Co-doped MnFe₂O₄ nanoparticles: magnetic anisotropy and interparticle interactions

• Bagher Aslibeiki,
• Parviz Kameli,
• Hadi Salamati,
• Giorgio Concas,
• Maria Salvador Fernandez,
• Alessandro Talone,
• Giuseppe Muscas and
• Davide Peddis

Beilstein J. Nanotechnol. 2019, 10, 856–865, doi:10.3762/bjnano.10.86

• (x = 0, 0.25, 0.5, 0.75, 1) were synthesized following a simple method based on solid-state ball milling and calcination of nitrate precursors and citric acid, discussed previously to prepare pure MnFe2O4 [22]. Manganese nitrate (Mn(NO3)2·4H2O, Merck, 99%), iron nitrate (Fe(NO3)3·9H2O, Merck, 99

• %), cobalt nitrate (Co(NO3)2·6H2O, Merck, 98.5%) and citric acid (C6H6O7, Merck, 99.5%) powders were mixed in a 1:1 molar ratio of total metal nitrates to citric acid. The powders were milled for 1 h in a planetary ball mill using agate balls, producing an amorphous precursor (Supporting Information File 1

Cytotoxicity of doxorubicin-conjugated poly[N-(2-hydroxypropyl)methacrylamide]-modified γ-Fe₂O₃ nanoparticles towards human tumor cells

• Zdeněk Plichta,
• Yulia Kozak,
• Rostyslav Panchuk,
• Viktoria Sokolova,
• Matthias Epple,
• Lesya Kobylinska,
• Pavla Jendelová and
• Daniel Horák

Beilstein J. Nanotechnol. 2018, 9, 2533–2545, doi:10.3762/bjnano.9.236

• chemical attachment of target biomolecules, reduces cytotoxicity, and controls particle uptake by the cells [10]. Coatings can be either of low molecular weight, such are carbohydrates and organic acids (ethylenediaminetetraacetic acid, tartaric acid, citric acid, succinic acid, bisphosphonic acid), or of

Fabrication of photothermally active poly(vinyl alcohol) films with gold nanostars for antibacterial applications

• Mykola Borzenkov,
• Maria Moros,
• Claudia Tortiglione,
• Serena Bertoldi,
• Nicola Contessi,
• Silvia Faré,
• Angelo Taglietti,
• Agnese D’Agostino,
• Piersandro Pallavicini,
• Maddalena Collini and
• Giuseppe Chirico

Beilstein J. Nanotechnol. 2018, 9, 2040–2048, doi:10.3762/bjnano.9.193

• properties of the films [20]. Citric acid was chosen as the crosslinking agent as, in comparison with the widely used method of crosslinking with glutaraldehyde, it is a non-toxic compound approved as a food additive, thus providing a green crosslinking route [20][25]. GNSs were synthesized via a seed-growth

• lead to new, easily prepared, NIR-activated, reusable, antibacterial materials suitable for surface coating. Experimental Materials PVA with an average molecular weight of 72000 g/mol (degree of hydrolysis 98%) was purchased from Sigma-Aldrich. Anhydrous citric acid and poly(ethylene glycol) (PEG-200

• stirred at ≈40 °C. 1.45 mL of PEGylated GNS solution were added dropwise and the mixture was stirred 5 h at ≈40 °C. Then, citric acid (0.1 g) was added and 5 mL of the resulting solution were cast into a Petri dish. Once the film was formed, it was sintered 20 min at 130 °C to complete crosslinking. The

Nanocomposites comprised of homogeneously dispersed magnetic iron-oxide nanoparticles and poly(methyl methacrylate)

• Sašo Gyergyek,
• David Pahovnik,
• Ema Žagar,
• Alenka Mertelj,
• Rok Kostanjšek,
• Miloš Beković,
• Marko Jagodič,
• Heinrich Hofmann and
• Darko Makovec

