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1.
Eur J Med Chem ; 199: 112294, 2020 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-32428792

RESUMO

Heteroarene-fused anthraquinone derivatives represent a class of perspective anticancer drug candidates capable of targeting multiple vital processes including drug resistance. Taking advantage of previously demonstrated potential of amide derivatives of heteroarene-fused anthraquinones, we herein dissected the role of the heterocyclic core in antitumor properties. A new series of naphtho[2,3-f]indole-3- and anthra[2,3-b]thiophene-3-carboxamides was synthesized via coupling the respective acids with cyclic diamines. New compounds demonstrated a submicromolar antiproliferative potency close to doxorubicin (Dox) against five tumor cell lines of various tissue origin. In contrast to Dox, the new compounds were similarly cytotoxic for HCT116 colon carcinoma cells (wild type p53) and their isogenic p53 knockout counterparts. Modification of the heterocyclic core changed the targeting properties: the best-in-series naphtho[2,3-f]indole-3-carboxamide 8 formed more affine complexes with DNA duplex than furan and thiophene analogs, a property that can be translated into a stronger inhibition of topoisomerase 1 mediated DNA unwinding. At tolerable doses the water soluble derivative 8 significantly inhibited tumor growth (up to 79%) and increased the lifespan (153%) of mice bearing P388 lymphoma transplants. Together with better solubility for parenteral administration and well tolerance by animals of the indole derivative 8 indicates prospects for further search of new antitumor drug candidates among the heteroarene-fused anthraquinones.

2.
Adv Mater ; 32(1): e1905504, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31736228

RESUMO

2D hexagonal boron nitride (hBN) is a wide-bandgap van der Waals crystal with a unique combination of properties, including exceptional strength, large oxidation resistance at high temperatures, and optical functionalities. Furthermore, in recent years hBN crystals have become the material of choice for encapsulating other 2D crystals in a variety of technological applications, from optoelectronic and tunneling devices to composites. Monolayer hBN, which has no center of symmetry, is predicted to exhibit piezoelectric properties, yet experimental evidence is lacking. Here, by using electrostatic force microscopy, this effect is observed as a strain-induced change in the local electric field around bubbles and creases, in agreement with theoretical calculations. No piezoelectricity is found in bilayer and bulk hBN, where the center of symmetry is restored. These results add piezoelectricity to the known properties of monolayer hBN, which makes it a desirable candidate for novel electromechanical and stretchable optoelectronic devices, and pave a way to control the local electric field and carrier concentration in van der Waals heterostructures via strain. The experimental approach used here also shows a way to investigate the piezoelectric properties of other materials on the nanoscale by using electrostatic scanning probe techniques.

3.
Langmuir ; 35(26): 8543-8556, 2019 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-31018639

RESUMO

This article summarizes more than 10 years of cooperation with Prof. Helmuth Möhwald. Here we describe how the research moved from light-regulated feedback sustainable systems and control biodevices to the current focus on infochemistry in aqueous solution. An important advanced characteristic of such materials and devices is the pH concentration gradient in aqueous solution. A major part of the article focuses on the use of localized illumination for proton generation as a reliable, minimal-reagent-consuming, stable light-promoted proton pump. The in situ scanning vibration electrode technique (SVET) and scanning ion-selective electrode technique (SIET) are efficient for the spatiotemporal evolution of ions on the surface. pH-sensitive polyelectrolyte (PEs) multilayers with different PE architectures are composed with a feedback loop for bionic devices. We show here that pH-regulated PE multilayers can change their properties-film thickness and stiffness, permeability, hydrophilicity, and/or fluorescence-in response to light or electrochemical or biological processes instead of classical acid/base titration.

4.
Nat Commun ; 10(1): 987, 2019 02 25.
Artigo em Inglês | MEDLINE | ID: mdl-30804336

RESUMO

The original version of this Article contained an error in the spelling of the author Matthew Holwill, which was incorrectly given as Mathew Holwill. This has now been corrected in both the PDF and HTML versions of the Article.

