@article{SchmitzHertzbergMakLaietal.2013, author = {Schmitz-Hertzberg, Sebastian-Tim and Mak, Wing Cheung and Lai, Kwok Kei and Teller, Carsten and Bier, Frank Fabian}, title = {Multifactorial design of Poly(D, L-lactic-co-glycolic acid) capsules with various release properties for differently sized filling agents}, series = {Journal of applied polymer science}, volume = {130}, journal = {Journal of applied polymer science}, number = {6}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0021-8995}, doi = {10.1002/app.39537}, pages = {4219 -- 4228}, year = {2013}, abstract = {The hydrolytic degradation and corresponding content release of capsules made of poly(d,l-lactic-co-glycolic acid) (PLGA) strongly depends on the composition and material properties of the initially applied copolymer. Consecutive or simultaneous release from capsule batches of combinable material compositions, therefore, offers high control over the bioavailability of an encapsulated drug. The keynote of this study was the creation of a superordinated database that addressed the correlation between the release kinetics of filling agents with different molecular weights from PLGA capsules of alternating composition. Fluorescein isothiocyanate (FITC)-dextran (with molecular weights of 4, 40, and 2000 kDa) was chosen as a model analyte, whereas the copolymers were taken from various 50:50 PLGA, 75:25 PLGA, and polylactide blends. With reference to recent publications, the capsule properties, such as the size, morphology, and encapsulation efficiency, were further modified during production. Hence, uniform microdisperse and polydisperse submicrometer nanocapsules were prepared by two different water-in-oil-in-water emulsification techniques, and additional effects on the size and morphology were achieved by capsule solidification in two different sodium salt buffers. The qualitative and quantitative examination of the physical capsule properties was performed by confocal laser scanning microscopy, scanning electron microscopy, and Coulter counting techniques to evaluate the capsule size distribution and the morphological appearance of the different batches. The corresponding agent release was quantified by fluorescence measurement of the FITC-dextran in the incubation media and by the direct measurement of the capsule brightness via fluorescence microscopy. In summary, the observed agent release showed a highly controllable flexibility depending on the PLGA blends, preparation methods, and molecular weight of the used filling substances. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4219-4228, 2013}, language = {en} } @article{SachseWuestenhagenSamalikovaetal.2013, author = {Sachse, Rita and W{\"u}stenhagen, Doreen Anja and Samalikova, Maria and Gerrits, Michael and Bier, Frank Fabian and Kubick, Stefan}, title = {Synthesis of membrane proteins in eukaryotic cell-free systems}, series = {Engineering in life sciences : Industry, Environment, Plant, Food}, volume = {13}, journal = {Engineering in life sciences : Industry, Environment, Plant, Food}, number = {1}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {1618-0240}, doi = {10.1002/elsc.201100235}, pages = {39 -- 48}, year = {2013}, abstract = {Cell-free protein synthesis (CFPS) is a valuable method for the fast expression of difficult-to-express proteins as well as posttranslationally modified proteins. Since cell-free systems circumvent possible cytotoxic effects caused by protein overexpression in living cells, they significantly enlarge the scale and variety of proteins that can be characterized. We demonstrate the high potential of eukaryotic CFPS to express various types of membrane proteins covering a broad range of structurally and functionally diverse proteins. Our eukaryotic cell-free translation systems are capable to provide high molecular weight membrane proteins, fluorescent-labeled membrane proteins, as well as posttranslationally modified proteins for further downstream analysis.}, language = {en} } @article{HuettlHettrichMilleretal.2013, author = {H{\"u}ttl, Christine and Hettrich, Cornelia and Miller, Reinhard and Paulke, Bernd-Reiner and Henklein, Petra and Rawel, Harshadrai Manilal and Bier, Frank Fabian}, title = {Self-assembled peptide amphiphiles function as multivalent binder with increased hemagglutinin affinity}, series = {BMC biotechnology}, volume = {13}, journal = {BMC biotechnology}, number = {22}, publisher = {BioMed Central}, address = {London}, issn = {1472-6750}, doi = {10.1186/1472-6750-13-51}, pages = {10}, year = {2013}, abstract = {Background: A promising way in diagnostic and therapeutic applications is the development of peptide amphiphiles (PAs). Peptides with a palmitic acid alkylchain were designed and characterized to study the effect of the structure modifications on self-assembling capabilities and the multiple binding capacity to hemagglutinin (HA), the surface protein of influenza virus type A. The peptide amphiphiles consists of a hydrophilic headgroup with a biological functionality of the peptide sequence and a chemically conjugated hydrophobic tail. In solution they self-assemble easily to micelles with a hydrophobic core surrounded by a closely packed peptide-shell. Results: In this study the effect of a multiple peptide binding partner to the receptor binding site of HA could be determined with surface plasmon resonance measurements. The applied modification of the peptides causes signal amplification in relationship to the unmodified peptide wherein the high constant specificity persists. The molecular assembly of the peptides was characterized by the determination of critical micelle concentration (CMC) with concentration of 10(-5) M and the colloidal size distribution. Conclusion: The modification of the physico-chemical parameters by producing peptide amphiphiles form monomeric structures which enhances the binding affinity and allows a better examination of the interaction with the virus surface protein hemagglutinin.}, language = {en} } @article{HoppeBiervonNickischRosenegk2013, author = {Hoppe, Sebastian and Bier, Frank Fabian and von Nickisch-Rosenegk, Markus}, title = {Rapid identification of novel immunodominant proteins and characterization of a specific linear epitope of campylobacter jejuni}, series = {PLoS one}, volume = {8}, journal = {PLoS one}, number = {5}, publisher = {PLoS}, address = {San Fransisco}, issn = {1932-6203}, doi = {10.1371/journal.pone.0065837}, pages = {15}, year = {2013}, abstract = {Campylobacter jejuni remains one of the major gut pathogens of our time. Its zoonotic nature and wide-spread distribution in industrialized countries calls for a quick and reliable diagnostic tool. Antibody-based detection presents a suitable means to identify pathogenic bacteria. However, the knowledge about immunodominant targets is limited. Thus, an approach is presented, which allows for the rapid screening of numerous cDNA derived expression clones to identify novel antigens. The deeper understanding of immunodominant proteins assists in the design of diagnostic tools and furthers the insight into the bacterium's pathogenicity as well as revealing potential candidates for vaccination. We have successfully screened 1536 clones of an expression library to identify 22 proteins that have not been described as immunodominant before. After subcloning the corresponding 22 genes and expression of full-length proteins, we investigated the immunodominant character by microarrays and ELISA. Subsequently, seven proteins were selected for epitope mapping. For cj0669 and cj0920c linear epitopes were identified. For cj0669, specificity assays revealed a specific linear epitope site. Consequently, an eleven amino acid residue sequence TLIKELKRLGI was analyzed via alanine scan, which revealed the glycine residue to be significant for binding of the antibody. The innovative approach presented herein of generating cDNAs of prokaryotes in combination with a microarray platform rendering time-consuming purification steps obsolete has helped to illuminate novel immunodominant proteins of C. jejuni. The findings of a specific linear epitope pave the way for a plethora of future research and the potential use in diagnostic applications such as serological screenings. Moreover, the current approach is easily adaptable to other highly relevant bacteria making it a formidable tool for the future discovery of antigens and potential biomarkers. Consequently, it is desirable to simplify the identification of structural epitopes, as this would extend the spectrum of novel epitopes to be detected.}, language = {en} }