K. Ulbrich, K. Holá, V. Šubr, A. Bakandritsos, J. Tuček, R. Zbořil: Targeted Drug Delivery with Polymers and Magnetic Nanoparticles: Covalent and Noncovalent Approaches, Release Control, and Clinical Studies, CHEMICAL REVIEWS, vol. 116, iss. 9, pp. 5338-5431, 2016.
DOI: 10.1021/acs.chemrev.5b00589, IF = 47.928
Abstract: Targeted delivery combined with controlled drug release has a pivotal role in the future of personalized medicine. This review covers the principles, advantages, and drawbacks of passive and active targeting based on various polymer and magnetic iron oxide nanoparticle carriers with drug attached by both covalent and noncovalent pathways. Attention is devoted to the tailored conjugation of targeting ligands (e.g., enzymes, antibodies, peptides) to drug carrier systems. Similarly, the approaches toward controlled drug release are discussed. Various polymer–drug conjugates based, for example, on polyethylene glycol (PEG), N-(2-hydroxypropyl)methacrylamide (HPMA), polymeric micelles, and nanoparticle carriers are explored with respect to absorption, distribution, metabolism, and excretion (ADME scheme) of administrated drug. Design and structure of superparamagnetic iron oxide nanoparticles (SPION) and condensed magnetic clusters are classified according to the mechanism of noncovalent drug loading involving hydrophobic and electrostatic interactions, coordination chemistry, and encapsulation in porous materials. Principles of covalent conjugation of drugs with SPIONs including thermo- and pH-degradable bonds, amide linkage, redox-cleavable bonds, and enzymatically-cleavable bonds are also thoroughly described. Finally, results of clinical trials obtained with polymeric and magnetic carriers are analyzed highlighting the potential advantages and future directions in targeted anticancer therapy.
M. Dubecký, L. Mitas, P. Jurečka: Noncovalent Interactions by Quantum Monte Carlo, CHEMICAL REVIEWS, vol. 116, iss. 9, pp. 5188-5215, 2016.
DOI: 10.1021/acs.chemrev.5b00577, IF = 47.928
Abstract: Quantum Monte Carlo (QMC) is a family of stochastic methods for solving quantum many-body problems such as the stationary Schrödinger equation. The review introduces basic notions of electronic structure QMC based on random walks in real space as well as its advances and adaptations to systems with noncovalent interactions. Specific issues such as fixed-node error cancellation, construction of trial wave functions, and efficiency considerations that allow for benchmark quality QMC energy differences are described in detail. Comprehensive overview of articles covers QMC applications to systems with noncovalent interactions over the last three decades. The current status of QMC with regard to efficiency, applicability, and usability by nonexperts together with further considerations about QMC developments, limitations, and unsolved challenges are discussed as well.
M. H. Kolář, P. Hobza: Computer Modeling of Halogen Bonds and Other σ-Hole Interactions, CHEMICAL REVIEWS, vol. 116, iss. 9, pp. 5155-5187, 2016.
DOI: 10.1021/acs.chemrev.5b00560, IF = 47.928
Abstract: In the field of noncovalent interactions a new paradigm has recently become popular. It stems from the analysis of molecular electrostatic potentials and introduces a label, which has recently attracted enormous attention. The label is σ-hole, and it was first used in connection with halogens. It initiated a renaissance of interest in halogenated compounds, and later on, when found also on other groups of atoms (chalcogens, pnicogens, tetrels and aerogens), it resulted in a new direction of research of intermolecular interactions. In this review, we summarize advances from about the last 10 years in understanding those interactions related to σ-hole. We pay particular attention to theoretical and computational techniques, which play a crucial role in the field.
V. Georgakilas, J. N. Tiwari, K. C. Kemp, J. A. Perman, A. B. Bourlinos, K. S. Kim, R. Zboril: Noncovalent Functionalization of Graphene and Graphene Oxide for Energy Materials, Biosensing, Catalytic, and Biomedical Applications, CHEMICAL REVIEWS, vol. 116, iss. 9, pp. 5464–5519, 2016.
DOI: 10.1021/acs.chemrev.5b00620, IF = 47.928
Abstract: This Review focuses on noncovalent functionalization of graphene and graphene oxide with various species involving biomolecules, polymers, drugs, metals and metal oxide-based nanoparticles, quantum dots, magnetic nanostructures, other carbon allotropes (fullerenes, nanodiamonds, and carbon nanotubes), and graphene analogues (MoS2, WS2). A brief description of π–π interactions, van der Waals forces, ionic interactions, and hydrogen bonding allowing noncovalent modification of graphene and graphene oxide is first given. The main part of this Review is devoted to tailored functionalization for applications in drug delivery, energy materials, solar cells, water splitting, biosensing, bioimaging, environmental, catalytic, photocatalytic, and biomedical technologies. A significant part of this Review explores the possibilities of graphene/graphene oxide-based 3D superstructures and their use in lithium-ion batteries. This Review ends with a look at challenges and future prospects of noncovalently modified graphene and graphene oxide.
P. Trouillas, J. C. Sancho-García, V. De Freitas, J. Gierschner, M. Otyepka, and O. Dangles: Stabilizing and Modulating Color by Copigmentation: Insights from Theory and Experiment, CHEMICAL REVIEWS, vol. 116, iss. 9, pp. 4937–4982, 2016.
