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109 results on '"Rahmanzadeh, Ramtin"'

1. Dynamic contrast in scanning microscopic OCT

Author

Münter, Michael, Endt, Malte vom, Pieper, Mario, Casper, Malte, Ahrens, Martin, Kohlfaerber, Tabea, Rahmanzadeh, Ramtin, König, Peter, Hüttmann, Gereon, and Schulz-Hildebrandt, Hinnerk

Subjects
Physics - Medical Physics, Electrical Engineering and Systems Science - Image and Video Processing
Abstract

While optical coherence tomography (OCT) provides a resolution down to 1 micrometer it has difficulties to visualize cellular structures due to a lack of scattering contrast. By evaluating signal fluctuations, a significant contrast enhancement was demonstrated using time-domain full-field OCT (FF-OCT), which makes cellular and subcellular structures visible. The putative cause of the dynamic OCT signal is ATP-dependent motion of cellular structures in a sub-micrometer range, which provides histology-like contrast. Here we demonstrate dynamic contrast with a scanning frequency-domain OCT (FD-OCT). Given the inherent sectional imaging geometry, scanning FD-OCT provides depth-resolved images across tissue layers, a perspective known from histopathology, much faster and more efficiently than FF-OCT. Both, shorter acquisition times and tomographic depth-sectioning reduce the sensitivity of dynamic contrast for bulk tissue motion artifacts and simplify their correction in post-processing. The implementation of dynamic contrast makes microscopic FD-OCT a promising tool for histological analysis of unstained tissues., Comment: 7 pages, 3 figures, 1 Video available on request

Published
2020
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3. Important factors for cell-membrane permeabilization by gold nanoparticles activated by nanosecond-laser irradiation

Author

Yao, Cuiping, Rudnitzki, Florian, Huettmann, Gereon, Zhang, Zhenxi, and Rahmanzadeh, Ramtin

Subjects
Quantitative Biology - Biomolecules, Physics - Biological Physics, Quantitative Biology - Tissues and Organs
Abstract

Purpose: Pulsed-laser irradiation of light-absorbing gold nanoparticles (AuNPs) attached to cells transiently increases cell membrane permeability for targeted molecule delivery. Here, we targeted EGFR on the ovarian carcinoma cell line OVCAR-3 with AuNPs. In order to optimize membrane permeability and to demonstrate molecule delivery into adherent OVCAR-3 cells, we systematically investigated different experimental conditions. Materials and methods: AuNPs (30 nm) were functionalized by conjugation of the antibody cetuximab against EGFR. Selective binding of the particles was demonstrated by silver staining, multiphoton imaging, and fluorescence-lifetime imaging. After laser irradiation, membrane permeability of OVCAR-3 cells was studied under different conditions of AuNP concentration, cell-incubation medium, and cell - AuNP incubation time. Membrane permeability and cell viability were evaluated by flow cytometry, measuring propidium iodide and fluorescein isothiocyanate - dextran uptake. Results: Adherently growing OVCAR-3 cells can be effectively targeted with EGFR-AuNP. Laser irradiation led to successful permeabilization, and 150 kDa dextran was successfully delivered into cells with about 70% efficiency. Conclusion: Antibody-targeted and laser-irradiated AuNPs can be used to deliver molecules into adherent cells. Efficacy depends not only on laser parameters but also on AuNP:cell ratio, cell-incubation medium, and cell - AuNP incubation time.

Published
2018
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21. Dynamic contrast in scanning microscopic OCT

Author

Münter, Michael, primary, vom Endt, Malte, additional, Pieper, Mario, additional, Casper, Malte, additional, Ahrens, Martin, additional, Kohlfaerber, Tabea, additional, Rahmanzadeh, Ramtin, additional, König, Peter, additional, Hüttmann, Gereon, additional, and Schulz-Hildebrandt, Hinnerk, additional

Published
2020
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26. Investigation of cell dynamics in 3D cell spheroids and cell interaction with 3D printed scaffolds by mOCT

Author

Kohlfaerber, Tabea, Ding, Shujun, Rahmanzadeh, Ramtin, Jüngst, Thomas, Groll, Jürgen, Schulz-Hildebrandt, Hinnerk, and Hüttmann, Gereon

Abstract

Optical coherence tomography is a non-invasive and label-free imaging modality based on the detection of backscattered light in samples. As microscopic OCT (mOCT) combines high axial and lateral resolution, an investigation of biological and printed samples at subcellular level is feasible. The additional excellent depth resolution enables mOCT to be a suitable quality control of 3D printed samples. The use of speckle variance adds information about cell viability. Here we present the feasibility of investigating cell viability within a cell spheroid and monitoring the cell interaction with bioprinted scaffolds using mOCT., Transactions on Additive Manufacturing Meets Medicine, Vol 1 (2019): Trans. AMMM

Published
2019
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34. Important factors for cell-membrane permeabilization by gold nanoparticles activated by nanosecond-laser irradiation

Author

Yao,Cuiping, Rudnitzki,Florian, Hüttmann,Gereon, Zhang,Zhenxi, Rahmanzadeh,Ramtin, Yao,Cuiping, Rudnitzki,Florian, Hüttmann,Gereon, Zhang,Zhenxi, and Rahmanzadeh,Ramtin