Beilstein J. Nanotechnol. 2018, 9, 1613–1622, doi:10.3762/bjnano.9.153

• dissolution of the Fe cations from the nanocomposite and the nanoparticles was tested with dissolution in the presence of citric acid at pH 1, where further details can be found in Supporting Information File 1. Characterization The particle size, crystallinity and dispersion over the nanocomposites were

• , NP-RA-PMMA and NC-3 in a solution of citric acid. Under sufficiently acidic conditions (pH < 6) the citric acid boosts the dissolution of iron oxide due to the chelate effect [32]. The results are presented as the wt % of dissolved Fe relative to the total Fe in the iron oxide nanoparticles. It was

A review of carbon-based and non-carbon-based catalyst supports for the selective catalytic reduction of nitric oxide

• Shahreen Binti Izwan Anthonysamy,
• Syahidah Binti Afandi,
• Mehrnoush Khavarian and
• Abdul Rahman Bin Mohamed

Beilstein J. Nanotechnol. 2018, 9, 740–761, doi:10.3762/bjnano.9.68

• ” reaction to improve low-temperature SCR activity. The sol–gel method has been used quite frequently for the development of nano-based catalysts. Basically, certain chemical solutions together with a foaming agent (citric acid) is mixed vigorously by stirring under room temperature to produce a homogeneous

• interaction and oxide–oxide interactions that are unreachable otherwise [38]. Xiong et al. [39] prepared magnetic iron–cerium–tungsten mixed oxide pellets using a citric acid sol–gel process assisted by microwave irradiation for the SCR-NH3 of NO. They found that the dispersion of both cerium oxide and

Tuning adhesion forces between functionalized gold colloidal nanoparticles and silicon AFM tips: role of ligands and capillary forces

• Sven Oras,
• Sergei Vlassov,
• Marta Berholts,
• Rünno Lõhmus and
• Karine Mougin

Beilstein J. Nanotechnol. 2018, 9, 660–670, doi:10.3762/bjnano.9.61

• [51] has been applied. The as-synthesized NPs solution [46][47] was centrifuged at 7,000 rpm for 20 min to pellet the NPs, decanted, and then re-suspended in a proper solvent to reduce the citric acid concentration. The supernatant containing the sodium citrate molecules is then removed and 10 mL of

Anchoring Fe₃O₄ nanoparticles in a reduced graphene oxide aerogel matrix via polydopamine coating

• Błażej Scheibe,
• Radosław Mrówczyński,
• Natalia Michalak,
• Karol Załęski,
• Michał Matczak,
• Mateusz Kempiński,
• Zuzanna Pietralik,
• Mikołaj Lewandowski,
• Stefan Jurga and
• Feliks Stobiecki

Beilstein J. Nanotechnol. 2018, 9, 591–601, doi:10.3762/bjnano.9.55

• ), respectively, which may originate from the presence of citric acid or polydopamine. The residual ether-type functional groups can be observed via C–O vibrational band at 1115 cm−1 (IX). The strong band at 1572 cm−1 (VI) could be attributed to a carboxylate C–O–Fe bond, which confirms covalent bonding between

• functional additives at the rGO defect sites, prevent unintended additives migration outside the aerogel and provide better structural stabilization of the whole aerogel structure. Experimental Graphite powder, iron(III) chloride hexahydrate, iron(II) chloride tetrahydrate, sodium nitride 99%, citric acid

• ) was added under vigorous stirring. After 30 minutes, 8 mL of citric acid were added. The process was continued at 95 °C for 90 minutes. Subsequently, the mixture was cooled down to room temperature (RT) and the obtained nanoparticles were washed with DI-H2O (3 × 200 mL) and finally dispersed in 100 mL

Green synthesis of fluorescent carbon dots from spices for in vitro imaging and tumour cell growth inhibition

• Nagamalai Vasimalai,
• Vânia Vilas-Boas,
• Juan Gallo,
• María de Fátima Cerqueira,
• Mario Menéndez-Miranda,
• José Manuel Costa-Fernández,
• Lorena Diéguez,
• Begoña Espiña and
• María Teresa Fernández-Argüelles

