Mimicking Primitive Photobacteria: Sustainable Hydrogen Evolution Based on Peptide–Porphyrin Co‐Assemblies with a Self‐Mineralized Reaction Center

Molecular evolution, with self‐organization of simple molecules towards complex functional systems, provides a new strategy for biomimetic architectonics and perspectives for understanding the complex processes of life. However, there remain many challenges to fabrication of systems comprising different types of units, which interact with one another to perform desired functions. Challenges arise from a lack of stability, dynamic properties, and functionalities that reconcile with a given environment. A co‐assembling fiber system composed of simple peptide and porphyrin is presented. This material is considered a prebiotic assembly of molecules that can be rather stable and flexibly self‐functionalized with the assistance of visible light in a “prebiotic soup”; acidic (pH 2), hot (70 °C), and mineral‐containing (Na⁺, Ti⁴⁺, Pt²⁺, and so forth) water. The co‐assembled peptide–porphyrin fiber, with self‐mineralized reaction centers, may serve as a primitive photobacteria‐like cellular model to achieve light harvesting, energy transfer, and ultimately sustainable hydrogen evolution.     

Electron transport and electrochemistry of mesomorphic fullerenes with long-range ordered lamellae

Fullerenes, C60, modified with long alkyl chains form long-range ordered lamellar mesophases permitting a high C60 content. The mesomorphic fullerenes feature reversible electrochemistry and a comparably high electron carrier mobility making them attractive components for fullerene-based soft materials.     

Self-assembly of S-layer-enveloped cytochrome c polyelectrolyte multilayers

We report a study of the electrostatic layer-by-layer self-assembly of electroactive polyelectrolyte multilayers incorporating the redox protein cytochrome c (cyt c) combined with recrystallization of the bacterial cell wall surface layer from Bacillus sphaericus CCM 2177 SbpA (S-layer). The polyelectrolyte multilayer assembly was prepared on flat gold electrodes with a nanometer-scale roughness that allowed monitoring of the film formation throughout all the assembly stages by atomic force microscopy measurements in liquid with respect to topography and forces. The deposition of alternating layers of sulfonated polyaniline and cyt c was carried out by adsorption from the corresponding solutions on a cyt c monolayer electrode. The electroactivity of cyt c within the assembly was confirmed by cyclic voltammetry. We showed that the surface properties of the electrode terminating layer change after each adsorption step accordingly. We also found that S-layer recrystallization on the top of the multilayer film was feasible while electroactivity of cyt c within a polyelectrolyte matrix was partially maintained. This approach offers a new strategy to design a biocompatible and permselective outer envelope of a polyelectrolyte multilayer, promising sensor applications.     

Thin films of cross-linked metallo-supramolecular coordination polyelectrolytes

We report on the synthesis of a new tristerpyridine ligand, tris(2,2':6',2' '-terpyridinyl-4'-oxymethyl)ethane (tritpy), as well as its introduction into metal ion induced self-assembly of cross-linked metallo-supramolecular coordination polyelectrolytes (MEPE). For cross-linking degrees of 9.5% and below, soluble homogeneous networks are obtained. The molar mass of the networks is large and depends on the cross-linking degree. Due to the charges in the MEPE, the soluble networks are suitable for film formation on the basis of layer-by-layer self-assembly and to study the details of film growth. UV-vis spectroscopy, X-ray reflectivity, AFM, and ellipsometry show that the film growth is linear and continuous. The multilayers exhibit no inner structure and have a very low surface roughness. The thickness of the adsorbed layer of MEPE networks is in the range of 3 nm. The important point is that an influence of cross-linking is not seen in multilayers, which is the opposite of what is observed for the MEPE in solution. Our experiments did not reveal an influence of the preparation procedure on the adsorption process, e.g., increasing the layer thickness.     

Anisotropic multicompartment micro- and nano-capsules produced via embedding into biocompatible PLL/HA films

We present a novel strategy to fabricate anisotropic multicompartment Janus capsules by embedding larger containers into a soft poly-L-lysine/hyaluronic acid (PLL/HA) polymeric film, followed by adsorption of smaller containers on top of their unmasked surface. This research is also attractive for developing substrates for cell cultures.     

Smart nanocontainers as depot media for feedback active coatings

Among the grand challenges at present are ways to develop systems with low consumption of raw materials and with little load on the environment. In view of this it is of utmost importance to avoid or to delay processes causing material destruction. This is especially urgent, since many protective substances have associated health hazards, and new routes to improve the situation are a main concern of this contribution. Nanocapsules (nanocontainers) with controlled release properties of the shell can be used to fabricate a new family of active coatings, with quick response to changes of the coating environment or coating integrity. The release of active materials encapsulated into nanocapsules is triggered by various external and internal factors, thus preventing spontaneous leakage of the active component. The coating can have several active functionalities when several types of nanocapsules loaded with corresponding active agent are incorporated simultaneously into a coating matrix. We highlight recent achievements in development and application of filled responsive containers in biomedical and self-healing protective coatings.