Continuum models of focused electron beam induced processing

• Milos Toth,
• Charlene Lobo,
• Vinzenz Friedli,
• Aleksandra Szkudlarek and
• Ivo Utke

Beilstein J. Nanotechnol. 2015, 6, 1518–1540, doi:10.3762/bjnano.6.157

• in this case are the NF3 precursor adsorbates (denoted by “a”), F radicals (α), and the reaction products SiF, SiF2, SiF3, and SiF4: The symbols in Equation 53 and Equation 54 represent the same quantities as the corresponding symbols in Equation 12 and Equation 13 (see Table 1). In Equation 55, Nn

• models. This particular model assumes that all available F radicals generated by electron-induced dissociation of NF3 are converted to SiFn by reacting with SiFn−1, and that any surplus fluorine atoms desorb as shown in Figure 15 (the desorption is assumed instant, hence the absence of a desorption flux

• in Equation 54). The probability of a reaction between F and each species SiFn−1 is assumed equal and the total F coverage is limited to 1 ML, hence the term (Nn−1/Nη)(1 − Θη) in Equation 55 that governs the partitioning of the available F radicals illustrated by the flow chart shown in Figure 15. It

Scalable, high performance, enzymatic cathodes based on nanoimprint lithography

• Dmitry Pankratov,
• Richard Sundberg,
• Javier Sotres,
• Dmitry B. Suyatin,
• Ivan Maximov,
• Sergey Shleev and
• Lars Montelius

Beilstein J. Nanotechnol. 2015, 6, 1377–1384, doi:10.3762/bjnano.6.142

• concomitant reduction of O2 directly to H2O in a trinuclear Cu cluster (T2/T3 Cu cluster) positioned 12–13 Å away [5][6][7], without releasing reactive O2 species, such as hydrogen peroxide or superoxide radicals [8][9]. Three-dimensional electrodes for enzyme-based cathodes are usually used to design high

High photocatalytic activity of V-doped SrTiO₃ porous nanofibers produced from a combined electrospinning and thermal diffusion process

• Panpan Jing,
• Wei Lan,
• Qing Su and
• Erqing Xie

Beilstein J. Nanotechnol. 2015, 6, 1281–1286, doi:10.3762/bjnano.6.132

• species, such as hydroxyl radicals (·OH) and superoxide anions (O2−). Since Fujishima and Honda first reported photo-electrochemical water splitting using a TiO2 electrode [7], many studies have been carried out on photocatalytic pollutant removal and electronic structures of semiconductors containing d0

The convenient preparation of stable aryl-coated zerovalent iron nanoparticles

• Olga A. Guselnikova,
• Andrey I. Galanov,
• Anton K. Gutakovskii and
• Pavel S. Postnikov

Beilstein J. Nanotechnol. 2015, 6, 1192–1198, doi:10.3762/bjnano.6.121

• repeatedly shown that diazonium cations give diazoates in basic media. These unstable diazotate species are able to spontaneously generate radicals [18], which react with the surface of the ZVI NPs resulting in highly stable, covalent linkages. Since the first demonstration in 1990, the formation of

• multilayer films on different surfaces (carbon, gold, iron) has been confirmed several times through the generated radicals from ADSs [32][33][34]. Since the 4-position group is an electron acceptor, the ortho positions to the substituents are chemically activated and the free radicals can perform a

• these indications of the generation of radicals from ADTs, we hypothesize that there are multilayers of 4-nitrophenyl groups that also contain thick organic layers, as illustrated by TEM. It is worth mentioning that the characteristics of the NP surface and attached functional groups have a key role for

Tattoo ink nanoparticles in skin tissue and fibroblasts

• Colin A. Grant,
• Peter C. Twigg,
• Richard Baker and
• Desmond J. Tobin

Beilstein J. Nanotechnol. 2015, 6, 1183–1191, doi:10.3762/bjnano.6.120

• to work was 1 in 100. Wamer and Yin found a phototoxic effect of eight decorative tattoo inks and permanent make-up inks that contained titanium dioxide on human dermal fibroblasts [38]. The phototoxic effect from the inks was attributed to the generation of hydroxyl radicals under UV excitation

