TY - JOUR A1 - Rübsam, Kristin A1 - Stomps, Benjamin René Harald A1 - Böker, Alexander A1 - Jakob, Felix A1 - Schwaneberg, Ulrich T1 - Anchor peptides: A green and versatile method for polypropylene functionalization JF - Polymer : the international journal for the science and technology of polymers KW - Material binding peptides KW - Anchor peptides KW - Surface modification KW - Immobilization Y1 - 2017 U6 - https://doi.org/10.1016/j.polymer.2017.03.070 SN - 0032-3861 SN - 1873-2291 VL - 116 SP - 124 EP - 132 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Zhang, Shuhao A1 - Bisterfeld, Carolin A1 - Bramski, Julia A1 - Vanparijs, Nane A1 - De Geest, Bruno G. A1 - Pietruszka, Jörg A1 - Böker, Alexander A1 - Reinicke, Stefan T1 - Biocatalytically Active Thin Films via Self-Assembly of 2-Deoxy-D-ribose-5-phosphate Aldolase-Poly(N-isopropylacrylamide) Conjugates JF - Bioconjugate chemistry N2 - 2-Deoxy-D-ribose-5-phosphate aldolase (DERA) is a biocatalyst that is capable of converting acetaldehyde and a second aldehyde as acceptor into enantiomerically pure mono- and diyhydroxyaldehydes, which are important structural motifs in a number of pharmaceutically active compounds. However, substrate as well as product inhibition requires a more-sophisticated process design for the synthesis of these motifs. One way to do so is to the couple aldehyde conversion with transport processes, which, in turn, would require an immobilization of the enzyme within a thin film that can be deposited on a membrane support. Consequently, we developed a fabrication process for such films that is based on the formation of DERA-poly(N-isopropylacrylamide) conjugates that are subsequently allowed to self-assemble at an air-water interface to yield the respective film. In this contribution, we discuss the conjugation conditions, investigate the interfacial properties of the conjugates, and, finally, demonstrate a successful film formation under the preservation of enzymatic activity. Y1 - 2017 U6 - https://doi.org/10.1021/acs.bioconjchem.7b00645 SN - 1043-1802 VL - 29 IS - 1 SP - 104 EP - 116 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Garakani, Tayebeh Mirzaei A1 - Richter, Marina Juliane A1 - Böker, Alexander T1 - Controlling the bio-inspired synthesis of silica JF - Journal of colloid and interface science N2 - The influence of different parameters on the silicification procedure using lysozyme is reported. When polyethoxysiloxane (PEOS), an internally crosslinked silica reservoir, is used, regular structures with a narrow size distribution could be obtained only via introducing the silica precursor in two steps including initial dropping and subsequent addition of residual oil phase in one portion. We found that mixing sequence of mineralizing agents in the presence of a positively charged surfactant plays a key role in terms of silica precipitation when tetraethoxyorthosilicate (TEOS) is the oil phase. In contrast, well mineralized crumpled features with high specific surface area could be synthesized in the presence of PEOS as a silica precursor polymer, regardless of mixing sequence. Moreover, introducing sodium dodecyl sulfate (SDS) as a negatively charged surfactant resulted in regular silica sphere formation only in combination with hexylene glycol (MPD) as a specific co-solvent. Finally, it is demonstrated that by inclusion of different nanoparticles even more sophisticated hybrid materials can be generated. KW - Silicification KW - Lysozyme KW - Polyetlioxysiloxane KW - High specific surface area KW - Surfactant KW - Nanoparticles KW - Hybrid materials Y1 - 2016 U6 - https://doi.org/10.1016/j.jcis.2016.10.069 SN - 0021-9797 SN - 1095-7103 VL - 488 SP - 322 EP - 334 PB - Elsevier CY - San Diego ER - TY - JOUR A1 - Tebaldi, Marli Luiza A1 - Charan, Himanshu A1 - Mavliutova, Liliia A1 - Böker, Alexander A1 - Glebe, Ulrich T1 - Dual-Stimuli Sensitive Hybrid Materials: Ferritin-PDMAEMA by Grafting-From Polymerization JF - Macromolecular chemistry and physics N2 - The combination of stimuli-responsive polymers and proteins that can transport drugs is a promising approach for drug delivery. The formation of ferritin-poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) conjugates by atom-transfer radical polymerization from the protein macroinitiator is described. PDMAEMA is a dual-stimuli-responsive polymer and the thermo- and pH-responsive properties of the resulting conjugates are studied in detail with dynamic light scattering (DLS). Additionally, it is demonstrated that the lower critical solution temperature (LCST) of the protein-polymer conjugates can be further adjusted by the ionic strength of the solution. The conjugates are also characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), matrix-assisted laser desorption ionization-time of flight (MALDI-ToF) mass spectrometry, and NMR spectroscopy. The obtained MALDI-ToF mass spectra are exceptional for protein-polymer conjugates and have not been so often reported. KW - grafting-from KW - MALDI-ToF MS KW - polymerization KW - proteins KW - responsivity Y1 - 2017 U6 - https://doi.org/10.1002/macp.201600529 SN - 1022-1352 SN - 1521-3935 