Tyr fluorescence decay is found to be a more sensitive sensor of Aβ1−40 aggregation than Aβ1−42 aggregation. The MD simulation of the peptide aggregation is compared with the experimental data and supports a four-rotamer model of Tyr.
    Methods and Applications in Fluorescence. 03/2013; 1(1):015006.
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    Jens U Sutter, David J S Birch, Olaf J Rolinski
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    ABSTRACT: We report the use of CdSe/ZnS core/shell quantum dots QDot800 (Invitrogen) as luminescence lifetime sensors for copper ions Cu2+(H2O)8 in solution with a sensitivity of <1 ppb that is relevant to intracellular copper concentrations. Excitation of QDot800 at 485 nm was found to be optimum in that it did not cause any change in the level of luminescence intensity or luminescence lifetime in the absence of copper ions. When excited at 485 nm a bi-exponential luminescence decay of QDot800 was observed suggesting the presence of two distinct emitting states, both capable of undergoing metal ion quenching that facilitates Cu2+ detection. Selectivity for copper, as against other transition metal ions, as well as other evidence, suggests the primary origin of the quenching is luminescence resonance energy transfer to both free and bound copper ions. The luminescence kinetics of quantum dots and their optimization and applicability for resonance energy transfer-based lifetime sensing in general is discussed.
    Measurement Science and Technology 04/2012; 23(5):055103. · 1.44 Impact Factor
  • Mariana Amaro, David J S Birch, Olaf J Rolinski
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    ABSTRACT: Aggregation of the peptide beta-amyloid is known to be associated with Alzheimer's disease. According to recent findings the most neurotoxic aggregates are the oligomers formed in the initial stages of the aggregation process. Here we use beta-amyloid's (Aβ's) intrinsic fluorophore tyrosine to probe the earliest peptide-to-peptide stages of aggregation, a region often merely labelled as a time lag, because negligible changes are observed by the commonly used probe ThT. Using spectrally resolved fluorescence decay time techniques and analysis we demonstrate how the distribution of 3 rotamer conformations of the single tyrosine in Aβ tracks the aggregation across the time lag and beyond according to the initial peptide concentration. At low Aβ concentrations (≤5 μM), negligible aggregation is observed and this is mirrored by little change in the fluorescence decay parameters, providing a useful baseline for comparison. At higher concentrations (≈50 μM), and contrary to what is generally accepted from ThT studies the rate of aggregation can be described by an exponential growth to a plateau in terms of the relative contributions of two of the three rotamers, with a characteristic aggregation time of ≈33 h.
    Physical Chemistry Chemical Physics 03/2011; 13(14):6434-41. · 4.20 Impact Factor
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    Jens U. Sutter, David J. S. Birch, Olaf J. Rolinski
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    ABSTRACT: We report changes in the photophysical properties of core-shell type CdSe/ZnS quantum dots (QDs) under optical irradiation. QDs either in aqueous solution or immobilized in a silica sol gel matrix have been excited at different wavelengths and fluxes. Illumination of the sample with 140 fs 700 nm Ti:sapphire laser pulses of the peak power of the order of 4 GW/cm2 caused gradual increase in the luminescence lifetime from an initial value of 3.5 increasing to 4.5 ns and an increase in luminescence intensity by ∼ 8%. Using about 16 GW/cm2 peak power resulted in a shortening of the luminescence lifetime to 3 ns and a decrease in intensity by ∼ 75%. Both photobrightening and photodarkening were fully reversible. We discuss the kinetics of photobrightening and photodarkening and investigate the suitability of QDs as luminescence lifetime sensors with tunable parameters.
    Applied Physics Letters 01/2011; 98(2):021108. · 3.79 Impact Factor
  • Olaf J Rolinski, Mariana Amaro, David J S Birch
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    ABSTRACT: Beta-amyloid (Abeta) aggregation, believed to be responsible for Alzheimer's disease, is monitored using its intrinsic fluorescence decay. Alterations in the fluorescence decay of tyrosine correlate with the Abeta aggregation at a much earlier stage than the traditionally used fluorescence intensity of Thioflavin T (ThT). Potentially the finding may underpin progress towards an earlier diagnosis of the onset of Alzheimer's disease and an improved approach to developing intervention therapies.
