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The separation of layered MFI into unilamellar nanosheets in solution confirms the general validity of soft-chemical exfoliation for zeolites and allows top-down production of films with potential applications in separation and catalysis.

Background: The proper sealing of the root canal seems to be critical to obtain a stable result of endodontic therapy. The sealer’s penetration into dentinal tubules during root canal treatment is probably a crucial factor to provide better clinical results. The aim of this study was to compare the effect of three irrigation protocols on the penetration of the epoxy sealer into dentinal tubules and two dyes used to stain the sealer. Methods: Ninety single-canaled human teeth with straight roots were used. The root canals were instrumented with Reciproc instruments up to the size 40/04 ISO. The teeth were divided into three groups (n = 30). The root canals of each group were rinsed accordingly: the control group 1: 5.25% sodium hypochlorite (NaOCl); the experimental group 2: smear layer removal (two times alternatively: 40% citric acid and 5.25% NaOCl) and NaOCl; the experimental group 3: smear layer removal (same as in group 2) and isopropyl alcohol. In each group the roots were further divided into 2 subgroups (n = 15). The root canals were obturated using warm vertical compaction technique of gutta-percha with AH Plus sealer marked with hydrophilic fluorescein (subgroup F) or hydrophobic porphyrin (subgroup P). After 72 h, one-millimeter-thick cross-sections were cut in two, five and eight millimeters distance from the apex. The depth of the penetration of the sealer into the dentinal tubules (resin tags) was measured with the use of a confocal laser microscope. Results: In of all the root parts, the longest resin tags were observed in group 2, whereas the shortest ones were found in group 1 (in the porphyrin subgroups all differences were statistically significant). Within the fluorescein subgroups, the differences between all groups were statistically significant in the middle section of the roots. In the apical and the coronal sections, significant differences were observed between group 1 and the other two groups. Conclusions: The isopropyl alcohol at the end of the irrigating protocol did not affect the higher sealer penetration of the sealer into the dentinal tubules compared with sodium hypochlorite. With the limitation of this study, the hydrophobic porphyrin may be considered as the favorable dye choice to stain endodontic sealers in further studies with confocal laser scanning microscopy, but the methods and reagents used should still be in the research phase.

Photosensitizers yielding superior photocurrents are crucial for copper-electrolyte-based highly efficient dye-sensitized solar cells (DSCs). Herein, two molecularly tailored organic sensitizers are presented, coded ZS4 and ZS5, through judiciously employing dithieno[3,2-b:2 ",3 "-d]pyrrole (DTP) as the pi-linker and hexyloxy-substituted diphenylquinoxaline (HPQ) or naphthalene-fused-quinoxaline (NFQ) as the auxiliary electron-accepting unit, respectively. Endowed with the HPQ acceptor, ZS4 shows more efficient electron injection and charge collection based on substantially reduced interfacial charge recombination as compared to ZS5. As a result, ZS4-based DSCs achieve a power conversion efficiency (PCE) of 13.2% under standard AM1.5G sunlight, with a high short-circuit photocurrent density (J(sc)) of 16.3 mA cm(-2), an open-circuit voltage (V-oc) of 1.05 V and a fill factor (FF) of 77.1%. Remarkably, DSCs sensitized with ZS4 exhibit an outstanding stability, retaining 95% of their initial PCE under continuous light soaking for 1000 h. It is believed that this is a new record efficiency reported so far for copper-electrolyte-based DSCs using a single sensitizer. The work highlights the importance of developing molecularly tailored photosensitizers for highly efficient DSCs with copper electrolyte.

DNA origami is a widely used DNA nanotechnology that allows construction of two-dimensional and three-dimensional nanometric shapes. The designability and rigidity of DNA origami make it an ideal material for construction of topologically linked molecules such as catenanes, which are attractive for their potential as motors and molecular machines. However, a general method for production of topologically linked DNA origami has been lacking. Here, we show that catenated single-stranded DNA circles can be produced and used as a universal scaffold for the production of topologically linked (catenated) DNA origami structures where the individual linked structures can be of any arbitrary design. Assembly of these topologically linked DNA origami structures is achieved via a simple one-pot annealing protocol.

