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Kosmos
Astronomia Astrofizyka
Inne

Kultura
Sztuka dawna i współczesna, muzea i kolekcje

Metoda
Metodologia nauk, Matematyka, Filozofia, Miary i wagi, Pomiary

Materia
Substancje, reakcje, energia
Fizyka, chemia i inżynieria materiałowa

Człowiek
Antropologia kulturowa Socjologia Psychologia Zdrowie i medycyna

Wizje
Przewidywania Kosmologia Religie Ideologia Polityka

Ziemia
Geologia, geofizyka, geochemia, środowisko przyrodnicze

Życie
Biologia, biologia molekularna i genetyka

Cyberprzestrzeń
Technologia cyberprzestrzeni, cyberkultura, media i komunikacja

Działalność
Wiadomości | Gospodarka, biznes, zarządzanie, ekonomia

Technologie
Budownictwo, energetyka, transport, wytwarzanie, technologie informacyjne

Beilstein Journal of Nanotechnology

Abstract
When particles incorporated within a mammalian organism come into contact with body fluids they will bind to soluble proteins or those within cellular membranes forming what is called a protein corona. This binding process is very complex and highly dynamic due to the plethora of proteins with different affinities and fractions in different body fluids and the large variation of compounds and structures of the particle surface. Interestingly, in the case of nanoparticles (NP) this protein corona is well suited to provide a guiding vehicle of translocation within body fluids and across membranes. This NP translocation may subsequently lead to accumulation in various organs and tissues and their respective cell types that are not expected to accumulate such tiny foreign bodies. Because of this unprecedented NP accumulation, potentially adverse biological responses in tissues and cells cannot be neglected a priori but require thorough investigations. Therefore, we studied the interactions and protein binding kinetics of blood serum proteins with a number of engineered NP as a function of their physicochemical properties. Here we show by in vitro incubation tests that the binding capacity of different engineered NP (polystyrene, elemental carbon) for selected serum proteins depends strongly on the NP size and the properties of engineered surface modifications. In the following attempt, we studied systematically the effect of the size (5, 15, 80 nm) of gold spheres (AuNP), surface-modified with the same ionic ligand; as well as 5 nm AuNP with five different surface modifications on the binding to serum proteins by using proteomics analyses. We found that the binding of numerous serum proteins depended strongly on the physicochemical properties of the AuNP. These in vitro results helped us substantially in the interpretation of our numerous in vivo biokinetics studies performed in rodents using the same NP. These had shown that not only the physicochemical properties determined the AuNP translocation from the organ of intake towards blood circulation and subsequent accumulation in secondary organs and tissues but also the the transport across organ membranes depended on the route of AuNP application. Our in vitro protein binding studies support the notion that the observed differences in in vivo biokinetics are mediated by the NP protein corona and its dynamical change during AuNP translocation in fluids and across membranes within the organism.

Beilstein J. Nanotechnol. 2014, 5, 1699–1711. doi:10.3762/bjnano.5.180

http://www.beilstein-journals.org/bjnano/content/5/1/180 2014/10/02 - 19:25

Abstract
Zn–silica nanocomposite thin films with varying Zn metal content, deposited by atom beam sputtering technique were subjected to 100 MeV Ag ion irradiation. Rutherford backscattering spectrometry reveals the loss of Zn with irradiation, which is observed to be greater from thin films with lower Zn content. The sputtered species collected on carbon-coated transmission electron microscopy (TEM) grids consist of Zn nanoparticles of sizes comparable to those present in the nanocomposite thin film. The process of size-dependent electronic sputtering of Zn is explained on the basis of an inelastic thermal spike model. The possibility of direct cluster emission is explained by pressure spike built inside the track, initiated by a temperature spike.

Beilstein J. Nanotechnol. 2014, 5, 1691–1698. doi:10.3762/bjnano.5.179

http://www.beilstein-journals.org/bjnano/content/5/1/179 2014/10/02 - 19:25

Abstract
Carbon nanotubes (CNTs) have been proposed and actively explored as multipurpose innovative nanoscaffolds for applications in fields such as material science, drug delivery and diagnostic applications. Their versatile physicochemical features are nonetheless limited by their scarce solubilization in both aqueous and organic solvents. In order to overcome this drawback CNTs can be easily non-covalently functionalized with different dispersants. In the present review we focus on the peculiar hydrophobic character of pristine CNTs that prevent them to easily disperse in organic solvents. We report some interesting examples of CNTs dispersants with the aim to highlight the essential features a molecule should possess in order to act as a good carbon nanotube dispersant both in water and in organic solvents. The review pinpoints also a few examples of dispersant design. The last section is devoted to the exploitation of the major quality of non-covalent functionalization that is its reversibility and the possibility to obtain stimuli-responsive precipitation or dispersion of CNTs.

Beilstein J. Nanotechnol. 2014, 5, 1675–1690. doi:10.3762/bjnano.5.178

http://www.beilstein-journals.org/bjnano/content/5/1/178 2014/10/02 - 19:25

Abstract
We prepare and investigate two-dimensional (2D) single-layer arrays and multilayered networks of gold nanoparticles derivatized with conjugated hetero-aromatic molecules, i.e., S-(4-{[2,6-bipyrazol-1-yl)pyrid-4-yl]ethynyl}phenyl)thiolate (herein S-BPP), as capping ligands. These structures are fabricated by a combination of self-assembly and microcontact printing techniques, and are characterized by electron microscopy, UV–visible spectroscopy and Raman spectroscopy. Selective binding of the S-BPP molecules to the gold nanoparticles through Au–S bonds is found, with no evidence for the formation of N–Au bonds between the pyridine or pyrazole groups of BPP and the gold surface. Subtle, but significant shifts with temperature of specific Raman S-BPP modes are also observed. We attribute these to dynamic changes in the orientation and/or increased mobility of the molecules on the gold nanoparticle facets. As for their conductance, the temperature-dependence for S-BPP networks differs significantly from standard alkanethiol-capped networks, especially above 220 K. Relating the latter two observations, we propose that dynamic changes in the molecular layers effectively lower the molecular tunnel barrier for BPP-based arrays at higher temperatures.