    Biosensors & bioelectronics 03/2010; 25(10):2249-52. · 5.43 Impact Factor
  • Olaf J Rolinski, Katherine Scobie, David J S Birch
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    ABSTRACT: We present a description of fluorescence decay kinetics in complex environments based on gamma functions rather than the conventional approach using exponentials. The gamma function description is tested in measurements on the temperature dependence of the protein human serum albumin (HSA), N-acetyl tryptophanamide (NATA), and 2, 5-dipenyl oxazole (PPO). The monitoring of macromolecular structure and dynamics is demonstrated by means of distinct tryptophan (Trp) rotamer populations and their interconversion in HSA.
    Physical Review E 06/2009; 79(5 Pt 1):050901. · 2.31 Impact Factor
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    ABSTRACT: We report the development of biophysical techniques based on circular dichroism (CD), diffuse reflectance infrared Fourier transform (DRIFT) and tryptophan (Trp) fluorescence to investigate in situ the structure of enzymes immobilised on solid particles. Their applicability is demonstrated using subtilisin Carlsberg (SC) immobilised on silica gel and Candida antartica lipase B immobilised on Lewatit VP.OC 1600 (Novozyme 435). SC shows nearly identical secondary structure in solution and in the immobilised state as evident from far UV CD spectra and amide I vibration bands. Increased near UV CD intensity and reduced Trp fluorescence suggest a more rigid tertiary structure on the silica surface. After immobilised SC is inactivated, these techniques reveal: a) almost complete loss of near UV CD signal, suggesting loss of tertiary structure; b) a shift in the amide I vibrational band from 1658 cm(-1) to 1632 cm(-1), indicating a shift from alpha-helical structure to beta-sheet; c) a substantial blue shift and reduced dichroism in the far UV CD, supporting a shift to beta-sheet structure; d) strong increase in Trp fluorescence intensity, which reflects reduced intramolecular quenching with loss of tertiary structure; and e) major change in fluorescence lifetime distribution, confirming a substantial change in Trp environment. DRIFT measurements suggest that pressing KBr discs may perturb protein structure. With the enzyme on organic polymer it was possible to obtain near UV CD spectra free of interference by the carrier material. However, far UV CD, DRIFT and fluorescence measurements showed strong signals from the organic support. In conclusion, the spectroscopic methods described here provide structural information hitherto inaccessible, with their applicability limited by interference from, rather than the particulate nature of, the support material.
    ChemPhysChem 05/2009; 10(9-10):1492-9. · 3.35 Impact Factor
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    ABSTRACT: We aimed to develop microsensors for eventual glucose monitoring in diabetes, based on fluorescence lifetime changes in glucose/galactose-binding protein (GBP) labelled with the environmentally sensitive fluorophore dye, badan. A mutant of GBP was labelled with badan near the binding site, the protein adsorbed to microparticles of CaCO3 as templates and encapsulated in alternating nano-layers of poly-l-lysine and heparin. We used fluorescence lifetime imaging (FLIM) with two-photon excitation and time-correlated single-photon counting to visualize the lifetime changes in the capsules. Addition of glucose increased the mean lifetime of GBP-badan by a maximum of ∼2 ns. Analysis of fluorescence decay curves was consistent with two GBP states, a short-lifetime component (∼0.8 ns), likely representing the open form of the protein with no bound glucose, and a long-lifetime component (∼3.1 ns) representing the closed form with bound glucose and where the lobes of GBP have closed round the dye creating a more hydrophobic environment. FLIM demonstrated that increasing glucose increased the fractional proportion of the long-lifetime component. We conclude that fluorescence lifetime-based glucose sensing using GBP encapsulated with nano-engineered layer-by-layer films is a glucose monitoring technology suitable for development in diabetes management.
    Biosensors & bioelectronics 01/2009; · 5.43 Impact Factor
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    ABSTRACT: Hydrated nanopores offer a unique environment for studying biological molecules under controlled conditions and fabricating sensors using fluorescence. Silica nanopores for example are non-toxic, biologically and optically compatible with protein, and can be easily synthesized to entrap protein and exclude potentially interfering macromolecules, while transmitting analytes of interest. A well known problem when polymerizing orthosilicates to fabricate silica sol-gel nanopores is the release of alcohol, which denatures proteins. We will describe how using the fluorescence of PRODAN (6-propionyl-2-(N,N-dimethylamino) naphthalene) to monitor methanol generated during polymerization has helped define a protocol with enhanced biocompatibility. The improved biocompatibility of sol-gel nanopores synthesized using tetramethyl orthosilicate (TMOS) has been demonstrated by preserving the unstable native trimer form of allophycocyanin (APC) for up to 500 Hrs without the need to covalently binding the subunits together. This has enabled the observation of native APC trimer by means of its fluorescence in a pore down to the single molecule level. In this paper we demonstrate how PRODAN and another polarity sensitive dye, 9-diethylamino-5H-benzo[alpha]phenoxazine-5-one, Nile red (NR) report on pore polarity and successfully extend protein encapsulation to nano-channels of alumina (Al2O3). Improved biocompatibility of nanopores has potential impact in nanomedicine where the ability to study single biomolecules is a primary goal as it underpins our understanding of disease pathology and therapeutics at the most fundamental level. In sensing also the advantages of nanopore isolation of metabolite-specific protein for detecting non-fluorescent metabolites has been demonstrated. Similar approaches can in principle be developed for both single-molecules and lab-on-a-chip sensors.