Decoration of inorganic substrates with surface-grafted and perpendicularly oriented conjugated polymers has gained substantial attention spurred by the development of new facile synthetic methodologies. We have recently shown that conjugated polymer brushes with interesting optoelectrical properties and presupposed ladder-like architecture could be obtained by a self-templating surface-initiated polymerization (ST-SIP). In this report, nanomechanical properties of ladder-like brushes composed of alkyl backbones supported by conjugated polyacetylene chains are investigated by means of AFM nanoindentation, quantitative nanomechanical mapping (QNM), and lateral force microscopy (LFM) in air and organic solvents. It is shown that conversion of deprotected linear poly(3-trimethylsilyl-2-propynyl methacrylate) (PTPM) brushes into ladder-type brushes using ST-SIP leads to pronounced changes in the structure and mechanical properties of the formed films. Ladder-type brushes possess an open (porous) structure and enhanced stiffness compared to the parent brushes. In contrast to linear brushes, the Young's modulus of ladder-like brushes is shown to be independent of solvent quality, due to the low conformational freedom of the grafted chains. The LFM measurements reveal slightly enhanced lubricating properties of linear brushes. However, the differences between linear and ladder-like brushes are much smaller than those reported for typical isotropically crosslinked films. Degrafting experiments reveal the predominantly intramolecular mechanism of ST-SIP and hence efficient generation of ladder-type conjugated polymers. The observation of structure-dependent changes of mechanical properties revealed in this study indicates new opportunities to fine-tune interface properties by exploiting stretched polymer chains in advanced architectures leading to low conformational freedom.

A variety of polymeric scaffolds with the ability to control cell detachment has been created for cell culture using stimuli-responsive polymers. However, the widely studied and commonly used thermo-responsive polymeric substrates always affect the properties of the cultured cells due to the temperature stimulus. Here, we present a different stimuli-responsive approach based on poly(3-acrylamidopropyl)trimethylammonium chloride) (poly(APTAC)) brushes with homogeneously embedded superparamagnetic iron oxide nanoparticles (SPIONs). Neuroblastoma cell detachment was triggered by an external magnetic field, enabling a non-invasive process of controlled transfer into a new place without additional mechanical scratching and chemical/biochemical compound treatment. Hybrid scaffolds obtained in simultaneous surface-initiated atom transfer radical polymerization (SI-ATRP) were characterized by atomic force microscopy (AFM) working in the magnetic mode, secondary ion mass spectrometry (SIMS), and X-ray photoelectron spectroscopy (XPS) to confirm the magnetic properties and chemical structure. Moreover, neuroblastoma cells were cultured and characterized before and after exposure to a neodymium magnet. Controlled cell transfer triggered by a magnetic field is presented here as well.

The high stability and conductivity of 3,4-disubstituted polythiophenes such as poly(3,4-ethylenedioxythiophene) (PEDOT) make them attractive candidates for commercial applications. However, next-generation nanoelectronic devices require novel macromolecular strategies for the precise synthesis of advanced polymer structures as well as their arrangement. In this report, we present a synthetic route to make ladder-like polymer brushes with poly(3,4-propylenedioxythiophene) (PProDOT)-conjugated chains. The brushes were prepared via a self-templating surface-initiated technique (ST-SIP) that combines the surface-initiated atom transfer radical polymerization (SI-ATRP) of bifunctional ProDOT-based monomers and subsequent oxidative polymerization of the pendant ProDOT groups in the parent brushes. The brushes prepared in this way were characterized by grazing-angle FTIR, XPS spectroscopy, and AFM. Steady-state and time-resolved photoluminescence measurements were used to extract the information about the structure and effective conjugation length of PProDOT-based chains. Stability tests performed in ambient conditions and under exposure to standardized solar light revealed the remarkable stability of the obtained materials. ispartof: INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES vol:23 issue:11 ispartof: location:Switzerland status: published

Alternating donor–acceptor conjugated polymers, widely investigated due to their applications in organic photovoltaics, are obtained mainly by cross-coupling reactions. Such a synthetic route exhibits limited efficiency and requires using, for example, toxic palladium catalysts. Furthermore, the coating process demands solubility of the macromolecules, provided by the introduction of alkyl side chains, which have an impact on the properties of the final material. Here, we present the synthetic route to ladder-like donor–acceptor polymer brushes using alternating copolymerization of modified styrene and maleic anhydride monomers, ensuring proper arrangement of the pendant donor and acceptor groups along the polymer chains grafted from a surface. As a proof of concept, macromolecules with pendant thiophene and benzothiadiazole groups were grafted by means of RAFT and metal-free ATRP polymerizations. Densely packed brushes with a thickness up to 200 nm were obtained in a single polymerization process, without the necessity of using metal-based catalysts or bulky substituents of the monomers. Oxidative polymerization using FeCl3 was then applied to form the conjugated chains in a double-stranded (ladder-like) architecture.

