The 3D printing with curing via post extrusion heating for inks based on a chitosan/b-glycerophosphate/NaHCO3 (CS/GP/ NaHCO3) mixture was demonstrated. The effect of molecular weight, deacetylation degree of chitosan, and solution concentration on the gelation process was investigated: the composition containing 2% of CS (molecular weight 900 kDa and deacetylation degree of 68%) and 0.1 M acetic acid mixed with GP in 0.4 M NaHCO3 demonstrated optimal rheological characteristics for direct ink writing. Mechanical properties of printed gels were in line with physically crosslinked 3D printed CS based ones reported in literature and higher than for 3D printed CS/GP systems.

Two- and three-component deep eutectic solvents (DES) based on acrylic acid (AA), acrylamide (AAm), and choline chloride (ChCl) were used to disintegrate bacterial cellulose into cellulose nanofibers (CNF). As a result, polymerizable precursors suitable for 3D printing with CNF as a rheology modifier and reinforcer with formation of interpenetrating double polymer network were obtained after UV curing. Composite hydrogels were formed by replacing ChCl with water. It was found that the introduction of amide groups into the acrylate polymer matrix resulted in an increase in compressive strength. The layered architecture of the 3D printed products provides greater mechanical strength compared to molded products. The structure of the composites was investigated using wide-angle X-ray scattering (WAXS), small-angle X-ray scattering (SAXS), atomic force microscopy (AFM) and polarized light microscopy. These studies suggest that the enhanced mechanical properties of the 3D printed hydrogels are associated with swelling and branching of CNF in the DES, as well as alignment of the filler during extrusion. For comparative analysis, composite hydrogels were also prepared using aqueous solutions of AA and AA/AAm with dispersed CNF. However, the 3D printing process was hampered in this case due to cellulose agglomeration. Mechanical testing revealed the formation of premature microcracks in these samples, which were not observed in composites produced using DES. Cytotoxicity of the composite hydrogels was also tested. The results provide valuable insights into the production of strong (up to 3.4 MPa) homogeneous composite hydrogels using 3D printing with nanocellulose filler.

Composite hydrogel of cross-linked polyacrylamide (PAAm) containing cellulose-g-poly(methacrylic acid) molecular brushes (MB) as a "soft" filler was prepared by thermoinitiated radical polymerization of acrylamide in the presence of MB. Interaction between linear PAAm and MB results in decrease in PAAm viscosity at high shear rates and increase in storage modulus of mixed solution. Even low amount of MB results in increasing of ultimate compression of PAAm hydrogel, while concentration of MB in semidilute solution regime results in significant increase of hydrogel strength from 2.3 to 6.0 MPa. The use of permeable "soft" filler also allows to preserve high conductivity of hydrogel combined with improved mechanical properties.

Here, for the first time, the structure of genes involved in sex determination in mammals (full Sry and partial Rspo1, Eif2s3x, and Eif2s3y) was analyzed for the European mole Talpa europaea with ovotestes in females. We confirmed male-specificity for Eif2s3y and Sry. Five exons were revealed for Rspo1 and the deep similarity with the structure of this gene in T. occidentalis was proved. The most intriguing result was obtained for the Sry gene, which, in placental mammals, initiates male development. We described two exons for this canonically single-exon gene: the first (initial) exon is only 15 bp while the second exon includes 450 bp. The exons are divided by an extended intron of about 1894 bp, including the fragment of the LINE retroposon. Moreover, in chromatogram fragments, which correspond to intron and DNA areas, flanking both exons, we revealed double peaks, similar to heterozygous nucleotide sites of autosomal genes. This may indicate the existence of two or more copies of the Sry gene. Proof of copies requires an additional in-depth study. We hypothesize that unusual structure and possible supernumerary copies of Sry may be involved in ovotestes formation.

Macromolecules of complex architecture find application as modifiers of commercial polymeric membrane materials. In this work, copolyimide molecular brushes (coPI) composed of polyimide backbone and poly(methacrylic acid) side chains were used to modify poly(m-phenylene iso-phthalamide) (PPA). Structure, physical, mechanical, and transport properties of dense nonporous PPA/coPI membranes containing up to 10 wt% coPI were studied. The effect of included coPI on the membrane structure was estimated using atomic force microscopy and mechanical tests. The coPI modifier contributes to the additional formation of free volume elements evenly distributed throughout the membrane. Transport properties of PPA/coPI membranes were investigated via sorption tests and pervaporation separation of methanol (MeOH) and methyl tert-butyl ether (MTBE) mixtures. The inclusion of coPI modifier in the PPA membrane leads to an increase in the total flux of the membrane. The highest separation factor was found for the PPA/coPI membrane containing 10 wt% coPI; transport properties of the best membrane were compared with the literature data on separation of the azeotropic MeOH-MTBE mixture.

