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Lammers T, Mertens ME, Schuster P, Rahimi K, Shi Y, Schulz V, Kuehne AJC, Jockenhoevel S, Kiessling F. Fluorinated polyurethane scaffolds for 19F magnetic resonance imaging. Chem Mater 2017; 29:2669-2671. [PMID: 28413258 PMCID: PMC5390858 DOI: 10.1021/acs.chemmater.6b04649] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Polymers are increasingly employed in implant materials. To reduce the incidence of complications, which in the case of vascular grafts include incorrect placement and restenosis, materials are needed which allow for image-guided implantation, as well as for accurate and efficient postoperative implant imaging. We here describe amorphous fluorinated polymers based on thermoplastic polyurethane (19F-TPU), and show that are useful starting materials for developing tissue-engineered vascular grafts which can be detected using 19F MRI.
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Affiliation(s)
- Twan Lammers
- Institute for Experimental Molecular Imaging, RWTH Aachen University Clinic, Pauwelsstrasse 30, 52074 Aachen, Germany
- Department of Targeted Therapeutics, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands
| | - Marianne E. Mertens
- Institute for Experimental Molecular Imaging, RWTH Aachen University Clinic, Pauwelsstrasse 30, 52074 Aachen, Germany
| | - Philipp Schuster
- Department of Biohybrid and Medical Textiles, AME-Helmholtz Institute for Biomedical Engineering and ITA-Institute for Textile Technology, RWTH Aachen University, Pauwelsstrasse 20, 52074 Aachen, Germany
| | - Khosrow Rahimi
- DWI-Leibniz Institute for Interactive Materials, Forckenbeckstrasse 50, 52074 Aachen, Germany
| | - Yang Shi
- Institute for Experimental Molecular Imaging, RWTH Aachen University Clinic, Pauwelsstrasse 30, 52074 Aachen, Germany
| | - Volkmar Schulz
- Institute for Experimental Molecular Imaging, RWTH Aachen University Clinic, Pauwelsstrasse 30, 52074 Aachen, Germany
| | - Alexander J. C. Kuehne
- DWI-Leibniz Institute for Interactive Materials, Forckenbeckstrasse 50, 52074 Aachen, Germany
| | - Stefan Jockenhoevel
- Department of Biohybrid and Medical Textiles, AME-Helmholtz Institute for Biomedical Engineering and ITA-Institute for Textile Technology, RWTH Aachen University, Pauwelsstrasse 20, 52074 Aachen, Germany
| | - Fabian Kiessling
- Institute for Experimental Molecular Imaging, RWTH Aachen University Clinic, Pauwelsstrasse 30, 52074 Aachen, Germany
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Frese J, Morgenroth A, Mertens ME, Koch S, Rongen L, Vogg ATJ, Zlatopolskiy BD, Neumaier B, Gesche VN, Lammers T, Schmitz-Rode T, Mela P, Jockenhoevel S, Mottaghy FM, Kiessling F. Nondestructive monitoring of tissue-engineered constructs. ACTA ACUST UNITED AC 2015; 59:165-75. [PMID: 24021591 DOI: 10.1515/bmt-2013-0029] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 08/13/2013] [Indexed: 11/15/2022]
Abstract
Abstract Tissue engineering as a multidisciplinary field enables the development of living substitutes to replace, maintain, or restore diseased tissue and organs. Since the term was introduced in medicine in 1987, tissue engineering strategies have experienced significant progress. However, up to now, only a few substitutes were able to overcome the gap from bench to bedside and have been successfully approved for clinical use. Substantial donor variability makes it difficult to predict the quality of tissue-engineered constructs. It is essential to collect sufficient data to ensure that poor or immature constructs are not implanted into patients. The fulfillment of certain quality requirements, such as mechanical and structural properties, is crucial for a successful implantation. There is a clear need for new nondestructive and real-time online monitoring and evaluation methods for tissue-engineered constructs, which are applicable on the biomaterial, tissue, cellular, and subcellular levels. This paper reviews current established nondestructive techniques for implant monitoring including biochemical methods and noninvasive imaging.