Polyelectrolyte multilayer (PEM) films and particularly hollow capsules composed of PEM shells have gained significant interest since their introduction. Their compositional versatility and easiness of preparation via so-called layer-by-layer assembly led to the development of numerous systems containing also stimuli-responsive components. This paper reviews the achievements related to the formation, determination of structure, and properties of PEM films and capsules responding to major physical, chemical, and biological stimuli. Their applications as e.g., microcarriers for controlled delivery release of active components, substrates for controlled cells' growth, coatings for enhanced surface adhesion, or self-healing anticorrosive systems are shown and discussed. The influence of various stimuli on integrity, permeability of the films or capsules shell are presented together with related applications in biomedicine for controlled drug release as well as in biotechnology and industrial protective coatings.

The aim was to assess the impact of irrigation protocols ended with ethanol or chlorhexidine on AH Plus penetration into dentinal tubules. 45 root canals were prepared to ISO 40/04, divided into three groups and irrigated with three protocols: Group 1 (control): 5.25% NaOCl; Group 2: 40% CA (citric acid), 5.25% NaOCl, 40% CA, water, ethanol; Group 3: 40% CA, 5.25% NaOCl, 40% CA, water, 2% chlorhexidine. Canals were filled using vertical condensation technique with gutta-percha and fluorescein-stained AH Plus sealer. After 72 h, 1 mm thick cross-sections were cut at 2, 5, 8 mm from the apex. Confocal laser microscope was used to measure the sealer penetration into dentinal tubules. Mean depth of sealer penetration (in micrometres) was 107, 131, 170 (Group 1); 146, 233, 317 (Group 2); 185, 301, 542 (Group 3); in apical, middle and coronal parts, respectively. Irrigation protocol ended with chlorhexidine resulted in the deeper sealer penetration compared with alcohol.

Layered zeolites, especially MWW, have been used to synthesize pillared micro/mesoporous hybrids with the goal to enhance catalytic activity towards larger molecules. The critical preparation step is expansion of the interlayer space by swelling with cationic surfactants at high pH. Recently reported solutions of MWW monolayers, obtained by exfoliation of the zeolite MCM-56, can be used to prepare analogous materials by flocculation (precipitation) with surfactant solutions. This previously unavailable approach is studied in this work with both high pH (0.2 M, pH > 13.3) and lower pH (0.01 M, pH~12) solutions, and resulted in finding conditions for preparation of catalysts that can be more active than pure microporous layers (zeolite) despite large content of unreactive silica pillars. Both the high and low pH conditions afforded similar expanded surfactant-MWW composites, but their behavior differed during pillaring with TEOS. Well-defined expanded interlayer distances indicated by a low angle reflection in XRD above 3 nm d-spacing was observed only with the high alkalinity preparations. An additional benefit was observed with TEOS treatment in the presence of isopropyl alcohol leading to a product showing high catalytic activity in model alkylation reaction (mesitylene with benzyl alcohol) proceeding faster than with the pure zeolite. The products obtained under different conditions were characterized by textural methods, nitrogen adsorption and QE-TPDA, and FT-IR to investigate acid site parameters. Notably, the MCM-56 used in this work was prepared with addition of aniline as the structure-promoting agent and is the second formulation affording exfoliable MWW materials.

Background To this day, the effects of sodium hypochlorite and chelating agents on the smear layer and on the dentine’s surface, remain not fully examined. The study is aimed to analyze the dentine's surface treated with 40% citric acid and 5.25% sodium hypochlorite according to two irrigation protocols. Materials and methods The study employed a computer-controlled Nikon Eclipse LV100 optical microscope. Ten roots split longitudinally with canals prepared mechanically using the MTwo system to a size of 40/04 were observed. The root halves were divided into two study groups, one half in each of the groups. According to two irrigation protocols, the dentine's surface was irrigated with 40% citric acid and 5.25% sodium hypochlorite, separated with water. Dentine surface was observed in a fixed place and photographed in 500 × magnification after each irrigation stage. The obtained images were then analyzed using computer software (NIS-Elements AR, GIMP-2.6, ImageJ 1.45s). Results Various speed of removal of the smear layer and varied morphological changes of the dentine's surface were observed in both examined groups. Double irrigation of the dentine with citric acid for 30 s resulted in complete removal of the smear layer, and double irrigation for 60 s resulted in increased mean diameter of the dentine tubules (degradation of the dentine's surface). Conclusions Double alternating irrigation with citric acid and sodium hypochlorite for 30 s yielded satisfactory results, while double irrigation for 60 s resulted in increased mean diameter of the dentine tubules. A real time assessment of the dentine’s surface changes after both tested solutions can improve understanding of the phenomena that occur during the irrigation and as a result it might help to improve clinical outcomes in root canal treatment.

