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

Enhancement of photocatalytic H₂ evolution of eosin Y-sensitized reduced graphene oxide through a simple photoreaction

• Weiying Zhang,
• Yuexiang Li,
• Shaoqin Peng and
• Xiang Cai

Beilstein J. Nanotechnol. 2014, 5, 801–811, doi:10.3762/bjnano.5.92

• decreases, as more and more O2 is consumed in the closed reaction system. The formed defect carbons (radicals) are active, and are expected to react to form C=C. As shown in Scheme 1, π-conjugated domains extend, which is consistent with the results shown in Figure 1 and Figure 2. At the same time , many

• holes occur in the RGO24 sheet (Figure 9B), which is consistent with the model shown in Scheme 1. The model is similar to the one reported in [51]. The ferromagnetic properties [51] of RGO obtained by a photoreaction and its paramagnetic resonance (EPR) spectra [38] indicate that there are some radicals

• or defect carbons at the zigzag hole edges of the RGO. The defect carbons or radicals are stable due to larger π-conjugated domains, which are expected to exist for a long time at room temperature [38][52]. When EY adsorbed at RGOx absorbs the visible light, the excited EY* forms by transferring its

Visible light photooxidative performance of a high-nuclearity molecular bismuth vanadium oxide cluster

• Johannes Tucher and
• Carsten Streb

Beilstein J. Nanotechnol. 2014, 5, 711–716, doi:10.3762/bjnano.5.83

• reported. Photocatalytic activity studies show faster reaction kinetics under anaerobic conditions, suggesting an oxygen-dependent quenching of the photoexcited cluster species. Further mechanistic analysis shows that the reaction proceeds via the intermediate formation of hydroxyl radicals which act as

• aerobic conditions [48]. This hypothesis is currently being investigated using TD-DFT and transient absorption spectroscopy methods. Identification of hydroxyl radicals as intermediates To gain further insight into the reaction mechanism involved in the photooxidation of indigo by 1, homogeneous dye

• degradation was performed in the presence of ethanol in the reaction mixture ([EtOH]:[1] = 50:1). Ethanol is a well-known hydroxyl radical scavenger [49], and the test was performed to demonstrate that hydroxyl radicals are involved as intermediate oxidizing species formed upon irradiation of 1 (see

Nanostructure sensitization of transition metal oxides for visible-light photocatalysis

• Hongjun Chen and
• Lianzhou Wang

Beilstein J. Nanotechnol. 2014, 5, 696–710, doi:10.3762/bjnano.5.82

• like hydroxyl radicals by directly reacting with surface hydroxyl groups or oxidizing adsorbed molecules (D → D+). The basic mechanisms of the photocatalytic process include these reduction and oxidation reactions as well as some secondary reactions, which forms the driving force of a number of

• ZnWO4 is lower than the HOMO of graphene. Since the CB position of ZnWO4 is lower than the LUMO of graphene, the photogenerated electrons can only stay at the CB of ZnWO4 and take part in the surface reaction to form radicals [103]. For visible light irradiation, the electrons are firstly excited from

• carbon nanodots can further excite TiO2 to generate electron–hole pairs, which will finally lead to the production of active oxygen radicals for the degradation of the methyl blue [112]. Besides TiO2/carbon nanodots, ZnO/carbon nanodots are also reported as superior photocatalysts for the degradation of

Effects of the preparation method on the structure and the visible-light photocatalytic activity of Ag₂CrO₄

• Difa Xu,
• Shaowen Cao,
• Jinfeng Zhang,
• Bei Cheng and
• Jiaguo Yu

Beilstein J. Nanotechnol. 2014, 5, 658–666, doi:10.3762/bjnano.5.77

• holes, and the active oxygen species, including superoxide radicals (O2•−) and hydroxyl radicals (OH•). In order to understand the possible mechanism of the photocatalytic degradation of MB over Ag2CrO4, we have determined the CB and VB position at the point of zero charge by a widely accepted approach

Enhanced photocatalytic activity of Ag–ZnO hybrid plasmonic nanostructures prepared by a facile wet chemical method

• Sini Kuriakose,
• Vandana Choudhary,
• Biswarup Satpati and
• Satyabrata Mohapatra

