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  • 1
    In: Photochemical & Photobiological Sciences, 2014, Vol.13(3), pp.548-562
    Description: The photoacid 8-hydroxypyren-1,3,6-trisulfonic acid (HPTS, pyranine) is a widely used model compound for the examination of excited state proton transfer (ESPT). We synthesized five super-photoacids with varying hydrophilicity and acidity on the basis of HPTS. By chemical modification of the three sulfonic acid substituents, the photoacidity is enhanced by up to more than five logarithmic units from p K * a 1.4 to 3.9 for the most acidic compound. As a result, nearly quantitative ESPT in DMSO can be observed. The novel photoacids were characterized by steady-state and time-resolved fluorescence techniques showing distinctively red shifted spectra compared to HPTS while maintaining a high quantum yield near 90%. Photostability of the compounds was checked by fluorescence correlation spectroscopy (FCS) and was found to be adequately high for ultrasensitive fluorescence spectroscopy. The described photoacids present a valuable palette for a wide range of applications, especially when the properties of HPTS, i.e. highly charged, low photostability and only moderate excited state acidity, are limiting.
    Keywords: Spectrometry ; Excited-State ; Acidity ; Quantum-Efficiency ; Sulfonic-Acids ; Palettes ; Hydrophilic-Properties ; Substituent ; Spektroskopie ; Angeregter Zustand ; Azidität ; Quantenausbeute ; Sulfonsäure ; Palette ; Hydrophilie ; Substituent ; Biology ; Chemistry;
    ISSN: 1474-905X
    E-ISSN: 1474-9092
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  • 2
    Language: English
    In: Biomaterials, 2010, Vol.31(8), pp.2388-2398
    Description: Specific transport of anti-cancer drugs into tumor cells may result in increased therapeutic efficacy and decreased adverse events. Expression of αvβ3 integrin is enhanced in various types of cancer and monoclonal antibodies (mAbs) directed against αvβ3 integrins hold promise for anti-cancer therapy. DI17E6 is a monoclonal antibody directed against αv integrins that inhibits growth of melanomas and and inhibits angiogenesis due to interference with αvβ3 integrins. Here, DI17E6 was covalently coupled to human serum albumin nanoparticles. Resulting nanoparticles specifically targeted αvβ3 integrin positive melanoma cells. Moreover, doxorubicin loaded DI17E6 nanoparticles showed increased cytotoxic activity in αvβ3-positive melanoma cells than the free drug. Therefore, DI17E6-coupled human serum albumin nanoparticles represent a potential delivery system for targeted drug transport into αvβ3-positive cells.
    Keywords: Albumin ; Chemotherapy ; Drug Delivery ; Ecm (Extracellular Matrix) ; Integrin ; Nanoparticles ; Medicine ; Engineering
    ISSN: 0142-9612
    E-ISSN: 1878-5905
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  • 3
    In: Photochemical & Photobiological Sciences, 2016, Vol.15(12), pp.1544-1557
    Description: Photoacids on the basis of pyrenol have been extensively studied in the past 60 years. As their photophysical properties strongly depend on the substituents at the aromatic scaffold, we introduced two reactive moieties with different electronic coefficients thus creating multi-wavelength fluorescent probes. One probe is capable of monitoring two orthogonal transformations by four fluorescence colors, distinguishable even by the naked human eye. Another derivative can act as a three-color sensor for a wide range of different pH values. Both the presented compounds allow for mimicking of fundamental and advanced two-input logic operations due to the multi-wavelength emission. Furthermore, these compounds can process information in a logically reversible way (Feynman gate).