Direct exfoliation of layered zeolites into solutions of monolayers has remained unresolved since the 1990s. Recently, zeolite MCM-56 with the MWW topology (layers denoted mww) has been exfoliated directly in high yield by soft-chemical treatment with tetrabutylammonium hydroxide (TBAOH). This has enabled preparation of zeolite-based hierarchical materials and intimate composites with other active species that are unimaginable via the conventional solid-state routes. The extension to other frameworks, which provides broader benefits, diversified activity, and functionality, is not routine and requires finding suitable synthesis formulations, viz. compositions and conditions, of the layered zeolites themselves. This article reports exfoliation and characterization of layers with ferrierite-related structure, denoted bifer, having rectangular lattice constants like those of the FER and CDO zeolites, and thickness of approximately 2 nm, which is twice that of the so-called fer layer. Several techniques were combined to prove the exfoliation, supported by simulations: AFM; in-plane, in situ, and powder X-ray diffraction; TEM; and SAED. The results confirmed (i) the structure and crystallinity of the layers without unequivocal differentiation between the FER and CDO topologies and (ii) uniform thickness in solution (monodispersity), ruling out significant multilayered particles and other impurities. The bifer layers are zeolitic with Bronsted acid sites, demonstrated catalytic activity in the alkylation of mesitylene with benzyl alcohol, and intralayer pores visible in TEM. The practical benefits are demonstrated by the preparation of unprecedented intimately mixed zeolite composites with the mww, with activity greater than the sum of the components despite high content of inert silica as pillars.

A broad spectrum of applications of magnetic nanoparticles leads to the need for the precise tuning of their magnetic properties. In this study, a series of magnetite and zinc-ferrite nanoparticles were successfully prepared by modified high-temperature synthesis in a controlled gas atmosphere. Nanoparticles with different zinc to iron ratios and pure Fe3O4 were obtained. The structure of the nanoparticles was studied by transmission electron microscopy and Mossbauer spectroscopy. These revealed the single domain character of the nanoparticles and the influence of the synthesis temperature and zinc to iron ratio on their shape and size. Chemical structure was characterized by inductively coupled plasma optical emission spectroscopy, energy dispersive X-ray spectroscopy and thermogravimetric analysis. X-ray photoelectron spectroscopy coupled with an argon gas cluster ion beam (Ar-GCIB) allowed the study of subsequent layers of the nanoparticles without altering their chemical structure. This revealed the presence of a carbon layer on all nanoparticles consisting of capping agents used in the synthesis and revealed the core-shell character of the zinc ferrite particles. In addition, different types of zinc infusions in the nanoparticle structure were observed when using different Zn/Fe ratios. Finally, magnetic studies performed by means of vibrating sample magnetometry proved the superparamagnetic behavior of all the samples.

The DNA origami technique allows the facile design and production of three-dimensional shapes from single template strands of DNA. These can act as functional devices with multiple potential applications but are constrained by practical limitations on size. Multi-functionality could be achieved by connecting together distinct DNA origami modules in an ordered manner. Arraying of non-identical, three-dimensional DNA origamis in an ordered manner is challenging due for example, to a lack of compatible rotational symmetries. Here we show that we can design and build ordered DNA structures using non-identical 3D building blocks by using DNA origami snub-cubes in left-handed and right-handed forms. These can be modified such that one form only binds to the opposite-handed form allowing regular arrays wherein building blocks demonstrate alternating chirality.

The article describes a systematic investigation of the effects of an aqueous NaOH treatment of 3D printed poly(lactic acid) (PLA) scaffolds for surface activation. The PLA surface undergoes several morphology changes and after an initial surface roughening, the surface becomes smoother again before the material dissolves. Erosion rates and surface morphologies can be controlled by the treatment. At the same time, the bulk mechanical properties of the treated materials remain unaltered. This indicates that NaOH treatment of 3D printed PLA scaffolds is a simple, yet viable strategy for surface activation without compromising the mechanical stability of PLA scaffolds., Zweitver��ffentlichungen der Universit��t Potsdam : Mathematisch-Naturwissenschaftliche Reihe; 1212