Beilstein J. Nanotechnol. 2018, 9, 530–544, doi:10.3762/bjnano.9.51

• -dots in the cancer cultures compared to the non-cancerous cells. Results showed that the spice-derived C-dots inhibited cell viability dose-dependently after a 24 h incubation period, displaying a higher toxicity in LN-229, than in HK-2 cells. As a control, C-dots synthesized from citric acid did not

• , TEM and ESI-QTOF-MS. Moreover, their bioimaging potential and toxicity have been evaluated in vitro in human glioblastoma LN-229 cells and in immortalized epithelial human kidney cells (HK-2). The effects on cancer and non-cancer cells have been also compared with C-dots synthesized from citric acid

• . Most common sources for the synthesis of carbon dots are graphite and citric acid. Graphite is used in top-down synthesis strategies, and uses dimethylformamide (DMF) as surface passivating agent [8]. However, since DMF is harmful to living cells, in this work carbon dots synthesized from graphite were

Sugarcane juice derived carbon dot–graphitic carbon nitride composites for bisphenol A degradation under sunlight irradiation

• Lan Ching Sim,
• Jing Lin Wong,
• Chen Hong Hak,
• Jun Yan Tai,
• Kah Hon Leong and
• Pichiah Saravanan

Beilstein J. Nanotechnol. 2018, 9, 353–363, doi:10.3762/bjnano.9.35

• acid [37] and rapeseed flower bee pollen [38] as precursors to produce CDs for the photocatalytic generation of H2 under visible light irradiation. In addition, Wang and co-workers used citric acid and urea as precursors to prepare N-doped CDs (NCDs). The NCD/g-C3N4 composite exhibited better

Co-reductive fabrication of carbon nanodots with high quantum yield for bioimaging of bacteria

• Jiajun Wang,
• Xia Liu,
• Gesmi Milcovich,
• Tzu-Yu Chen,
• Edel Durack,
• Sarah Mallen,
• Yongming Ruan,
• Xuexiang Weng and
• Sarah P. Hudson

Beilstein J. Nanotechnol. 2018, 9, 137–145, doi:10.3762/bjnano.9.16

• introduces secondary pollution products. Therefore, in order to promote and extend their range of applications, new methods to obtain C-dots with high QY are required. Citric acid, citrate, urea or thiourea have been used in the past to obtain high-QY C-dots with different growth mechanisms proposed [18][19

• ][20]. Qu et al. obtained graphene quantum dots with a quantum yield of 78% and 71% using citric acid and urea or citric acid and thiourea as the precursors, respectively. They demonstrated that N or N/S doping led to the high QY of the C-dots. Zeng et al. prepared C-dots with a relatively high QY

• value (45%) using citric acid and urea as precursors via a facile hydrothermal method. They evidenced that surface passivation by urea resulted in the high QY of the C-dots. Herein we report a C-dot synthetic procedure with remarkable QY (37%) by a one-step hydrothermal chemical reduction method, where

Enhanced photoelectrochemical water splitting performance using morphology-controlled BiVO₄ with W doping

• Xin Zhao and
• Zhong Chen

Beilstein J. Nanotechnol. 2017, 8, 2640–2647, doi:10.3762/bjnano.8.264

• syntheses can be found in the Experimental section. The films in Figure 1a–c were prepared using EG precursor solutions containing 0.5 mL EG solution of V, 0.5 mL EG solution of Bi, 0.015 mL EG solution of W, and 0.15 mL EG solution of citric acid (CA) to which 2 mL of a mixture of water and EG with

• , which can increase the reaction rate and, thus, is very suitable for homogenous doping. In this study, it was successfully employed in preparing W-doped BiVO4 films with the following sequences. First, a mixture of cations is formed with the aid of an organic complexing agent, citric acid and EG