DOI: 10.1021/acs.chemrev.5b00507, IF = 47.928
Abstract: Natural anthocyanin pigments/dyes and phenolic copigments/co-dyes form noncovalent complexes, which stabilize and modulate (in particular blue, violet, and red) colors in flowers, berries, and food products derived from them (including wines, jams, purees, and syrups). This noncovalent association and their electronic and optical implications constitute the copigmentation phenomenon. Over the past decade, experimental and theoretical studies have enabled a molecular understanding of copigmentation. This review revisits this phenomenon to provide a comprehensive description of the nature of binding (the dispersion and electrostatic components of π–π stacking, the hydrophobic effect, and possible hydrogen-bonding between pigment and copigment) and of spectral modifications occurring in copigmentation complexes, in which charge transfer plays an important role. Particular attention is paid to applications of copigmentation in food chemistry.
J. Řezáč, P. Hobza: Benchmark Calculations of Interaction Energies in Noncovalent Complexes and Their Applications, CHEMICAL REVIEWS vol. 116, iss. 9, pp. 5038-5071, 2016.
DOI: 10.1021/acs.chemrev.5b00526, IF = 47.928
Abstract: Data sets of benchmark interaction energies in noncovalent complexes are an important tool for quantifying the accuracy of computational methods used in this field, as well as for the development of new computational approaches. This review is intended as a guide to conscious use of these data sets. We discuss their construction and accuracy, list the data sets available in the literature, and demonstrate their application to validation and parametrization of quantum-mechanical computational methods. In practical model systems, the benchmark interaction energies are usually obtained using composite CCSD(T)/CBS schemes. To use these results as a benchmark, their accuracy should be estimated first. We analyze the errors of this methodology with respect to both the approximations involved and the basis set size. We list the most prominent data sets covering various aspects of the field, from general ones to sets focusing on specific types of interactions or systems. The benchmark data are then used to validate more efficient computational approaches, including those based on explicitly correlated methods. Special attention is paid to the transition to large systems, where accurate benchmarking is difficult or impossible, and to the importance of nonequilibrium geometries in parametrization of more approximate methods.
M. B. Gawande, A. Goswami, F. Felpin, T. Asefa, X. Huang, R. Silva, X. Zou, R. Zboril, R. S. Varma: Cu and Cu-Based Nanoparticles: Synthesis and Applications in Catalysis, CHEMICAL REVIEWS, vol. 116, iss. 6, pp. 3722-3811, 2016.
DOI: 10.1021/acs.chemrev.5b00482, IF = 47.928
Abstract: The applications of copper (Cu) and Cu-based nanoparticles, which are based on the earth-abundant and inexpensive copper metal, have generated a great deal of interest in recent years, especially in the field of catalysis. The possible modification of the chemical and physical properties of these nanoparticles using different synthetic strategies and conditions and/or via postsynthetic chemical treatments has been largely responsible for the rapid growth of interest in these nanomaterials and their applications in catalysis. In addition, the design and development of novel support and/or multimetallic systems (e.g., alloys, etc.) has also made significant contributions to the field. In this comprehensive review, we report different synthetic approaches to Cu and Cu-based nanoparticles (metallic copper, copper oxides, and hybrid copper nanostructures) and copper nanoparticles immobilized into or supported on various support materials (SiO2, magnetic support materials, etc.), along with their applications in catalysis. The synthesis part discusses numerous preparative protocols for Cu and Cu-based nanoparticles, whereas the application sections describe their utility as catalysts, including electrocatalysis, photocatalysis, and gas-phase catalysis. We believe this critical appraisal will provide necessary background information to further advance the applications of Cu-based nanostructured materials in catalysis.
J. Tuček, P. Błoński, Z. Sofer, P. Šimek, M. Petr, M. Pumera, M. Otyepka, R. Zbořil: Sulfur Doping Induces Strong Ferromagnetic Ordering in Graphene: Effect of Concentration and Substitution Mechanism, ADV. MATER. vol. 28, iss. 25, pp. 5045-5053, 2016.
DOI: 10.1002/adma.201600939, IF = 19.791
Abstract: Imprinting ferromagnetism to a graphene structure by substitution of carbon atoms with sulfur is reported. S-doped graphene (4.2 at%) shows strong ferromagnetic properties with saturation magnetization exceeding 5.5 emu g−1 at 2 K, which is among the highest values reported for any sp-based system. The remarkable magnetic response is attributed to delocalization of electrons from sulfur injected into the graphene conduction band.
C. C. Givelet, P. I. Dron, J. Wen, T. F. Magnera, M. Zamadar, K. Čépe, H. Fujiwara, Y. Shi, M. R. Tuchband, N. Clark, R. Zbořil, J. Michl: Challenges in the Structure Determination of Self-Assembled Metallacages: What Do Cage Cavities Contain, Internal Vapor Bubbles or Solvent and/or Counterions?, J. AM. CHEM. SOC. vol. 138, iss. 20, pp. 6676-6687, 2016.
DOI: 10.1021/jacs.5b12050, IF = 13.858
Abstract: Proving the structures of charged metallacages obtained by metal ion coordination-driven solution self-assembly is challenging, and the common use of routine NMR spectroscopy and mass spectrometry is unreliable. Carefully determined diffusion coefficients from diffusion-ordered proton magnetic resonance (DOSY NMR) for six cages of widely differing sizes lead us to propose a structural reassignment of two molecular cages from a previously favored trimer to a pentamer or hexamer, and another from a trimer to a much higher oligomer, possibly an intriguing tetradecamer. In the former case, strong support for the reassignment to a larger cage is provided by an observation of a slow reversible transformation of the initially formed cage into a smaller but spectrally very similar one upon dilution. In the latter case, freeze-fracture transmission electron micrographs demonstrate that at least some of the solutions are colloidal, and high-resolution electron transmission and atomic force microscopy images are compatible with a tetradecamer but not a trimer. Comparison of solute partial molar volumes deduced from measurement of solution density with volumes anticipated from molecular models argues strongly against the presence of large voids (solvent vapor bubbles) in cages dissolved in nitromethane. The presence of bubbles was previously proposed in an attempt to account for the bilinear nature of the Eyring plot of the rate constant for pyridine ligand edge exchange reaction in one of the cages and for the unusual activation parameters in the high-temperature regime. An alternative interpretation is proposed now.