Beilstein J. Nanotechnol. 2014, 5, 639–650, doi:10.3762/bjnano.5.75

• ZnO [40]. The photogenerated electrons created by the above mentioned processes react with dissolved O2 molecules forming superoxide anion radicals, while holes react with H2O leading to the formation of hydroxyl radicals, both of which cause the degradation of the MB dye. These reactions can be

Artificial sunlight and ultraviolet light induced photo-epoxidation of propylene over V-Ti/MCM-41 photocatalyst

• Van-Huy Nguyen,
• Shawn D. Lin,
• Jeffrey Chi-Sheng Wu and
• Hsunling Bai

Beilstein J. Nanotechnol. 2014, 5, 566–576, doi:10.3762/bjnano.5.67

• photocatalytic reaction occurs only when the illumination with light enables the generation of highly reactive species such as hydroxyl radicals (OH•) and oxy radicals (O•) [1]. The light intensity in photocatalysis has attracted considerable attention. The positive effect of increasing the light intensity on

Chemi- vs physisorption in the radical functionalization of single-walled carbon nanotubes under microwaves

• Victor Mamane,
• Guillaume Mercier,
• Junidah Abdul Shukor,
• Jérôme Gleize,
• Aziz Azizan,
• Yves Fort and
• Brigitte Vigolo

Beilstein J. Nanotechnol. 2014, 5, 537–545, doi:10.3762/bjnano.5.63

• conditions, the aryl radicals can give rise to the growth of aryl chains at the SWNT surface [35]. All these possible over-reaction processes are summarized in Scheme 2. The proposed polyaromatic structure for f-SWNT-15min sample can explain the intense broad fluorescence band observed during the Raman

An ultrasonic technology for production of antibacterial nanomaterials and their coating on textiles

• Anna V. Abramova,
• Vladimir O. Abramov,
• Aharon Gedanken,
• Ilana Perelshtein and
• Vadim M. Bayazitov

Beilstein J. Nanotechnol. 2014, 5, 532–536, doi:10.3762/bjnano.5.62

• after washing. Antimicrobial textiles can be produced by coating textiles with antibacterial nanoparticles (NPs). NPs such as zinc oxide NPs are known to have antibacterial properties due to OH• radicals, which result from defects in their crystal structure [2]. In the case of power ultrasound

Mesoporous cerium oxide nanospheres for the visible-light driven photocatalytic degradation of dyes

• Subas K. Muduli,
• Songling Wang,
• Shi Chen,
• Chin Fan Ng,
• Cheng Hon Alfred Huan,
• Tze Chien Sum and
• Han Sen Soo

Beilstein J. Nanotechnol. 2014, 5, 517–523, doi:10.3762/bjnano.5.60

• , suggesting that the mechanism of photocatalytic activity under visible-light irradiation involves predominantly hydroxyl radicals as the active species. Keywords: cerium oxide; dye degradation; mesoporous; photocatalysis; visible light; Introduction The degradation of organic pollutants by affordable and

• radicals. Chemical scavengers were employed to investigate the mechanism of the photocatalytic processes and to identify the major contributors to the photocatalytic processes. The concentration of RhB, monitored at 554 nm, was used as the proxy to identify the active agent in the decomposition of RhB

• is most pronounced in the presence of the hole scavenger, with impaired activity in the presence of both •OH and •OOH/•O2− scavengers. Interestingly, the electron scavenger does not significantly affect the photodegradation experiments. The participation of •OH radicals was confirmed with the use of

Applicability and costs of nanofiltration in combination with photocatalysis for the treatment of dye house effluents

• Wolfgang M. Samhaber and
• Minh Tan Nguyen

Beilstein J. Nanotechnol. 2014, 5, 476–484, doi:10.3762/bjnano.5.55

• to its ability to oxidize and to destruct dyes simultaneously while the conventional treatment methods either concentrate or transfer dyes to a solid phase [7][8][9][10][11]. Fundamentally, organic compounds are decomposed by means of reactive species such as hydroxyl radicals (OH•), which are

Some reflections on the understanding of the oxygen reduction reaction at Pt(111)

• Ana M. Gómez-Marín,
• Ruben Rizo and
• Juan M. Feliu

Beilstein J. Nanotechnol. 2013, 4, 956–967, doi:10.3762/bjnano.4.108

• clear. In this media, H2O2 has been identified under some conditions as a stable ORR intermediate product [26][27][28][29][30][31], thus indicating an incomplete electron transfer. Nevertheless, the production of hydroxyl radicals, OH•, during the reaction has also been reported [32], and the reduction