Fulleropeptide esters as potential self-assembled antioxidants

• Mira S. Bjelaković,
• Tatjana J. Kop,
• Jelena Đorđević and
• Dragana R. Milić

Beilstein J. Nanotechnol. 2015, 6, 1065–1071, doi:10.3762/bjnano.6.107

• affinities. Water-soluble fullerene–alanine adducts were tested as cytoprotective agents showing high effectiveness for removing the reactive oxygen species, such as superoxide anions and hydroxyl radicals [19][20]. The study of the penetration of fulleropeptide nanoparticles through skin represents a major

• significant antioxidant capacity to remove hydroxyl and superoxide radicals when incorporated into liposomes [23]. With respect to the design and synthesis of fulleropyrrolidine-based hybrids, we previously showed the synthesis of fullerene–steroid esters [24] and triple hybrids consisting of fullerene

Effects of swift heavy ion irradiation on structural, optical and photocatalytic properties of ZnO–CuO nanocomposites prepared by carbothermal evaporation method

• Sini Kuriakose,
• D. K. Avasthi and
• Satyabrata Mohapatra

Beilstein J. Nanotechnol. 2015, 6, 928–937, doi:10.3762/bjnano.6.96

• of CuO. This helps to inhibit the recombination of photogenerated electrons and holes and improves the charge separation efficiency. The oxygen molecules adsorbed on the photocatalyst form superoxide anion radicals (•O2−) due to their interaction with electrons in the conduction band of ZnO. Surface

• hydroxyl groups produce highly reactive hydroxyl (•OH) radicals by reacting with holes in the valence band of CuO. The dye molecules are degraded by the reaction with both radicals (•OH and •O2−) [39][41]. For better understanding of the underlying mechanism, Yang et al. [42][43] have monitored the

• formation of hydroxyl radicals (•OH) and superoxide radicals (•O2−) during visible-light-induced photocatalytic degradation of acid orange and 4-nitrophenol. The formation of hydroxyl radicals (•OH) was detected by photoluminescence studies using terephthalic acid as a probe molecule, while 1,4-benzoquinone

Tm-doped TiO₂ and Tm₂Ti₂O₇ pyrochlore nanoparticles: enhancing the photocatalytic activity of rutile with a pyrochlore phase

• Desiré M. De los Santos,
• Javier Navas,
• Teresa Aguilar,
• Antonio Sánchez-Coronilla,
• Concha Fernández-Lorenzo,
• Rodrigo Alcántara,
• Jose Carlos Piñero,
• Ginesa Blanco and
• Joaquín Martín-Calleja

Beilstein J. Nanotechnol. 2015, 6, 605–616, doi:10.3762/bjnano.6.62

• . Surface hydroxy groups can react with photogenerated holes, inhibiting the recombination of an electron–hole pair, and thus enhancing charge transfer [33]. Additionally, they can also lead to the production of hydroxyl radicals, a highly oxidizing species in the degradation of organic compounds [34]. UV

• electrons and holes produce a reaction with attached molecules on the material surface and create reactive radicals. The electrons in the conduction band react with O2 to form superoxide anion radicals (O2−•) and the holes in the valence band react with water to form hydroxyl radicals (•OH). The activated

• radicals play a role in degrading pollutants [45]. It is generally suggested that the rate-limiting steps of the photocatalytic reaction of semiconductors are electron–hole recombination and electron transfer from the semiconductor surface to the adsorbed oxygen molecules [45][46][47][48]. In our case, the

Novel ZnO:Ag nanocomposites induce significant oxidative stress in human fibroblast malignant melanoma (Ht144) cells

• Syeda Arooj,
• Samina Nazir,
• Akhtar Nadhman,
• Nafees Ahmad,
• Bakhtiar Muhammad,
• Ishaq Ahmad,
• Kehkashan Mazhar and
• Rashda Abbasi