Myocardin-related transcription factors (MRTFs) are coactivators of serum response factor (SRF), and thereby regulate cytoskeletal gene expression in response to actin dynamics. MRTFs have also been implicated in transcription of heat shock protein (HSP)-encoding genes in fly ovaries, but the mechanisms remain unclear. Here, we demonstrate that, in mammalian cells, MRTFs are dispensable for gene induction of HSP-encoding genes. However, the widely used small-molecule inhibitors of the MRTF-SRF transcription pathway, derived from CCG-1423, also efficiently inhibit gene transcription of HSP-encoding genes in both fly and mammalian cells in the absence of MRTFs. Quantifying RNA synthesis and RNA polymerase distribution demonstrates that CCG-1423-derived compounds have a genome-wide effect on transcription. Indeed, tracking nascent transcription at nucleotide resolution reveals that CCG-1423-derived compounds reduce RNA polymerase II elongation, and severely dampen the transcriptional response to heat shock. The effects of CCG-1423-derived compounds therefore extend beyond the MRTF-SRF pathway into nascent transcription, opening novel opportunities for their use in transcription research.

The high specificity of human antibodies to blood group A and B antigens is impressive, especially when considering the structural difference between these antigens (tetrasaccharides) is a NHAc versus a hydroxyl group on the terminal monosaccharide residue. It is well established that in addition to anti-A and anti-B there is a third antibody, anti-A,B capable of recognizing both A and B antigens. To analyze this AB specificity, we synthesized a tetrasaccharide, where the NHAc of the A antigen was replaced with an NH2. This NH2 group was then used to attach the glycan to an affinity resin, creating an AB epitope (ABep) adsorbent where the critical site for recognition by A and B antibodies was not accessible, while the rest of the (conformationally compact) tetrasaccharide remained accessible. Anti-ABep antibodies were then isolated from blood group O donors and found to have expected A,B specificity against immobilized and red cell bound synthetic antigens, including ABep, and were able to agglutinate both A and B red cells. The amount of these anti-ABep (anti-A,B) antibodies found in the blood of group O donors was comparable to levels of anti-A and anti-B found in group B and A individuals. Using STD-NMR the location for the AB epitope on the tetrasaccharide was found. Antibodies were isolated from the blood of group O individuals that bound equally to antigens A and B, including agglutination of erythrocytes both A and B. STD NMR data correspond to the topography of the predicted epitope: STD-active H atoms, shown in red, are concentrated at the same epitope subsite. image

Nuclear actin has been demonstrated to be essential for optimal transcription, but the molecular mechanisms and direct binding partner for actin in the RNA polymerase complex have remained unknown. By using purified proteins in a variety of biochemical assays, we demonstrate a direct and specific interaction between monomeric actin and Cdk9, the kinase subunit of the positive transcription elongation factor b (P-TEFb) required for RNA polymerase II pause-release. This interaction efficiently prevents actin polymerization, is not dependent on kinase activity of Cdk9 and is not involved with releasing P-TEFb from its inhibitor 7SK snRNP complex. Supporting the specific role for actin in the elongation phase of transcription, chromatin immunoprecipitation followed by deep sequencing (ChIP-seq) reveals that actin interacts with genes only upon their active transcription elongation. This study therefore provides novel insights into the mechanisms by which actin facilitates the transcription process.

The aim of this study was to develop self-healable and robust electroconductive film based on polyaniline copolymer for application as electrode in flexible supercapacitor. For this purpose, the electroconductive polymer brushes (EPB) was elaborated. The synthesis of EPB is based on graft polymerizations of acrylamide (AAm) on poly(vinyl alcohol) (PVA) with formation of PVA-PAAm polymer brush and subsequent graft copolymerization of aniline and p-phenylenediamine on PVA-PAAm resulting in formation of EPB with electroconducting copoly(aniline-co-p-phenylenediamine) (PAPhDA). It was found that the ratio between PVA and PAAm at the first stage greatly influence the electrochemical performance of the EPBs. Electroconducting films were prepared by casting of EPB solution with subsequent drying. Investigation of electrical current distribution through the film with AFM reveal more uniform distribution of PAPhDA in EPB in comparison with reference PVA-PAPhDA and PAAm-PAPhDA samples. It was demonstrated that mechanical characteristics and electrical conductivity values of films restore at large extent after curring and self-healing under optimal relative humidity level (58