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Abstract
Nanoparticles are frequently suggested as diagnostic agents. However, except for iron oxide nanoparticles, diagnostic nanoparticles have been barely incorporated into clinical use so far. This is predominantly due to difficulties in achieving acceptable pharmacokinetic properties and reproducible particle uniformity as well as to concerns about toxicity, biodegradation, and elimination. Reasonable indications for the clinical utilization of nanoparticles should consider their biologic behavior. For example, many nanoparticles are taken up by macrophages and accumulate in macrophage-rich tissues. Thus, they can be used to provide contrast in liver, spleen, lymph nodes, and inflammatory lesions (eg, atherosclerotic plaques). Furthermore, cells can be efficiently labeled with nanoparticles, enabling the localization of implanted (stem) cells and tissue-engineered grafts as well as in vivo migration studies of cells. The potential of using nanoparticles for molecular imaging is compromised because their pharmacokinetic properties are difficult to control. Ideal targets for nanoparticles are localized on the endothelial luminal surface, whereas targeted nanoparticle delivery to extravascular structures is often limited and difficult to separate from an underlying enhanced permeability and retention (EPR) effect. The majority of clinically used nanoparticle-based drug delivery systems are based on the EPR effect, and, for their more personalized use, imaging markers can be incorporated to monitor biodistribution, target site accumulation, drug release, and treatment efficacy. In conclusion, although nanoparticles are not always the right choice for molecular imaging (because smaller or larger molecules might provide more specific information), there are other diagnostic and theranostic applications for which nanoparticles hold substantial clinical potential.
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Affiliation(s)
- Fabian Kiessling
- From the Department of Experimental Molecular Imaging, RWTH-Aachen University, Aachen, Germany (F.K., M.E.M., T.L.); and Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY (J.G.)
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Mertens ME, Koch S, Schuster P, Wehner J, Wu Z, Gremse F, Schulz V, Rongen L, Wolf F, Frese J, Gesché VN, van Zandvoort M, Mela P, Jockenhoevel S, Kiessling F, Lammers T. USPIO-labeled textile materials for non-invasive MR imaging of tissue-engineered vascular grafts. Biomaterials 2014; 39:155-63. [PMID: 25465443 DOI: 10.1016/j.biomaterials.2014.10.076] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 10/21/2014] [Accepted: 10/23/2014] [Indexed: 02/06/2023]
Abstract
Non-invasive imaging might assist in the clinical translation of tissue-engineered vascular grafts (TEVG). It can e.g. be used to facilitate the implantation of TEVG, to longitudinally monitor their localization and function, and to provide non-invasive and quantitative feedback on their remodeling and resorption. We here incorporated ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles into polyvinylidene fluoride (PVDF)-based textile fibers, and used them to prepare imageable tissue-engineered vascular grafts (iTEVG). The USPIO-labeled scaffold materials were molded with a mixture of fibrin, fibroblasts and smooth muscle cells, and then endothelialized in a bioreactor under physiological flow conditions. The resulting grafts could be sensitively detected using T1-, T2- and T2*-weighted MRI, both during bioreactor cultivation and upon surgical implantation into sheep, in which they were used as an arteriovenous shunt between the carotid artery and the jugular vein. In vivo, the iTEVG were shown to be biocompatible and functional. Post-mortem ex vivo analyses provided evidence for efficient endothelialization and for endogenous neo-vascularization within the biohybrid vessel wall. These findings show that labeling polymer-based textile materials with MR contrast agents is straightforward and safe, and they indicate that such theranostic tissue engineering approaches might be highly useful for improving the production, performance, personalization and translation of biohybrid vascular grafts.
