Ameloblastin (AMBN), an important component of the self-assembled enamel extra cellular matrix, contains several in silico predicted phosphorylation sites. However, to what extent these sites actually are phosphorylated and the possible effects of such post-translational modifications are still largely unknown. Here we report on in vitro experiments aimed at investigating what sites in AMBN are phosphorylated by casein kinase 2 (CK2) and protein kinase A (PKA) and the impact such phosphorylation has on self-assembly and calcium binding. All predicted sites in AMBN can be phosphorylated by CK2 and/or PKA. The experiments show that phosphorylation, especially in the exon 5 derived part of the molecule, is inversely correlated with AMBN self-assembly. These results support earlier findings suggesting that AMBN self-assembly is mostly dependent on the exon 5 encoded region of the AMBN gene. Phosphorylation was significantly more efficient when the AMBN molecules were in solution and not present as supramolecular assemblies, suggesting that post-translational modification of AMBN must take place before the enamel matrix molecules self-assemble inside the ameloblast cell. Moreover, phosphorylation of exon 5, and the consequent reduction in self-assembly, seem to reduce the calcium binding capacity of AMBN suggesting that post-translational modification of AMBN also can be involved in control of free Ca2+ during enamel extra cellular matrix biomineralization. Finally, it is speculated that phosphorylation can provide a functional crossroad for AMBN either to be phosphorylated and act as monomeric signal molecule during early odontogenesis and bone formation, or escape phosphorylation to be subsequently secreted as supramolecular assemblies that partake in enamel matrix structure and mineralization.

• Klíčová slova
• Ca2+- binding, ameloblastin, casein kinase 2, enamel, intrinsically disordered proteins, phosphorylation, protein kinase A, self-assembly,
• Publikační typ
• časopisecké články MeSH

Lignin serves as a significant contributor to the natural stock of non-fossilized carbon, second only to cellulose in the biosphere. In this review article, we focus on the self-assembly properties of lignin and their contribution to its effective utilization and valorization. Traditionally, investigations on self-assembly properties of lignin have aimed at understanding the lignification process of the cell wall and using it for efficient delignification for commercial purposes. In recent years (mainly the last three years), an increased number of attempts and reports of technical-lignin nanostructure synthesis with controlled particle size and morphology have been published. This has renewed the interests in the self-assembly properties of technical lignins and their possible applications. Based on the sources and processing methods of lignin, there are significant differences between its structure and properties, which is the primary obstacle in the generalized understanding of the lignin structure and the lignification process occurring within cell walls. The reported studies are also specific to source and processing methods. This work has been divided into two parts. In the first part, the aggregation propensity of lignin based on type, source and extraction method, temperature, and pH of solution is discussed. This is followed by a critical overview of non-covalent interactions and their contribution to the self-associative properties of lignin. The role of self-assembly towards the understanding of xylogenesis and nanoparticle synthesis is also discussed. A particular emphasis is placed on the interaction and forces involved that are used to explain the self-association of lignin.

• Klíčová slova
• lignin, lignin nanoparticles, noncovalent interactions, self-assembly,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Tubulin self-assembly into microtubules is a fascinating natural phenomenon. Its importance is not just crucial for functional and structural biological processes, but it also serves as an inspiration for synthetic nanomaterial innovations. The modulation of the tubulin self-assembly process without introducing additional chemical inhibitors/promoters or stabilizers has remained an elusive process. This work reports a versatile and vigorous strategy for controlling tubulin self-assembly by nanosecond electropulses (nsEPs). The polymerization assessed by turbidimetry is dependent on nsEPs dosage. The kinetics of microtubules formation is tightly linked to the nsEPs effects on structural properties of tubulin, and tubulin-solvent interface, assessed by autofluorescence, and the zeta potential. Moreover, the overall size of tubulin assessed by dynamic light scattering is affected as well. Additionally, atomic force microscopy imaging reveals the formation of different assemblies reflecting applied nsEPs. It is suggested that changes in C-terminal modification states alter tubulin polymerization-competent conformations. Although the assembled tubulin preserve their integral structure, they might exhibit a broad range of new properties important for their functions. Thus, these transient conformation changes of tubulin and their collective properties can result in new applications.