Electronic energy transfer and the migration of electrons generated via photoinduced electron transfer are key processes for the conversion of solar energy in natural photosynthetic systems. The proper arrangement of chromophores, electron donors and acceptors, or molecular wires on the scale of nanometers is a prerequisite for creating synthetic systems capable of achieving the high energy conversion efficiencies seen in nature. Ordered polymer layers that are adsorbed-to, or grafted-from, surfaces can serve as systems for harvesting of light and directional transfer of energy and electrons in confined environments. Moreover, ordered layers can act as templates for the desired ordering of different photoactive nanoobjects necessary for the development of optoelectronic devices, molecular electronics, and nanosensors. Herein, various macromolecular strategies are reviewed for synthesizing and arranging polymer chains on surfaces to improve the transport of electrons and excitation energy at interfaces. Specifically, the versatile layer-by-layer assembly method for forming thin films from polyelectrolytes and other charged nanoobjects, and the formation of surface-tethered polymer brushes, especially conjugated ones, with various chain architectures are presented together with their applications. The impact of various macromolecular architectures and compositions are discussed in relation to the performance of the polymer and polymer-templated films. Further development of the field could focus on precise engineering of macromolecules with complex architectures, precise positioning of active groups along the chains, towards mimicking the natural systems and their performance.

The synthesis of surface-grafted polymers with variable functionality requires the careful selection of polymerization methods that also enable spatially controlled grafting, which is crucial for the fabrication of, e.g., nano (micro) sensor or nanoelectronic devices. The development of versatile, simple, economical, and eco-friendly synthetic strategies is important for scaling up the production of such polymer brushes. We have recently shown that poly (3-methylthienyl methacrylate) (PMTM) and poly (3-trimethylsilyl-2-propynyl methacrylate) (PTPM) brushes with pendant thiophene and acetylene groups, respectively, could be used for the production of ladder-like conjugated brushes that are potentially useful in the mentioned applications. However, the previously developed syntheses of such brushes required the use of high volumes of reagents, elevated temperature, or high energy UV-B light. Therefore, we present here visible light-promoted metal-free surface-initiated ATRP (metal-free SI-ATRP) that allows the economical synthesis of PMTM and PTPM brushes utilizing only microliter volumes of reaction mixtures. The versatility of this approach was shown by the formation of homopolymers but also the block copolymer conjugated brushes (PMTM and PTPM blocks in both sequences) and patterned films using TEM grids serving as photomasks. A simple reaction setup with only a monomer, solvent, commercially available organic photocatalyst, and initiator decorated substrate makes the synthesis of these complex polymer structures achievable for non-experts and ready for scaling up.

Izabela Czyzynska-Cichon,1,* Małgorzata Janik-Hazuka,2,* Joanna Szafraniec-Szczęsny,2,3 Krzysztof Jasinski,4 Władysław P Węglarz,4 Szczepan Zapotoczny,2 Stefan Chlopicki1,5 1Jagiellonian University, Jagiellonian Centre for Experimental Therapeutics (JCET), Krakow, 30-348, Poland; 2Jagiellonian University, Faculty of Chemistry, Krakow, 30-387, Poland; 3Jagiellonian University Medical College, Faculty of Pharmacy, Department of Pharmaceutical Technology and Biopharmaceutics, Krakow, 30-688, Poland; 4Institute of Nuclear Physics Polish Academy of Sciences, Department of Magnetic Resonance Imaging, Krakow, 31-342, Poland; 5Jagiellonian University Medical College, Faculty of Medicine, Department of Pharmacology, Krakow, 31-531, Poland*These authors contributed equally to this workCorrespondence: Stefan Chlopicki; Szczepan Zapotoczny Email stefan.chlopicki@jcet.eu; zapotocz@chemia.uj.edu.plBackground: Vascular drug delivery becomes a promising direction in the development of novel therapeutic strategies in the treatment of cardiovascular pathologies, such as hypertension. However, targeted delivery of hydrophobic substances, with poor bioavailability, remains a challenge. Here, we described the hypotensive effects of a low dose of curcumin delivered to the vascular wall using hyaluronic acid-based nanocapsules.Methods: The group of hypertensive TGR(m-Ren2)27 rats, was administrated respectively with the vehicle, curcumin solution or curcumin delivered using hyaluronic acid-based nanocapsules (HyC12-Cur), for 7 days each, maintaining the wash-out period between treatments. Arterial blood pressure (systolic - SBP, diastolic – DBP) and heart rate (HR) were monitored continuously using a telemetry system (Data Science International), and Mean Arterial Pressure (MAP) was calculated from SBP and DBP.Results: In hypertensive rats, a low dose of curcumin (4.5 mg/kg) administrated in HyC12-Cur for 7 days resulted in a gradual inhibition of SBP, DBP and MAP increase without an effect on HR. At the end of HyC12-Cur – based treatment changes in SBP, DBP and MAP amounted to − 2.0± 0.8 mmHg, − 3.9± 0.7 mmHg and − 3.3± 0.7 mmHg, respectively. In contrast, the administration of a curcumin solution (4.5 mg/kg) did not result in a significant hypotensive effect and the animals constantly developed hypertension. Vascular delivery of capsules with curcumin was confirmed using newly developed fluorine-rich nanocapsules (HyFC10-PFOB) with a shell based on a HA derivative and similar size as HyC12-Cur. HyFC10-PFOB gave fluorine signals in rat aortas analyzed ex vivo with a 19F NMR technique after a single intragastric administration.Conclusion: These results suggest that nanocapsules based on hyaluronic acid, the ubiquitous glycosaminoglycan of the extracellular matrix and an integral part of endothelial glycocalyx, may represent a suitable approach to deliver hydrophobic, poorly bioavailable compounds, to the vascular wall.Keywords: nanocapsules, hyaluronic acid, 19F NMR, curcumin, hypertension, targeted vascular delivery