    Conference proceedings: ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference 01/2009; 2009:4154-7.
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    ABSTRACT: Star-shaped oligofluorene consists of highly-fluorescent macromolecules of considerable interest for organic electronics. Here, we demonstrate controlled micro-patterning of these organic nanostructured molecules by blending them with custom-synthesized photo-curable aliphatic polymer matrices to facilitate solventless inkjet printing. The printed microstructures are spherical with minimum dimensions of 12μm diameter and 1μm height when using a cartridge delivering ∼1pL droplets. We evaluate the physical characteristics of the printed structures. Photoluminescence studies indicate that the blend materials possess similar fluorescence properties to neat materials in solid films or toluene solution. The fluorescence lifetime consists of two components, respectively 0.68±0.01ns (τ 1) and 1.23±0.12ns (τ 2). This work demonstrates that inkjet printing of such blends provides an attractive method of handling fluorescent nano-scaled molecules for photonic and optoelectronic applications.
    Applied Physics A 01/2009; 97(1):119-123. · 1.69 Impact Factor
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    Olaf J Rolinski, David J S Birch
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    ABSTRACT: Some fluorescence dyes in complex media, such as those found in biology, demonstrate nonextensive kinetics, which implies representing their fluorescence decays in terms of lifetime distributions rather than simple exponentials. Complex kinetics usually discourage application to lifetime sensors, as it is believed, that additional molecular mechanisms employed for detection of an analyte will make the resulting kinetics ambiguous and the sensor response inconclusive. In this paper we investigate theoretically the applicability of complex dye kinetics as a fluorescence resonance energy transfer based lifetime sensor and demonstrate that the nonextensive nature of its kinetics does not decrease the sensing performance, and indeed even provides richer structural information than a simple exponential behavior.
    The Journal of Chemical Physics 11/2008; 129(14):144507. · 3.12 Impact Factor
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    Olaf J Rolinski, Andrew Martin, David J S Birch
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    ABSTRACT: A nonextensive model of decay kinetics has been used to describe fluorescence behavior of tryptophan in human serum albumin on binding two flavonoids, quercetin and morin. We demonstrate that this approach, alternative to multiexponential representation of usually complex decays of tryptophan, is more adequate and can be beneficial in noninvasive lifetime sensing based on intrinsic fluorescence.
    Annals of the New York Academy of Sciences 02/2008; 1130:314-9. · 4.38 Impact Factor
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    ABSTRACT: Here we describe progress toward our objective of detecting single nonfluorescent hydrated metal ions. Single-ion detection represents detection and spectroscopy at the ultimate sensitivity level of approximately 1.6 x 10(-24) M. Achieving this goal would provide a breakthrough in analytical science and allow much more detailed insight into sensor-ion interaction than that available with conventional bulk detection methods. We combine recent advances in confocal microscopy with the sensitivity and the noninvasive nature of fluorescence by analyzing Förster resonance energy transfer between sensor fluorophores and transition metal ions.
    Annals of the New York Academy of Sciences 02/2008; 1130:62-7. · 4.38 Impact Factor
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    Olaf J Rolinski, Andrew Martin, David J S Birch
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    ABSTRACT: Human serum albumin (HSA) complexation with quercetin, a flavonoid commonly present in human diet, was monitored by means of fluorescence decays of the single HSA tryptophan - Trp214. Data analysis based on fitting to multiexponential functions and determining the lifetime distributions revealed a high sensitivity of tryptophan fluorescence to binding quercetin. Results are discussed in terms of the rotamer model for tryptophan, HSA-quercetin complexation and potential HSA to quercetin energy transfer. Evidence for quercetin stabilising tryptophan rotamers in HSA is presented.