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Affiliation(s)
- Marianne E Mertens
- Dept. of Experimental Molecular Imaging, University Clinic, RWTH Aachen University, Pauwelsstrasse 30, 52074 Aachen, Germany
| | - Sabine Koch
- Dept. of Tissue Engineering & Textile Implants, Applied Medical Engineering, Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstrasse 20, 52074 Aachen, Germany
| | - Philipp Schuster
- Institut für Textiltechnik, RWTH Aachen University, Otto-Blumenthal-Strasse 1, 52074 Aachen, Germany
| | - Jakob Wehner
- Dept. of Experimental Molecular Imaging, University Clinic, RWTH Aachen University, Pauwelsstrasse 30, 52074 Aachen, Germany
| | - Zhuojun Wu
- Dept. of Experimental Molecular Imaging, University Clinic, RWTH Aachen University, Pauwelsstrasse 30, 52074 Aachen, Germany; Institute for Molecular Cardiovascular Research, University Clinic, RWTH Aachen University, Pauwelsstrasse 30, 52074 Aachen, Germany
| | - Felix Gremse
- Dept. of Experimental Molecular Imaging, University Clinic, RWTH Aachen University, Pauwelsstrasse 30, 52074 Aachen, Germany
| | - Volkmar Schulz
- Dept. of Experimental Molecular Imaging, University Clinic, RWTH Aachen University, Pauwelsstrasse 30, 52074 Aachen, Germany
| | - Lisanne Rongen
- Dept. of Tissue Engineering & Textile Implants, Applied Medical Engineering, Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstrasse 20, 52074 Aachen, Germany
| | - Frederic Wolf
- Dept. of Tissue Engineering & Textile Implants, Applied Medical Engineering, Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstrasse 20, 52074 Aachen, Germany
| | - Julia Frese
- Dept. of Tissue Engineering & Textile Implants, Applied Medical Engineering, Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstrasse 20, 52074 Aachen, Germany
| | - Valentine N Gesché
- Institut für Textiltechnik, RWTH Aachen University, Otto-Blumenthal-Strasse 1, 52074 Aachen, Germany
| | - Marc van Zandvoort
- Institute for Molecular Cardiovascular Research, University Clinic, RWTH Aachen University, Pauwelsstrasse 30, 52074 Aachen, Germany
| | - Petra Mela
- Dept. of Tissue Engineering & Textile Implants, Applied Medical Engineering, Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstrasse 20, 52074 Aachen, Germany
| | - Stefan Jockenhoevel
- Dept. of Tissue Engineering & Textile Implants, Applied Medical Engineering, Helmholtz Institute for Biomedical Engineering, RWTH Aachen University, Pauwelsstrasse 20, 52074 Aachen, Germany; Institut für Textiltechnik, RWTH Aachen University, Otto-Blumenthal-Strasse 1, 52074 Aachen, Germany.
| | - Fabian Kiessling
- Dept. of Experimental Molecular Imaging, University Clinic, RWTH Aachen University, Pauwelsstrasse 30, 52074 Aachen, Germany.
| | - Twan Lammers
- Dept. of Experimental Molecular Imaging, University Clinic, RWTH Aachen University, Pauwelsstrasse 30, 52074 Aachen, Germany; Dept. of Controlled Drug Delivery, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands.
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Mertens ME, Frese J, Bölükbas DA, Hrdlicka L, Golombek S, Koch S, Mela P, Jockenhövel S, Kiessling F, Lammers T. FMN-coated fluorescent USPIO for cell labeling and non-invasive MR imaging in tissue engineering. Theranostics 2014; 4:1002-13. [PMID: 25157279 PMCID: PMC4142292 DOI: 10.7150/thno.8763] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 03/24/2014] [Indexed: 12/26/2022] Open
Abstract
Non-invasive magnetic resonance imaging (MRI) is gaining significant attention in the field of tissue engineering, since it can provide valuable information on in vitro production parameters and in vivo performance. It can e.g. be used to monitor the morphology, location and function of the regenerated tissue, the integrity, remodeling and resorption of the scaffold, and the fate of the implanted cells. Since cells are not visible using conventional MR techniques, ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles are routinely employed to label and monitor the cells embedded in tissue-engineered implants. We here set out to optimize cell labeling procedures with regard to labeling efficiency, biocompatibility and in vitro validation during bioreactor cultivation, using flavin mononucleotide (FMN)-coated fluorescent USPIO (FLUSPIO). Efficient FLUSPIO uptake is demonstrated in three different cell lines, applying relatively short incubation times and low labeling concentrations. FLUSPIO-labeled cells were successfully employed to visualize collagen scaffolds and tissue-engineered vascular grafts. Besides promoting safe and efficient cell uptake, an exquisite property of the non-polymeric FMN-coating is that it renders the USPIO fluorescent, providing a means for in vitro, in vivo and ex vivo validation via fluorescence microscopy and fluorescence reflectance imaging (FRI). FLUSPIO cell labeling is consequently considered to be a suitable tool for theranostic tissue engineering purposes.
