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Döge N, Hadam S, Volz P, Wolf A, Schönborn KH, Blume-Peytavi U, Alexiev U, Vogt A. Identification of polystyrene nanoparticle penetration across intact skin barrier as rare event at sites of focal particle aggregations. JOURNAL OF BIOPHOTONICS 2018; 11:e201700169. [PMID: 29178669 DOI: 10.1002/jbio.201700169] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 11/23/2017] [Indexed: 06/07/2023]
Abstract
The question whether nanoparticles can cross the skin barrier is highly debated. Even in intact skin rare events of deeper penetration have been reported, but technical limitations and possible artifacts require careful interpretation. In this study, horizontal scanning by 2-photon microscopy (2 PM) of full-thickness human skin samples placed in a lateral position yielded highly informative images for skin penetration studies of fluorescently tagged nanoparticles. Scanning of large fields of view allowed for detailed information on interfollicular and follicular penetration in tissue blocks without damaging the sample. Images in histomorphological correlation showed that 2P-excited fluorescence signals of fluorescently tagged 20 and 200 nm polystyrene nanoparticles preferentially accumulated in the stratum corneum (SC) and in the upper part of vellus hair follicles (HFs). Rare events of deeper penetration in the SC and in the infundibulum of vellus HFs were observed at sites of high focal particle aggregations. Wide-field 2 PM allows for imaging of nanoparticle penetration in large tissue blocks, whereas total internal reflection microscopy (TIRFM) enables selective detection of individual nanoparticles as well as clusters of nanoparticles in the SC and within the epidermal layer directly beneath the SC, thus confirming barrier crossing with high sensitivity.
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Affiliation(s)
- Nadine Döge
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Clinical Research Center for Hair and Skin Science, Department of Dermatology and Allergy, Berlin, Germany
- Institute for Pharmacy, Pharmacology and Toxicology, Freie Universität Berlin, Berlin, Germany
| | - Sabrina Hadam
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Clinical Research Center for Hair and Skin Science, Department of Dermatology and Allergy, Berlin, Germany
| | - Pierre Volz
- Department of Physics, Freie Universität Berlin, Berlin, Germany
| | - Alexander Wolf
- Department of Physics, Freie Universität Berlin, Berlin, Germany
| | | | - Ulrike Blume-Peytavi
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Clinical Research Center for Hair and Skin Science, Department of Dermatology and Allergy, Berlin, Germany
| | - Ulrike Alexiev
- Department of Physics, Freie Universität Berlin, Berlin, Germany
| | - Annika Vogt
- Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Clinical Research Center for Hair and Skin Science, Department of Dermatology and Allergy, Berlin, Germany
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2
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Effect of drug solubility and lipid carrier on drug release from lipid nanoparticles for dermal delivery. Eur J Pharm Biopharm 2017; 110:39-46. [DOI: 10.1016/j.ejpb.2016.10.021] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 10/24/2016] [Accepted: 10/29/2016] [Indexed: 11/22/2022]
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3
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Boreham A, Volz P, Peters D, Keck CM, Alexiev U. Determination of nanostructures and drug distribution in lipid nanoparticles by single molecule microscopy. Eur J Pharm Biopharm 2017; 110:31-38. [DOI: 10.1016/j.ejpb.2016.10.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Revised: 10/27/2016] [Accepted: 10/28/2016] [Indexed: 01/11/2023]
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Tian H, Fürstenberg A, Huber T. Labeling and Single-Molecule Methods To Monitor G Protein-Coupled Receptor Dynamics. Chem Rev 2016; 117:186-245. [DOI: 10.1021/acs.chemrev.6b00084] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- He Tian
- Laboratory of Chemical Biology
and Signal Transduction, The Rockefeller University, 1230 York
Avenue, New York, New York 10065, United States
| | - Alexandre Fürstenberg
- Laboratory of Chemical Biology
and Signal Transduction, The Rockefeller University, 1230 York
Avenue, New York, New York 10065, United States
| | - Thomas Huber
- Laboratory of Chemical Biology
and Signal Transduction, The Rockefeller University, 1230 York
Avenue, New York, New York 10065, United States
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Application of single molecule fluorescence microscopy to characterize the penetration of a large amphiphilic molecule in the stratum corneum of human skin. Int J Mol Sci 2015; 16:6960-77. [PMID: 25826528 PMCID: PMC4424999 DOI: 10.3390/ijms16046960] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 03/12/2015] [Accepted: 03/13/2015] [Indexed: 11/16/2022] Open
Abstract
We report here on the application of laser-based single molecule total internal reflection fluorescence microscopy (TIRFM) to study the penetration of molecules through the skin. Penetration of topically applied drug molecules is often observed to be limited by the size of the respective drug. However, the molecular mechanisms which govern the penetration of molecules through the outermost layer of the skin are still largely unknown. As a model compound we have chosen a larger amphiphilic molecule (fluorescent dye ATTO-Oxa12) with a molecular weight >700 Da that was applied to excised human skin. ATTO-Oxa12 penetrated through the stratum corneum (SC) into the viable epidermis as revealed by TIRFM of cryosections. Single particle tracking of ATTO-Oxa12 within SC sheets obtained by tape stripping allowed us to gain information on the localization as well as the lateral diffusion dynamics of these molecules. ATTO-Oxa12 appeared to be highly confined in the SC lipid region between (intercellular space) or close to the envelope of the corneocytes. Three main distinct confinement sizes of 52 ± 6, 118 ± 4, and 205 ± 5 nm were determined. We conclude that for this amphiphilic model compound several pathways through the skin exist.