Beilstein J. Nanotechnol. 2015, 6, 570–582, doi:10.3762/bjnano.6.59

• thus exciting the photosensitizer to produce reactive oxygen species (ROS) such as singlet oxygen (1O2) and hydroxyl radicals (HO•) [6][7]. Photo-oxidation holds promises for the targeted treatment and controlled elimination of cancer cells [8]. ZnO NPs have also shown photo-oxidative anticancer

Palladium nanoparticles anchored to anatase TiO₂ for enhanced surface plasmon resonance-stimulated, visible-light-driven photocatalytic activity

• Kah Hon Leong,
• Hong Ye Chu,
• Shaliza Ibrahim and
• Pichiah Saravanan

Beilstein J. Nanotechnol. 2015, 6, 428–437, doi:10.3762/bjnano.6.43

• possesses an appropriate band gap that ensure the simultaneous formation of superoxide anions (•O2−) and hydroxyl (•OH) radicals for the oxidation of organic compounds [6]. Despite all these advantages, TiO2 has two major drawbacks, which are (1) a wide band gap (ca. 3.2 eV for anatase) that restricts the

• resonance excites the electrons below the Fermi level of the Pd NPs in the VB to be transferred into the CB leaving behind the positive charges (h+) in the VB. As the CB of TiO2 is an electron acceptor, it readily accepts the electrons that are transferred from the Pd NPs to form superoxide anion radicals

• (•O2−). This is followed by protonation that yields •HO2 radicals. These instable •HO2 radicals further form H2O2 and lead to the formation of hydroxyl radicals (•OH), an active species that is responsible for the degradation of AMX. Besides that, when Pd NPs interacts with TiO2, it will form a

Nanoparticle shapes by using Wulff constructions and first-principles calculations

• Georgios D. Barmparis,
• Zbigniew Lodziana,
• Nuria Lopez and
• Ioannis N. Remediakis

Beilstein J. Nanotechnol. 2015, 6, 361–368, doi:10.3762/bjnano.6.35

• ). Right: With adsorbed SCH3 radicals (29 nm in diameter, 502900 atoms, 10600 of which are step-edge atoms; (211) faces occupy almost 100% of the total area). Schematic representation of the adsorption of a surfactant on a gold surface. Spheres represent gold (yellow), silver (grey) and bromine (red) and

Synthesis of boron nitride nanotubes and their applications

• Saban Kalay,
• Zehra Yilmaz,
• Ozlem Sen,
• Melis Emanet,
• Emine Kazanc and
• Mustafa Çulha

Beilstein J. Nanotechnol. 2015, 6, 84–102, doi:10.3762/bjnano.6.9

• . The most commonly preferred chemical functionalization is through the –OH on B atoms and –NH2 groups at the edges and defects, as shown in Figure 3 [15][44][63][64][65]. In one study, BNNTs were functionalized with amine groups by ammonia plasma irradiation [63]. It was predicted that NH2∙ radicals

• produced by NH3 plasma attached to B atom at the defects and edges whereas H∙ radicals attached to the N atoms of BNNTs. It was shown the amine-functionalized BNNTs (AF-BNNTs) were dispersible in chloroform. To investigate further chemical functionalization, the AF-BNNTs were coated with 3-bromopropanoyl

Formation of stable Si–O–C submonolayers on hydrogen-terminated silicon(111) under low-temperature conditions

• Yit Lung Khung,
• Siti Hawa Ngalim,
• Andrea Scaccabarozzi and
• Dario Narducci

Beilstein J. Nanotechnol. 2015, 6, 19–26, doi:10.3762/bjnano.6.3

• Si–O–C bonds from ethynylbenzyl alcohol solution while the UV photochemical route ensures that the alcohol-based alkyne may also form Si–C bonds, thus producing a monolayer of mixed linkages. The results suggested the importance of surface radicals as well as the type of terminal group as being