In order to create new high efficient anticancer drugs for photodynamic therapy (PDT) the triple complexes on the basis of the zero-valent selenium (Se0) nanoparticles, graft copolymer (Cell-graft-PMAA) and photosensitizer-fotoditazin (FD) with various priority of introduction of the components have been synthesized and studied. The comparative studies of the spectral and morphological characteristics of the triple complexes (Cell-graft-PMAA/SeNPs) (the 1st method) and (Cell-graft-PMAA/FD/SeNPs) (the 2nd method) with the similar characteristics of FD and double complexes of the variable composition (SeNPs/Cell-graft-PMAA, SeNPs/FD and Cell-graft-PMAA/FD) were carried out by means of UV/IR spectroscopy, luminescence and atomic force microscopy. By means of the UV spectroscopy it was demonstrated that the value of the optical density in the range of PDT wavelength (Q-range) is higher in the triple systems by 30–40

In this paper, we report on novel polyimide (PI) nanocomposites filled with binary mixtures of metal oxide (either TiO2 or ZrO2) nanoparticles and nanocarbon (either carbon nanofibers (CNFs) or functionalized carbon nanotubes (CNT(f)s)). The structure and morphology of the materials obtained were comprehensively studied. An exhaustive investigation of their thermal and mechanical properties was performed. We revealed a synergistic effect of the nanoconstituents with regard to a number of functional characteristics of the PIs compared with single-filler nanocomposites, including thermal stability, stiffness (below and above glass transition temperature), yield point, and temperature of flowing. Moreover, the possibility of manipulating the properties of the materials by choosing a proper combination of the nanofillers was demonstrated. The results obtained can become a platform in the design of PI-based engineering materials with tailored characteristics capable of operating in extreme conditions.

Green method for preparation of ion-conducting membranes (ICM) based on bacterial cellulose nanofibers (CNF) modified by a copolymer of sodium acrylate and 2-acrylamido-2-methylpropanesulfonic acid was elaborated. FTIR and NMR data confirmed grafting of poly-acrylate onto cellulose surface. Formation of porous structure of the ICM was controlled by SEM and AFM. The maximal ionic conductivity of the membranes reaches 1.5 and 3.1 mS·cm−1 (60 °C and 98

The aim of this work was to study the influence of water as a co-solvent on the interaction between a polymerizable ionic liquid—choline acrylate (ChA)—and bacterial cellulose. Bacterial cellulose dispersed in ChA is a new type of UV-curable biopolymer-based ink that is a prospective material for the 3D printing of green composite ion-gels. Higher cellulose content in inks is beneficial for the ecological and mechanical properties of materials, and leads to increased viscosity and the yield stress of such systems and hampers printability. It was found that the addition of water results in (1) a decrease in the solvent viscosity and yield stress; and (2) a decrease in the stability of dispersion toward phase separation under stress. In this work, an optimal composition in the range of 30–40 wt% water content demonstrating 97–160 Pa of yield stress was found that ensures the printability and stability of inks. The rheological properties of inks and mechanical characteristics (0.7–0.8 MPa strength and 1.1–1.2 MPa Young’s modulus) were obtained. The mechanism of influence of the ratio ChA/water on the properties of ink was revealed with atomic force microscopy, wide-angle X-ray diffraction studies of bacterial cellulose after regeneration from solvent, and computer simulation of ChA/water mixtures and their interaction with the cellulose surface.

This feature article is devoted to the evaluation of different techniques for producing colloidal polyelectrolyte brushes (CPEBs) based on cellulose nanofibers modified with grafted polyacrylates. The paper also reviews the potential applications of these CPEBs in designing electrode materials and as reinforcing additives. Additionally, we discuss our own perspectives on investigating composites with CPEBs. Herein, polyacrylic acid (PAA) was grafted onto the surface of cellulose nanofibers (CNFs) employing a “grafting from” approach. The effect of the PAA shell on the morphological structure of a composite with polypyrrole (PPy) was investigated. The performance of as-obtained CNF-PAA/PPy as organic electrode material for supercapacitors was examined. Furthermore, this research highlights the ability of CNF-PAA filler to act as an additional crosslinker forming a physical sub-network due to the hydrogen bond interaction inside chemically crosslinked polyacrylamide (PAAm) hydrogels. The enhancement of the mechanical properties of the material with a concomitant decrease in its swelling ratio compared to a pristine PAAm hydrogel was observed. The findings were compared with the recent theoretical foundation pertaining to other similar materials.