Abstract

Cuiping Yao,1,2,* Florian Rudnitzki,2,* Gereon Hüttmann,2,3 Zhenxi Zhang,1 Ramtin Rahmanzadeh2 1Key Laboratory of Biomedical Information Engineering of Education Ministry, Institute of Biomedical Analytical Technology and Instrumentation, School of Life Science and Technology, Xi’an Jiaotong University, Xi’an, China; 2Institute of Biomedical Optics, University of Lübeck, Lübeck, 3Airway Research Center North (ARCN), Member of the German Center for Lung Research (DZL), Kiel, Germany *These authors contributed equally to this work Purpose: Pulsed-laser irradiation of light-absorbing gold nanoparticles (AuNPs) attached to cells transiently increases cell membrane permeability for targeted molecule delivery. Here, we targeted EGFR on the ovarian carcinoma cell line OVCAR-3 with AuNPs. In order to optimize membrane permeability and to demonstrate molecule delivery into adherent OVCAR-3 cells, we systematically investigated different experimental conditions. Materials and methods: AuNPs (30 nm) were functionalized by conjugation of the antibody cetuximab against EGFR. Selective binding of the particles was demonstrated by silver staining, multiphoton imaging, and fluorescence-lifetime imaging. After laser irradiation, membrane permeability of OVCAR-3 cells was studied under different conditions of AuNP concentration, cell-incubation medium, and cell–AuNP incubation time. Membrane permeability and cell viability were evaluated by flow cytometry, measuring propidium iodide and fluorescein isothiocyanate–dextran uptake. Results: Adherently growing OVCAR-3 cells can be effectively targeted with EGFR-AuNP. Laser irradiation led to successful permeabilization, and 150 kDa dextran was successfully delivered into cells with about 70% efficiency. Conclusion: Antibody-targeted and laser-irradiated AuNPs can be used to deliver molecules into adherent cells. Efficacy depends not only on laser parameters but also on Au

Published
2017

43. Light-Induced Permeabilization of Liposomes with a new Porphyrin and its Chlorin and Bacteriochlorin.

Author

ENZIAN, Paula, KIRCHERT, Elisabeth, KLEINEBERG, Nina, SCHELL, Christian, and RAHMANZADEH, Ramtin

Abstract

The intracellular delivery of therapeutic agents is a central challenge in the treatment of different diseases. Light sensitive liposomes can release their cargo with high temporal and spatial precision. The light sensitivity of the liposomes is based on incorporated photosensitizers. Since light penetration into human tissue is higher at wavelengths greater than 650 nm, we synthesized the chlorin and bacteriochlorin derivative from the new photosensitizer 5,10-Di-(4-hydroxyphenyl)-15,20-diphenyl-porphyrin. Both, chlorin and bacteriochlorin showed a higher absorption peak at 650 nm than the porphyrin. Interestingly, the bacteriochlorin showed a stable additional absorption peak at 740 nm. To investigate the potential of the derivates for light-induced release from liposomes we incorporated them into liposomes. Liposomes with the porphyrin, the chlorin and bacteriochlorin released their cargo effectively after light irradiation. Liposomes with the bacteriochlorin showed release also after irradiation at 740 nm. Additionally, we investigated the potential of the bacteriochlorin as a sensitizer for PDT. The bacteriochlorin showed good cell killing results when irradiated at 740 nm compared to the photosensitizer BPD irradiated at 690 nm. We believe that the synthesized porphyrin 5,10-DiOH and its chlorin and bacteriochlorin derivatives are interesting candidates for photodynamic applications and need further investigation. [ABSTRACT FROM AUTHOR]

Published
2023
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44. Indocyanine green as effective antibody conjugate for intracellular molecular targeted photodynamic therapy.

Author

Sijia Wang, Hüttmann, Gereon, Rudnitzki, Florian, Diddens-Tschoeke, Heyke, Zhenxi Zhang, and Rahmanzadeh, Ramtin

Subjects
INDOCYANINE green, PHOTODYNAMIC therapy, IMMUNOGLOBULINS, BACTERIAL conjugation, INTRACELLULAR membranes, ANGIOGRAPHY, CARDIAC output, LIVER function tests, THERAPEUTICS
Abstract

The fluorescent dye indocyanine green (ICG) is clinically approved and has been applied for ophthalmic and intraoperative angiography, measurement of cardiac output and liver function, or as contrast agent in cancer surgery. Though ICG is known for its photochemical effects, it has played a minor role so far in photodynamic therapy or techniques for targeted protein-inactivation. Here, we investigated ICG as an antibody-conjugate for the selective inactivation of the protein Ki-67 in the nucleus of cells. Conjugates of the Ki-67 antibody TuBB-9 with different amounts of ICG were synthesized and delivered into HeLa and OVCAR-5 cells through conjugation to the nuclear localization sequence. Endosomal escape of the macromolecular antibodies into the cytoplasm was optically triggered by photochemical internalization with the photosensitizer BPD. The second light irradiation at 690 nm inactivated Ki-67 and subsequently caused cell death. Here, we show that ICG as an antibody-conjugate can be an effective photosensitizing agent. Best effects were achieved with 1.8 ICG molecules per antibody. Conjugated to antibodies, the ICG absorption peaks vary proportionally with concentration. The absorption of ICG above 650 nm within the optical window of tissue opens the possibility of selective Ki-67 inactivation deep inside of tissues. [ABSTRACT FROM AUTHOR]

Published
2016
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