Low water solubility frequently compromises the therapeutic efficacy of drugs and other biologically active molecules. Here, we report on coacervate polysaccharide nanoparticles (CPNs) that can transport and release a model hydrophobic drug, piroxicam, to the cells in response to changes in temperature. The proposed, temperature-responsive drug delivery system is based on ionic derivatives of natural polysaccharides&mdash, curdlan and hydroxypropyl cellulose. Curdlan was modified with trimethylammonium groups, while the anionic derivative of hydroxypropyl cellulose was obtained by the introduction of styrenesulfonate groups. Thermally responsive nanoparticles of spherical shape and average hydrodynamic diameter in the range of 250&ndash, 300 nm were spontaneously formed in water from the obtained ionic polysaccharides as a result of the coacervation process. Their morphology was visualized using SEM and AFM. The size and the surface charge of the obtained objects could be tailored by adjusting the polycation/polyanion ratio. Piroxicam (PIX) was effectively entrapped inside the nanoparticles. The release profile of the drug from the CPNs-PIX was found to be temperature-dependent in the range relevant for biomedical applications.

Silicon wafers as semiconductors are essential components of integrated circuits in electronic devices. For this reason, modification of the silicon surface is an important factor in the manufacturing of new hybrid materials applied in micro- and nanoelectronics. Herein, copolymer brushes of hydrophilic poly(2-hydroxyethyl acrylate) (PHEA) and hydrophobic poly(tert-butyl acrylate) (PtBA) were grafted from silicon wafers via simplified electrochemically mediated atom transfer radical polymerization (seATRP) according to a surface-initiated approach. The syntheses of PHEA-b-PtBA copolymers were carried out with diminished catalytic complex concentration (successively 25 and 6 ppm of Cu). In order to optimize the reaction condition, the effect of the addition of a supporting electrolyte was investigated. A controlled increase in PHEA brush thickness was confirmed by atomic force microscopy (AFM). Various other parameters including contact angles and free surface energy (FSE) for the modified silicon wafer were presented. Furthermore, the effect of the presence of a sacrificial initiator in solution on the thickness of the grafted brushes was reported. Successfully fabricated inorganic&ndash, organic hybrid nanomaterials show potential application in biomedicine and microelectronics devices, e.g., biosensors.

The nanoemulsion-based delivery systems have gained particular attention due to effective encapsulation and protection of hydrophobic active compounds. However, several features like limited stability, cellular uptake or release of payloads still need to be addressed. We investigated the uptake of the nanocapsules based on the amphiphilic derivative of hyaluronate with oleic acid cores (oil-in-water nanoemulsion) and their anticancer activity in vitro. The core-shell nanocapsules exhibiting long term stability in dispersion showed an enhanced uptake by cancer cells and effectively killed them only if composed of hyaluronate-based shells and oleic acid cores - the anionic chitosan-based shells and/or corn oil cores were used for control experiments. We concluded that the nanocapsules stabilized by the amphiphilic derivative of hyaluronic acid may serve as very stable and efficient delivery systems for oil-soluble compounds without necessity of application of low molecular weight (co)surfactants. The in vitro studies indicated anticancer activity of such delivered oleic acid and crucial role of hyaluronate shell of the nanocapsules in its efficient delivery and enzyme-triggered disintegration inside cells. Corn oil was shown as a nutrient that can serve as an inert vehicle in the studied nanoemulsion that exhibit application potential in food, dietary supplement industry and medicine.