• undisputed. However, as early as 2005, Wood et al. brought to attention that the cleavage of Si–H to form initial silyl radicals might not be the only mode for hydrosilylation to occur [12]. Typically, the commonly accepted notion is that thermal hydrosilylation requires temperatures above 150 °C in order to

• cleave the silicon–hydrogen bond at the surface to form surface radicals. However previous studies had shown that hydrosilylation could also proceed at a lower temperature (110 °C). Wood et al. further suggested a reaction mechanism in which trace oxygen is involved in the extraction of hydrogen off from

Interaction of dermatologically relevant nanoparticles with skin cells and skin

• Annika Vogt,
• Fiorenza Rancan,
• Sebastian Ahlberg,
• Berouz Nazemi,
• Chun Sik Choe,
• Maxim E. Darvin,
• Sabrina Hadam,
• Ulrike Blume-Peytavi,
• Kateryna Loza,
• Jörg Diendorf,
• Matthias Epple,
• Christina Graf,
• Eckart Rühl,
• Martina C. Meinke and
• Jürgen Lademann

Beilstein J. Nanotechnol. 2014, 5, 2363–2373, doi:10.3762/bjnano.5.245

• toxicity were also shown for iron oxide nanoparticles [44]. In our group, we established protocols for the detection of free radicals in cells and in whole skin by electron paramagnetic resonance (EPR) spectroscopy. To detect nanoparticle-induced free radicals in cells, EPR on cell suspensions by using the

• spin probe TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) was established. This semi-stable radical is a nitroxide and reacts with short-living radicals, giving the hydroxylamine which is EPR silent. The EPR signal of the spin probe decreases if radicals are present. After the addition of TEMPO to living

• cells, the EPR signal decreases slowly over time due to the metabolism of the cells. An irradiation of the cells with light in the UVB wavelength range induced additional radicals and decreased the EPR intensity of TEMPO faster and more drastically compared to untreated cells. When 75 nm silica

Liquid-phase exfoliated graphene: functionalization, characterization, and applications

• Mildred Quintana,
• Jesús Iván Tapia and
• Maurizio Prato

Beilstein J. Nanotechnol. 2014, 5, 2328–2338, doi:10.3762/bjnano.5.242

• the production of highly reactive chemical species including peroxides and radicals formed from the sonochemical reaction of the solvent in air [20]. The combined mechanochemical effects of ultrasonication prompt the exfoliation of graphite in organic solvents, surfactant solutions, or mixed organic

• linearly with the magnitude of the steric potential barrier. Production of larger graphene sheets As previously mentioned, ultrasonication is a highly energetic process that produces strongly oxidizing chemical species, such as radicals and peroxides. These radicals typically oxidize carbon atoms in

• graphene close to the defects and at the edges. Under prolonged periods of ultrasonication, the oxidation can cut graphene sheets into small pieces. A well-known strategy to mitigate the damage induced by radicals in different biological processes is through the addition of antioxidant. Following this

Nanobioarchitectures based on chlorophyll photopigment, artificial lipid bilayers and carbon nanotubes

• Marcela Elisabeta Barbinta-Patrascu,
• Stefan Marian Iordache,
• Ana Maria Iordache,
• Nicoleta Badea and
• Camelia Ungureanu

Beilstein J. Nanotechnol. 2014, 5, 2316–2325, doi:10.3762/bjnano.5.240

• , which has been exploited in the preparation of anti-aging cosmetics and sunscreen creams to protect skin against free radicals formed by the body or by UV sunlight [10]. The goal of this work is to achieve antioxidant and antibacterial bionanomaterials based on liposomes and carbon nanotubes, which

• samples was determined by chemiluminescence (CL) assay using a chemiluminometer (Turner Design, TD 20/20, USA). A wide range of oxygen free radicals (reactive oxygen species, ROS) [27][28] was formed by a generator system based on H2O2 in an alkaline buffer solution (Tris·HCl, pH 8.6) mimicking an