Beilstein J. Nanotechnol. 2014, 5, 1664–1674. doi:10.3762/bjnano.5.177

http://www.beilstein-journals.org/bjnano/content/5/1/177 2014/10/02 - 19:25

Abstract
This paper presents computational simulations of single-mode and bimodal atomic force microscopy (AFM) with particular focus on the viscoelastic interactions occurring during tip–sample impact. The surface is modeled by using a standard linear solid model, which is the simplest system that can reproduce creep compliance and stress relaxation, which are fundamental behaviors exhibited by viscoelastic surfaces. The relaxation of the surface in combination with the complexities of bimodal tip–sample impacts gives rise to unique dynamic behaviors that have important consequences with regards to the acquisition of quantitative relationships between the sample properties and the AFM observables. The physics of the tip–sample interactions and its effect on the observables are illustrated and discussed, and a brief research outlook on viscoelasticity measurement with intermittent-contact AFM is provided.

Beilstein J. Nanotechnol. 2014, 5, 1649–1663. doi:10.3762/bjnano.5.176

http://www.beilstein-journals.org/bjnano/content/5/1/176 2014/09/27 - 12:05

Abstract
We present an exploratory study of multimodal tapping-mode atomic force microscopy driving more than three cantilever eigenmodes. We present tetramodal (4-eigenmode) imaging experiments conducted on a thin polytetrafluoroethylene (PTFE) film and computational simulations of pentamodal (5-eigenmode) cantilever dynamics and spectroscopy, focusing on the case of large amplitude ratios between the fundamental eigenmode and the higher eigenmodes. We discuss the dynamic complexities of the tip response in time and frequency space, as well as the average amplitude and phase response. We also illustrate typical images and spectroscopy curves and provide a very brief description of the observed contrast. Overall, our findings are promising in that they help to open the door to increasing sophistication and greater versatility in multi-frequency AFM through the incorporation of a larger number of driven eigenmodes, and in highlighting specific future research opportunities.

Beilstein J. Nanotechnol. 2014, 5, 1637–1648. doi:10.3762/bjnano.5.175

http://www.beilstein-journals.org/bjnano/content/5/1/175 2014/09/26 - 05:17

Abstract
Precise knowledge regarding cellular uptake of nanoparticles is of great importance for future biomedical applications. Four different endocytotic uptake mechanisms, that is, phagocytosis, macropinocytosis, clathrin- and caveolin-mediated endocytosis, were investigated using a mouse macrophage (J774A.1) and a human alveolar epithelial type II cell line (A549). In order to deduce the involved pathway in nanoparticle uptake, selected inhibitors specific for one of the endocytotic pathways were optimized regarding concentration and incubation time in combination with fluorescently tagged marker proteins. Qualitative immunolocalization showed that J774A.1 cells highly expressed the lipid raft-related protein flotillin-1 and clathrin heavy chain, however, no caveolin-1. A549 cells expressed clathrin heavy chain and caveolin-1, but no flotillin-1 uptake-related proteins. Our data revealed an impeded uptake of 40 nm polystyrene nanoparticles by J774A.1 macrophages when actin polymerization and clathrin-coated pit formation was blocked. From this result, it is suggested that macropinocytosis and phagocytosis, as well as clathrin-mediated endocytosis, play a crucial role. The uptake of 40 nm nanoparticles in alveolar epithelial A549 cells was inhibited after depletion of cholesterol in the plasma membrane (preventing caveolin-mediated endocytosis) and inhibition of clathrin-coated vesicles (preventing clathrin-mediated endocytosis). Our data showed that a combination of several distinguishable endocytotic uptake mechanisms are involved in the uptake of 40 nm polystyrene nanoparticles in both the macrophage and epithelial cell line.

Beilstein J. Nanotechnol. 2014, 5, 1625–1636. doi:10.3762/bjnano.5.174

http://www.beilstein-journals.org/bjnano/content/5/1/174 2014/09/24 - 15:47

Abstract
Particle_in_Cell-3D is a powerful method to quantify the cellular uptake of nanoparticles. It combines the advantages of confocal fluorescence microscopy with fast and precise semi-automatic image analysis. In this work we present how this method was applied to investigate the impact of 310 nm silica nanoparticles on human vascular endothelial cells (HUVEC) in comparison to a cancer cell line derived from the cervix carcinoma (HeLa). The absolute number of intracellular silica nanoparticles within the first 24 h was determined and shown to be cell type-dependent. As a second case study, Particle_in_Cell-3D was used to assess the uptake kinetics of 8 nm and 30 nm ceria nanoparticles interacting with human microvascular endothelial cells (HMEC-1). These small nanoparticles formed agglomerates in biological medium, and the particles that were in effective contact with cells had a mean diameter of 417 nm and 316 nm, respectively. A significant particle size-dependent effect was observed after 48 h of interaction, and the number of intracellular particles was more than four times larger for the 316 nm agglomerates. Interestingly, our results show that for both particle sizes there is a maximum dose of intracellular nanoparticles at about 24 h. One of the causes for such an interesting and unusual uptake behavior could be cell division.

Beilstein J. Nanotechnol. 2014, 5, 1616–1624. doi:10.3762/bjnano.5.173

http://www.beilstein-journals.org/bjnano/content/5/1/173 2014/09/24 - 15:47

Abstract
Grain/interphase boundaries/interfaces of varying misorientations, free volume fractions, curvatures and irregularities are present in materials, both 3D and 2D, regardless of whether these materials are crystalline or amorphous/glassy. Therefore, a question arises about the central idea on which a general description of grain/interphase boundaries/interfaces can and should be based. It is suggested that a generalized model of a structural/basic unit (crystalline, non-crystalline or of any scale), which depends on the interatomic (including electronic) interactions, the spatial distribution of the atoms and electrons, the number of atoms and free volume fraction present in the structural/basic unit and the experimental conditions should serve the purpose. As the development of a quantitative model, which reflects the effects of all these variables is difficult, slightly defective material boundaries are often modeled by treating the entire boundary as planar and by using the concepts of crystallography. For highly disordered boundaries, a description in terms of a representative volume, made up of a non-crystalline basic unit or a combination of such units, which depend on interatomic (including electronic) interactions and forces, is advocated. The size, shape, free volume fraction and number of atoms in the representative volume could differ with material composition and experimental conditions. In the latter approach, it is assumed that all processes connected to a problem on hand is contained within this representative volume. The unresolved issues are identified.