X. Chia, A. Adriano, P. Lazar, Z. Sofer, J. Luxa, M. Pumera: Layered Platinum Dichalcogenides (PtS 2 , PtSe 2 , and PtTe 2 ) Electrocatalysis: Monotonic Dependence on the Chalcogen Size , ADV. FUNCT. MATER. 2016.
DOI: 10.1002/adfm.201505402, IF = 12.124
Abstract: Presently, research in layered transition metal dichalcogenides (TMDs) for numerous electrochemical applications have largely focused on Group 6 TMDs, especially MoS2 and WS2, whereas TMDs belonging to other groups are relatively unexplored. This work unravels the electrochemistry of Group 10 TMDs: specifically PtS2, PtSe2, and PtTe2. Here, the inherent electroactivities of these Pt dichalcogenides and the effectiveness of electrochemical activation on their charge transfer and electrocatalytic properties are thoroughly examined. By performing density functional theory (DFT) calculations, the electrochemical and electrocatalytic behaviors of the Pt dichalcogenides are elucidated. The charge transfer and electrocatalytic attributes of the Pt dichalcogenides are strongly associated with their electronic structures. In terms of charge transfer, electrochemical activation has been successful for all Pt dichalcogenides as evident in the faster heterogeneous electron transfer (HET) rates observed in electrochemically reduced Pt dichalcogenides. Interestingly, the hydrogen evolution reaction (HER) performance of the Pt dichalcogenides adheres to a trend of PtTe2 > PtSe2 > PtS2 whereby the HER catalytic property increases down the chalcogen group. Importantly, the DFT study shows this correlation to their electronic property in which PtS2 is semiconducting, PtSe2is semimetallic, and PtTe2 is metallic. Furthermore, Pt dichalcogenides are effectively activated for HER. Distinct electronic structures of Pt dichalcogenides account for their different responses to electrochemical activation. Among all activated Pt dichalcogenides, PtS2 shows most accentuated improvement as a HER electrocatalyst with an exceptional 50% decline in HER overpotential. Knowledge on Pt dichalcogenides provides valuable insights in the field of TMD electrochemistry, in particular, for the currently underrepresented Group 10 TMDs.
J. Tuček, Z. Sofer, D. Bouša, M. Pumera, K. Holá, A. Malá, K. Poláková, M. Havrdová, K. Čépe, O. Tomanec, R. Zbořil: Air-stable superparamagnetic metal nanoparticles entrapped in graphene oxide matrix, NATURE COMMUNICATIONS vol. 7, pp. 12879, 2016.
DOI: 10.1038/ncomms12879, IF = 12.124
Abstract: Superparamagnetism is a phenomenon caused by quantum effects in magnetic nanomaterials. Zero-valent metals with diameters below 5 nm have been suggested as superior alternatives to superparamagnetic metal oxides, having greater superspin magnitudes and lower levels of magnetic disorder. However, synthesis of such nanometals has been hindered by their chemical instability. Here we present a method for preparing air-stable superparamagnetic iron nanoparticles trapped between thermally reduced graphene oxide nanosheets and exhibiting ring-like or core-shell morphologies depending on iron concentration. Importantly, these hybrids show superparamagnetism at room temperature and retain it even at 5 K. The corrected saturation magnetization of 185 Am2 kg–1 is among the highest values reported for iron-based superparamagnets. The synthetic concept is generalized exploiting functional groups of graphene oxide to stabilize and entrap cobalt, nickel and gold nanoparticles, potentially opening doors for targeted delivery, magnetic separation and imaging applications.
Jayaramulu, K., Datta, K. K. R., Rösler, C., Petr, M., Otyepka, M., Zboril, R. and Fischer, R. A.: Biomimetic Superhydrophobic/Superoleophilic Highly Fluorinated Graphene Oxide and ZIF-8 Composites for Oil–Water Separation, ANGEWANDTE CHEMIE INTERNATIONAL EDITION, vol. 55, iss. 3, pp. 1178-1182, 2016.
DOI: 10.1002/anie.201507692, IF = 11.994
Abstract: Superhydrophobic/superoleophilic composites HFGO@ZIF-8 have been prepared from highly fluorinated graphene oxide (HFGO) and the nanocrystalline zeolite imidazole framework ZIF-8. The structure-directing and coordination-modulating properties of HFGO allow for the selective nucleation of ZIF-8 nanoparticles at the graphene surface oxygen functionalities. This results in localized nucleation and size-controlled ZIF-8 nanocrystals intercalated in between HFGO layers. The composite microstructure features fluoride groups bonded at the graphene. Self-assembly of a unique micro-mesoporous architecture is achieved, where the micropores originate from ZIF-8 nanocrystals, while the functionalized mesopores arise from randomly organized HFGO layers separated by ZIF-8 nanopillars. The hybrid material displays an exceptional high water contact angle of 162° and low oil contact angle of 0° and thus reveals very high sorption selectivity, fast kinetics, and good absorbencies for nonpolar/polar organic solvents and oils from water. Accordingly, Sponge@HFGO@ZIF-8 composites are successfully utilized for oil–water separation.
J. Isonet al.: Tools and data services registry: a community effort to document bioinformatics resources, NUCLEIC ACIDS RES vol. 44, iss. D1, pp. D38-D47, 2016.
