A basis for molecular factories: multifunctionality and immobilization of biomolecule-polymer assemblies

Bio-inspired planar polymer membranes are synthetic membranes designed to be combined with biomolecules such as proteins, enzymes or peptides. These membranes provide both an increased mechanical stability as well as an environment to preserve the functionality of the biomolecules. In this thesis, two different kinds of planar membrane systems are demonstrated. In the first project, a sensor for phenolic compounds based on a bio-inspired polymer membrane was developed. Functional surfaces were generated by combining enzymes with polymer membranes composed of an amphiphilic, asymmetric block copolymer. Firstly, polymer films which were formed at the air-water interface were transferred onto silica solid support, by using the Langmuir-Blodgett method. The films were characterized according to their properties, including film thickness, wettability, topography, and roughness. The most promising membranes were used for enzyme attachment. Two model enzymes, laccase and tyrosinase, were adsorbed to the surface and their activity regarding the conversion of phenolic compounds was measured. This project is described in Chapter 1 in detail. In the second project, the interaction of the model pore-forming peptide melittin was studied in combination with a planar synthetic membrane. The investigation focused the interaction of melittin with amphiphilic block copolymer-based synthetic planar membranes as well as the insertion of melittin into these membranes to induce pore formation. Some specific molecular properties of the block copolymers and of the resulting membranes were selected for the investigation, such as hydrophilic to hydrophobic block ratio, membrane thickness and surface roughness. Through melittin addition to the synthetic membranes, melittin insertion requirements were better understood. This project is described in Chapter 2 in detail. Each chapter contains a separate introduction, material and methods section and conclusion and outlook specific to the project.20 In summary, in this thesis the properties of different combinations and applications of polymer-based membranes with biomolecules were investigated to a deeper level

Amphiphilic Peptide Self-Assembly: Expansion to Hybrid Materials

The design of functional systems with sizes in the nanometer range is a key challenge in fields such as biomedicine, nanotechnology, and engineering. Some of the most promising materials nowadays consist of self-assembling peptides or peptide–polymer hybrid materials because of their versatility and the resulting properties that can be achieved with these structures. Self-assembly of pure amphiphilic peptides or in combination with block copolymers results in a large variety of nanostructures (micelles, nanoparticles (NPs), compartments, planar membranes) each with different characteristics and tunable properties. Here, we describe such novel peptide- or peptide–polymer-based supramolecular nanostructures and emphasize their functionality and various promising applications

Biomimetic Planar Polymer Membranes Decorated with Enzymes as Functional Surfaces

Functional surfaces were generated by a combination of enzymes with polymer membranes composed of an amphiphilic, asymmetric block copolymer poly(ethyleneglycol)-block-poly(γ-methyl-ε-caprolactone)-block-poly[(2-dimethylamino)ethylmethacrylate]. First, polymer films formed at the air–water interface were transferred in different sequences onto silica solid support using the Langmuir–Blodgett technique, generating homogeneous monolayers and bilayers. A detailed characterization of these films provided insight into their properties (film thickness, wettability, topography, and roughness). On the basis of these findings, the most promising membranes were selected for enzyme attachment. Functional surfaces were then generated by the adsorption of two model enzymes that can convert phenol and its derivatives (laccase and tyrosinase), well known as high-risk pollutants of drinking and natural water. Both enzymes preserved their activity upon immobilization with respect to their substrates. Depending on the properties of the polymer films, different degrees of enzymatic activity were observed: bilayers provided the best conditions in terms of both overall stability and enzymatic activity. The interaction between amphiphilic triblock copolymer films and enzymes is exploited to engineer “active surfaces” with specific functionalities and high efficacy resulting from the intrinsic activity of the biomolecules that is preserved by an appropriate synthetic environment

How Do the Properties of Amphiphilic Polymer Membranes Influence the Functional Insertion of Peptide Pores?