Beilstein J. Nanotechnol. 2014, 5, 1603–1615. doi:10.3762/bjnano.5.172

http://www.beilstein-journals.org/bjnano/content/5/1/172 2014/09/24 - 15:47

Abstract
Background: Investigations on adverse biological effects of nanoparticles (NPs) in the lung by in vitro studies are usually performed under submerged conditions where NPs are suspended in cell culture media. However, the behaviour of nanoparticles such as agglomeration and sedimentation in such complex suspensions is difficult to control and hence the deposited cellular dose often remains unknown. Moreover, the cellular responses to NPs under submerged culture conditions might differ from those observed at physiological settings at the air–liquid interface.
Results: In order to avoid problems because of an altered behaviour of the nanoparticles in cell culture medium and to mimic a more realistic situation relevant for inhalation, human A549 lung epithelial cells were exposed to aerosols at the air–liquid interphase (ALI) by using the ALI deposition apparatus (ALIDA). The application of an electrostatic field allowed for particle deposition efficiencies that were higher by a factor of more than 20 compared to the unmodified VITROCELL deposition system. We studied two different amorphous silica nanoparticles (particles produced by flame synthesis and particles produced in suspension by the Stöber method). Aerosols with well-defined particle sizes and concentrations were generated by using a commercial electrospray generator or an atomizer. Only the electrospray method allowed for the generation of an aerosol containing monodisperse NPs. However, the deposited mass and surface dose of the particles was too low to induce cellular responses. Therefore, we generated the aerosol with an atomizer which supplied agglomerates and thus allowed a particle deposition with a three orders of magnitude higher mass and of surface doses on lung cells that induced significant biological effects. The deposited dose was estimated and independently validated by measurements using either transmission electron microscopy or, in case of labelled NPs, by fluorescence analyses. Surprisingly, cells exposed at the ALI were less sensitive to silica NPs as evidenced by reduced cytotoxicity and inflammatory responses.
Conclusion: Amorphous silica NPs induced qualitatively similar cellular responses under submerged conditions and at the ALI. However, submerged exposure to NPs triggers stronger effects at much lower cellular doses. Hence, more studies are warranted to decipher whether cells at the ALI are in general less vulnerable to NPs or specific NPs show different activities dependent on the exposure method.

Beilstein J. Nanotechnol. 2014, 5, 1590–1602. doi:10.3762/bjnano.5.171

http://www.beilstein-journals.org/bjnano/content/5/1/171 2014/09/21 - 18:28

Abstract
Graphene research and in particular the topic of chemical functionalization of graphene has exploded in the last decade. The main aim is to increase the solubility and thereby enhance the processability of the material, which is otherwise insoluble and inapplicable for technological applications when stacked in the form of graphite. To this end, initially, graphite was oxidized under harsh conditions to yield exfoliated graphene oxide sheets that are soluble in aqueous media and amenable to chemical modifications due to the presence of carboxylic acid groups at the edges of the lattice. However, it was obvious that the high-defect framework of graphene oxide cannot be readily utilized in applications that are governed by charge-transfer processes, for example, in solar cells. Alternatively, exfoliated graphene has been applied toward the realization of some donor–acceptor hybrid materials with photo- and/or electro-active components. The main body of research regarding obtaining donor–acceptor hybrid materials based on graphene to facilitate charge-transfer phenomena, which is reviewed here, concerns the incorporation of porphyrins and phthalocyanines onto graphene sheets. Through illustrative schemes, the preparation and most importantly the photophysical properties of such graphene-based ensembles will be described. Important parameters, such as the generation of the charge-separated state upon photoexcitation of the organic electron donor, the lifetimes of the charge-separation and charge-recombination as well as the incident-photon-to-current efficiency value for some donor–acceptor graphene-based hybrids, will be discussed.

Beilstein J. Nanotechnol. 2014, 5, 1580–1589. doi:10.3762/bjnano.5.170

http://www.beilstein-journals.org/bjnano/content/5/1/170 2014/09/21 - 18:28

Abstract
The growth of cortical neurons on three dimensional structures of spatially defined (structured) randomly oriented, as well as on vertically aligned, carbon nanotubes (CNT) is studied. Cortical neurons are attracted towards both types of CNT nano-architectures. For both, neurons form clusters in close vicinity to the CNT structures whereupon the randomly oriented CNTs are more closely colonised than the CNT pillars. Neurons develop communication paths via neurites on both nanoarchitectures. These neuron cells attach preferentially on the CNT sidewalls of the vertically aligned CNT architecture instead than onto the tips of the individual CNT pillars.

Beilstein J. Nanotechnol. 2014, 5, 1575–1579. doi:10.3762/bjnano.5.169

http://www.beilstein-journals.org/bjnano/content/5/1/169 2014/09/21 - 18:28

Abstract
The performance of field effect transistors comprised of a zigzag graphene nanoribbon that is symmetrically doped with boron nitride (BN) as a channel material, is numerically studied for the first time. The device merit for digital applications is investigated in terms of the on-, the off- and the on/off-current ratio. Due to the strong effect of the substrate roughness on the performance of graphene devices, three common substrate materials (SiO2, BN and mica) are examined. Rough surfaces are generated by means of a Gaussian auto-correlation function. Electronic transport simulations are performed in the framework of tight-binding Hamiltonian and non-equilibrium Green's function (NEGF) formalisms. The results show that with an appropriate selection of the substrate material, the proposed devices can meet the on/off-current ratio required for future digital electronics.

Beilstein J. Nanotechnol. 2014, 5, 1569–1574. doi:10.3762/bjnano.5.168

http://www.beilstein-journals.org/bjnano/content/5/1/168 2014/09/21 - 18:28

Abstract
Cellulose/calcium phosphate hybrid materials were synthesized via an ionic liquid-assisted route. Scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, infrared spectroscopy, and thermogravimetric analysis/differential thermal analysis show that, depending on the reaction conditions, cellulose/hydroxyapatite, cellulose/chlorapatite, or cellulose/monetite composites form. Preliminary studies with MC3T3-E1 pre-osteoblasts show that the cells proliferate on the hybrid materials suggesting that the ionic liquid-based process yields materials that are potentially useful as scaffolds for regenerative therapies.