The first direct exfoliation of zeolites in high yield expands potential for catalysts, membranes, and tailored composites., The most effective approach to practical exploitation of the layered solids that often have unique valuable properties—such as graphene, clays, and other compounds—is by dispersion into colloidal suspensions of monolayers, called liquid exfoliation. This fundamentally expected behavior can be used to deposit monolayers on supports or to reassemble into hierarchical materials to produce, by design, catalysts, nanodevices, films, drug delivery systems, and other products. Zeolites have been known as extraordinary catalysts and sorbents with three-dimensional structures but emerged as an unexpected new class of layered solids contributing previously unknown valuable features: catalytically active layers with pores inside or across. The self-evident question of layered zeolite exfoliation has remained unresolved for three decades. Here, we report the first direct exfoliation of zeolites into suspension of monolayers as proof of the concept, which enables diverse applications including membranes and hierarchical catalysts with improved access.

Pioglitazone, a popular antidiabetic drug, which was recently shown to be effective in the treatment of skin ulcers, was successfully encapsulated in polysaccharide nanoparticles and used as a bioactive component of the wound-dressing material based on modified bacterial nanocellulose. Alginate and hydroxypropyl cellulose were used as a matrix for the nanoparticulate drug-delivery system. The matrix composition and particles&rsquo, size, as well as drug encapsulation efficiency and loading, were optimized. Pioglitazone hydrochloride (PIO) loaded particles were coated with chitosan introduced into the crosslinking medium, and covalently attached to the surface of bacterial nanocellulose functionalized with carboxyl groups. PIO was released from the surface of the hybrid material in a controlled manner for 5 days. Preliminary cytotoxicity studies confirmed safety of the system at PIO concentrations as high as 20 mg/mL. The obtained hybrid system may have potential application in the treatment of skin ulcers e.g., in diabetic foot.

BACKGROUND After the mechanical preparation of a root canal, the canal walls are covered with a smear layer. In order to deeply clean the dentinal tubules, removal of the smear layer is recommended. There is no consensus on the length of time of rinsing with chelating agents or irrigation with alternating chelating agents and sodium hypochlorite (NaOCl). OBJECTIVES The aim of the study was to evaluate the effectiveness of smear layer removal using 4 irrigation protocols. MATERIAL AND METHODS We prepared 42 straight root canals to size ISO40/04 and assigned them into 4 study groups (n = 10) and a control group (n = 2). The root canals were irrigated as follows: in the control group, 180 s with 5.25% NaOCl; in group 1, 60 s with 40% citric acid (CA) and 120 s with NaOCl; in group 2, 120 s with CA and 120 s with NaOCl; in group 3, 30 s CA, 30 s with NaOCl, 30 s CA and 120 s with NaOCl; and in group 4, 60 s with CA, 30 s with NaOCl, 60 s with CA, and 120 s with NaOCl. The roots were split longitudinally and the root canals were observed under ×200-500 magnification. The root canal walls were analyzed in areas 2 mm, 6 mm and 10 mm from the apex. RESULTS In the apical and medial sections, the best effects were achieved in groups 3 and 4. In coronal sections, no significant differences between experimental groups were found. CONCLUSIONS Within the limitations of this study, it can be concluded that irrigation with alternating NaOCl and CA was the most effective at smear layer removal, regardless of the irrigation time.

Modification of membrane surface fabricated from bionanocellulose (BNC) carboxymethylcellulose (CMC) blend (BNC-CMC) with covalently bounded silicone layer was carried out in view of developing the novel, moist wound dressing material. The procedure was initiated with the reaction of aminopropyltriethoxysilane (APS) with carboxymethyl groups of CMC resulting with amide bound formation. The thickness of the silicone layer was further increased in the base-catalyzed polycondensation of silicone precursors: vinyltriethoxysilane (VES) or allyltrimethoxysilane (ATMS) initiated by N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC). Surface modification was confirmed using various physicochemical methods such as FTIR, SEM, XPS and contact angle measurements. Swelling and drying tests confirmed that silicone-modified materials have considerable better water storage properties than the pristine BNC-CMC nanocomposite. The fabricated silicone modified BNC-CMC membranes are promising materials for wound dressing ensuring improved hydrobalance as the protective layer slows the evaporation of water.

Silicone micromaterials were synthesized using two surfactant-free methods: the Stöber synthesis or solidification in spontaneously formed emulsions (the Ouzo effect) and their physicochemical properties were evaluated. The effect of the chemical structure of a silicone precursor on the morphology of formed microstructures was considered. For that purpose, various organosilicon compounds containing in their structure T-units and D-units, methyl groups, ethylene linkages, and cyclotetrasiloxane rings were used as silicone precursors. All materials existed as sub-micron sized particles, although they differed considerably in morphology and dispersity (spherical particles with a diameter of about 490 and 740 nm, cauliflower-like structures, large rough-surfaced aggregates). The chemical composition of the microstructure surface was examined using XPS. The porosity of silicone materials was assessed on the basis of nitrogen adsorption isotherms. The specific surface area (SBET) varied substantially and ranged from 5 to 379 m2/g. For the first time the microelastic modulus of the silicone materials was determined using AFM measurements. We found that the structure of the organic part had a large impact on the microelasticity of the material. The microelastic modulus of the silicone materials (11–33 GPa) was significantly lower compared to silica (59 GPa). Keywords: Silicone, Microstructures, Sol-gel processes, Microelastic modulus, Morphology, Porosity