• Klíčová slova
• microtubules, nanosecond pulsed electric field, self-assembly, tubulin,
• MeSH
• elektřina * MeSH
• hydrodynamika MeSH
• kinetika MeSH
• kvarterní struktura proteinů MeSH
• mikrotubuly metabolismus   MeSH
• molekulární modely MeSH
• multimerizace proteinu * MeSH
• tubulin chemie   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• tubulin MeSH

Although the behavior of the confined semi-dilute solutions of self-assembling copolymers represents an important topic of basic and applied research, it has eluded the interest of scientists. Extensive series of dissipative particle dynamics simulations have been performed on semi-dilute solutions of A5B5 chains in a selective solvent for A in slits using a DL-MESO simulation package. Simulations of corresponding bulk systems were performed for comparison. This study shows that the associates in the semi-dilute bulk solutions are partly structurally organized. Mild steric constraints in slits with non-attractive walls hardly affect the size of the associates, but they promote their structural arrangement in layers parallel to the slit walls. Attractive walls noticeably affect the association process. In slits with mildly attractive walls, the adsorption competes with the association process. At elevated concentrations, the associates start to form in wide slits when the walls are sparsely covered by separated associates, and the association process prevents the full coverage of the surface. In slits with strongly attractive walls, adsorption is the dominant behavior. The associates form in wide slits at elevated concentrations only after the walls are completely and continuously covered by the adsorbed chains.

• Klíčová slova
• confined copolymer, dissipative particle dynamics, polymer–wall interaction, selective solvent, self-assembly, slit,
• Publikační typ
• časopisecké články MeSH

Nature presents the collective behavior of living organisms aiming to accomplish complex tasks, inspiring the development of cooperative micro/nanorobots. Herein, the spontaneous assembly of hematite-based microrobots with different shapes is presented. Autonomous motile light-driven hematite/Pt microrobots with cubic and walnut-like shapes are prepared by hydrothermal synthesis, followed by the deposition of a Pt layer to design Janus structures. Both microrobots show a fuel-free motion ability under light irradiation. Because of the asymmetric orientation of the magnetic dipole moment in the crystal, cubic hematite/Pt microrobots can self-assemble into ordered microchains, contrary to the random aggregation observed for walnut-like microrobots. The microchains exhibit different synchronized motions under light irradiation depending on the mutual orientation of the individual microrobots during the assembly, which allows them to accomplish multiple tasks, including capturing, picking up, and transporting microscale objects, such as yeast cells and suspended matter in water extracted from personal care products, as well as degrading polymeric materials. Such light-powered self-assembled microchains demonstrate an innovative cooperative behavior for small-scale multitasking artificial robotic systems, holding great potential toward cargo capture, transport, and delivery, and wastewater remediation.

• Klíčová slova
• cargo transport, collective behavior, micromotors, photo-Fenton degradation, self-assembly, swarming,
• MeSH
• magnetismus MeSH
• polymery * MeSH
• voda * MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• ferric oxide MeSH Prohlížeč
• polymery * MeSH
• voda * MeSH

Biomimetic chiral optoelectronic materials can be utilized in electronic devices, biosensors and artificial enzymes. Herein, this work reports the chiro-optical properties and architectural arrangement of optoelectronic materials generated from self-assembly of initially nonchiral oligothiophene-porphyrin derivatives and random coil synthetic peptides. The photo-physical- and structural properties of the materials were assessed by absorption-, fluorescence- and circular dichroism spectroscopy, as well as dynamic light scattering, scanning electron microscopy and theoretical calculations. The materials display a three-dimensional ordered helical structure and optical activity that are observed due to an induced chirality of the optoelectronic element upon interaction with the peptide. Both these properties are influenced by the chemical composition of the oligothiophene-porphyrin derivative, as well as the peptide sequence. We foresee that our findings will aid in developing self-assembled optoelectronic materials with dynamic architectonical accuracies, as well as offer the possibility to generate the next generation of materials for a variety of bioelectronic applications.

• Klíčová slova
• circular dichroism, oligothiophene, porphyrin, self-assembly, synthetic peptides,
• MeSH
• biomimetické materiály * MeSH
• mikroskopie elektronová rastrovací MeSH
• peptidy chemie   MeSH
• porfyriny * chemie   MeSH
• sekvence aminokyselin MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• peptidy MeSH
• porfyriny * MeSH

Racemic and highly enantioenriched 3-methoxycarbonyl, 3-carboxy, and 3-hydroxymethyl derivatives of dibenzo[6]helicene were prepared. The Langmuir layers of these helicenes were formed at the air-water interface and transferred onto solid substrates to afford Langmuir-Blodgett films, which were then studied by ambient atomic force microscopy and (chir)optical spectroscopy. Significant differences were found in the behaviour of the Langmuir layers as well as in the morphology, UV/Vis, electronic circular dichroism (ECD), and fluorescence spectra of the Langmuir-Blodgett thin films depending on the molecular chirality and nature of the polar group. The experimental results were supported by molecular dynamics simulations.