Pore-forming peptides are of high biological relevance particularly as cytotoxic agents, but their properties are also applicable for the permeabilization of lipid membranes for biotechnological applications, which can then be translated to the more stable and versatile polymeric membranes. However, their interactions with synthetic membranes leading to pore formation are still poorly understood, hampering the development of peptide-based nanotechnological applications, such as biosensors or catalytic compartments. To elucidate these interactions, we chose the model peptide melittin, the main component of bee venom. Here, we present our systematic investigation on how melittin interacts with and inserts into synthetic membranes, based on amphiphilic block copolymers, to induce pore formation in three different setups (planar membranes and micrometric and nanometric vesicles). By varying selected molecular properties of block copolymers and resulting membranes (e.g., hydrophilic to hydrophobic block ratio, membrane thickness, surface roughness, and membrane curvature) and the stage of melittin addition to the synthetic membranes, we gained a deeper understanding of melittin insertion requirements. In the case of solid-supported planar membranes, melittin interaction was favored by membrane roughness and thickness, but its insertion and pore formation were hindered when the membrane was excessively thick. The additional property provided by micrometric vesicles, curvature, increased the functional insertion of melittin, which was evidenced by the even more curved nanometric vesicles. Using nanometric vesicles allowed us to estimate the pore size and density, and by changing the stage of melittin addition, we overcame the limitations of peptideâEuro"polymer membrane interaction. Mirroring the functionality assay of planar membranes, we produced glucose-sensing vesicles. The design of synthetic membranes permeabilized with melittin opens a new path toward the development of biosensors and catalytic compartments based on pore-forming peptides functionally inserted in synthetic planar or three-dimensional membranes

Functional Surfaces: Bio-Hybrid Membranes for Biosensing

Combining natural enzymes with synthetic membranes on solid support enables creation of functional surfaces able to serve for efficient biosensing. Enzymes (laccase and tyrosinase) integrated on soft copolymer mono- and bilayer membranes preserve their activity and specifically detect the presence of phenols. The straightforward approach to create these bio-hybrid membranes allows changing the enzyme type and thus producing functional surfaces for sensitive detection of desired molecules

Chapter 6 Bio-inspired Polymer Membranes

Bio-inspired polymer membranes are artificial membranes designed to be combined with biomolecules (proteins, enzymes, mimics, nucleic acids), and provide both an increased mechanical stability of the overall system and an environment to preserve the functionality of the biomolecules. Here, we present synthetic membranes resulting from the self-assembly of amphiphilic block copolymers, both as 3D assemblies (polymer vesicles), and as 2D planar membranes (free standing films or membranes on solid/porous supports). Whilst in their early stage of research, the advantages of bio-inspired membranes support them as ideal candidates for the development of hybrid materials with multifunctionality and selectivity resulting from the presence of the biomolecules, and with stability and robustness due to the synthetic membrane. By serving as mimics of natural membranes with improved properties, bio-inspired synthetic membranes are on focus today for various applications in domains such as medicine, environment, and technology

Acute post-operation cardiac insufficiency in artifical blood circulation conditions (new approach to diagnosis, analysis and selection of trends of curative effect)

Available from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

Biomimetic Planar Polymer Membranes Decorated with Enzymes as Functional Surfaces

Functional surfaces were generated by a combination of enzymes with polymer membranes composed of an amphiphilic, asymmetric block copolymer poly­(ethyleneglycol)-<i>block</i>-poly­(γ-methyl-ε-caprolactone)-<i>block</i>-poly­[(2-dimethylamino)­ethylmethacrylate]. First, polymer films formed at the air–water interface were transferred in different sequences onto silica solid support using the Langmuir–Blodgett technique, generating homogeneous monolayers and bilayers. A detailed characterization of these films provided insight into their properties (film thickness, wettability, topography, and roughness). On the basis of these findings, the most promising membranes were selected for enzyme attachment. Functional surfaces were then generated by the adsorption of two model enzymes that can convert phenol and its derivatives (laccase and tyrosinase), well known as high-risk pollutants of drinking and natural water. Both enzymes preserved their activity upon immobilization with respect to their substrates. Depending on the properties of the polymer films, different degrees of enzymatic activity were observed: bilayers provided the best conditions in terms of both overall stability and enzymatic activity. The interaction between amphiphilic triblock copolymer films and enzymes is exploited to engineer “active surfaces” with specific functionalities and high efficacy resulting from the intrinsic activity of the biomolecules that is preserved by an appropriate synthetic environment