• solutions of Bi, V and W in water or EG. The first three samples were prepared using precursor solutions of Bi, V and W in EG. The solutions were mixed according to the stoichiometric ratio (Bi/V/W = 100:97:3 corresponding to volume a ratio of 500 µL:485 µL:15 µL) for 3% W-doped BiVO4. Citric acid (CA) was

The role of ligands in coinage-metal nanoparticles for electronics

• Ioannis Kanelidis and
• Tobias Kraus

Beilstein J. Nanotechnol. 2017, 8, 2625–2639, doi:10.3762/bjnano.8.263

• , and only remain stable in dispersion if ligands reduce their attractive interactions [85]. The lower Hamaker constant of the ligand shell, its entropic behavior, and its ω-functionalities can make nanoparticles colloidally stable in organic or aqueous environments. Ligands such as citric acid [86

Methionine-mediated synthesis of magnetic nanoparticles and functionalization with gold quantum dots for theranostic applications

• Arūnas Jagminas,
• Agnė Mikalauskaitė,
• Vitalijus Karabanovas and
• Jūrate Vaičiūnienė

Beilstein J. Nanotechnol. 2017, 8, 1734–1741, doi:10.3762/bjnano.8.174

• magnetization value of the magnetic core. To eliminate this drawback, several methods for the deposition of the gold directly onto the surface of magnetic NPs have been proposed that are based on the reduction of Au(III) species by the typical reducing agents such as borohydride, ascorbic acid and citric acid

Nanocrystalline ZrO₂ and Pt-doped ZrO₂ catalysts for low-temperature CO oxidation

• Amit Singhania and
• Shipra Mital Gupta

Beilstein J. Nanotechnol. 2017, 8, 264–271, doi:10.3762/bjnano.8.29

• industrial applications. The above method involves combustion of an aqueous solution of metal nitrates and a fuel (glycine [32], citric acid [33], sucrose [4] and hexamethylenetetramine [34]). The combustion reaction is an exothermic redox reaction that takes place between metal nitrate and the fuel

Facile fabrication of luminescent organic dots by thermolysis of citric acid in urea melt, and their use for cell staining and polyelectrolyte microcapsule labelling

• Nadezhda M. Zholobak,
• Anton L. Popov,
• Alexander B. Shcherbakov,
• Nelly R. Popova,
• Mykhailo M. Guzyk,
• Valeriy P. Antonovich,
• Alla V. Yegorova,
• Yuliya V. Scrypynets,
• Inna I. Leonenko,
• Alexander Ye. Baranchikov and
• Vladimir K. Ivanov

Beilstein J. Nanotechnol. 2016, 7, 1905–1917, doi:10.3762/bjnano.7.182

• General and Inorganic Chemistry of the Russian Academy of Sciences, Moscow 119991, Russia National Research Tomsk State University, Tomsk 634050, Russia 10.3762/bjnano.7.182 Abstract Luminescent organic dots (O-dots) were synthesized via a one-pot, solvent-free thermolysis of citric acid in urea melt

• applications of O-dots for alive/fixed cell staining and labelling of layer-by-layer polyelectrolyte microcapsules were evaluated. Keywords: cell culture; citric acid; layer-by-layer (LbL)-microcapsules; luminescence; organic dots (O-dots); staining; toxicity; Introduction Luminescent nanosized semiconductor

• File 1, Figure S4). Among the numerous families of O-dots, the most popular nanostructures are prepared by a “bottom up” route, via the thermolysis of various organic compounds. For example, when heated citric acid and its salts are transformed easily into O-dots [20][21][22][23][24][25] (see

Influence of synthesis conditions on microstructure and phase transformations of annealed Sr₂FeMoO_6−x nanopowders formed by the citrate–gel method

• Marta Yarmolich,
• Nikolai Kalanda,
• Sergey Demyanov,
• Herman Terryn,
• Jon Ustarroz,
• Maksim Silibin and
• Gennadii Gorokh