    Keywords: Transformation ; Mimicry ; Fluorescence ; Eye ; Information Processing ; Probes ; Fluorescent Indicators ; Ph Effects ; Scaffolds ; Aromatics ; Color ; Biosensors;
    ISSN: 1474-905X
    E-ISSN: 1474-9092
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  • 4
    Language: English
    In: Advanced Drug Delivery Reviews, Oct 31, 2006, Vol.58(9-10), p.878(19)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.addr.2006.07.004 Byline: Katja Schenke-Layland (a), Iris Riemann (b), Odile Damour (c), Ulrich A. Stock (d)(e), Karsten Konig (b) Keywords: Multiphoton imaging; Non-invasive microscopy; Second harmonic generation; Cardiovascular tissue engineering; Heart valve; Skin equivalent; ECM; Collagen; Elastin Abstract: Near-infrared multiphoton microscopes and in vivo femtosecond laser tomographs are novel powerful diagnostic tools for intra-tissue drug screening and high-resolution structural imaging applicable to many areas of biomedical research. Deep tissue cells and extracellular matrix (ECM) compartments can be visualized in situ with submicron resolution without the need for tissue processing. In particular, the reduced fluorescent coenzyme NAD(P)H, flavoproteins, keratin, melanin, and elastin are detected by two-photon excited autofluorescence, whereas myosin, tubulin and the ECM protein collagen can be imaged additionally by second harmonic generation (SHG). Therefore, these innovative multiphoton technologies have been used to probe architecture and state of a variety of native tissues, as well as of tissue-engineered constructs, giving insights on the interaction between scaffolds and seeded cells in vitro prior implantation. Moreover, non-invasive 4-D multiphoton tomographs are employed in clinical studies to examine the diffusion behavior, the intra-tissue accumulation of topically applied cosmetic and pharmaceutical components, and their interaction with skin cells. Author Affiliation: (a) Cardiovascular Research Laboratory, University of California Los Angeles (UCLA), 675 Charles E. Young Drive South, MRL 3-579, Los Angeles, CA 90095-1760, USA (b) Fraunhofer Institute of Biomedical Technology (IBMT), 66386 St. Ingbert, Germany (c) Laboratoire des Substituts Cutanes (LSC), HA[acute accent]pital Edouard Herriot- Pavillon I, 69437 Lyon Cedex 03, France (d) Department of Medical Physics and Biophysics, Humboldt University, University Hospital Charite, 10098 Berlin, Germany (e) Department of Cardiac Surgery, Heart Center Brandenburg, 16321Bernau/Berlin, Germany Article History: Received 30 January 2006; Accepted 13 July 2006 Article Note: (footnote) [star] This review is part of the Advanced Drug Delivery Reviews theme issue on "Multi-Photon Imaging: Diseases and Therapies", Vol., 58/7, 2006.
    Keywords: Tubulin ; Lasers ; Coenzymes ; Melanin ; Fluorescence ; Optical Instruments ; Myosin ; Keratin ; Drug Delivery Systems ; Proteins
    ISSN: 0169-409X
    Source: Cengage Learning, Inc.
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  • 5
    Language: English
    In: Lasers in surgery and medicine, November 2012, Vol.44(9), pp.719-25
    Description: Aim of the current study was to localize and differentiate between tumor (glioma) and healthy tissue in rat brains on a cellular level. Near-infrared multiphoton microscopy takes advantage of the simultaneous absorption of two or more photons to analyze various materials such as cell and tissue components via the observation of endogenous fluorophores such as NAD(P)H, FAD, porphyrins, melanin, elastin, and collagen, with a very high resolution, without inducing the problems of photo-bleaching on out-of-focus areas. In vitro and in vivo studies on healthy rat brains as well as C6 glioma cell line allografts have been performed. Near-infrared laser pulses (λ = 690-1060 nm, τ ~140 fs) generated by an ultrafast Ti:Sapphire tunable laser system (Chameleon, Coherent GmbH, Santa Clara, CA) were coupled into a laser scanning microscope (LSM 510 META, Carl Zeiss, Germany) to observe high quality images. Several image acquisitions have been performed by varying the zoom scale of the multiphoton microscope, image acquisition time and the wavelength (765, 840 nm) to detect various tissue components. With a penetration depth of ~200 µm in vitro and about 30-60 µm in vivo into the brain tissue it was possible to differentiate between tumor and healthy brain tissue even through thin layers of blood. Near-infrared multiphoton microscopy allows the observation and possibly differentiation between tumor (glioma) and healthy tissue in rat brains on a cellular level. Our findings suggest that a further miniaturization of this technology might be very useful for scientific and clinical applications in neurosurgery.