DOI: 10.1093/nar/gkv1116, IF = 10.162
Abstract: Life sciences are yielding huge data sets that underpin scientific discoveries fundamental to improvement in human health, agriculture and the environment. In support of these discoveries, a plethora of databases and tools are deployed, in technically complex and diverse implementations, across a spectrum of scientific disciplines. The corpus of documentation of these resources is fragmented across the Web, with much redundancy, and has lacked a common standard of information. The outcome is that scientists must often struggle to find, understand, compare and use the best resources for the task at hand. Here we present a community-driven curation effort, supported by ELIXIR—the European infrastructure for biological information—that aspires to a comprehensive and consistent registry of information about bioinformatics resources. The sustainable upkeep of this Tools and Data Services Registry is assured by a curation effort driven by and tailored to local needs, and shared amongst a network of engaged partners. As of November 2015, the registry includes 1785 resources, with depositions from 126 individual registrations including 52 institutional providers and 74 individuals. With community support, the registry can become a standard for dissemination of information about bioinformatics resources: we welcome everyone to join us in this common endeavour. The registry is freely available at https://bio.tools.
O. Kozák, M. Sudolská, G. Pramanik, P. Cígler, M. Otyepka, R. Zbořil: Photoluminescent Carbon Nanostructures, CHEMISTRY OF MATERIALS vol. 28, iss. 12, pp. 4085-4128, 2016.
DOI: 10.1021/acs.chemmater.6b01372, IF = 9.466
Abstract: Photoluminescent nanosized allotropes of carbon have attracted considerable interest because of their diverse optical properties depending on their crystal structure, size, and morphology, and chemical functionalization. Here, we present the first critical review covering the photoluminescence (PL) properties, their control, and origin in various carbon allotropes and their composites. Different mechanisms by which carbon nanostructures exhibit PL are discussed, involving excitonic PL in carbon nanotubes, thermally activated delayed fluorescence in spherical fullerenes, the presence of impurity–vacancy color centers in nanodiamonds, aromatic sp2 domains in reduced graphene oxide, and surface chromophores or defect-related PL in carbon dots. We critically analyze the intrinsic and external effects affecting the PL properties (spectral shift, decay, quantum yield) from both experimental data and theoretical calculations. The key parameters addressed include, for example, the type and content of impurity elements in nanodiamonds (NV and SiV centers), chemical composition in reduced graphene oxides, external effects (temperature, solvent) in C60 fullerene, structural type (single-wall versus multi-wall carbon nanotubes), and the roles of doping and surface functional groups in the PL behavior of carbon/graphene dots.
T. Pluháček, K. Lemr, D. Ghosh, D. Milde, J. Novák, V. Havlíček: Characterization of microbial siderophores by mass spectrometry, MASS SPEC REV vol. 35, iss. 1, pp. 35-47, 2016.
DOI: 10.1002/mas.21461, IF = 9.373
Abstract: Siderophores play important roles in microbial iron piracy, and are applied as infectious disease biomarkers and novel pharmaceutical drugs. Inductively coupled plasma and molecular mass spectrometry (ICP-MS) combined with high resolution separations allow characterization of siderophores in complex samples taking advantages of mass defect data filtering, tandem mass spectrometry, and iron-containing compound quantitation. The enrichment approaches used in siderophore analysis and current ICP-MS technologies are reviewed. The recent tools for fast dereplication of secondary metabolites and their databases are reported. This review on siderophores is concluded with their recent medical, biochemical, geochemical, and agricultural applications in mass spectrometry context.
S. Bottaro, P. Banáš, J. Šponer, G. Bussi: Free Energy Landscape of GAGA and UUCG RNA Tetraloops, THE JOURNAL OF PHYSICAL CHEMISTRY LETTERS vol. 7, iss. 20, pp. 4032-4038, 2016.
DOI: 10.1021/acs.jpclett.6b01905, IF = 9.353
Abstract: We report the folding thermodynamics of ccUUCGgg and ccGAGAgg RNA tetraloops using atomistic molecular dynamics simulations. We obtain a previously unreported estimation of the folding free energy using parallel tempering in combination with well-tempered metadynamics. A key ingredient is the use of a recently developed metric distance, eRMSD, as a biased collective variable. We find that the native fold of both tetraloops is not the global free energy minimum using the AmberχOL3 force field. The estimated folding free energies are 30.2 ± 0.5 kJ/mol for UUCG and 7.5 ± 0.6 kJ/mol for GAGA, in striking disagreement with experimental data. We evaluate the viability of all possible one-dimensional backbone force field corrections. We find that disfavoring the gauche+ region of α and ζ angles consistently improves the existing force field. The level of accuracy achieved with these corrections, however, cannot be considered sufficient by judging on the basis of available thermodynamic data and solution experiments.
T. M. Lima, C. G. S. Lima, A. K. Rathi, M. B. Gawande, J. Tucek, E. A. Urquieta-González, R. Zbořil, M. W. Paixão, R. S. Varma: Magnetic ZSM-5 zeolite: a selective catalyst for the valorization of furfuryl alcohol to γ-valerolactone, alkyl levulinates or levulinic acid, GREEN CHEM., vol. 18, iss. 20, pp. 5586-5593, 2016.
DOI: 10.1039/c6gc01296e, IF = 9.125
Abstract: A magnetic ZSM-5 zeolite with a core–shell type structure was synthesized, fully characterized and had its catalytic activity evaluated on the valorization of bio-derived furfuryl alcohol. The catalytic system displayed a tuneable selectivity to γ-valerolactone, alkyl levulinates and even levulinic acid by simply changing the reaction conditions. Furthermore, the catalyst could be easily recovered and reused for several reaction cycles without significant losses in its catalytic activity.
