TY - GEN A1 - Bourgat, Yannick A1 - Tiersch, Brigitte A1 - Koetz, Joachim A1 - Menzel, Henning T1 - Enzyme degradable polymersomes from chitosan-g-[poly-l-lysine-block-epsilon-caprolactone] copolymer T2 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - The scope of this study includes the synthesis of chitosan-g-[peptide-poly-epsilon-caprolactone] and its self-assembly into polymeric vesicles employing the solvent shift method. In this way, well-defined core-shell structures suitable for encapsulation of drugs are generated. The hydrophobic polycaprolactone side-chain and the hydrophilic chitosan backbone are linked via an enzyme-cleavable peptide. The synthetic route involves the functionalization of chitosan with maleimide groups and the preparation of polycaprolactone with alkyne end-groups. A peptide functionalized with a thiol group on one side and an azide group on the other side is prepared. Thiol-ene click-chemistry and azide-alkyne Huisgen cycloaddition are then used to link the chitosan and poly-epsilon-caprolactone chains, respectively, with this peptide. For a preliminary study, poly-l-lysin is a readily available and cleavable peptide that is introduced to investigate the feasibility of the system. The size and shape of the polymersomes are studied by dynamic light scattering and cryo-scanning electron microscopy. Furthermore, degradability is studied by incubating the polymersomes with two enzymes, trypsin and chitosanase. A dispersion of polymersomes is used to coat titanium plates and to further test the stability against enzymatic degradation. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1382 KW - chitosan KW - click chemistry KW - drug delivery system KW - enzyme KW - polymersomes KW - poly‐ ε ‐ caprolactone Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-566584 SN - 1866-8372 IS - 1 ER - TY - JOUR A1 - Bourgat, Yannick A1 - Tiersch, Brigitte A1 - Koetz, Joachim A1 - Menzel, Henning T1 - Enzyme degradable polymersomes from chitosan-g-[poly-l-lysine-block-epsilon-caprolactone] copolymer JF - Macromolecular bioscience N2 - The scope of this study includes the synthesis of chitosan-g-[peptide-poly-epsilon-caprolactone] and its self-assembly into polymeric vesicles employing the solvent shift method. In this way, well-defined core-shell structures suitable for encapsulation of drugs are generated. The hydrophobic polycaprolactone side-chain and the hydrophilic chitosan backbone are linked via an enzyme-cleavable peptide. The synthetic route involves the functionalization of chitosan with maleimide groups and the preparation of polycaprolactone with alkyne end-groups. A peptide functionalized with a thiol group on one side and an azide group on the other side is prepared. Thiol-ene click-chemistry and azide-alkyne Huisgen cycloaddition are then used to link the chitosan and poly-epsilon-caprolactone chains, respectively, with this peptide. For a preliminary study, poly-l-lysin is a readily available and cleavable peptide that is introduced to investigate the feasibility of the system. The size and shape of the polymersomes are studied by dynamic light scattering and cryo-scanning electron microscopy. Furthermore, degradability is studied by incubating the polymersomes with two enzymes, trypsin and chitosanase. A dispersion of polymersomes is used to coat titanium plates and to further test the stability against enzymatic degradation. KW - chitosan KW - click chemistry KW - drug delivery system KW - enzyme KW - polymersomes KW - poly‐ ε ‐ caprolactone Y1 - 2020 U6 - https://doi.org/10.1002/mabi.202000259 SN - 1616-5187 SN - 1616-5195 VL - 21 IS - 1 SP - 1 EP - 9 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Wöhl-Bruhn, Stefanie A1 - Badar, Muhammad A1 - Bertz, Andreas A1 - Tiersch, Brigitte A1 - Koetz, Joachim A1 - Menzel, Henning A1 - Müller, Peter P. A1 - Bunjes, Heike T1 - Comparison of in vitro and in vivo protein release from hydrogel systems JF - Journal of controlled release N2 - Hydrogel systems based on hydroxyethyl starch-polyethylene glycol methacrylate (HES-P(EG)(6)MA) or hydroxyethyl starch methacrylate (HES-MA) were used to assess the protein release behavior. Here, we analyzed the in vitro release of FITC-anti-human antibodies incorporated in either HES-P(EG)(6)MA or HES-MA hydrogel delivery systems in PBS or human serum. In addition, hydrogel disks and microparticles prepared from the two polymers were subcutaneously implanted in BALB/c mice. The in vivo release of FITC-IgG was non-invasively monitored by an in vivo imaging system (IVIS 200) over a time period of up to 3 months. The imaging system allowed to asses individual animals over time, therefore only a small number of animals was required to obtain high quality data. The reduction in fluorescence intensity at the site of administration was compared to in vitro release profiles. These investigations demonstrated a sustained release from HES-MA hydrogel disks compared to rapidly degrading HES-P(EG)(6)MA disks and microparticles. The sustained release from HES-MA disks could be further optimized by using increased polymer concentrations. Human serum as in vitro release medium reflected better the in vivo release from HES-P(EG)(6)MA systems than PBS, suggesting that the presence of organic substances like proteins or lipids may play a significant role for the release kinetics. KW - In vivo imaging system (IVIS) KW - Hydrogel disks KW - Hydrogel microparticles KW - Release