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Alexiev U, Farrens DL. Fluorescence spectroscopy of rhodopsins: insights and approaches. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2013; 1837:694-709. [PMID: 24183695 DOI: 10.1016/j.bbabio.2013.10.008] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 10/11/2013] [Accepted: 10/16/2013] [Indexed: 01/30/2023]
Abstract
Fluorescence spectroscopy has become an established tool at the interface of biology, chemistry and physics because of its exquisite sensitivity and recent technical advancements. However, rhodopsin proteins present the fluorescence spectroscopist with a unique set of challenges and opportunities due to the presence of the light-sensitive retinal chromophore. This review briefly summarizes some approaches that have successfully met these challenges and the novel insights they have yielded about rhodopsin structure and function. We start with a brief overview of fluorescence fundamentals and experimental methodologies, followed by more specific discussions of technical challenges rhodopsin proteins present to fluorescence studies. Finally, we end by discussing some of the unique insights that have been gained specifically about visual rhodopsin and its interactions with affiliate proteins through the use of fluorescence spectroscopy. This article is part of a Special Issue entitled: Retinal Proteins - You can teach an old dog new tricks.
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Affiliation(s)
- Ulrike Alexiev
- Physics Department, Freie Universität Berlin, Berlin, Germany.
| | - David L Farrens
- Departments of Biochemistry and Molecular Biology, Oregon Health Sciences University, USA
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Conformational dynamics of helix 8 in the GPCR rhodopsin controls arrestin activation in the desensitization process. Proc Natl Acad Sci U S A 2011; 108:18690-5. [PMID: 22039220 DOI: 10.1073/pnas.1015461108] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Arrestins are regulatory molecules for G-protein coupled receptor function. In visual rhodopsin, selective binding of arrestin to the cytoplasmic side of light-activated, phosphorylated rhodopsin (P-Rh*) terminates signaling via the G-protein transducin. While the "phosphate-sensor" of arrestin for the recognition of receptor-attached phosphates is identified, the molecular mechanism of arrestin binding and the involvement of receptor conformations in this process are still largely hypothetic. Here we used fluorescence pump-probe and time-resolved fluorescence depolarization measurements to investigate the kinetics of arrestin conformational changes and the corresponding nanosecond dynamical changes at the receptor surface. We show that at least two sequential conformational changes of arrestin occur upon interaction with P-Rh*, thus providing a kinetic proof for the suggested multistep nature of arrestin binding. At the cytoplasmic surface of P-Rh*, the structural dynamics of the amphipathic helix 8 (H8), connecting transmembrane helix 7 and the phosphorylated C-terminal tail, depends on the arrestin interaction state. We find that a high mobility of H8 is required in the low-affinity (prebinding) but not in the high-affinity binding state. High-affinity arrestin binding is inhibited when a bulky, inflexible group is bound to H8, indicating close interaction. We further show that this close steric interaction of H8 with arrestin is mandatory for the transition from prebinding to high-affinity binding; i.e., for arrestin activation. This finding implies a regulatory role for H8 in activation of visual arrestin, which shows high selectivity to P-Rh* in contrast to the broad receptor specificity displayed by the two nonvisual arrestins.
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Boreham A, Kim TY, Spahn V, Stein C, Mundhenk L, Gruber AD, Haag R, Welker P, Licha K, Alexiev U. Exploiting Fluorescence Lifetime Plasticity in FLIM: Target Molecule Localization in Cells and Tissues. ACS Med Chem Lett 2011; 2:724-8. [PMID: 24900259 DOI: 10.1021/ml200092m] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Accepted: 08/09/2011] [Indexed: 11/30/2022] Open
Abstract
The mechanisms of drug-receptor interactions and the controlled delivery of drugs via biodegradable and biocompatible nanoparticulate carriers are active research fields in nanomedicine. Many clinically used drugs target G-protein coupled receptors (GPCRs) due to the fact that signaling via GPCRs is crucial in physiological and pathological processes and thus central for the function of biological systems. In this letter, a fast and reliable ratiometric fluorescence lifetime imaging microscopy (rmFLIM) approach is described to analyze the distribution of protein-ligand complexes in the cellular context. Binding of the fluorescently labeled antagonist naloxone to the G-protein coupled μ-opioid receptor is used as an example. To show the broad applicability of the rmFLIM method, we extended this approach to investigate the distribution of polymer-based nanocarriers in histological liver sections.