VL - 218 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Wu, Lei A1 - Glebe, Ulrich A1 - Böker, Alexander T1 - Fabrication of Thermoresponsive Plasmonic Core-Satellite Nanoassemblies with a Tunable Stoichiometry via Surface-Initiated Reversible Addition-Fragmentation Chain Transfer Polymerization from Silica Nanoparticles JF - Advanced materials interfaces N2 - This work presents a fabrication of thermoresponsive plasmonic core-satellite nanoassemblies. The structure has a silica nanoparticle core surrounded by gold nanoparticle satellites using thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) chains as scaffolds. The thiol-terminated PNIPAM shell is densely grafted on the silica core via surface-initiated reversible addition-fragmentation chain transfer polymerization and used to anchor numerous gold nanoparticle satellites with a tunable stoichiometry. Below and above lower critical solution temperature, the chain conformation of PNIPAM reversibly changes between swollen and shrunken state. The reversible change of the polymer size varies the refractive index of the local medium surrounding the satellites and the distance between them. The two effects together lead to the thermoresponsive plasmonic properties of the nanoassemblies. Under different satellite densities, two distinctive plasmonic features appear. KW - gold KW - hybrid materials KW - polymeric materials KW - silica KW - surface plasmon resonance Y1 - 2017 U6 - https://doi.org/10.1002/admi.201700092 SN - 2196-7350 VL - 4 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Reinicke, Stefan A1 - Rees, Huw C. A1 - Espeel, Pieter A1 - Vanparijs, Nane A1 - Bisterfeld, Carolin A1 - Dick, Markus A1 - Rosencrantz, Ruben R. A1 - Brezesinski, Gerald A1 - de Geest, Bruno G. A1 - Du Prez, Filip E. A1 - Pietruszka, Jörg A1 - Böker, Alexander T1 - Immobilization of 2-Deoxy-D-ribose-5-phosphate Aldolase in Polymeric Thin Films via the Langmuir-Schaefer Technique JF - ACS applied materials & interfaces N2 - A synthetic protocol for the fabrication of ultrathin polymeric films containing the enzyme 2-deoxy-D-ribose-5-phosphate aldolase from Escherichia coli (DERA(EC)) is presented. Ultrathin enzymatically active films are useful for applications in which only small quantities of active material are needed and at the same time quick response and contact times without diffusion limitation are wanted. We show how DERA as an exemplary enzyme can be immobilized in a thin polymer layer at the air-water interface and transferred to a suitable support by the Langmuir-Schaefer technique under full conservation of enzymatic activity. The polymer in use is a poly(N-isopropylacrylamide-co-N-2-thiolactone acrylamide) (P(NIPAAm-co-TlaAm)) statistical copolymer in which the thiolactone units serve a multitude of purposes including hydrophobization of the polymer, covalent binding of the enzyme and the support and finally cross-linking of the polymer matrix. The application of this type of polymer keeps the whole approach simple as additional cocomponents such as cross-linkers are avoided. KW - Langmuir-Schaefer KW - enzyme immobilization KW - 2-deoxy-D-ribose-5-phosphate aldolase KW - polymeric thin film KW - poly(N-isopropylacrylamide) KW - thiolactone Y1 - 2017 U6 - https://doi.org/10.1021/acsami.6b13632 SN - 1944-8244 VL - 9 SP - 8317 EP - 8326 PB - American Chemical Society CY - Washington ER - TY - JOUR A1 - Charan, Himanshu A1 - Glebe, Ulrich A1 - Anand, Deepak A1 - Kinzel, Julia A1 - Zhu, Leilei A1 - Bocola, Marco A1 - Garakani, Tayebeh Mirzaei A1 - Schwaneberg, Ulrich A1 - Böker, Alexander T1 - Nano-thin walled micro-compartments from transmembrane protein-polymer conjugates JF - Soft matter N2 - The high interfacial activity of protein-polymer conjugates has inspired their use as stabilizers for Pickering emulsions, resulting in many interesting applications such as synthesis of templated micro-compartments and protocells or vehicles for drug and gene delivery. In this study we report, for the first time, the stabilization of Pickering emulsions with conjugates of a genetically modified transmembrane protein, ferric hydroxamate uptake protein component A (FhuA). The lysine residues of FhuA with open pore (FhuA Delta CVFtev) were modified to attach an initiator and consequently controlled radical polymerization (CRP) carried out via the grafting-from technique. The resulting conjugates of FhuA Delta CVFtev with poly(N-isopropylacrylamide) (PNIPAAm) and poly((2-dimethylamino) ethyl methacrylate) (PDMAEMA), the so-called building blocks based on transmembrane proteins (BBTP), have been shown to engender larger structures. The properties such as pH-responsivity, temperature-responsivity and interfacial activity of the BBTP were analyzed using UV-Vis spectrophotometry and pendant drop tensiometry. The BBTP were then utilized for the synthesis of highly stable Pickering emulsions, which could remain non-coalesced for well over a month. A new UV-crosslinkable monomer was synthesized and copolymerized with NIPAAm from the protein. The emulsion droplets, upon crosslinking of polymer chains, yielded micro-compartments. Fluorescence microscopy