Beilstein J. Nanotechnol. 2016, 7, 1202–1207, doi:10.3762/bjnano.7.111

• citric acid monohydrate C6H8O7·H2O (99.9%) as starting materials. First, the aqueous solutions of 0.4 mol dm−3 Sr(NO3)2 and 2 mol dm−3 Fe(NO3)3 were mixed in a molar ratio of Sr/Fe 2:1, and then citric acid was added to the solution in a molar ratio of citric acid/Fe 6.5:1. After this, the 0.2 mol dm−3

Multiwalled carbon nanotube hybrids as MRI contrast agents

• Nikodem Kuźnik and
• Mateusz M. Tomczyk

Beilstein J. Nanotechnol. 2016, 7, 1086–1103, doi:10.3762/bjnano.7.102

• by reaction of oMWCNT with citric acid (2 h at 80 °C) [33]. The presence of several oxygen groups in the neighborhood, which is a common situation for the disrupted aromatic skeleton, additionally supported by the presence of π-electrons forms a chelating cavity for the metal ion. Lamanna used such a

Large-scale fabrication of achiral plasmonic metamaterials with giant chiroptical response

• Morten Slyngborg,
• Yao-Chung Tsao and
• Peter Fojan

Beilstein J. Nanotechnol. 2016, 7, 914–925, doi:10.3762/bjnano.7.83

• solution temperature of 273 ± 0.5 K for 100 min. The substrate with 600 nm interpore distance was prepared by anodization in 2 M citric acid solution at 285 V and with a solution temperature of 293 ± 0.5 K for 20 min. More details on the fabrication of the original mold has been reported previously [39

Facile synthesis of water-soluble carbon nano-onions under alkaline conditions

• Gaber Hashem Gaber Ahmed,
• Rosana Badía Laíño,
• Josefa Angela García Calzón and
• Marta Elena Díaz García

Beilstein J. Nanotechnol. 2016, 7, 758–766, doi:10.3762/bjnano.7.67

• , Na2HPO4 and citric acid were purchased from Sigma-Aldrich, AlCl3·6H2O and Pb(Ac)2·3H2O were purchased from Montplet & Esteban S.A., Barcelona (http://www.montplet.es/), Ce(NO3)3·6H2O was purchased from Fluka, Switzerland, HgCl2 was purchased from Porus (http://poruslabs.com/), and CdCl2 was purchased from

• experiments. Photoluminescence measurements In a typical procedure, the photoluminescence properties of the C-nanoparticles were evaluated by diluting 200 μL of the corresponding C-nanoparticle solution with a pH 6 universal buffer solution (0.2 M Na2HPO4/0.1 M citric acid) to a final volume of 5 mL. The PL

• solution (so that the total concentration of metal was 10 ppm) and then adjusting the volume to 5 mL with a universal buffer solution pH 6 (0.2 M Na2HPO4/0.1 M citric acid). The PL was measured as mentioned above with the same instrumental settings. A 1 cm quartz cuvette was used. PL quantum yield

Influence of calcium on ceramide-1-phosphate monolayers

• Joana S. L. Oliveira,
• Gerald Brezesinski,
• Alexandra Hill and
• Arne Gericke

Beilstein J. Nanotechnol. 2016, 7, 236–245, doi:10.3762/bjnano.7.22

• ) was purchased from Matreya, LLC (PA, USA). EDTA (≥99.4%), NaCl (≥99.5%), NaOH (≥99.5%), CaCl2 (≥99%) and HCl were purchased from Sigma Aldrich GmbH (Taufkirchen, Germany). Chloroform (≥99.9%) and citric acid monohydrate (≥99.5%) were purchased from Carl Roth GmbH (Karlsruhe, Germany) and methanol

Nanostructured surfaces by supramolecular self-assembly of linear oligosilsesquioxanes with biocompatible side groups

• Maria Nowacka,
• Anna Kowalewska and
• Tomasz Makowski

Beilstein J. Nanotechnol. 2015, 6, 2377–2387, doi:10.3762/bjnano.6.244

• , citric acid, thioglycolic or acid). The adsorption of both silsesquioxane oligomers and organic primers was confirmed with attenuated total reflectance infrared spectroscopy. The observed physiochemical and textural variations in the adsorbed materials correlate with the differences in the chemical