• /liposomes hybrids to scavenge free radicals. The oxygen radical scavenging ability of the samples was evaluated in terms of antioxidant activity (see Equation 2 in the section Characterization methods). The antioxidant profile of the liposomes and bio-composites displayed in Figure 8 reveals that nanocarbon

Carbon nano-onions (multi-layer fullerenes): chemistry and applications

• Juergen Bartelmess and
• Silvia Giordani

Beilstein J. Nanotechnol. 2014, 5, 1980–1998, doi:10.3762/bjnano.5.207

• form reactive bis-radicals [31]. After ultrasonication and heating of the CNOs and BODA in N-methyl-2-pyrrolidone (NMP) in a pressure vessel, a CNO–BODA copolymer was obtained. NMP suspensions of the CNO–BODA copolymer were found to be very stable, even at high concentrations of up to 0.67 mg·mL−1

PVP-coated, negatively charged silver nanoparticles: A multi-center study of their physicochemical characteristics, cell culture and in vivo experiments

• Sebastian Ahlberg,
• Alexandra Antonopulos,
• Jörg Diendorf,
• Ralf Dringen,
• Matthias Epple,
• Rebekka Flöck,
• Wolfgang Goedecke,
• Christina Graf,
• Nadine Haberl,
• Jens Helmlinger,
• Fabian Herzog,
• Frederike Heuer,
• Stephanie Hirn,
• Christian Johannes,
• Stefanie Kittler,
• Manfred Köller,
• Katrin Korn,
• Wolfgang G. Kreyling,
• Fritz Krombach,
• Jürgen Lademann,
• Kateryna Loza,
• Eva M. Luther,
• Marcelina Malissek,
• Martina C. Meinke,
• Daniel Nordmeyer,
• Anne Pailliart,
• Jörg Raabe,
• Fiorenza Rancan,
• Barbara Rothen-Rutishauser,
• Eckart Rühl,
• Carsten Schleh,
• Andreas Seibel,
• Christina Sengstock,
• Lennart Treuel,
• Annika Vogt,
• Katrin Weber and
• Reinhard Zellner

Beilstein J. Nanotechnol. 2014, 5, 1944–1965, doi:10.3762/bjnano.5.205

• radiation induce genomic DSB, there is evidence in both cases that radicals are involved [114][115]. In the case of bleomycin, reasonable models suggest that metal ions play a role during DSB formation [116]. In the case of silver nanoparticles, it has also been proposed that DNA damage may result from

• radicals whose formation is catalyzed from silver ions generated after uptake of silver by phagocytosis [110]. In contrast to chemical modifications of genomic DNA by reactive oxygen species (ROS) which are difficult to prove, the presence of DSB that result from a radical attack are more easily to detect

• during cell culture processing. While V79B was originally isolated from lung tissue, the two other cell lines used in our study were derived from ovaries. The observed data raise the question whether tissues have a different sensitivity towards silver nanoparticles or possibly against free radicals. In

Carbon-based smart nanomaterials in biomedicine and neuroengineering

• Antonina M. Monaco and
• Michele Giugliano

Beilstein J. Nanotechnol. 2014, 5, 1849–1863, doi:10.3762/bjnano.5.196

• transformation into myofibroblasts. Their results showed an up-regulated expression of a specific differentiation marker, accompanied, however, by an increased generation of the most biologically significant free radicals, the reactive oxygen species (ROS). NDs: Among the applications of NDs, the most important

Silicon and germanium nanocrystals: properties and characterization

• Ivana Capan,
• Alexandra Carvalho and
• José Coutinho

Beilstein J. Nanotechnol. 2014, 5, 1787–1794, doi:10.3762/bjnano.5.189

• to the oxide interface have two important effects, namely (i) to quench the low energy absorption region and (ii) a blue-shift of some particularly intense transitions. Another important aspect is the role of defects. Si dangling bonds or radicals are strongly localized being effective traps for both

Influence of surface-modified maghemite nanoparticles on in vitro survival of human stem cells