• Klíčová slova
• Langmuir-Blodgett films, arenes, chirality, helical structures, self-assembly,
• Publikační typ
• časopisecké články MeSH

HYPOTHESIS: Poly(vinyl alcohol)-g-poly(methyl methacrylate) (PVA-g-PMMA) amphiphilic copolymers self-assemble to form multi-micellar colloidal systems. EXPERIMENTS: A PVA-g-PMMA copolymer containing 16-17% w/w of PMMA was synthesized by the free radical graft polymerization of methyl methacrylate on a PVA backbone by utilizing cerium(IV) ammonium nitrate as initiator and tetramethylethylenediamine (TEMED) as initiation activator. The aggregation behavior of the copolymer in water was comprehensively characterized by dynamic light scattering (DLS) and static light scattering (SLS), small angle neutron scattering (SANS), asymmetrical flow field-flow fractionation (A4F) and transmission electron microscopy (TEM). The colloidal stability before and after non-covalent crosslinking of PVA domains with boric acid was assessed by DLS. Finally, nanoparticles were nano spray-dried. FINDINGS: This copolymer self-assembles in water to form a complex nanostructure of low aggregation number particles (ca. 12-15 nm in diameter) that aggregate into larger ones with size ca. 60-80 nm, as determined by SANS and TEM. In addition, boric acid-crosslinking preserves the nanoparticle size, while conferring full physical stability under extreme dilution conditions. Nano spray-drying consolidates the crosslnking and enables the production of a dry flowing powder that upon re-dispersion in water regenerates the nanoparticles without major size changes.

• Klíčová slova
• Asymmetric flow field-flow fractionation (A4F), Nano spray-drying, Poly(vinyl alcohol)-poly(methyl methacrylate) amphiphilic nanoparticles, Polymer self-assembly, Small-angle neutron scattering (SANS),
• Publikační typ
• časopisecké články MeSH

Amphiphilic gradient copolymers represent a promising alternative to extensively used block copolymers due to their facile one-step synthesis by statistical copolymerization of monomers of different reactivity. Herein, an in-depth analysis is provided of micelles based on amphiphilic gradient poly(2-oxazoline)s with different chain lengths to evaluate their potential for micellar drug delivery systems and compare them to the analogous diblock copolymer micelles. Size, morphology, and stability of self-assembled nanoparticles, loading of hydrophobic drug curcumin, as well as cytotoxicities of the prepared nanoformulations are examined using copoly(2-oxazoline)s with varying chain lengths and comonomer ratios. In addition to several interesting differences between the two copolymer architecture classes, such as more compact self-assembled structures with faster exchange dynamics for the gradient copolymers, it is concluded that gradient copolymers provide stable curcumin nanoformulations with comparable drug loadings to block copolymer systems and benefit from more straightforward copolymer synthesis. The study demonstrates the potential of amphiphilic gradient copolymers as a versatile platform for the synthesis of new polymer therapeutics.

• Klíčová slova
• gradient copolymers, nanomedicine, poly(2-oxazoline)s, self-assembly,
• MeSH
• hydrofobní a hydrofilní interakce MeSH
• kurkumin * chemie   MeSH
• micely * MeSH
• nosiče léků chemie   MeSH
• polymery chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kurkumin * MeSH
• micely * MeSH
• nosiče léků MeSH
• polymery MeSH

The modification of metal electrode surfaces with functional organic molecules is an important part of organic electronics. The interaction of the buckminsterfullerene fragment molecule pentaindenocorannulene with a Cu(100) surface is studied by scanning tunneling microscopy, dispersion-enabled density functional theory, and force field calculations. Experimental and theoretical methods suggest that two adjacent indeno groups become oriented parallel to the surface upon adsorption under mild distortion of the molecular frame. The binding mechanism between molecule and surface is dominated by strong electrostatic interaction owing to Pauli repulsion. Two-dimensional aggregation at room temperature leads to a single lattice structure in which all molecules are oriented unidirectionally. Their relative arrangement in the lattice suggests noncovalent intermolecular interaction through C-H⋅⋅⋅π bonding.

• Klíčová slova
• 2D self-assembly, density functional theory, fullerenes, metal surfaces, scanning tunneling microscopy,
• Publikační typ
• časopisecké články MeSH