    Journal of Biomedical Optics 01/2007; 12(3):034013. · 2.75 Impact Factor
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    ABSTRACT: The aim of this study was to test the hypothesis that glucose can be monitored non-invasively by measuring NAD(P)H-related fluorescence lifetime of cells in an in vitro cell culture model. Autofluorescence decay functions were measured in 3T3-L1 adipocytes by time-correlated single-photon counting (excitation 370nm, emission 420-480nm). Free NADH had a two-exponential decay but cell autofluorescence fitted best to a three-exponential decay. Addition of 30mM glucose caused a 29% increase in autofluorescence intensity, a significantly shortened mean lifetime (from 7.23 to 6.73ns), and an increase in the relative amplitude and fractional intensity of the short-lifetime component at the expense of the two longer-lifetime components. Similar effects were seen with rotenone, an agent that maximizes mitochondrial NADH. 3T3-L1 fibroblasts stained with the fluorescent mitochondrial marker, rhodamine 123 showed a 16% quenching of fluorescence intensity when exposed to 30mM glucose, and an increase in the relative amplitude and fractional intensity of the short lifetime at the expense of the longer lifetime component. We conclude that, though the effect size is relatively small, glucose can be measured non-invasively in cells by monitoring changes in the lifetimes of cell autofluorescence or of a dye marker of mitochondrial metabolism. Further investigation and development of fluorescence intensity and lifetime sensing is therefore indicated for possible non-invasive metabolic monitoring in human diabetes.
    Journal of Photochemistry and Photobiology B Biology 09/2005; 80(2):122-9. · 3.11 Impact Factor
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    ABSTRACT: There is an urgent need to develop technology for continuous in vivo glucose monitoring in subjects with diabetes mellitus. Problems with existing devices based on electrochemistry have encouraged alternative approaches to glucose sensing in recent years, and those based on fluorescence intensity and lifetime have special advantages, including sensitivity and the potential for non-invasive measurement when near-infrared light is used. Several receptors have been employed to detect glucose in fluorescence sensors, and these include the lectin concanavalin A (Con A), enzymes such as glucose oxidase, glucose dehydrogenase and hexokinase/glucokinase, bacterial glucose-binding protein, and boronic acid derivatives (which bind the diols of sugars). Techniques include measuring changes in fluorescence resonance energy transfer (FRET) between a fluorescent donor and an acceptor either within a protein which undergoes glucose-induced changes in conformation or because of competitive displacement; measurement of glucose-induced changes in intrinsic fluorescence of enzymes (e.g. due to tryptophan residues in hexokinase) or extrinsic fluorophores (e.g. using environmentally sensitive fluorophores to signal protein conformation). Non-invasive glucose monitoring can be accomplished by measurement of cell autofluorescence due to NAD(P)H, and fluorescent markers of mitochondrial metabolism can signal changes in extracellular glucose concentration. Here we review the principles of operation, context and current status of the various approaches to fluorescence-based glucose sensing.
    Biosensors and Bioelectronics 07/2005; 20(12):2555-65. · 5.44 Impact Factor
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    O. Rolinski, D. Birch
    12/2004: pages 56-70;
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    ABSTRACT: Experimental results on the use of micrometer-sized InGaN/GaN light-emitting diodes (micro-LEDs) for time-resolved fluorescence spectroscopy are reported.
    Lasers and Electro-Optics Society, 2004. LEOS 2004. The 17th Annual Meeting of the IEEE; 12/2004
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    ABSTRACT: Our newly developed fluorescence resonance energy transfer (FRET) based technique, fluorescence nanotomography (FN), is used to determine the morphology and dynamics of some soft materials and bio-molecules by attaching donor (D) fluorophores and acceptors (A) to the investigated structure and using fluorescence lifetime measurements to reveal the D-A distance distribution function rhoDA(r). We report the effect of the limited sizes of the donor and acceptor, effect of porous polymer, and molecular structure and phase transition in phospholipid bilayers.
    Biosensors and Bioelectronics 11/2004; 20(3):424-30. · 5.44 Impact Factor

Publication Stats

513 Citations
106.79 Total Impact Points

Institutions

  • 2008–2013
    • Scottish Universities Physics Alliance
      Glasgow, Scotland, United Kingdom
  • 1998–2011
    • University of Strathclyde
      • • Department of Physics
      • • Department of Pure and Applied Chemistry
      Glasgow, SCT, United Kingdom
  • 2005
    • King College
      Guymon, Oklahoma, United States
    • King's College London
      Londinium, England, United Kingdom