• Michal Babič,
• Daniel Horák,
• Lyubov L. Lukash,
• Tetiana A. Ruban,
• Yurii N. Kolomiets,
• Svitlana P. Shpylova and
• Oksana A. Grypych

Beilstein J. Nanotechnol. 2014, 5, 1732–1737, doi:10.3762/bjnano.5.183

• intracellular overload may cause cytotoxicity due to formation of free radicals. The cytotoxicity of non-coated, D-mannose- and PDMAAm-coated γ-Fe2O3 nanoparticles was evaluated by using a MTT assay with 4BL human cells. The assay is dependent on the ability of viable cells to metabolise a water-soluble

Ionic liquid-assisted formation of cellulose/calcium phosphate hybrid materials

• Ahmed Salama,
• Mike Neumann,
• Christina Günter and
• Andreas Taubert

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

• species in the surrounding medium like O2 or water leads to singlet oxygen radicals and superoxide radical anions. According to the authors, these may then act as nucleation sites. One unresolved question here is the fact that these results differ significantly from other work [16][18] where calcium

Characterization and photocatalytic study of tantalum oxide nanoparticles prepared by the hydrolysis of tantalum oxo-ethoxide Ta₈(μ₃-O)₂(μ-O)₈(μ-OEt)₆(OEt)₁₄

• Subia Ambreen,
• N D Pandey,
• Peter Mayer and
• Ashutosh Pandey

Beilstein J. Nanotechnol. 2014, 5, 1082–1090, doi:10.3762/bjnano.5.121

• lower. This may be due to the scattering of light from surface of the catalyst leading to the reduction in light penetration through the solution, which in turn reduces the rate of formation of radicals. Also, it may be assumed that the activated molecules get deactivated due to the collisions with the

• was studied at pH 4, 7 and 10. It was observed that the rate of degradation of rhodamine B increases with the increase in pH from 4 to 7. It appears that, when more hydroxy ions (OH−) are available, they combine with the holes (h+) of the semiconductor resulting in the production of hydroxyl radicals

• . These radicals are responsible for the degradation of dye by oxidative process. However, a further increase of the pH value provides excess OH− ions that get absorbed on the catalyst surface and obstruct the approach of the dye molecule to the catalyst surface and slow down the rate of degradation of

Growth and characterization of CNT–TiO₂ heterostructures

• Yucheng Zhang,
• Ivo Utke,
• Johann Michler,
• Gabriele Ilari,
• Marta D. Rossell and
• Rolf Erni

Beilstein J. Nanotechnol. 2014, 5, 946–955, doi:10.3762/bjnano.5.108

• reactions [12]. Alternatively, Wang et al. propose that electrons and holes are generated in the semiconducting CNTs, which act as a sensitizer [9]. The electrons are injected into the conduction band of TiO2 to form superoxide radicals and the holes into the valence band of TiO2 to form hydroxyl radicals

Pyrite nanoparticles as a Fenton-like reagent for in situ remediation of organic pollutants

• Carolina Gil-Lozano,
• Elisabeth Losa-Adams,
• Alfonso F.-Dávila and
• Luis Gago-Duport

Beilstein J. Nanotechnol. 2014, 5, 855–864, doi:10.3762/bjnano.5.97

• hydroxyl radicals (OH•) that trigger the formation of other reactive intermediates (e.g., HO2• and O2•−). Due to their high oxidation potential (E0 = 2.8 V), hydroxyl radicals attack most organic pollutants with rate constants in the order of 106 to 109 M−1·s−1 [4][5]. In practice, the formation of OH• to

• accumulated in solution (Figure 3, curve b). This observation suggests a less efficient conversion of H2O2 into free radicals, which would be consistent with a lower rate of iron delivery to solution than in the case of the nanoparticles. This hypothesis is consistent with PHREEQC calculations [27] of the

• nanoparticles rapidly supply the solution with iron, which induces the rapid transformation of H2O2 into OH• radicals, according to the Fenton reaction scheme. The dye concentration was indirectly proportional to the degradation rate (Figure 6), indicating that the best catalytic activities were reached by