Chromatin is composed of DNA and its associated proteins, and has an essential role in all cellular processes, including those taking place during Drosophila oogenesis. In order to understand the molecular basis of chromatin-based processes, such as transcription, it is essential to be able to study how and when different proteins, such as transcription factors, histones and RNA polymerases, interact with chromatin. One of the most popular methods to study this is chromatin immunoprecipitation followed by next generation sequencing (ChIP-seq). Here, we describe a ChIP-seq protocol that has been optimized for Drosophila ovaries, focusing on sample preparation through preliminary data processing.

Inks for 3D printing were prepared by dispersing bacterial cellulose nanofibers (CNF) functionalized with methacrylate groups in a polymerizable deep eutectic solvent (DES) based on choline chloride and acrylic acid with water as a cosolvent. After 3D printing and UV-curing, the double-network composite gel consisting of chemically and physically crosslinked structures composed from sub-networks of modified CNF and polymerized DES, respectively, was formed. The rheological properties of inks, as well as mechanical and shape memory properties of the 3D-printed gels, were investigated in dynamic and static modes. It was shown that the optimal amount of water allows improvement of the mechanical properties of the composite gel due to the formation of closer contacts between the modified CNF. The addition of 12 wt% water results in an increase in strength and ultimate elongation to 11.9 MPa and 300%, respectively, in comparison with 5.5 MPa and 100% for an anhydrous system. At the same time, the best shape memory properties were found for an anhydrous system: shape fixation and recovery coefficients were 80.0 and 95.8%, respectively.

Surface modification of polylactide films was performed using a dielectric barrier discharge (DBD) with the aim of increasing proliferative activity of human fibroblasts on these films. It has been shown that during the plasma treatment of the polylactide film, nonlinear processes occur depending on the processing time. The effect of the dielectric barrier discharge on the modification of polylactide films was evaluated using IR spectroscopy, AFM, XPS, TSDC, and the wetting angle of the surface. The optimal processing time in DBD of polylactide films is 3 min for this installation, the proliferative activity increases by 10% compared to the original film. This treatment time provides an increased concentration of oxygen-containing groups, optimal relief, and free surface energy of 55 mJ/m(2) on the surface.

Myocardin-related transcription factor A (MRTF-A), a coactivator of serum response factor (SRF), regulates the expression of many cytoskeletal genes in response to cytoplasmic and nuclear actin dynamics. Here we describe a novel mechanism to regulate MRTF-A activity within the nucleus by showing that lamina-associated polypeptide 2α (Lap2α), the nucleoplasmic isoform of Lap2, is a direct binding partner of MRTF-A, and required for the efficient expression of MRTF-A/SRF target genes. Mechanistically, Lap2α is not required for MRTF-A nuclear localization, unlike most other MRTF-A regulators, but is required for efficient recruitment of MRTF-A to its target genes. This regulatory step takes place prior to MRTF-A chromatin binding, because Lap2α neither interacts with, nor specifically influences active histone marks on MRTF-A/SRF target genes. Phenotypically, Lap2α is required for serum-induced cell migration, and deregulated MRTF-A activity may also contribute to muscle and proliferation phenotypes associated with loss of Lap2α. Our studies therefore add another regulatory layer to the control of MRTF-A-SRF-mediated gene expression, and broaden the role of Lap2α in transcriptional regulation.

3D-printing of stimuli-responsible electroactive gels containing biopolymers, such as cellulose nanocrystals (CNC), is a prospective area of material science. Deep eutectic solvents (DES) have shown a potential interest for applications in electroactive materials as well as for processing of cellulose. In this work, CNC obtained by two methods of processing microcrystalline cellulose were used for preparation of inks containing 6-15 wt% of CNC in polymerizable DES based on choline chloride/acrylic acid. The impact of rheological properties of the inks on 3D-printability was evaluated. The effect of CNC content on the morphology and ionic conductivity of 3D-printed electroactive composite gels was investigated using atomic force microscopy and impedance spectroscopy measurements. The potential application of the obtained materials for designing of a 3D-printed tactile sensor have been demonstrated.