Beilstein J. Nanotechnol. 2014, 5, 1553–1568. doi:10.3762/bjnano.5.167

http://www.beilstein-journals.org/bjnano/content/5/1/167 2014/09/17 - 01:17

Abstract
Copper sulfide is a promising p-type inorganic semiconductor for optoelectronic devices such as solar cells, due its small band gap energy and its electrical properties. In this work nanocrystalline copper sulfide (CuxS), with two stoichiometric ratios (x = 2, 1.8) was obtained by one-pot synthesis at 220, 230, 240 and 260 °C in an organic solvent and amorphous CuxS was obtained in aqueous solution. Nanoparticle-like nucleation centers are formed at lower temperatures (220 °C), mixtures of morphologies (nanorods, nanodisks and nanoprisms) are seen at 230 and 240 °C, in which the nanodisks are predominant, while big hexagonal/prismatic crystals are obtained at 260 °C according to TEM results. A mixture of chalcocite and digenite phases was found at 230 and 240 °C, while a clear transition to a pure digenite phase was seen at 260 °C. The evolution of morphology and transition of phases is consistent to the electrical, optical, and morphological properties of the copper sulfide. In fact, digenite Cu1.8S is less resistive (346 Ω/sq) and has a lower energy band gap (1.6 eV) than chalcocite Cu2S (5.72 × 105 Ω/sq, 1.87 eV). Low resistivity was also obtained in CuxS synthesized in aqueous solution, despite its amorphous structure. All CuxS products could be promising for optoelectronic applications.

Beilstein J. Nanotechnol. 2014, 5, 1542–1552. doi:10.3762/bjnano.5.166

http://www.beilstein-journals.org/bjnano/content/5/1/166 2014/09/17 - 01:17

Abstract
Due to the abundance of nanomaterials in medical devices and everyday products, toxicological effects related to nanoparticles released from these materials, e.g., by mechanical wear, are a growing matter of concern. Unfortunately, appropriate nanoparticles required for systematic toxicological evaluation of these materials are still lacking. Here, the ubiquitous presence of surface ligands, remaining from chemical synthesis are a major drawback as these organic residues may cause cross-contaminations in toxicological studies. Nanoparticles synthesized by pulsed laser ablation in liquid are a promising alternative as this synthesis route provides totally ligand-free nanoparticles. The first part of this article reviews recent methods that allow the size control of laser-fabricated nanoparticles, focusing on laser post irradiation, delayed bioconjugation and in situ size quenching by low salinity electrolytes. Subsequent or parallel applications of these methods enable precise tuning of the particle diameters in a regime from 4–400 nm without utilization of any artificial surface ligands. The second paragraph of this article highlights the recent progress concerning the synthesis of composition controlled alloy nanoparticles by laser ablation in liquids. Here, binary and ternary alloy nanoparticles with totally homogeneous elemental distribution could be fabricated and the composition of these particles closely resembled bulk implant material. Finally, the model AuAg was used to systematically evaluate composition related toxicological effects of alloy nanoparticles. Here Ag+ ion release is identified as the most probable mechanism of toxicity when recent toxicological studies with gametes, mammalian cells and bacteria are considered.

Beilstein J. Nanotechnol. 2014, 5, 1523–1541. doi:10.3762/bjnano.5.165

http://www.beilstein-journals.org/bjnano/content/5/1/165 2014/09/12 - 11:47

Abstract
Due to the abundance of nanomaterials in medical devices and everyday products, toxicological effects related to nanoparticles released from these materials, e.g., by mechanical wear, are a growing matter of concern. Unfortunately, appropriate nanoparticles required for systematic toxicological evaluation of these materials are still lacking. Here, the ubiquitous presence of surface ligands, remaining from chemical synthesis are a major drawback as these organic residues may cause cross-contaminations in toxicological studies. Nanoparticles synthesized by pulsed laser ablation in liquid are a promising alternative as this synthesis route provides totally ligand-free nanoparticles. The first part of this article reviews recent methods that allow the size control of laser-fabricated nanoparticles, focusing on laser post irradiation, delayed bioconjugation and in situ size quenching by low salinity electrolytes. Subsequent or parallel applications of these methods enable precise tuning of the particle diameters in a regime from 4–400 nm without utilization of any artificial surface ligands. The second paragraph of this article highlights the recent progress concerning the synthesis of composition controlled alloy nanoparticles by laser ablation in liquids. Here, binary and ternary alloy nanoparticles with totally homogeneous elemental distribution could be fabricated and the composition of these particles closely resembled bulk implant material. Finally, the model AuAg was used to systematically evaluate composition related toxicological effects of alloy nanoparticles. Here Ag+ ion release is identified as the most probable mechanism of toxicity when recent toxicological studies with gametes, mammalian cells and bacteria are considered.

Beilstein J. Nanotechnol. 2014, 5, 1523–1541. doi:10.3762/bjnano.5.165

http://www.beilstein-journals.org/bjnano/content/5/1/165 2014/09/12 - 11:47

Abstract
Hydrophobic photoluminescent carbon nanodots (CNDs) were fabricated by using citric acid and L-tyrosine precursor molecules through a simple, facile thermal oxidation process in air. These CNDs (less than 4 nm in size) exhibited a characteristic excitation wavelength dependent emission and upconversion emission properties and are insoluble in water, but soluble in organic solvents. FTIR and 1H NMR analyses showed a selective participation of L-tyrosine molecule during the carbonization process at 220 °C without a disturbance of its benzylic protons and aromatic phenyl ring bearing hydroxy group. TEM and XRD studies revealed a quasi-spherical morphology and poor-crystalline nature of CNDs. Because the presence of the hydroxy group of L-tyrosine is dominating at the surface, these CNDs are also soluble in water under basic conditions. The effects of base and silver nanoparticles on the luminescence properties of CNDs were studied and a quenching of fluorescence was observed. These tyrosine-passivated CNDs are applicable for both biologically and commercially.

Beilstein J. Nanotechnol. 2014, 5, 1513–1522. doi:10.3762/bjnano.5.164

http://www.beilstein-journals.org/bjnano/content/5/1/164 2014/09/12 - 11:47

Abstract
Hydrophobic photoluminescent carbon nanodots (CNDs) were fabricated by using citric acid and L-tyrosine precursor molecules through a simple, facile thermal oxidation process in air. These CNDs (less than 4 nm in size) exhibited a characteristic excitation wavelength dependent emission and upconversion emission properties and are insoluble in water, but soluble in organic solvents. FTIR and 1H NMR analyses showed a selective participation of L-tyrosine molecule during the carbonization process at 220 °C without a disturbance of its benzylic protons and aromatic phenyl ring bearing hydroxy group. TEM and XRD studies revealed a quasi-spherical morphology and poor-crystalline nature of CNDs. Because the presence of the hydroxy group of L-tyrosine is dominating at the surface, these CNDs are also soluble in water under basic conditions. The effects of base and silver nanoparticles on the luminescence properties of CNDs were studied and a quenching of fluorescence was observed. These tyrosine-passivated CNDs are applicable for both biologically and commercially.