5.
Nat Commun ; 10(1): 230, 2019 01 16.
Artigo em Inglês | MEDLINE | ID: mdl-30651554

RESUMO

Despite a rich choice of two-dimensional materials, which exists these days, heterostructures, both vertical (van der Waals) and in-plane, offer an unprecedented control over the properties and functionalities of the resulted structures. Thus, planar heterostructures allow p-n junctions between different two-dimensional semiconductors and graphene nanoribbons with well-defined edges; and vertical heterostructures resulted in the observation of superconductivity in purely carbon-based systems and realisation of vertical tunnelling transistors. Here we demonstrate simultaneous use of in-plane and van der Waals heterostructures to build vertical single electron tunnelling transistors. We grow graphene quantum dots inside the matrix of hexagonal boron nitride, which allows a dramatic reduction of the number of localised states along the perimeter of the quantum dots. The use of hexagonal boron nitride tunnel barriers as contacts to the graphene quantum dots make our transistors reproducible and not dependent on the localised states, opening even larger flexibility when designing future devices.

6.
Ultrason Sonochem ; 51: 439-443, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30072259

RESUMO

Progress in understanding of energy transfer in nature and human being requires novel approaches to the processing of solids on demand, in specially those with composition gradients and those thermodynamically and kinetically inaccessible. We demonstrate that rapidly oscillating microbubbles are useful for materials processing, because they manipulate surface temperature and creates temperature gradients in predictable way. Ultrasonic treatment leads to an increase in the surface area of particles up to 180 m2g-1 and the formation of micropores in metal phase and mesopores in metal oxide phase. The spatially and temporally unique energy dissipation conditions promise new interfaces with higher level of complexity and applications among others in catalysis, energy storage, drug delivery.

7.
ACS Appl Mater Interfaces ; 9(28): 24282-24289, 2017 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-28654237

RESUMO

Energy-transfer reactions are the key for living open systems, biological chemical networking, and the development of life-inspired nanoscale machineries. It is a challenge to find simple reliable synthetic chemical networks providing a localization of the time-dependent flux of matter. In this paper, we look to photocatalytic reaction on TiO2 from different angles, focusing on proton generation and introducing a reliable, minimal-reagent-consuming, stable inorganic light-promoted proton pump. Localized illumination was applied to a TiO2 surface in solution for reversible spatially controlled "inorganic photoproton" isometric cycling, the lateral separation of water-splitting reactions. The proton flux is pumped during the irradiation of the surface of TiO2 and dynamically maintained at the irradiated surface area in the absence of any membrane or predetermined material structure. Moreover, we spatially predetermine a transient acidic pH value on the TiO2 surface in the irradiated area with the feedback-driven generation of a base as deactivator. Importantly we describe how to effectively monitor the spatial localization of the process by the in situ scanning ion-selective electrode technique (SIET) measurements for pH and the scanning vibrating electrode technique (SVET) for local photoelectrochemical studies without additional pH-sensitive dye markers. This work shows the great potential for time- and space-resolved water-splitting reactions for following the investigation of pH-stimulated processes in open systems with their flexible localization on a surface.

8.
Phys Chem Chem Phys ; 19(8): 6286-6291, 2017 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-28195290

RESUMO

An understanding of the nature and conditions of nonlinear processes in open systems is important for modulation of the microstructure of solids at a new level of complexity. We demonstrate that cavitation generated by high intensity ultrasound (HIUS) triggers nonlinear processes in microparticles and layers of titanium. We reveal a non-monotonic dependence of the size of grains in the treated solids on sonication time, and oscillation of titanium grain sizes vs. time of ultrasonic treatment, indicating the influence of two opposing forces: cavitation driven impact of shock heating and shear stress on surfaces. These nonlinear self-organization processes in solids promise new microstructured materials with applications among others in bio- and geosciences.

9.
Ultrason Sonochem ; 35(Pt B): 556-562, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-27236831

RESUMO

High intensity ultrasound (HIUS) is a novel and efficient tool for top-down nanostructuring of multi-phase metal systems. Ultrasound-assisted structuring of the phase in metal alloys relies on two main mechanisms including interfacial red/ox reactions and temperature driven solid state phase transformations which affect surface composition and morphology of metals. Physical and chemical properties of sonication medium strongly affects the structuring pathways as well as morphology and composition of catalysts. HIUS can serve as a simple, fast, and effective approach for the tuning of structure and surface properties of metal particles, opening the new perspectives in design of robust and efficient catalysts.