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Duttenhoefer F, Mertens ME, Vizkelety J, Gremse F, Stadelmann VA, Sauerbier S. Magnetic resonance imaging in zirconia‐based dental implantology. Clin Oral Implants Res 2014; 26:1195-202. [DOI: 10.1111/clr.12430] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/03/2014] [Indexed: 11/30/2022]
Affiliation(s)
- Fabian Duttenhoefer
- Department of Oral and Craniomaxillofacial Surgery University Hospital Freiburg Freiburg Germany
| | - Marianne E. Mertens
- Department of Experimental Molecular Imaging Helmholtz‐Institute for Biomedical Engineering RWTH‐Aachen University Aachen Germany
| | - Josef Vizkelety
- Department of Oral and Craniomaxillofacial Surgery University Hospital Freiburg Freiburg Germany
| | - Felix Gremse
- Department of Experimental Molecular Imaging Helmholtz‐Institute for Biomedical Engineering RWTH‐Aachen University Aachen Germany
| | | | - Sebastian Sauerbier
- Department of Oral and Craniomaxillofacial Surgery University Hospital Freiburg Freiburg Germany
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Mertens ME, Hermann A, Bühren A, Olde-Damink L, Möckel D, Gremse F, Ehling J, Kiessling F, Lammers T. Iron Oxide-labeled Collagen Scaffolds for Non-invasive MR Imaging in Tissue Engineering. Adv Funct Mater 2014; 24:754-762. [PMID: 24569840 PMCID: PMC3837415 DOI: 10.1002/adfm.201301275] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Non-invasive imaging holds significant potential for implementation in tissue engineering. It can e.g. be used to monitor the localization and function of tissue-engineered implants, as well as their resorption and remodelling. Thus far, however, the vast majority of efforts in this area of research have focused on the use of ultrasmall super-paramagnetic iron oxide (USPIO) nanoparticle-labeled cells, colonizing the scaffolds, to indirectly image the implant material. Reasoning that directly labeling scaffold materials might be more beneficial (enabling imaging also in case of non-cellularized implants), more informative (enabling the non-invasive visualization and quantification of scaffold degradation) and more easy to translate into the clinic (since cell-free materials are less complex from a regulatory point-of-view), we here prepared three different types of USPIO nanoparticles, and incorporated them both passively and actively (via chemical conjugation; during collagen crosslinking) into collagen-based scaffold materials. We furthermore optimized the amount of USPIO incorporated into the scaffolds, correlated the amount of entrapped USPIO with MR signal intensity, showed that the labeled scaffolds are highly biocompatible, demonstrated that scaffold degradation can be visualized using MRI and provided initial proof-of-principle for the in vivo visualization of the scaffolds. Consequently, USPIO-labeled scaffold materials seem to be highly suitable for image-guided tissue engineering applications.
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Affiliation(s)
- Marianne E. Mertens
- Department for Experimental Molecular Imaging University Clinic and Helmholtz Institute for Biomedical Engineering RWTH - Aachen University Pauwelsstrasse 20, 52074 Aachen (Germany)
| | - Alina Hermann
- Matricel GmbH Kaiserstraße 100 52134 Herzogenrath (Germany)
| | - Anne Bühren
- Matricel GmbH Kaiserstraße 100 52134 Herzogenrath (Germany)
| | | | - Diana Möckel
- Department for Experimental Molecular Imaging University Clinic and Helmholtz Institute for Biomedical Engineering RWTH - Aachen University Pauwelsstrasse 20, 52074 Aachen (Germany)
| | - Felix Gremse
- Department for Experimental Molecular Imaging University Clinic and Helmholtz Institute for Biomedical Engineering RWTH - Aachen University Pauwelsstrasse 20, 52074 Aachen (Germany)
| | - Josef Ehling
- Department for Experimental Molecular Imaging University Clinic and Helmholtz Institute for Biomedical Engineering RWTH - Aachen University Pauwelsstrasse 20, 52074 Aachen (Germany)
| | - Fabian Kiessling
- Department for Experimental Molecular Imaging University Clinic and Helmholtz Institute for Biomedical Engineering RWTH - Aachen University Pauwelsstrasse 20, 52074 Aachen (Germany)
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Rizzo LY, Golombek SK, Mertens ME, Pan Y, Laaf D, Broda J, Jayapaul J, Möckel D, Subr V, Hennink WE, Storm G, Simon U, Jahnen-Dechent W, Kiessling F, Lammers T. In Vivo Nanotoxicity Testing using the Zebrafish Embryo Assay. J Mater Chem B 2013; 1. [PMID: 24179674 DOI: 10.1039/c3tb20528b] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Nanoparticles are increasingly used for biomedical purposes. Many different diagnostic and therapeutic applications are envisioned for nanoparticles, but there are often also serious concerns regarding their safety. Given the fact that numerous new nanomaterials are being developed every day, and that not much is known about the long-term toxicological impact of exposure to nanoparticles, there is an urgent need to establish efficient methods for nanotoxicity testing. The zebrafish (Danio rerio) embryo assay has recently emerged as an interesting 'intermediate' method for in vivo nanotoxicity screening, enabling (semi-) high-throughput analyses in a system significantly more complex than cultured cells, but at the same time also less 'invasive' and less expensive than large-scale biocompatibility studies in mice or rats. The zebrafish embryo assay is relatively well-established in the environmental sciences, but it has not yet gained wide notice in the nanomedicine field. Using prototypic polymeric drug carriers, gold-based nanodiagnostics and nanotherapeutics, and iron oxide-based nanodiagnostics, we here show that toxicity testing using zebrafish embryos is easy, efficient and informative, and faithfully reflects, yet significantly extends, cell-based toxicity testing. We therefore expect that the zebrafish embryo assay will become a popular future tool for in vivo nanotoxicity screening.