Beilstein J. Nanotechnol. 2014, 5, 1513–1522. doi:10.3762/bjnano.5.164

http://www.beilstein-journals.org/bjnano/content/5/1/164 2014/09/12 - 11:47

Abstract
Unspecific adhesion of bacteria is usually the first step in the formation of biofilms on abiotic surfaces, yet it is unclear up to now which forces are governing this process. Alongside long-ranged van der Waals and electrostatic forces, short-ranged hydrophobic interaction plays an important role. To characterize the forces involved during approach and retraction of an individual bacterium to and from a surface, single cell force spectroscopy is applied: A single cell of the apathogenic species Staphylococcus carnosus isolate TM300 is used as bacterial probe. With the exact same bacterium, hydrophobic and hydrophilic surfaces can be probed and compared. We find that as far as 50 nm from the surface, attractive forces can already be recorded, an indication of the involvement of long-ranged forces. Yet, comparing the surfaces of different surface energy, our results corroborate the model that large, bacterial cell wall proteins are responsible for adhesion, and that their interplay with the short-ranged hydrophobic interaction of the involved surfaces is mainly responsible for adhesion. The ostensibly long range of the attraction is a result of the large size of the cell wall proteins, searching for contact via hydrophobic interaction. The model also explains the strong (weak) adhesion of S. carnosus to hydrophobic (hydrophilic) surfaces.

Beilstein J. Nanotechnol. 2014, 5, 1501–1512. doi:10.3762/bjnano.5.163

http://www.beilstein-journals.org/bjnano/content/5/1/163 2014/09/12 - 11:47

Abstract
It is shown, by using depth profiling with a secondary neutral mass spectrometer and structure investigations by XRD and TEM, that at low temperatures, at which the bulk diffusion is frozen, a complete homogenization can take place in the Cu/Au thin film system, which leads to formation of intermetallic phases. Different compounds can be formed depending on the initial thickness ratio. The process starts with grain boundary interdiffusion, which is followed by a formation of reaction layers at the grain boundaries that leads to the motion of the newly formed interfaces perpendicular to the grain boundary plane. Finally, the homogenization finishes when all the pure components have been consumed. The process is asymmetric: It is faster in the Au layer. In Au(25nm)/Cu(50nm) samples the final state is the ordered AuCu3 phase. Decrease of the film thicknesses, as expected, results in the acceleration of the process. It is also illustrated that changing the thickness ratio either a mixture of Cu-rich AuCu and AuCu3 phases (in Au(25nm)/Cu(25nm) sample), or a mixture of disordered Cu- as well as Au-rich solid solutions (in Au(25nm)/Cu(12nm) sample) can be produced. By using a simple model the interface velocity in both the Cu and Au layers were estimated from the linear increase of the average composition and its value is about two orders of magnitude larger in Au (ca. 10−11 m/s) than in Cu (ca. 10−13 m/s).

Beilstein J. Nanotechnol. 2014, 5, 1491–1500. doi:10.3762/bjnano.5.162

http://www.beilstein-journals.org/bjnano/content/5/1/162 2014/09/12 - 11:47

Abstract
The interfacing of colloidal nanoparticles with mammalian cells is now well into its second decade. In this review our goal is to highlight the more generally accepted concepts that we have gleaned from nearly twenty years of research. While details of these complex interactions strongly depend, amongst others, upon the specific properties of the nanoparticles used, the cell type, and their environmental conditions, a number of fundamental principles exist, which are outlined in this review.

Beilstein J. Nanotechnol. 2014, 5, 1477–1490. doi:10.3762/bjnano.5.161

http://www.beilstein-journals.org/bjnano/content/5/1/161 2014/09/09 - 14:48

Abstract
We report a sonochemical method of functionalizing superparamagnetic iron oxide nanoparticles (SPION) with (3-aminopropyl)triethoxysilane (APTES). Mechanical stirring, localized hot spots and other unique conditions generated by an acoustic cavitation (sonochemical) process were found to induce a rapid silanization reaction between SPION and APTES. FTIR, XPS and XRD measurements were used to demonstrate the grafting of APTES on SPION. Compared to what was reported in literature, the results showed that the silanization reaction time was greatly minimized. More importantly, the product displayed superparamagnetic behaviour at room temperature with a more than 20% higher saturation magnetization.

Beilstein J. Nanotechnol. 2014, 5, 1472–1476. doi:10.3762/bjnano.5.160

http://www.beilstein-journals.org/bjnano/content/5/1/160 2014/09/08 - 15:29

Abstract
By using scanning tunnelling potentiometry we characterized the lateral variation of the electrochemical potential µec on the gold-induced Ge(001)-c(8 × 2)-Au surface reconstruction while a lateral current flows through the sample. On the reconstruction and across domain boundaries we find that µec shows a constant gradient as a function of the position between the contacts. In addition, nanoscale Au clusters on the surface do not show an electronic coupling to the gold-induced surface reconstruction. In combination with high resolution scanning electron microscopy and transmission electron microscopy, we conclude that an additional transport channel buried about 2 nm underneath the surface represents a major transport channel for electrons.

Beilstein J. Nanotechnol. 2014, 5, 1463–1471. doi:10.3762/bjnano.5.159

http://www.beilstein-journals.org/bjnano/content/5/1/159 2014/09/05 - 19:49

Abstract
The biocompatibility and ease of functionalization of gold nanoparticles underlie significant potential in biotechnology and biomedicine. Eight different proteins were examined in the preparation of gold nanoparticles (AuNPs) in aqueous medium under microwave irradiation. Six of the proteins resulted in the formation of AuNPs. The intrinsic pH of the proteins played an important role in AuNPs with strong surface plasmon bands. The hydrodynamic size of the nanoparticles was larger than the values observed by TEM and ImageJ. The formation of a protein layer on the AuNPs accounts for this difference. The AuNPs exhibited sensitivity towards varying pH conditions, which was confirmed by determining the difference in the isoelectric points studied by using pH-dependent zeta potential titration. Cytotoxicity studies revealed anticancerous effects of the AuNPs at a certain micromolar concentration by constraining the growth of cancer cells with different efficacies due to the use of different proteins as capping agents. The positively charged AuNPs are internalized by the cells to a greater level than the negatively charged AuNPs. These AuNPs synthesized with protein coating holds promise as anticancer agents and would help in providing a new paradigm in area of nanoparticles.