R. K. Sharma, S. Dutta, S. Sharma, R. Zboril, R. S. Varma, M. B. Gawande: Fe3O4(iron oxide)-supported nanocatalysts: synthesis, characterization and applications in coupling reactions, GREEN CHEM. vol. 18, iss. 11, pp. 3184-3209, 2016.
DOI: 10.1039/c6gc00864j, IF = 9.125
Abstract: The use of magnetic nanoparticles as a solid support material for the development of magnetically retrievable catalytic systems has led to a dramatic expansion of their potential applications as they enable environmentally-friendly and sustainable catalytic processes. These quasi-homogeneous catalysts possess numerous benefits such as ease of isolation and separation from the desired reaction mixtures using an external magnet and excellent recyclability. Consequently, much effort has been directed towards the synthesis of magnetically isolable nano-sized particles by developing methods such as co-precipitation, thermal decomposition, microemulsion, hydrothermal techniques etc. Further, in order to render them suitable for catalytic applications, several protection strategies such as surfactant/polymer, silica and carbon coating of magnetic nanoparticles or embedding them in a matrix/support have been reported in the literature. This review focuses on the substantial progress made in the fabrication of nanostructured catalysts with special emphasis on the protection and functionalization of the magnetite nanoparticles (Fe3O4). Finally, considering the importance of coupling chemistry in the field of organic synthesis, a broad overview of the applications of these magnetite nanoparticle-based catalysts in several types of coupling reactions has been presented. The future of catalysis lies in the rational design and development of novel, highly active and recyclable nanocomposite catalysts which would eventually pave the pathway for the establishment of green and sustainable technologies.
A. K. Rathi, M. B. Gawande, J. Pechousek, J. Tucek, C. Aparicio, M. Petr, O. Tomanec, R. Krikavova, Z. Travnicek, R. S. Varma, R. Zboril: Maghemite decorated with ultra-small palladium nanoparticles (γ-Fe2O3–Pd): applications in the Heck–Mizoroki olefination, Suzuki reaction and allylic oxidation of alkenes, GREEN CHEM. vol. 18, iss. 8, pp. 2363-2373, 2016.
DOI: 10.1039/c5gc02264a, IF = 9.125
Abstract: A nanocatalyst comprising ultra-small Pd/PdO nanoparticles (<5 nm) supported on maghemite was prepared by a co-precipitation protocol using inexpensive raw materials and was deployed successfully in various significant synthetic transformations, namely the Heck–Mizoroki olefination (up to 95%), the Suzuki reaction (60–95%), and the allylic oxidation of alkenes under milder conditions. The chemical nature, morphology, size, and loading of palladium nanoparticles over the magnetic support were studied by TEM/EDX, HAADF-STEM chemical mapping, XPS, AAS, and in-field 57Fe Mössbauer spectroscopy. The cost-effective catalyst could be easily separated from the reaction mixture by using an external magnet and reused four times without any loss of activity; chemical stability and recyclability aspects of the catalyst were investigated.
K. J. Datta, M. B. Gawande, K. K. R. Datta, V. Ranc, J. Pechousek, M. Krizek, J. Tucek, R. Kale, P. Pospisil, R. S. Varma, T. Asefa, G. Zoppellaro, R. Zboril: Micro–mesoporous iron oxides with record efficiency for the decomposition of hydrogen peroxide: morphology driven catalysis for the degradation of organic contaminants, J. MATER. CHEM. A vol. 4, iss. 2, pp. 596-604, 2016.
DOI: 10.1039/c5ta08386a, IF = 8.867
Abstract: A template-free solid-state synthesis of a morphologically controlled and highly organized iron(III)oxide micro–mesoporous Fenton catalyst has been engineered through a simple two-step synthetic procedure. The 3D nanoassembly of hematite nanoparticles (5–7 nm) organized into a rod/flower-like morphology shows the highest rate constant reported to date for the decomposition of H2O2 (1.43 × 10−1 min−1) with superior efficiency for the degradation of aromatic (phenol, benzene, ethylbenzene) and chlorinated (trichloroethylene) pollutants in contaminated water. The morphological arrangement of nanoparticles is therefore considered one of the key variables that drive catalysis.
K. Jayaramulu, T. Toyao, V. Ranc, C. Rösler, M. Petr, R. Zboril, Y. Horiuchi, M. Matsuoka, R. A. Fischer: An in situ porous cuprous oxide/nitrogen-rich graphitic carbon nanocomposite derived from a metal–organic framework for visible light driven hydrogen evolution, J. MATER. CHEM. A, vol. 4, pp. 18037–18042, 2016, 2016.
DOI: 10.1039/c6ta07424c, IF = 8.867
Abstract: We report a simple methodology for synthesizing a hybrid of cuprous oxide (Cu2O) nanoparticles with a size less than 6 nm embedded into a porous graphitic nitrogen-rich carbon matrix. The mesoporous composite, Cu2O@C3N, with a surface area of 112 m2 g−1 was prepared by mild pyrolysis (450 °C) of a copper based metal organic framework, Cu3(BTC)2 loaded with urea, (H2N)2CO. The Cu2O@C3N shows a band gap energy of 1.97 eV and acts as an efficient photocatalyst for hydrogen evolution from water under visible light. The amount of evolved H2 is more than 2 times higher than that evolved over pristine carbon nitride and cuprous oxide under the same conditions. Importantly, the composite maintains its catalytic activity even after three catalytic cycles maintaining similar yields. Therefore, the nitrogen-rich porous carbon support serves as a functional scaffold preventing the agglomeration of Cu2O nanoparticles. The key factors responsible for enhanced hydrogen evolution from water are improved visible light absorption, suppressed charge carrier recombination, increased charge separation and high surface area of the composite. We investigated the effect of different pyrolysis temperatures set at 550 and 700 °C on the photocatalytic hydrogen evolution rates. The pyrolysis conditions affect not only the phase transition of copper (copper oxide at 550 °C and pure copper metal at 700 °C) in the resultant composites, but also nitrogen amount incorporation. We believe that this work provides a new insight into the design and fabrication of various efficient and cost-effective nitrogen-rich carbon composites (alternative for noble metals) with superior photocatalytic hydrogen evolution activity.