Challenges in realizing ultraflat materials surfaces

• Takashi Yatsui,
• Wataru Nomura,
• Fabrice Stehlin,
• Olivier Soppera,
• Makoto Naruse and
• Motoichi Ohtsu

Beilstein J. Nanotechnol. 2013, 4, 875–885, doi:10.3762/bjnano.4.99

• gas in the DPP etching, which produced the oxygen radicals O* to etch the protrusions of the diamond substrate and ultimately yielded an ultra-flat surface. Since the photon energy of the laser is lower than Ed of O2, the conventional O2 adiabatic photochemical reaction was avoided. Furthermore, the

Structural, optical and photocatalytic properties of flower-like ZnO nanostructures prepared by a facile wet chemical method

• Sini Kuriakose,
• Neha Bhardwaj,
• Jaspal Singh,
• Biswarup Satpati and
• Satyabrata Mohapatra

Beilstein J. Nanotechnol. 2013, 4, 763–770, doi:10.3762/bjnano.4.87

• form superoxide anion radicals (•O2−) (Equation 6). The holes generated in the valence band of ZnO react with surface hydroxy groups to produce highly reactive hydroxyl (•OH) radicals (Equation 7). The photogenerated holes can lead to the production of •OH radicals through the dissociation of water

• (Equation 8). The highly reactive hydroxyl radicals (•OH) and superoxide radicals (•O2−) react with MB adsorbed on ZnO nanostructures and lead to the degradation of MB. These underlying processes can be summarized by the equations [44]. Conclusion In summary, we have synthesized flower-like ZnO

Synthesis of indium oxi-sulfide films by atomic layer deposition: The essential role of plasma enhancement

• Cathy Bugot,
• Nathanaëlle Schneider,
• Daniel Lincot and
• Frédérique Donsanti

Beilstein J. Nanotechnol. 2013, 4, 750–757, doi:10.3762/bjnano.4.85

• to the high reactivity of radicals, PEALD generally allows the achievement of many chemical reactions that cannot occur with thermal ALD [13][19]. Here In2(S,O)3 films could be grown while using O2 plasma as oxygen source. But the growth of pure In2O3 films remained unsuccessful. This suggests that

Ellipsometry and XPS comparative studies of thermal and plasma enhanced atomic layer deposited Al₂O₃-films

• Jörg Haeberle,
• Karsten Henkel,
• Hassan Gargouri,
• Franziska Naumann,
• Bernd Gruska,
• Michael Arens,
• Massimo Tallarida and
• Dieter Schmeißer

Beilstein J. Nanotechnol. 2013, 4, 732–742, doi:10.3762/bjnano.4.83

• the last decade the research have been extended to plasma enhanced ALD (PE-ALD) in which the H2O as oxygen source is replaced by a plasma exposure (O2, O3) [1][17][18]. Caused by the higher reactivity of the plasma generated oxygen radicals the PE-ALD extends the capabilities of ALD such as improved

• significant reduction of the O/Al ratio as shown in Figure 8. It points out that at these lower temperatures (80 °C, rt) the oxygen radicals are less efficient in oxidizing the aluminum precursor. This is true also for the chemisorbed organic precursor molecules. At first sight our results might contradict

Photocatalytic antibacterial performance of TiO₂ and Ag-doped TiO₂ against S. aureus. P. aeruginosa and E. coli

• Kiran Gupta,
• R. P. Singh,
• Ashutosh Pandey and
• Anjana Pandey

Beilstein J. Nanotechnol. 2013, 4, 345–351, doi:10.3762/bjnano.4.40

• blocking of respiration and cell death of the bacteria [10]. Another remarkable mechanism of the antimicrobial activity of Ag nanoparticles is related to the formation of free radicals and consequent free-radical-induced oxidative damage of the cell membranes of bacteria [11][12]. But the same result was

Functionalization of vertically aligned carbon nanotubes

• Eloise Van Hooijdonk,
• Carla Bittencourt,
• Rony Snyders and
• Jean-François Colomer

Beilstein J. Nanotechnol. 2013, 4, 129–152, doi:10.3762/bjnano.4.14