Beilstein J. Nanotechnol. 2014, 5, 1452–1462. doi:10.3762/bjnano.5.158

http://www.beilstein-journals.org/bjnano/content/5/1/158 2014/09/05 - 19:49

Beilstein J. Nanotechnol. 2014, 5, 1450–1451. doi:10.3762/bjnano.5.157

http://www.beilstein-journals.org/bjnano/content/5/1/157 2014/09/05 - 19:49

Abstract
A general concept for parallel near-field photochemical and radiation-induced chemical processes for the fabrication of nanopatterns of a self-assembled monolayer (SAM) of (3-aminopropyl)triethoxysilane (APTES) is explored with three different processes: 1) a near-field photochemical process by photochemical bleaching of a monomolecular layer of dye molecules chemically bound to an APTES SAM, 2) a chemical process induced by oxygen plasma etching as well as 3) a combined near-field UV-photochemical and ozone-induced chemical process, which is applied directly to an APTES SAM. All approaches employ a sandwich configuration of the surface-supported SAM, and a lithographic mask in form of gold nanostructures fabricated through colloidal sphere lithography (CL), which is either exposed to visible light, oxygen plasma or an UV–ozone atmosphere. The gold mask has the function to inhibit the photochemical reactions by highly localized near-field interactions between metal mask and SAM and to inhibit the radiation-induced chemical reactions by casting a highly localized shadow. The removal of the gold mask reveals the SAM nanopattern.

Beilstein J. Nanotechnol. 2014, 5, 1441–1449. doi:10.3762/bjnano.5.156

http://www.beilstein-journals.org/bjnano/content/5/1/156 2014/09/05 - 19:49

Abstract
Semiconductor quantum dots (QD) and superparamagnetic iron oxide nanocrystals (SPIO) have exceptional physical properties that are well suited for biomedical applications in vitro and in vivo. For future applications, the direct injection of nanocrystals for imaging and therapy represents an important entry route into the human body. Therefore, it is crucial to investigate biological responses of the body to nanocrystals to avoid harmful side effects. In recent years, we established a system to embed nanocrystals with a hydrophobic oleic acid shell either by lipid micelles or by the amphiphilic polymer poly(maleic anhydride-alt-1-octadecene) (PMAOD). The goal of the current study is to investigate the uptake processes as well as pro-inflammatory responses in the liver after the injection of these encapsulated nanocrystals. By immunofluorescence and electron microscopy studies using wild type mice, we show that 30 min after injection polymer-coated nanocrystals are primarily taken up by liver sinusoidal endothelial cells. In contrast, by using wild type, Ldlr-/- as well as Apoe-/- mice we show that nanocrystals embedded within lipid micelles are internalized by Kupffer cells and, in a process that is dependent on the LDL receptor and apolipoprotein E, by hepatocytes. Gene expression analysis of pro-inflammatory markers such as tumor necrosis factor alpha (TNFα) or chemokine (C-X-C motif) ligand 10 (Cxcl10) indicated that 48 h after injection internalized nanocrystals did not provoke pro-inflammatory pathways. In conclusion, internalized nanocrystals at least in mouse liver cells, namely endothelial cells, Kupffer cells and hepatocytes are at least not acutely associated with potential adverse side effects, underlining their potential for biomedical applications.

Beilstein J. Nanotechnol. 2014, 5, 1432–1440. doi:10.3762/bjnano.5.155

http://www.beilstein-journals.org/bjnano/content/5/1/155 2014/09/02 - 20:47

Abstract
The development of new fabrication techniques of plasmonic nanocomposites with specific properties is an ongoing issue in the plasmonic and nanophotonics community. In this paper we report detailed investigations on the modifications of the microstructural and plasmonic properties of metal–titania nanocomposite films induced by swift heavy ions. Au–TiO2 and Ag–TiO2 nanocomposite thin films with varying metal volume fractions were deposited by co-sputtering and were subsequently irradiated by 100 MeV Ag8+ ions at various ion fluences. The morphology of these nanocomposite thin films before and after ion beam irradiation has been investigated in detail by transmission electron microscopy studies, which showed interesting changes in the titania matrix. Additionally, interesting modifications in the plasmonic absorption behavior for both Au–TiO2 and Ag–TiO2 nanocomposites were observed, which have been discussed in terms of ion beam induced growth of nanoparticles and structural modifications in the titania matrix.

Beilstein J. Nanotechnol. 2014, 5, 1419–1431. doi:10.3762/bjnano.5.154

http://www.beilstein-journals.org/bjnano/content/5/1/154 2014/09/02 - 20:47

Abstract
The advantages of liquid fuel cells (LFCs) over conventional hydrogen–oxygen fuel cells include a higher theoretical energy density and efficiency, a more convenient handling of the streams, and enhanced safety. This review focuses on the use of different types of organic fuels as an anode material for LFCs. An overview of the current state of the art and recent trends in the development of LFC and the challenges of their practical implementation are presented.

Beilstein J. Nanotechnol. 2014, 5, 1399–1418. doi:10.3762/bjnano.5.153

http://www.beilstein-journals.org/bjnano/content/5/1/153 2014/08/30 - 12:06

Abstract
Background: Mechanosensing of cells, particularly the cellular response to substrates with different elastic properties, has been discovered in recent years, but almost exclusively in mammalian cells. Much less attention has been paid to mechanosensing in other cell systems, such as in eukaryotic human pathogens.
Results: We report here on the influence of substrate stiffness on the adhesion of the human pathogen Acanthamoebae castellanii (A. castellanii). By comparing the cell adhesion area of A. castellanii trophozoites on polydimethylsiloxane (PDMS) substrates with different Young’s moduli (4 kPa, 29 kPa, and 128 kPa), we find significant differences in cell adhesion area as a function of substrate stiffness. In particular, the cell adhesion area of A. castellanii increases with a decreasing Young’s modulus of the substrate.
Conclusion: The dependence of A. castellanii adhesion on the elastic properties of the substrate is the first study suggesting a mechanosensory effect for a eukaryotic human pathogen. Interestingly, the main targets of A. castellanii infections in the human body are the eye and the brain, i.e., very soft environments. Thus, our study provides first hints towards the relevance of mechanical aspects for the pathogenicity of eukaryotic parasites.