    Keywords: Brain Neoplasms -- Diagnosis ; Glioma -- Diagnosis ; Microscopy, Fluorescence, Multiphoton -- Methods
    ISSN: 01968092
    E-ISSN: 1096-9101
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  • 6
    Language: English
    In: Photochemical & photobiological sciences : Official journal of the European Photochemistry Association and the European Society for Photobiology, 30 November 2016, Vol.15(12), pp.1544-1557
    Description: Photoacids on the basis of pyrenol have been extensively studied in the past 60 years. As their photophysical properties strongly depend on the substituents at the aromatic scaffold, we introduced two reactive moieties with different electronic coefficients thus creating multi-wavelength fluorescent probes. One probe is capable of monitoring two orthogonal transformations by four fluorescence colors, distinguishable even by the naked human eye. Another derivative can act as a three-color sensor for a wide range of different pH values. Both the presented compounds allow for mimicking of fundamental and advanced two-input logic operations due to the multi-wavelength emission. Furthermore, these compounds can process information in a logically reversible way (Feynman gate).
    Keywords: Chemistry Techniques, Analytical -- Methods ; Fluorescent Dyes -- Chemistry
    E-ISSN: 1474-9092
    Source: MEDLINE/PubMed (U.S. National Library of Medicine)
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  • 7
    Language: English
    In: Lasers in Surgery and Medicine, November 2012, Vol.44(9), pp.719-725
    Keywords: Multiphoton ; Brain Tumor ; In Vivo Laser Diagnostic ; Autofluorescence
    ISSN: 0196-8092
    E-ISSN: 1096-9101
    Source: John Wiley & Sons, Inc.
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  • 8
    Language: English
    In: Cell and Tissue Banking: International Journal for Banking, Engineering and Transplantation of Cells and Tissues, Dec, 2012, Vol.13(4), p.663(9)
    Description: Byline: Kelvin G. M. Brockbank (1,2,3), Katja Schenke-Layland (4,5,6), Elizabeth D. Greene (1), Zhenzhen Chen (1), Olaf Fritze (7), Martina Schleicher (7), Renate Kaulitz (8), Iris Riemann (9), Falko Fend (10), Johannes M. Albes (11), Ulrich A. Stock (7), Milan Lisy (7) Keywords: Cryopreservation; Heart valve; Allogeneic; Transplantation Abstract: The purpose of this study was evaluation of an ice-free cryopreservation method for heart valves in an allogeneic juvenile pulmonary sheep implant model and comparison with traditionally frozen cryopreserved valves. Hearts of 15 crossbred Whiteface sheep were procured in Minnesota. The valves were processed in South Carolina and the pulmonary valves implanted orthotopically in 12 black faced Heidschnucke sheep in Germany. The ice-free cryopreserved valves were cryopreserved in 12.6 mol/l cryoprotectant (4.65, 4.65, and 3.31 mol/l of dimethylsulfoxide, formamide and 1,2-propanediol) and stored at -80degC. Frozen valves were cryopreserved by controlled slow rate freezing in 1.4 mol/l dimethylsulfoxide and stored in vapor-phase nitrogen. Aortic valve tissues were used to evaluate the impact of preservation without implantation. Multiphoton microscopy revealed reduced but not significantly damaged extracellular matrix before implantation in frozen valves compared with ice-free tissues. Viability assessment revealed significantly less metabolic activity in the ice-free valve leaflets and artery samples compared with frozen tissues (P 〈 0.05). After 3 and 6 months in vivo valve function was determined by two-dimensional echo-Doppler and at 7 months the valves were explanted. Severe valvular stenosis with right heart failure was observed in recipients of frozen valves, the echo data revealed increased velocity and pressure gradients compared to ice-free valve recipients (P = 0.0403, P = 0.0591). Histo-pathology showed significantly thickened leaflets in the frozen valves (P 〈 0.05) and infiltrating CD3+ T-cells (P 〈 0.05) compared with ice-free valve leaflets. Multiphoton microscopy at explant revealed reduced inducible autofluorescence and extracellular matrix damage in the frozen explants and well preserved structures in the ice-free explant leaflets. In conclusion, ice-free cryopreservation of heart valve transplants at -80degC avoids ice formation, tissue-glass cracking and preserves extracellular matrix integrity resulting in minimal inflammation and improved hemodynamics in allogeneic juvenile sheep. Author Affiliation: (1) Cell and Tissue Systems, Inc., 2231 Technical Parkway, Suite A, North Charleston, SC, 29406, USA (2) Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, USA (3) Deparment of Regenerative Medicine and Cell Biology, Medical University of South Carolina, Charleston, SC, USA (4) Cardiovascular Research Laboratories, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA (5) Deparment of Cell and Tissue Engineering, Fraunhofer Institute for Interfacial Engineering and Biotechnology (IGB), Stuttgart, Germany (6) Inter-University Centre for Medical Technology Stuttgart-Tubingen (IZST), Eberhard Karls University Tubingen, Tubingen, Germany (7) Deparment of Thoracic, Cardiac and Vascular Surgery, University Hospital Tuebingen, Tuebingen, Germany (8) Deparment of Pediatric Cardiology, University Hospital Tuebingen, Tuebingen, Germany (9) Fraunhofer Institute of Biomedical Technology, St. Ingbert, Germany (10) Deparment of General Pathologie and Pathological Anatomy, University Hospital Tuebingen, Tuebingen, Germany (11) Deparment of Cardiac Surgery, Heart Centre Brandenburg, Bernau, Germany Article History: Registration Date: 19/12/2011 Received Date: 01/06/2011 Accepted Date: 19/12/2011 Online Date: 03/01/2012 Article note: This paper received an Outstanding Abstract Award and was presented orally at the 2009 American Association of Tissue Banks Annual Meeting in Las Vegas, Nevada.