Polymers with pendant pyridine groups (PPPGs) are pH responsive weak polyelectrolytes potentially attractive for many applications such as sensors, antibacterial coatings, and ion gating systems. Synthesis of PPPGs by classical atom transfer radical polymerization (ATRP) is very challenging due to highly probable formation of monomer/metal complexes. In response to that, we report here a facile synthetic strategy to obtain surface-grafted PPPGs that utilizes light-mediated ATRP. Metal-free surface-initiated ATRP catalyzed by 10-phenylphenothiazine is used to polymerize three isomeric monomers with methacrylate groups attached at various positions of a pyridine ring. The reactivity of the isomers is compared for selection of optimal monomer structure leading to thick brushes. The polymerizations are conducted under visible light, at ambient conditions, and using only microliter volumes of the reaction mixture that is important for reducing the complexity and costs of the process as well as limiting chemical waste. The observed linear dependency of the brush thickness vs polymerization time for poly(pyridin-3-yl methacrylate) (PP3M) grafted from indium tin oxide or silicon wafers indicated the controlled characteristics of the developed method. The obtained PP3M brush demonstrated pH responsive behavior associated with protonation of pyridine groups in acidic solution and adoption of highly stretched conformation below pKa.

This feature paper focuses on recently introduced double-stranded surface-grafted polymer brushes with ladder-like architecture, the method of their synthesis, self-templating surface-initiated polymerization (ST-SIP), as well as their unique properties. ST-SIP synthetic approach is based on a sequential polymerization of a bifunctional monomer leading to formation of multimonomer chains in the first step followed by a second polymerization producing ladder-like structures. This approach was developed primarily for conjugated polymer brushes, which synthesis using other methods is challenging. Such brushes enable anisotropic conductance at the nanometer scale that is highly demanded for e.g., photovoltaic and optoelectronic applications. ST-SIP was applied to form ladder-like brushes containing polyacetylene, polythiophene and polyethynylpyridine conjugated chains arranged normally to the grafting surface and exhibiting high electrical conductance as measured using conductive atomic force microscopy. The conjugated chains were shown to exhibit long term stability that is one of the crucial benefit of this novel brush topology. The nanomechanical characterization revealed enhanced stiffness and high elasticity of the ladder-like structures compared to the parent single-stranded brushes. The double-stranded brush topology due to anisotropic conductance, unique nanomechanical properties and versatility of ST-SIP approach, have a high potential for fabrication of robust nanocoating for tailoring (bio)interafaces.

Novel system based on bionanocellulose modified with carboxymethyl groups (mBNC) and covalently attached hydrogel submicron particles with encapsulated curcumin was prepared and its usefulness for the preparation of bioactive wound dressing materials was demonstrated. In order to obtain a well-controlled delivery system, curcumin was first encapsulated in Pluronic® P103 micelles and subsequently entrapped in the particles prepared by the extrusion method using commercially available, relatively inexpensive and biocompatible polymers: sodium alginate (ALG) and hydroxypropyl cellulose (HPC). The size of the particles and the feed ratio of curcumin and ALG were optimized during the synthesis in respect with the curcumin loading and release profile. The particles were coated with chitosan and successfully immobilized on the surface of mBNC using EDC/NHC chemistry. The particles attached to the mBNC surface released the curcumin in a sustain, well controlled manner, resembling that of the unbounded particles. Their presence allows for prolonged bioactivity of the potential wound dressing material.

N-dodecyl derivative of cationically modified chitosan was used to prepare core-shell nanocapsules templated on liquid cores. Surfactant-free method based on ultrasound-assisted direct emulsification of aqueous solution of polysaccharide with oleic acid was applied. Formation of spherical capsules was confirmed by scanning and transmission electron microscopies. Dynamic light scattering measurements were used to determine physicochemical parameters of the obtained particles as well as to follow the process of multilayer shell formation. Confocal microscopy was applied to examine the ability of encapsulation of hydrophobic compounds inside the cores of the nanocapsules. Performed studies confirmed that hydrophobically modified cationic chitosan provides long-term stabilization of oil-in-water emulsion for biomedical applications as no toxic effect was observed in acute oral toxicity studies.