TY - GEN A1 - Avitabile, Daniele A1 - Salchert, Katrin A1 - Werner, Carsten A1 - Capogrossi, Maurizio C. A1 - Pesce, Maurizio T1 - Growth induction and low-oxygen apoptosis inhibition of human CD34+ progenitors in collagen gels T2 - BioMed Research International N2 - Various reports have indicated low survival of injected progenitors into unfavorable environments such as the ischemic myocardium or lower limb tissues. This represents a major bottleneck in stem-cell-based cardiovascular regenerative medicine. Strategies to enhance survival of these cells in recipient tissues have been therefore sought to improve stem cell survival and ensure long-term engraftment. In the present contribution, we show that embedding human cord blood-derived CD34(+) cells into a collagen I-based hydrogel containing cytokines is a suitable strategy to promote stem cell proliferation and protect these cells from anoxia-induced apoptosis. Y1 - 2013 U6 - https://doi.org/10.1155/2013/542810 SN - 2314-6133 SN - 2314-6141 SP - 542810 ER - TY - GEN A1 - Wetzel, Stefanie A1 - Allertz, Peter J. A1 - Koschnicke, Sören A1 - Tasso, Mariana A1 - Salchert, Katrin T1 - Immobilized enzymes – valuable tools for the indication of temperature events T2 - Biocatalysis and Biotransformation N2 - The enzymes trypsin and urease were covalently tethered to cellulose to utilize their ability to produce colored products as a consequence of enzymatic activity. Therefore, cellulose had to be chemically modified first in order to generate appropriate chemical functionalities. Different approaches including periodate supported oxidation followed by immobilization via reductive amination, insertion of a reactive polymer interface, and cross-linking inside the cellulose matrix were utilized for the immobilization. The success of immobilization was assessed by the quantification of surface-bound protein as well as by recording of enzymatic activities under different conditions. The enzymatic activity of trypsin and urease was maintained best when a hydrophilic intermediate polymer layer was used for immobilization. The applicability of immobilized enzymes as temperature indicators was demonstrated using cross-linked urease. KW - Cellulose KW - immobilization KW - trypsin KW - urease KW - reactive polymer KW - temperature label Y1 - 2013 U6 - https://doi.org/10.3109/10242422.2013.777433 SN - 1024-2422 SN - 1029-2446 VL - 31 IS - 2 SP - 100 EP - 113 ER - TY - GEN A1 - Allertz, Peter J. A1 - Berger, Steffen A1 - Sellenk, Grit A1 - Dittmer, Christin A1 - Dietze, Marco A1 - Stahmann, Klaus-Peter A1 - Salchert, Katrin T1 - Approaching Immobilization of Enzymes onto Open Porous Basotect® T2 - Catalysts N2 - For the first time, commercial macroporous melamine formaldehyde foam Basotect® (BT) was used as a basic carrier material for both adsorptive and covalent enzyme immobilization. In order to access inherent amino groups, the Basotect® surface was pretreated with hydrochloric acid. The resulting material revealed 6 nmol of superficial amino groups per milligram Basotect®. Different optimized strategies for tethering the laccase from Trametes versicolor and the lipase from Thermomyces lanuginosus onto the pre-treated Basotect® surface were studied. Particularly, for covalent immobilization, two different strategies were pursued: lipase was tethered via a cross-linking method using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, and laccase was bound after functionalizing Basotect® with hydrophilic copolymer poly(ethylene-alt-maleic anhydride) (PEMA). Prior to laccase immobilization, the PEMA coating of Basotect® was verified by ATR-FTIR analysis. Subsequent quantification of available high-reactive PEMA anhydride moieties revealed an amount of 1028 ± 73 nmol per mg Basotect®. The surface-bound enzyme amounts were quantified as 4.1–5.8 μg per mg Basotect®. A theoretical surface-covered enzyme mass for the ideal case that an enzyme monolayer was immobilized onto the Basotect® surface was calculated and compared to the amount of adsorptive and covalently bound enzymes before and after treatment with SDS. Furthermore, the enzyme activities were determined for the different immobilization approaches, and the stability during storage over time and against sodium dodecyl sulfate treatment was monitored. Additionally, PEMA-BT-bound laccase was tested for the elimination of anthropogenic micropollutant bisphenol A from contaminated water in a cost-effective and environmentally-friendly way and resulted in a degradation rate higher than 80%. KW - Basotect® KW - Enzyme immobilization KW - Laccase KW - Lipase KW - PEMA KW - EDC KW - Bisphenol A Y1 - 2017 U6 - https://doi.org/10.3390/catal7120359 SN - 2073-4344 VL - 7 IS - 12 ER - TY - GEN A1 - Müller, Felix A1 - Torger, Bernhard A1 - Allertz, Peter J. A1 - Jähnichen, Klaus A1 - Keßler, Stefan A1 - Müller, Martin A1 - Simon, Frank A1 - Salchert, Katrin A1 - Mäurer, Haike A1 - Pospiech, Doris T1 - Multifunctional crosslinkable itaconic acid copolymers for enzyme immobilization T2 - European Polymer Journal N2 - UV-Crosslinkable itaconic copolymers are developed to provide new multifunctional materials for coatings which combine crosslinkable functionalities and the possibility to immobilize enzymes. The polymer-immobilized enzymes were used for water treatment to decompose persistent organic molecules. Introduction of suitable comonomers allows tailoring the mechanical and chemical properties for special applications. Copolymers containing MMA and itaconic anhydride were chosen because of the formation of long-term stable anhydride functionalities. These anhydride functionalities are employed to attach enzymes covalently. 4-Benzoylphenyl methacrylate is used as comonomer for UV-initiated crosslinking. Terpolymers are successfully obtained by radical copolymerization in solution. The copolymers are compared to poly(ethylene-alt-maleic anhydride) [P(EMA)] often used with respect to enzyme immobilization, activity and hydrolytic stability. The hydrolysis stability of the copolymers against water is studied by ATR-FTIR spectroscopy. Thin films are prepared on glass substrates in a layer-by-layer procedure by spin-coating. The layer formation is monitored by ATR-FTIR spectroscopy. UV-crosslinking of the copolymer films is performed taking the optimal irradiation dose that avoids polymer degradation. ATR-FTIR spectroscopy verifies the coupling reaction between amino groups of the enzyme and the anhydride groups on the surface of the crosslinked polymer film. The syringaldazine (4-hydroxy-3,5-dimethoxybenzaldehyde azine) test and 2,2´-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assay demonstrate that the immobilized enzymes maintain their activities. The functional copolymers showed a significant effect in reduction of persistent organic pollutants in contaminated waste water. KW - ATR-FTIR spectroscopy KW - Crosslinking KW - Enzyme-immobilization KW - Itaconc acid KW - Methacrylate copolymer Y1 - 2018 U6 - https://doi.org/10.1016/j.eurpolymj.2018.03.014 VL - 102 SP - 47 EP - 55 ER -