    Keywords: Tissue Engineering -- Analysis ; T Cells -- Analysis ; Propylene Glycol -- Analysis ; Pamphlets -- Analysis ; Fluorescence -- Analysis ; Transplantation -- Analysis
    ISSN: 1389-9333
    Source: Cengage Learning, Inc.
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  • 9
    Language: English
    In: Biomaterials, 2010, Vol.31(20), pp.5306-5311
    Description: Transplantation of cryopreserved heart valves (allografts) is limited by immune responses, inflammation, subsequent structural deterioration and an expensive infrastructure. In previous studies we demonstrated that conventional frozen cryopreservation (FC) is accompanied by serious alterations of extracellular matrix (ECM) structures. As the main culprit of the observed damages ice crystal formation was identified. Objective of this study was the application principles of cryoprotection as observed in nature, occurring in animals or plants, for ice-free cryopreservation (IFC) of heart valves. Using IFC, valves were processed and stored above the glass transition temperature of the cryoprotectant formulation (−124 °C) at −80 °C to avoid any ice formation, tissue-glass cracking and preserving ECM. After implantation in the orthotopic pulmonary position in sheep, we demonstrate that IFC resulted in cell free matrices, while maintaining crucial ECM-components such as elastin and collagen, translating into superior hemodynamics. In contrast, we reveal that FC valves showed ECM damage that was not restored , and T-cell inflammation of the stroma with significant leaflet thickening. Compared to currently applied FC practice IFC also reduced infrastructural needs for preservation, storage and shipping. These results have important implications for clinical valve transplantation including the promise of better long-term function and lower costs.
    Keywords: Allograft Heart Valves ; Transplantation ; Cryopreservation ; Ice-Free ; Medicine ; Engineering
    ISSN: 0142-9612
    E-ISSN: 1878-5905
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  • 10
    Language: English
    In: European Journal of Opthalmology, May 2011, Vol.21(3), pp.237-242
    Description: Purpose TO investigate femtosecond laser-assisted nanosurgery of the anterior lens capsule in a prospective in vitro study. Methods Eight anterior lens capsules obtained during conventional phaco surgery were irradiated with a nonamplified 80-MHz near-infrared 800-nm titanium:sapphire femtosecond laser. Line intratissue laser cuts were examined by femtosecond multiphoton laser scanning microscopy (MLSM) and transmission electron microscopy (TEM). Results Speed parameters of the laser beam, laser ablation time, and pulse power determined the width of the lesions, which ranged from 220±40 nm (SD) to 1.49±0.15 μm. Both MLSM and TEM revealed minimal collateral alterations in the tissue surrounding the laser cuts. Conclusions Nonamplified near-infrared femtosecond laser pulses at low pulse energies may be a promising strategy for precise noncontact nanosurgery of the anterior lens capsule with minimal collateral damage to surrounding tissue. High-resolution MLSM offers 3-dimensional, noninvasive, non-destructive imaging at submicrometer resolution within seconds before and after ablation.
    Keywords: Anterior Lens Capsule ; Cataract Surgery ; Continuous Curvilinear Capsulorhexis ; Femtosecond Laser Ablation ; Multiphoton Laser Scanning Microscopy ; Medicine
    ISSN: 1120-6721
    E-ISSN: 1724-6016
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