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Affiliation(s)
- A. Boreham
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
| | - T.-Y. Kim
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
| | - V. Spahn
- Klinik für Anästhesiologie, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203 Berlin, Germany
| | - C. Stein
- Klinik für Anästhesiologie, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12203 Berlin, Germany
| | - L. Mundhenk
- Institut für Tierpathologie, Freie Universität Berlin, Robert-von-Ostertag-Strasse 15, 14163 Berlin, Germany
| | - A. D. Gruber
- Institut für Tierpathologie, Freie Universität Berlin, Robert-von-Ostertag-Strasse 15, 14163 Berlin, Germany
| | - R. Haag
- Institut für Chemie und Biochemie, Freie Universität Berlin, Takustrasse 3, 14195 Berlin, Germany
| | - P. Welker
- mivenion GmbH, Robert-Koch-Platz 4, 10115 Berlin, Germany
| | - K. Licha
- mivenion GmbH, Robert-Koch-Platz 4, 10115 Berlin, Germany
| | - U. Alexiev
- Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
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Kim TY, Schlieter T, Haase S, Alexiev U. Activation and molecular recognition of the GPCR rhodopsin--insights from time-resolved fluorescence depolarisation and single molecule experiments. Eur J Cell Biol 2011; 91:300-10. [PMID: 21803442 DOI: 10.1016/j.ejcb.2011.03.009] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Revised: 03/29/2011] [Accepted: 03/29/2011] [Indexed: 10/18/2022] Open
Abstract
The cytoplasmic surface of the G-protein coupled receptor (GPCR) rhodopsin is a key element in membrane receptor activation, molecular recognition by signalling molecules, and receptor deactivation. Understanding of the coupling between conformational changes in the intramembrane domain and the membrane-exposed surface of the photoreceptor rhodopsin is crucial for the elucidation of the molecular mechanism in GPCR activation. As little is known about protein dynamics, particularly the conformational dynamics of the cytoplasmic surface elements on the nanoseconds timescale, we utilised time-resolved fluorescence anisotropy experiments and site-directed fluorescence labelling to provide information on both, conformational space and motion. We summarise our recent advances in understanding rhodopsin dynamics and function using time-resolved fluorescence depolarisation and single molecule fluorescence experiments, with particular focus on the amphipathic helix 8, lying parallel to the cytoplasmic membrane surface and connecting transmembrane helix 7 with the long C-terminal tail.
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Affiliation(s)
- Tai-Yang Kim
- Physics Department, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany
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Dutta A, Kim TY, Moeller M, Wu J, Alexiev U, Klein-Seetharaman J. Characterization of membrane protein non-native states. 2. The SDS-unfolded states of rhodopsin. Biochemistry 2010; 49:6329-40. [PMID: 20575562 DOI: 10.1021/bi100339x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Little is known about the molecular nature of residual structure in unfolded states of membrane proteins. A screen of chemical denaturants to maximally unfold the mammalian membrane protein and prototypic G protein coupled receptor rhodopsin, without interference from aggregation, described in an accompanying paper (DOI 10.1021/bi100338e ), identified sodium dodecyl sulfate (SDS), alone or in combination with other chemicals, as the most suitable denaturant. Here, we initiate the biophysical characterization of SDS-denatured states of rhodopsin. Using absorption, steady-state and time-resolved fluorescence spectroscopy, dynamic light scattering, and cysteine accessibility studies, tertiary structure of denatured states was characterized. In agreement with the pattern of secondary structure changes detected by circular dichroism described in the accompanying paper (DOI 10.1021/bi100338e ), tertiary structure changes are distinct over four SDS concentration ranges based on the expected predominant micellar structures. Dodecyl maltoside (DM)/SDS mixed micelle spheres (0.05-0.3% SDS) turn into SDS spheres (0.3-3% SDS) that gradually (3-15% SDS) become cylindrical (above 15% SDS). Denatured states in SDS spheres and cylinders show a relatively greater burial of cysteine and tryptophan residues and are more compact as compared to the states observed in mixed micellar structures. Protein structural changes at the membrane/water interface region are most prominent at very low SDS concentrations but reach transient stability in the compact conformations in SDS spheres. This is the first experimental evidence for the formation of a compact unfolding intermediate state with flexible surface elements in a membrane protein.
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Affiliation(s)
- Arpana Dutta
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA
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