A. Sitt, J. Soukupova, D. Miller, D. Verdi, R. Zboril, H. Hess, J. Lahann: Microscale Rockets and Picoliter Containers Engineered from Electrospun Polymeric Microtubes, SMALL, vol. 12, iss. 11, pp. 1432-1439, 2016.
DOI: 10.1002/smll.201503467, IF = 8.643
Abstract: Chemically functional core/shell microtubes made of biodegradable polymers are fabricated using coaxial electrospinning. The luminal walls are chemically functionalized, allowing for regioselective chemical binding or adsorption inside the microtube. Attaching catalytic nanoparticles or enzymes to the luminal walls converts the microtubes into bubble-propelled microrockets. Upon exposure to ultrasound, the microtubes undergo shape shifting, transforming them into picoliter-scale containers.
S. Kalytchuk, O. Zhovtiuk, S. V. Kershaw, R. Zbořil, A. L. Rogach: Temperature-Dependent Exciton and Trap-Related Photoluminescence of CdTe Quantum Dots Embedded in a NaCl Matrix: Implication in Thermometry, SMALL vol. 12, iss. 4, pp. 466-476, 2016.index
DOI: 10.1002/smll.201501984, IF = 8.643
Abstract: Temperature-dependent optical studies of semiconductor quantum dots (QDs) are fundamentally important for a variety of sensing and imaging applications. The steady-state and time-resolved photoluminescence properties of CdTe QDs in the size range from 2.3 to 3.1 nm embedded into a protective matrix of NaCl are studied as a function of temperature from 80 to 360 K. The temperature coefficient is found to be strongly dependent on QD size, with the highest sensitivity obtained for the smallest size of QDs. The emission from solid-state CdTe QD-based powders is maintained with high color purity over a wide range of temperatures. Photoluminescence lifetime data suggest that temperature dependence of the intrinsic radiative lifetime in CdTe QDs is rather weak, and it is mostly the temperature-dependent nonradiative decay of CdTe QDs which is responsible for the thermal quenching of photoluminescence intensity. By virtue of the temperature-dependent photoluminescence behavior, high color purity, photostability, and high photoluminescence quantum yield (26%–37% in the solid state), CdTe QDs embedded in NaCl matrices are useful solid-state probes for thermal imaging and sensing over a wide range of temperatures within a number of detection schemes and outstanding sensitivity, such as luminescence thermochromic imaging, ratiometric luminescence, and luminescence lifetime thermal sensing.
ATLAS Collaboration: Observation of Long-Range Elliptic Azimuthal Anisotropies in
s√=13 and 2.76 TeV pp Collisions with the ATLAS DetectorPHYS. REV. LETT. vol. 116, iss. 17, 2016. DOI: 10.1103/PhysRevLett.116.172301, IF = 8.462
Abstract: ATLAS has measured two-particle correlations as a function of the relative azimuthal angle,
ATLAS Collaboration: Measurement of the
ZZ Production Cross Section in pp Collisions at s√=13 TeV with the ATLAS DetectorPHYS. REV. LETT. vol. 116, iss. 10, 2016. DOI: 10.1103/physrevlett.116.101801, IF = 8.462
Y. Sarigiannis, Α. Kolokithas-Ntoukas, N. Beziere, R. Zbořil, E. Papadimitriou, K. Avgoustakis, M. Lamprou, Z. Medrikova, E. Rousalis, V. Ntziachristos, A. Bakandritsos: Synthesis and evaluation of condensed magnetic nanocrystal clusters with in vivo multispectral optoacoustic tomography for tumour targeting, BIOMATERIALS vol. 91, pp. 128-139, 2016.
DOI: 10.1016/j.biomaterials.2016.03.015, IF = 8.402
Colloidal clusters of magnetic iron oxide nanocrystals (MIONs), particularly in the condensed pattern (co-CNCs), have emerged as new superstructures to improve further the performance of MIONs in applications pertaining to magnetic manipulation (drug delivery) and magnetic resonance imaging (MRI). Exploitation of the advantages they represent and their establishment in the area of nanomedicine demands a particular set of assets. The present work describes the development and evaluation of MION-based co-CNCs featuring for the first time such assets: High magnetization, as well as magnetic content and moment, high relaxivities (r2 = 400 and ) and intrinsic loss power (2.3 nH m2 kgFe−1) are combined with unprecedented colloidal stability and structural integrity, stealth and drug-loading properties. The reported nanoconstructs are endowed with additional important features such as cost-effective synthesis and storage, prolonged self-life and biocompatibility. It is finally showcased with in vivo multispectral optoacoustic tomography how these properties culminate in a system suitable for targeting breast cancer and for forceful in vivo manipulation with low magnetic field gradients.