10.
Langmuir ; 32(43): 11072-11085, 2016 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-27485504

RESUMO

This review examines the concepts how cavitation bubble collapse affects crystalline structure, the crystallization of newly formed structures, and recrystallization. Although this subject can be discussed in a broad sense across the area of metastable crystallization, our main focus is discussing specific examples of the inorganic solids: metal, intermetallics, metal oxides, and silicon. First, the temperature up to which ultrasound heats solids is discussed. Cavitation-induced changes in the crystal size of intermetallic phases in binary AlNi (50 wt % of Ni) alloys allow an estimation of local temperatures on surfaces and in bulk material. The interplay between atomic solid-state diffusion and recrystallization during bubble collapses in heterogeneous systems is revealed. Furthermore, cavitation triggered red/ox processes at solid/liquid interfaces and their influence on recrystallization are discussed for copper aluminum nanocomposites, zinc, titanium, magnesium-based materials, and silicon. Cavitation-driven highly nonequilibrium conditions can affect the thermodynamics and kinetics of mesoscopic phase formation in heterogeneous systems and in many cases boost the macroscopic performance of composite materials, notably in catalytic alloy and photocatalytic semiconductor oxide properties, corrosion resistance, nanostructured surface biocompatibility, and optical properties.

11.
Angew Chem Int Ed Engl ; 55(42): 13001-13004, 2016 10 10.
Artigo em Inglês | MEDLINE | ID: mdl-27439779

RESUMO

We introduce a simple concept of a light induced pH change, followed by high amplitude manipulation of the mechanical properties of an adjacent polymer film. Irradiation of a titania surface is known to cause water splitting, and this can be used to reduce the environmental pH to pH 4. The mechanical modulus of an adjacent pH sensitive polymer film can thus be changed by more than an order of magnitude. The changes can be localized, maintained for hours and repeated without material destruction.

12.
Macromol Biosci ; 16(10): 1422-1431, 2016 10.
Artigo em Inglês | MEDLINE | ID: mdl-27276439

RESUMO

Polyelectrolyte block copolymer micelles assembled thin film is switched in response to local photocatalytic reactions on titanium dioxide, resulting in a layer of variable height, stiffness in response to visible light irradiation. Preosteoblasts migrate toward stiffer side of the substrates.


Assuntos
Movimento Celular , Elasticidade , Membranas Artificiais , Micelas , Osteoblastos/metabolismo , Titânio/química , Animais , Linhagem Celular , Camundongos , Osteoblastos/citologia
13.
Small ; 12(18): 2450-8, 2016 05.
Artigo em Inglês | MEDLINE | ID: mdl-26997362

RESUMO

Elucidation of the nature of hydrogen interactions with palladium nanoparticles is expected to play an important role in the development of new catalysts and hydrogen-storage nanomaterials. A facile scaled-up synthesis of uniformly sized single-crystalline palladium nanoparticles with various shapes, including regular nanocubes, nanocubes with protruded edges, rhombic dodecahedra, and branched nanoparticles, all stabilized with a mesoporous silica shell is developed. Interaction of hydrogen with these nanoparticles is studied by using temperature-programmed desorption technique and by performing density functional theory modeling. It is found that due to favorable arrangement of Pd atoms on their surface, rhombic dodecahedral palladium nanoparticles enclosed by {110} planes release a larger volume of hydrogen and have a lower desorption energy than palladium nanocubes and branched nanoparticles. These results underline the important role of {110} surfaces in palladium nanoparticles in their interaction with hydrogen. This work provides insight into the mechanism of catalysis of hydrogenation/dehydrogenation reactions by palladium nanoparticles with different shapes.