Beilstein J. Nanotechnol. 2014, 5, 1393–1398. doi:10.3762/bjnano.5.152

http://www.beilstein-journals.org/bjnano/content/5/1/152 2014/08/30 - 12:06

Abstract
Besides the lung and skin, the gastrointestinal (GI) tract is one of the main targets for accidental exposure or biomedical applications of nanoparticles (NP). Biological responses to NP, including nanotoxicology, are caused by the interaction of the NP with cellular membranes and/or cellular entry. Here, the physico-chemical characteristics of NP are widely discussed as critical determinants, albeit the exact mechanisms remain to be resolved. Moreover, proteins associate with NP in physiological fluids, forming the protein corona potentially transforming the biological identity of the particle and thus, adding an additional level of complexity for the bio–nano responses.
Here, we employed amorphous silica nanoparticles (ASP) and epithelial GI tract Caco-2 cells as a model to study the biological impact of particle size as well as of the protein corona. Caco-2 or mucus-producing HT-29 cells were exposed to thoroughly characterized, negatively charged ASP of different size in the absence or presence of proteins. Comprehensive experimental approaches, such as quantifying cellular metabolic activity, microscopic observation of cell morphology, and high-throughput cell analysis revealed a dose- and time-dependent toxicity primarily upon exposure with ASP30 (Ø = 30 nm). Albeit smaller (ASP20, Ø = 20 nm) or larger particles (ASP100; Ø = 100 nm) showed a similar zeta potential, they both displayed only low toxicity. Importantly, the adverse effects triggered by ASP30/ASP30L were significantly ameliorated upon formation of the protein corona, which we found was efficiently established on all ASP studied. As a potential explanation, corona formation reduced ASP30 cellular uptake, which was however not significantly affected by ASP surface charge in our model. Collectively, our study uncovers an impact of ASP size as well as of the protein corona on cellular toxicity, which might be relevant for processes at the nano–bio interface in general.

Beilstein J. Nanotechnol. 2014, 5, 1380–1392. doi:10.3762/bjnano.5.151

http://www.beilstein-journals.org/bjnano/content/5/1/151 2014/08/27 - 20:15

Abstract
Highly monodispersed Cu–Pt bimetallic nanoclusters were synthesized by a facile synthesis approach. Analysis of transmission electron microscopy (TEM) and spherical aberration (Cs)-corrected scanning transmission electron microscopy (STEM) images shows that the average diameter of the Cu–Pt nanoclusters is 3.0 ± 1.0 nm. The high angle annular dark field (HAADF-STEM) images, intensity profiles, and energy dispersive X-ray spectroscopy (EDX) line scans, allowed us to study the distribution of Cu and Pt with atomistic resolution, finding that Pt is embedded randomly in the Cu lattice. A novel simulation method is applied to study the growth mechanism, which shows the formation of alloy structures in good agreement with the experimental evidence. The findings give insight into the formation mechanism of the nanosized Cu–Pt bimetallic catalysts.

Beilstein J. Nanotechnol. 2014, 5, 1371–1379. doi:10.3762/bjnano.5.150

http://www.beilstein-journals.org/bjnano/content/5/1/150 2014/08/27 - 20:15

Abstract
In the emerging market of nano-sized products, silver nanoparticles (Ag NPs) are widely used due to their antimicrobial properties. Human interaction with Ag NPs can occur through the lung, skin, gastrointestinal tract, and bloodstream. However, the inhalation of Ag NP aerosols is a primary concern. To study the possible effects of inhaled Ag NPs, an in vitro triple cell co-culture model of the human alveolar/airway barrier (A549 epithelial cells, human peripheral blood monocyte derived dendritic and macrophage cells) together with an air–liquid interface cell exposure (ALICE) system was used in order to reflect a real-life exposure scenario. Cells were exposed at the air–liquid interface (ALI) to 0.03, 0.3, and 3 µg Ag/cm2 of Ag NPs (diameter 100 nm; coated with polyvinylpyrrolidone: PVP). Ag NPs were found to be highly aggregated within ALI exposed cells with no impairment of cell morphology. Furthermore, a significant increase in release of cytotoxic (LDH), oxidative stress (SOD-1, HMOX-1) or pro-inflammatory markers (TNF-α, IL-8) was absent. As a comparison, cells were exposed to Ag NPs in submerged conditions to 10, 20, and 30 µg Ag/mL. The deposited dose per surface area was estimated by using a dosimetry model (ISDD) to directly compare submerged vs ALI exposure concentrations after 4 and 24 h. Unlike ALI exposures, the two highest concentrations under submerged conditions promoted a cytotoxic and pro-inflammatory response after 24 h. Interestingly, when cell cultures were co-incubated with lipopolysaccharide (LPS), no synergistic inflammatory effects were observed. By using two different exposure scenarios it has been shown that the ALI as well as the suspension conditions for the lower concentrations after 4 h, reflecting real-life concentrations of an acute 24 h exposure, did not induce any adverse effects in a complex 3D model mimicking the human alveolar/airway barrier. However, the highest concentrations used in the ALI setup, as well as all concentrations under submerged conditions after 24 h, reflecting more of a chronic lifetime exposure concentration, showed cytotoxic as well as pro-inflammatory effects. In conclusion, more studies need to address long-term and chronic Ag NP exposure effects.

Beilstein J. Nanotechnol. 2014, 5, 1357–1370. doi:10.3762/bjnano.5.149

http://www.beilstein-journals.org/bjnano/content/5/1/149 2014/08/27 - 20:15

Abstract
This study addresses the electrochemical surface faceting and restructuring of Ir(210) single crystal electrodes. Cyclic voltammetry measurements and in situ scanning tunnelling microscopy are used to probe structural changes and variations in the electrochemical behaviour after potential cycling of Ir(210) in 0.1 M H2SO4. Faceted structures are obtained electrochemically as a function of time by cycling at a scanrate of 1 V·s−1 between −0.28 and 0.70 V vs SCE, i.e., between the onset of hydrogen evolution and the surface oxidation regime. The electrochemical behaviour in sulfuric acid solution is compared with that of thermally faceted Ir(210), which shows a sharp characteristic voltammetric peak for (311) facets. Structures similar to thermally-induced faceted Ir(210) are obtained electrochemically, which typically correspond to polyoriented facets at nano-pyramids. These structures grow anisotropically in a preferred direction and reach a height of about 5 nm after 4 h of cycling. The structural changes are reflected in variations of the electrocatalytic activity towards carbon monoxide adlayer oxidation.