E. Voulgari, A. Bakandritsos, S. Galtsidis, V. Zoumpourlis, B. P. Burke, G. S. Clemente, C. Cawthorne, S. J. Archibald, J. Tuček, R. Zbořil, V. Kantarelou, A. G. Karydas, K. Avgoustakis: Synthesis, characterization and in vivo evaluation of a magnetic cisplatin delivery nanosystem based on PMAA-graft-PEG copolymers, JOURNAL OF CONTROLLED RELEASE vol. 243, pp. 342-356, 2016.
DOI: 10.1016/j.jconrel.2016.10.021, IF = 7.786
Abstract: The development of anticancer drug delivery systems which retain or enhance the cytotoxic properties of the drug to tumorous tissues, while reducing toxicity to other organs is of key importance. We investigated different poly(methacrylic acid)-g-poly(ethyleneglycol methacrylate) polymers as in situ coating agents for magnetite nanocrystallites. The obtained magnetic nano-assemblies were in turn thoroughly characterized for their structural, colloidal and physicochemical properties (drug loading capacity/release, magnetic field triggered drug release, cell uptake and localization) in order to select the best performing system. With the focus on in vivo validation of such magnetic drug delivery systems for first time, we selected cisplatin as the drug, since it is a potent anticancer agent which exhibits serious side effects due to lack of selectivity. In addition, cisplatin would offer facile determination of the metal content in the animal tissues for biodistribution studies. Alongside post-mortem Pt determination in the tissues, the biodistribution of the drug nanocarriers was also monitored in real time with PET-CT (positron emission tomography/computed tomography) with and without the presence of magnetic field gradients; using a novel chelator-free method, the nanoparticles were radiolabeled with 68Ga without having to alter their structure with chemical modifications for conjugation of radiochelators. The ability to be radiolabeled in such a straightforward but very robust way, along with their measured high MRI response, renders them attractive for dual imaging, which is an important functionality for translational investigations. Their anticancer properties were evaluated in vitro and in vivo, in a cisplatin resistant HT-29 human colon adenocarcinoma model, with and without the presence of magnetic field gradients. Enhanced anticancer efficacy and reduced toxicity was recorded for the cisplatin-loaded nanocarriers in comparison to the free cisplatin, particularly when a magnetic field gradient was applied at the tumor site. Post mortem and real-time tissue distribution studies did not reveal increased cisplatin concentration in the tumor site, suggesting that the enhanced anticancer efficacy of the cisplatin-loaded nanocarriers is driven by mechanisms other than increased cisplatin accumulation in the tumors.
G. D. Peppas, A. Bakandritsos, V. P. Charalampakos, E. C. Pyrgioti, J. Tucek, R. Zboril, I. F. Gonos: Ultrastable Natural Ester Based Nanofluids for High Voltage Insulation Applications, ACS APPL. MATER. INTERFACES, vol. 8, iss. 38, pp. 25202–25209, 2016.
DOI: 10.1021/acsami.6b06084, IF = 7.504
Abstract: Nanofluids for high voltage insulation systems have emerged as a potential substitute of liquid dielectrics in industrial applications. Nevertheless, the sedimentation of nanoparticles has been so far a serious barrier for their wide and effective exploitation. The present work reports on the development and in-depth characterization of colloidally ultrastable natural ester oil insulation systems, containing iron oxide nanocrystals, which lift the problem of sedimentation and phase separation. Compared to state-of the-art systems, the final product is endowed with increased dielectric strength, faster thermal response, lower dielectric losses (decreased dissipation factor- tanδ) and very high endurance during discharge stressing. The developed nanofluid is studied and compared with a similar system containing commercial iron oxide nanoparticles, the latter demonstrating extensive sedimentation. Herein, the dielectric properties of the nanofluids are analyzed at various concentrations by means of breakdown voltage and dissipation factor measurements. The characterization techniques unequivocally demonstrate the high performance-reliability of the reported nanofluid, which constitutes a significant breakthrough in the field of high voltage insulation technologies.
V. Georgakilas, A. Koutsioukis, M. Petr, J. Tucek, R. Zboril: Remarkable enhancement of the electrical conductivity of carbon nanostructured thin films after compression, NANOSCALE vol. 8, iss. 22, pp. 11413-11417, 2016.
DOI: 10.1039/c5nr09025c, IF = 7.367
Abstract: In this work, we demonstrate a significant improvement in the electrical conductivity of carbon nanostructured thin films, composed of graphene nanosheets and multiwalled carbon nanotubes, by compression/polishing. It is shown that the sheet resistance of compressed thin films of carbon nanostructures and hybrids is remarkably decreased in comparison with that of as-deposited films. The number of the interconnections, the distance between the nanostructures as well as their orientation are highly altered by the compression favoring the electrical conductivity of the compressed samples.
Z. Wang, A. Susha, B. Chen, C. Reckmeier, O. Tomanec, R. Zboril, H. Zhong, A. Rogach: Poly(vinylpyrrolidone) Supported Copper Nanoclusters: Glutathione Enhanced Blue Photoluminescence for Application in Phosphor Converted Light Emitting Devices, NANOSCALE, vol. 8, pp. 7197-7202, 2016.
DOI: 10.1039/c6nr00806b, IF = 7.367
Abstract: Poly(vinylpyrrolidone) supported Cu nanoclusters were synthesized by reduction of Cu (II) ions with asorbic acid in water, and initially showed blue photoluminescence with a quantum yield of 8%. An enhancement of the emission quantum yield has been achieved by treatment of Cu clusters with different electron-rich ligands, with the most pronounced effect (photoluminescence quantum yield of 27%) achieved with glutathione. The bright blue emission of glutathione treated Cu NCs is fully preserved in the solid state powder, which has been combined with commercial green and red phosphors to fabricate down-conversion white light emitting diodes with high colour rendering index of 92.