proved that these compartments are of micrometer scale, while cryo-scanning electron microscopy and scanning force microscopy analysis yielded a thickness in the range of 11.1 +/- 0.6 to 38.0 +/- 18.2 nm for the stabilizing layer of the conjugates. Such micro-compartments would prove to be beneficial in drug delivery applications, owing to the possibility of using the channel of the transmembrane protein as a gate and the smart polymer chains as trigger switches to tune the behavior of the capsules. Y1 - 2017 U6 - https://doi.org/10.1039/c6sm02520j SN - 1744-683X SN - 1744-6848 VL - 13 SP - 2866 EP - 2875 PB - Royal Society of Chemistry CY - Cambridge ER - TY - GEN A1 - Nguyen, Vu Hoa A1 - Richert, S. A1 - Park, Hyunji A1 - Böker, Alexander A1 - Schnakenberg, Uwe T1 - Single interdigital transducer as surface acoustic wave impedance sensor T2 - Biosensors N2 - Surface acoustic wave (SAW) devices are well-known for gravimetric sensor applications. In biosensing applications, chemical-and biochemically evoked adsorption processes at surfaces are detected in liquid environments using delay-line or resonator sensor configurations, preferably in combination with appropriate microfluidic devices. In this paper, a novel SAW-based impedance sensor type is introduced which uses only one interdigital electrode transducer (IDT) simultaneously as SAW generator and sensor element. It is shown that the amplitude of the reflected S-11 signal directly depends on the input impedance of the SAW device. The input impedance is strongly influenced by mass adsorption which causes a characteristic and measurable impedance mismatch. KW - SAW impedance sensor KW - microfluidic KW - PHEMA Y1 - 2017 U6 - https://doi.org/10.1016/j.protcy.2017.04.032 SN - 2212-0173 VL - 27 SP - 70 EP - 71 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Liebeck, Bernd Michael A1 - Hidalgo, Natalia A1 - Roth, Georg A1 - Popescu, Crisan A1 - Böker, Alexander T1 - Synthesis and characterization of Methyl Cellulose/Keratin Hydrolysate Composite Membranes JF - Polymers / Molecular Diversity Preservation International N2 - It is known that aqueous keratin hydrolysate solutions can be produced from feathers using superheated water as solvent. This method is optimized in this study by varying the time and temperature of the heat treatment in order to obtain a high solute content in the solution. With the dissolved polypeptides, films are produced using methyl cellulose as supporting material. Thereby, novel composite membranes are produced from bio-waste. It is expected that these materials exhibit both protein and polysaccharide properties. The influence of the embedded keratin hydrolysates on the methyl cellulose structure is investigated using Fourier transform infrared spectroscopy (FTIR) and wide angle X-ray diffraction (WAXD). Adsorption peaks of both components are present in the spectra of the membranes, while the X-ray analysis shows that the polypeptides are incorporated into the semi-crystalline methyl cellulose structure. This behavior significantly influences the mechanical properties of the composite films as is shown by tensile tests. Since further processing steps, e.g., crosslinking, may involve a heat treatment, thermogravimetric analysis (TGA) is applied to obtain information on the thermal stability of the composite materials. KW - bio-based KW - composite materials KW - methyl cellulose KW - keratin KW - superheated water Y1 - 2017 U6 - https://doi.org/10.3390/polym9030091 SN - 2073-4360 VL - 9 PB - MDPI CY - Basel ER - TY - JOUR A1 - Wagner, Tom A1 - Oded, Meirav A1 - Shenhar, Roy A1 - Böker, Alexander T1 - Two-dimensionally ordered AuNP array formation via microcontact printing on lamellar diblock copolymer films JF - Polymers for advanced technologies N2 - The construction of nano-sized, two-dimensionally ordered nanoparticle (NP) superstructures is important for various advanced applications such as photonics, sensing, catalysis, or nano-circuitry. Currently, such structures are fabricated using the templated organization approach, in which the templates are mainly created by photo-lithography or laser-lithography and other invasive top-down etching procedures. In this work, we present an alternative bottom-up preparation method for the controlled deposition of NPs into hierarchical structures. Lamellar polystyrene-block-poly(2-vinylpyridinium) thin films featuring alternating stripes of neutral PS and positively charged P2VP domains serve as templates, allowing for the selective adsorption of negatively charged gold NPs. Dense NP assembly is achieved by a simple immersion process, whereas two-dimensionally ordered arrays of NPs are realized by microcontact printing (mu CP), utilizing periodic polydimethylsiloxane wrinkle grooves loaded with gold NPs. This approach enables the facile construction of hierarchical NP arrays with variable geometries. Copyright (C) 2016 John Wiley & Sons, Ltd. KW - block copolymers KW - electrostatic assembly KW - microcontact printing KW - gold nanoparticles Y1 - 2017 U6 - https://doi.org/10.1002/pat.3853 SN - 1042-7147 SN - 1099-1581 VL - 28 SP - 623 EP - 628 PB - Wiley CY - Hoboken ER -