Beilstein J. Nanotechnol. 2014, 5, 1349–1356. doi:10.3762/bjnano.5.148

http://www.beilstein-journals.org/bjnano/content/5/1/148 2014/08/25 - 18:58

Abstract
The surface topography of the human wrist skin is studied by using optical and atomic force microscopy (AFM) methods. By using these techniques the surface roughness power spectrum is obtained. The Persson contact mechanics theory is used to calculate the contact area for different magnifications, for the dry and wet skin. The measured friction coefficient between a glass ball and dry and wet skin can be explained assuming that a frictional shear stress σf ≈ 13 MPa and σf ≈ 5 MPa, respectively, act in the area of real contact during sliding. These frictional shear stresses are typical for sliding on surfaces of elastic bodies. The big increase in friction, which has been observed for glass sliding on wet skin as the skin dries up, can be explained as result of the increase in the contact area arising from the attraction of capillary bridges. Finally, we demonstrated that the real contact area can be properly defined only when a combination of both AFM and optical methods is used for power spectrum calculation.

Beilstein J. Nanotechnol. 2014, 5, 1341–1348. doi:10.3762/bjnano.5.147

http://www.beilstein-journals.org/bjnano/content/5/1/147 2014/08/23 - 20:51

Abstract
The laser-induced damage threshold (LIDT) is widely used as an index for evaluating an optical component’s resistance to laser light. However, a degradation in the performance of an optical component is also caused by continuous irradiation with laser light having an energy density below the LIDT. Therefore, here we focused on the degradation in performance of an optical component caused by continuous irradiation with femtosecond laser light having a low energy density, i.e., laser-induced degradation. We performed an in situ observation and analysis of an increase in scattering light intensity in fused silica substrates. In experiments conducted using a pulsed laser with a wavelength of 800 nm, a pulse width of 160 fs and pulse repetition rate of 1 kHz, we found that the scattered light intensity increased starting from a specific accumulated fluence, namely, that the laser-induced degradation had a threshold. We evaluated the threshold fluence Ft as 6.27 J/cm2 and 9.21 J/cm2 for the fused silica substrates with surface roughnesses of 0.20 nm and 0.13 nm in Ra value, respectively, showing that the threshold decreased as the surface roughness increased. In addition, we found that the reflected light spectrum changed as degradation proceeded. We analyzed the details of the degradation by measuring instantaneous reflectance changes with a pump–probe method; we observed an increase in the generation probability of photogenerated carriers in a degraded silica substrate and a damaged silica substrate and observed a Raman signal originating from a specific molecular structure of silica. From these findings, we concluded that compositional changes in the molecular structure occurred during degradation due to femtosecond laser irradiation having an energy density below the LIDT.

Beilstein J. Nanotechnol. 2014, 5, 1334–1340. doi:10.3762/bjnano.5.146

http://www.beilstein-journals.org/bjnano/content/5/1/146 2014/08/21 - 22:41

Abstract
The research of cycloparaphenylenes (CPPs), the smallest armchair carbon nanotube, has been a quest for the past decades which experienced a revival in 2008 when the first synthesis was achieved. Since then CPPs with various ring sizes have been realized. The incorporation of substituents and the synthesis of CPPs with building blocks different from phenyl rings bear challenges of their own. Such structures, however, are highly interesting, as they allow for an incorporation of CPPs as defined nano-objects for other applications. Therefore, this review provides a status report about the current efforts in synthesizing CPPs beyond the parent unsubstituted oligo-phenylene structure.

Beilstein J. Nanotechnol. 2014, 5, 1320–1333. doi:10.3762/bjnano.5.145

http://www.beilstein-journals.org/bjnano/content/5/1/145 2014/08/21 - 22:41

Abstract
Camptothecin (CPT; (S)-(+)-4-ethyl-4-hydroxy-1H-pyrano[3',4':6,7]indolizino[1,2-b]quinoline-3,14-(4H,12H)-dione) is a highly cytotoxic natural alkaloid that has not yet found use as chemotherapeutic agent due to its poor water-solubility and chemical instability and, as a consequence, no effective administration means have been designed. In this work, camptothecin has been successfully loaded into iron oxide superparamagnetic nanoparticles with an average size of 14 nm. It was found that surface modification of the nanoparticles by polyethylene glycol enables loading a large amount of camptothecin. While the unloaded nanoparticles do not induce apoptosis in the H460 lung cancer cell line, the camptothecin-loaded nanoparticle formulations exhibit remarkable pro-apoptotic activity. These results indicate that camptothecin retains its biological activity after loading onto the magnetic nanoparticles. The proposed materials represent novel materials based on naturally occurring bioactive molecules loaded onto nanoparticles to be used as chemotherapeutic formulations. The procedure seems apt to be extended to other active molecules extracted from natural products. In addition, these materials offer the potential of being further implemented for combined imaging and therapeutics, as magnetic nanoparticles are known to be multifunctional tools for biomedicine.

Beilstein J. Nanotechnol. 2014, 5, 1312–1319. doi:10.3762/bjnano.5.144

http://www.beilstein-journals.org/bjnano/content/5/1/144 2014/08/21 - 22:41

Abstract
“...each metal has a certain power, which is different from metal to metal, of setting the electric fluid in motion...” Count Alessandro Volta. Inspired by the first rechargeable magnesium battery prototype at the dawn of the 21st century, several research groups have embarked on a quest to realize its full potential. Despite the technical accomplishments made thus far, challenges, on the material level, hamper the realization of a practical rechargeable magnesium battery. These are marked by the absence of practical cathodes, appropriate electrolytes and extremely sluggish reaction kinetics. Over the past few years, an increased interest in this technology has resulted in new promising materials and innovative approaches aiming to overcome the existing hurdles. Nonetheless, the current challenges call for further dedicated research efforts encompassing fundamental understanding of the core components and how they interact with each other to offering new innovative solutions. In this review, we seek to highlight the most recent developments made and offer our perspectives on how to overcome some of the remaining challenges.

Beilstein J. Nanotechnol. 2014, 5, 1291–1311. doi:10.3762/bjnano.5.143

http://www.beilstein-journals.org/bjnano/content/5/1/143 2014/08/21 - 22:41