V. Urbanova, F. Karlicky, A. Matej, F. Sembera, Z. Janousek, J. A. Perman, V. Ranc, K. Cepe, J. Michl, M. Otyepka, R. Zboril: Fluorinated graphenes as advanced biosensors - Effect of fluorine coverage on electron transfer properties and adsorption of biomolecules, NANOSCALE, Advance Article, 2016.
DOI: 10.1039/c6nr00353b, IF = 7.367
Abstract: Graphene derivatives are promising materials for the electrochemical sensing of diverse biomolecules and development of new biosensors owing to their improved electron transfer kinetics compared to pristine graphene. Here, we report complex electrochemical behavior and electrocatalytic performance of variously fluorinated graphene derivatives prepared by reaction of graphene with a nitrogen-fluorine mixture at 2 bars pressure. The fluorine content was simply controlled by varying the reaction time and temperature. The studies revealed that electron transfer kinetics and electrocatalytic activity of CFx strongly depend on the degree of fluorination. The versatility of fluorinated graphene as a biosensor platform was demonstrated by cyclic voltammetry for different biomolecules essential in physiological processes, i.e. NADH, ascorbic acid and dopamine. Importantly, the highest electrochemical performance, even higher than pristine graphene, was obtained for fluorinated graphene with the lowest fluorine content (CF0.084) due to its high conductivity and enhanced adsorption properties combining - stacking interaction with graphene regions with hydrogen-bonding interaction with fluorine atoms.
N. Liaros, J. Tucek, K. Dimos, A. Bakandritsos, K. S. Andrikopoulos, D. Gournis, R. Zboril, S. Couris: The effect of the degree of oxidation on broadband nonlinear absorption and ferromagnetic ordering in graphene oxide, NANOSCALE vol. 8, iss. 5, pp. 2908-2917, 2016.
DOI: 10.1039/c5nr07832f, IF = 7.367
Abstract: We report on the effect of the degree of oxidation on the broadband non-linear optical response and magnetic behavior of graphene oxide, as well as on a route for obtaining reduced graphene oxide with enhanced optical properties without sacrificing the high dispersibility of the parent graphene oxide. As more sp3 states evolved with the rise in oxidation degree, it turned out that the sp2/sp3 fraction and sp2 clustering are crucial parameters for tuning the broadband non-linear optical absorption over a wide range from ps to ns laser pulses for both visible and infrared laser irradiation. This was clearly confirmed by two different approaches, namely by a synthetic route through the gradual oxidation of graphene oxide from 1 to 3 oxidizing cycles, and reversely by in situ reduction of graphene oxide by UV laser irradiation. Furthermore, as the sp3 states carry localized magnetic moments, ferromagnetic ordering is observed at low temperatures. The magnetization and temperature at which ferromagnetic ordering evolves are found to increase on increasing the oxidation degree. The tuning of non-linear optical and magnetic properties of graphene oxide by oxidation/reduction thus provides an easy way to endow graphene oxide with tunable physical features highly required in both optoelectronics and spintronics applications.
V. Georgakilas, A. B. Bourlinos, E. Ntararas, A. Ibraliu, D. Gournis, K. Dimos, A. Kouloumpis, and R. Zboril: Graphene nanobuds: Synthesis and selective organic derivatisation, CARBON, vol. 110, pp. 51-55, 2016.
DOI: 10.1016/j.carbon.2016.09.003, IF = 6.337
Abstract: Herein, the formation and selective organic derivatisation of graphene nanobud, an all carbon nanohybrid comprised by C60 and graphene, are presented. C60 cages are directly attached to the graphenic surface with stable covalent bonds. Importantly, prepared graphene nanobud shows remarkable dispersibility, decreased number of defects and highly aromatic character that are associated to improved electrical conductivity compared to pristine graphene. The high chemical reactivity of the curved sp2 carbon atoms of C60 led to a selective covalent attachment of organic groups onto C60 avoiding damage of the graphene aromatic system.
M. Havrdova, K. Hola, J. Skopalik, K. Tomankova, M. Petr, K. Cepe, K. Polakova, J. Tucek, A. B. Bourlinos, R. Zboril: Toxicity of carbon dots – Effect of surface functionalization on the cell viability, reactive oxygen species generation and cell cycle, CARBON vol. 99, pp. 238-248, 2016.
DOI: 10.1016/j.carbon.2015.12.027, IF = 6.337
Abstract: Carbon dots (CDs) are fluorescent nanoprobes offering a great potential in biological and medical applications due to their superior biocompatibility compared to metal chalcogenide quantum dots (e.g., CdSe). Key factors determining their cytotoxicity and cellular/intracellular tracking involve chemical nature and charge of surface functional groups. For the first time, we present a comprehensive cytotoxic study including cell cycle analysis of carbon dots differing in surface functionalization, namely pristine CDs (CDs-Pri) with negative charge due to carboxylic groups, polyethyleneglycol modified dots with neutral charge (CDs-PEG), and polyethylenimine coated dots with a positive charge (CDs-PEI). The CDs in vitro toxicity was studied on standard mouse fibroblasts (NIH/3T3). The results suggest that neutral CDs-PEG are the most promising for biological applications as they do not induce any abnormalities in cell morphology, intracellular trafficking, and cell cycle up to concentrations of 300 μg mL−1. Negatively charged CDs-Pri arrested the G2/M phase of the cell cycle, stimulated proliferation and led to higher oxidative stress, however they did not enter the cell nucleus. In contrast, positively charged CDs-PEI are the most cytotoxic, entering into the cell nucleus and inducing the largest changes in G0/G1 phase of cell cycle, even at concentrations of around 100 μg mL−1.