14.
Ultrason Sonochem ; 26: 9-14, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25804865

RESUMO

Crystallographic property such as crystallite size has been used for evaluation of the temperature up to which high intensity ultrasound can heat metal particles depending on physical properties of sonication medium and particle concentration. We used >100 µm metal particles as an in situ indicator for ultrasonically induced temperature in the particle interior. Based on powder X-ray diffraction monitoring of Al3Ni2 crystallite sizes after ultrasound treatment the average minimum temperature T particle(min) of sonicated particles in various sonication media was estimated. Additionally, it was found that crystallite size in ultrasonically treated metal particle depends on the frequency of interparticle collision. Through the adjustment of particle concentration, it is possible to either accelerate the atomic diffusion or force the melting and recrystallization processes. Overall, the energy released from collapsing cavitation bubble can be controllably transferred to the sonication matter through the appropriate choice of sonication medium and the adjustment of particle concentration.

15.
Chem Commun (Camb) ; 51(36): 7606-9, 2015 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-25703146

RESUMO

We present sonogenerated magnesium-hydrogen sponges for effective reactive hard templating. Formation of differently organized nanomaterials is possible by variation of sonochemical parameters and solution composition: Fe2O3 nanorods or composite dendritic Fe2O3/Fe3O4 nanostructures.

16.
Photochem Photobiol ; 91(1): 59-67, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25263082

RESUMO

The mechanism of the photodegradation of azo dyes via ultrasonication is studied using a combination of the high-performance liquid chromatography and UV-vis spectroscopy with detailed analysis of the kinetics. Based on the kinetics studies of the sonodegradation, it was proposed that the degradation of azo dyes was a multistage process that involved: (1) the direct attack of azo bonds and phenyl rings of dyes by the sonochemically formed reactive oxygen species; (2) the activation of semiconductor particles by the light emitted during cavitation and the triggering of the photocatalytic pathways of dye degradation and (3) increase of the adsorption capacity of the semiconductor particles due to the sonomechanically induced interparticle collisions. The detailed kinetics study can help in following an effective process up-scaling. It was demonstrated that extremely short pulses of light flashes in a cavitated mixture activated the surface of photocatalysts and significantly enhanced dye degradation processes.

17.
Ultrason Sonochem ; 23: 142-7, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25453211

RESUMO

High intensity ultrasound treatment has been used to generate electrocatalytically active (toward hydrogen evolution) surface on AlNi (50 wt.% Ni) alloy particles. Acoustic cavitation is responsible for the initiation of redox processes on the catalyst surface leading to changes in its composition. Cavitation impact on the surface composition of the metal alloy could be controlled by manipulating the sonication medium during ultrasound treatment. Evaluation of electrocatalytic performance, as well as surface composition studies of ultrasonically generated catalysts showed the advantageous use of sonication medium with reducing ability and high vapor pressure for the generation of highly efficient interface on Al-Ni alloy particles for water splitting reaction.

18.
Ultrason Sonochem ; 23: 26-30, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25171834

RESUMO

Crystallite size of the intermetallics is one of the most important parameters that can influence kinetics of catalytic reactions. Analysis of the crystallite sizes of Al3Ni and Al3Ni2 intermetallic phases using Scherrer and Williamson-Hall methods reveals that the sonomechanical impact of ultrasound on suspensions of AlNi particles in ethanol results in crystallites growth and microstrain reduction.

20.
Langmuir ; 28(24): 9168-73, 2012 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-22381053

RESUMO

Here, a new surface enhanced Raman spectroscopy (SERS) platform suitable for gas phase sensing based on the extended organization of poly-N-isopropylacrylamide (pNIPAM)-coated nanostars over large areas is presented. This system yields high and homogeneous SERS intensities, and simultaneously traps organic chemical agents as pollutants from the gas phase. pNIPAM-coated gold nanostars were organized into parallel linear arrays. The optical properties of the fabricated substrates are investigated, and applicability for advanced sensing is demonstrated through the detection in the gas phase of pyrene traces, a well-known polyaromatic hydrocarbon.


Assuntos
Resinas Acrílicas/química , Nanoestruturas/química , Hidrocarbonetos Policíclicos Aromáticos/química , Pirenos/química , Gases/química , Tamanho da Partícula , Análise Espectral Raman , Propriedades de Superfície
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