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Affiliation(s)
- Larissa Y Rizzo
- Department of Experimental Molecular Imaging, University Clinic and Helmholtz Institute for Biomedical Engineering, RWTH - Aachen University, Aachen, Germany
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Kunjachan S, Jayapaul J, Mertens ME, Storm G, Kiessling F, Lammers T. Theranostic systems and strategies for monitoring nanomedicine-mediated drug targeting. Curr Pharm Biotechnol 2012; 13:609-22. [PMID: 22214503 DOI: 10.2174/138920112799436302] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2010] [Accepted: 11/04/2010] [Indexed: 11/22/2022]
Abstract
Nanomedicine formulations are considered to be superior to standard low-molecular-weight drugs because of an increased drug accumulation at the pathological site and a decreased localization to healthy non-target tissues, together leading to an improved balance between the efficacy and the toxicity of (chemo-) therapeutic interventions. To better understand and further improve nanomedicine-mediated drug targeting, it is important to design systems and strategies which are able to provide real-time feedback on the localization, the release and the therapeutic efficacy of these formulations. The advances made over the past few years with regard to the development of novel imaging agents and techniques have provided a broad basis for the design of theranostic nanomedicine materials, i.e. multicomponent carrier constructs in which drugs and imaging agents are combined, and which can be used to address issues related to drug localization, drug release and drug efficacy. Here, we summarize several recent efforts in this regard, and we show that theranostic systems and strategies hold significant potential for monitoring and improving nanomedicine-mediated drug targeting.
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Affiliation(s)
- Sijumon Kunjachan
- Department of Experimental Molecular Imaging, RWTH - Aachen University, Pauwelsstrasse 30, 52074 Aachen, Germany
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Steinmetz NF, Mertens ME, Taurog RE, Johnson JE, Commandeur U, Fischer R, Manchester M. Potato virus X as a novel platform for potential biomedical applications. Nano Lett 2010; 10:305-12. [PMID: 20017489 PMCID: PMC2958517 DOI: 10.1021/nl9035753] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We demonstrate that nanoparticles formed from the rod-shaped plant virus Potato virus X (PVX) can serve as a novel platform for biomedical applications. Bioconjugation protocols including amine modification and "click" chemistry allowed the efficient functionalization of PVX with biotins, dyes, and PEGs. Fluorescent-labeled and PEGylated PVX particles revealed that different fluorescent labels have a profound effect on PVX-cell interactions. Applying bioconjugation chemistries to PVX opens the door for chemical functionalization with targeting and therapeutic molecules.
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Affiliation(s)
- Nicole F. Steinmetz
- Department of Cell Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
- Center of Integrative Molecular Biosciences, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Marianne E. Mertens
- Department of Cell Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
- Institute for Biology VII, Department of Molecular Biotechnology, RWTH Aachen University, Worringer Weg 1
| | - Rebecca E. Taurog
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - John E. Johnson
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Ulrich Commandeur
- Institute for Biology VII, Department of Molecular Biotechnology, RWTH Aachen University, Worringer Weg 1
| | - Rainer Fischer
- Institute for Biology VII, Department of Molecular Biotechnology, RWTH Aachen University, Worringer Weg 1
- Fraunhofer Institute for Molecular Biology and Applied Ecology, Forckenbeckstrasse 6, 52074 Aachen, Germany
- To whom correspondence should be addressed: , Tel: +49-241-6085-11021, Fax: +49-241-6085-11025; , Tel: +1-858-784-8086, Fax: +1-858-784-7979
| | - Marianne Manchester
- Department of Cell Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
- Center of Integrative Molecular Biosciences, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
- To whom correspondence should be addressed: , Tel: +49-241-6085-11021, Fax: +49-241-6085-11025; , Tel: +1-858-784-8086, Fax: +1-858-784-7979
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