KW - In vivo-in vitro correlation KW - Hydroxyethyl starch (HES) Y1 - 2012 U6 - https://doi.org/10.1016/j.jconrel.2012.05.049 SN - 0168-3659 VL - 162 IS - 1 SP - 127 EP - 133 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Bertz, Andreas A1 - Wöhl-Bruhn, Stefanie A1 - Miethe, Sebastian A1 - Tiersch, Brigitte A1 - Koetz, Joachim A1 - Hust, Michael A1 - Bunjes, Heike A1 - Menzel, Henning T1 - Encapsulation of proteins in hydrogel carrier systems for controlled drug delivery influence of network structure and drug size on release rate JF - Journal of biotechnology N2 - Novel hydrogels based on hydroxyethyl starch modified with polyethylene glycol methacrylate (HES-P(EG)(6)MA) were developed as delivery system for the controlled release of proteins. Since the drug release behavior is supposed to be related to the pore structure of the hydrogel network the pore sizes were determined by cryo-SEM, which is a mild technique for imaging on a nanometer scale. The results showed a decreasing pore size and an increase in pore homogeneity with increasing polymer concentration. Furthermore, the mesh sizes of the hydrogels were calculated based on swelling data. Pore and mesh size were significantly different which indicates that both structures are present in the hydrogel. The resulting structural model was correlated with release data for bulk hydrogel cylinders loaded with FITC-dextran and hydrogel microspheres loaded with FITC-IgG and FITC-dextran of different molecular size. The initial release depended much on the relation between hydrodynamic diameter and pore size while the long term release of the incorporated substances was predominantly controlled by degradation of the network of the much smaller meshes. KW - Hydrogel KW - Hydrogel microspheres KW - Network structure KW - Release studies KW - Protein delivery KW - Mesh size Y1 - 2013 U6 - https://doi.org/10.1016/j.jbiotec.2012.06.036 SN - 0168-1656 VL - 163 IS - 2 SP - 243 EP - 249 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Navarro, Salvador A1 - Shkilnyy, Andriy A1 - Tiersch, Brigitte A1 - Taubert, Andreas A1 - Menzel, Henning T1 - Preparation, characterization, and thermal gelation of amphiphilic alkyl-poly(ethyleneimine) N2 - Amphiphilic alkyl-poly(ethyleneimine)s (alkyl-PEI) with different degrees of polymerization have been produced by alkaline hydrolysis of alkyl-poly(2-methyl-2-oxazoline). Potentiometric titration of the alkyl-PEI shows the influence of the alkyl chain and the degree of polymerization on the titration curves and hence on the polymer conformation. Karl Fischer titration has been used to determine the water content in the polymers. Subsequent X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC) measurements prove the existence of different hydration states of the PEI even under dry storage conditions. Upon cooling from hot aqueous Solutions, hydrogels form. The gelation concentration decreases with increasing degree of polymerization of the PEI segment. Scanning electron microscopy (SEM and cryo-SEM) of the hydrogels reveal an alkyl-PEI fibrous network composed of fan-like units. DSC shows that the percentages of bound and free water in the hydrogels depend on the concentration of polar amino groups. Y1 - 2009 UR - http://pubs.acs.org/journal/langd5 U6 - https://doi.org/10.1021/La9013569 SN - 0743-7463 ER - TY - JOUR A1 - Gharagozloo-Hubmann, Kati A1 - Kulikovska, Olga A1 - Boerger, Volker A1 - Menzel, Henning A1 - Stumpe, Joachim T1 - Surface relief gratings in azobenzene-containing polymers with linear and star-branched architectures : a comparison N2 - The influence of molecular architecture on light-induced SRG formation was investigated. Polymers with different degree of branching were synthesized by ATRP and functionalized with azobenzene chromophores. The polymers differ only in their architecture - linear, 4-, 6-, or 12-arms stars. The photo-induced dichroism as well as the efficiency of SRG formation was similar for all polymers of this series. New consideration for the origin of the driving force was used to explain this behavior. The comparable SRG inscription rate in differently branched polymers can be rationalized by assuming that azobenzene acts as an internal molecular motor and can cause a non-turbulent motion on a scale smaller than that on which normal entanglement restriction forces act. Y1 - 2009 UR - http://www3.interscience.wiley.com/journal/10003495/home U6 - https://doi.org/10.1002/macp.200900218 SN - 1022-1352 ER - TY - JOUR A1 - Stumpe, Joachim A1 - Geue, Thomas A1 - Fischer, Thomas M. A1 - Menzel, Henning T1 - Photochemically induced changes of structures in LB-multilayers of amphotropic polymers Y1 - 1995 ER - TY - JOUR A1 - Menzel, Henning A1 - Rüther, M. A1 - Stumpe, Joachim A1 - Fischer, Thomas M. T1 - Discrimination of structural order and chromophore aggregation as factors effecting the photo-reorientation of azobenzene in co-polyglutamate LB-films Y1 - 1998 ER - TY - JOUR A1 - Ziegler, A. A1 - Fischer, Thomas M. A1 - Menzel, Henning A1 - Stumpe, Joachim T1 - Photo-Induced modification and photo-orientation in LB-multilayers of thermotropic polymers containing azobenzene side groups Y1 - 1998 ER - TY - JOUR A1 - Menzel, Henning A1 - Rüther, M. A1 - Stumpe, Joachim A1 - Fischer, Thomas M. T1 - Discrimination of structural order and chromophore aggregation as factors effecting the photo-reorientation of Azobenzene in copolyglutamate LB-films. Y1 - 1998 ER -