• used bare or primed, prior to the coating with LPSQ-COOH/X, with a monolayer of N-acetylcysteine, citric acid or thioglycolic acid. The primers are bound to mica by ionic bonds (carboxylates) and simultaneously provide the substrate with new organic functions capable of hydrogen bonding [49]. Atomic

• small molecules [49]. They should be simultaneously capable of the formation of surface salts and hydrogen bonds with functional groups in side chains of LPSQ-COOH/X. Consequently, thioglycolic acid (TG), citric acid (CA) and N-acetylcysteine (NAC) were selected and used as primers to modify the surface

Radiation losses in the microwave K_u band in magneto-electric nanocomposites

• Talwinder Kaur,
• Sachin Kumar,
• Jyoti Sharma and
• A. K. Srivastava

Beilstein J. Nanotechnol. 2015, 6, 1700–1707, doi:10.3762/bjnano.6.173

• stoichiometric proportions, at ambient temperature under constant magnetic stirring. Citric acid acts as fuel and chelating agent and is added to the salt solution in a molar ratio of cations to citric acid of 1:1.5. To obtain the fine particles and to enhance the reaction mechanism, ammonium hydroxide (NH4OH

Silica micro/nanospheres for theranostics: from bimodal MRI and fluorescent imaging probes to cancer therapy

• Shanka Walia and
• Amitabha Acharya

Beilstein J. Nanotechnol. 2015, 6, 546–558, doi:10.3762/bjnano.6.57

• -shell-encapsulated hybrid nanomaterials consisting of paramagnetic Gd3+ ions and QDs or Au nanocrystals. The citric-acid-capped gold colloids and CdSe/ZnS QDs were silanized by using mercaptopropyltrimethoxysilane (MPS) as surfactant. Further, a Gd3+-DOTA (tetraazacyclododecanetetraacetic acid) complex

• Fe3O4 NPs that were incorporated in silica and functionalized with a carboxylic acid group for bioconjugation. The synthesis involved coating silica around citric-acid-coated Fe3O4 NPs by using the Stöber process. The MPS-activated silica-coated Fe3O4 NPs were then conjugated with TGA-modified CdTe NPs

• was performed by using a vibrating sample magnetometer (VSM). The saturation magnetization of citric-acid-coated Fe3O4 NPs was found to be 40.97 emu/g, which was reduced to 9.90 emu/g after silica coating and was further decreased to 2.26 emu/g after addition of the CdTe QDs. For cell targeting

Imaging the intracellular degradation of biodegradable polymer nanoparticles

• Anne-Kathrin Barthel,
• Martin Dass,
• Melanie Dröge,
• Jens-Michael Cramer,
• Daniela Baumann,
• Markus Urban,
• Katharina Landfester,
• Volker Mailänder and
• Ingo Lieberwirth

Beilstein J. Nanotechnol. 2014, 5, 1905–1917, doi:10.3762/bjnano.5.201

• . It is speculated that L-lactic acid, which is the degradation product of PLLA, is transformed into water and CO2 via the citric acid cycle [9]. In addition to many other factors such as temperature or pH [10], the degree of crystallinity and the molecular weight of the PLLA affect the rate of

Real-time monitoring of calcium carbonate and cationic peptide deposition on carboxylate-SAM using a microfluidic SAW biosensor

• Anna Pohl and
• Ingrid M. Weiss

Beilstein J. Nanotechnol. 2014, 5, 1823–1835, doi:10.3762/bjnano.5.193

• organic biomolecules and calcium carbonate in the presence of carboxylate surfaces could be reproducibly quantified in real-time assays. Here, we report a case study with calcium carbonate, both in pure aqueous systems and in the presence of citric acid. We also investigated the two cationic peptides ES9

• function of time. The influence of the concentration of calcium carbonate relative to the solubility equilibrium and the flow rate on the SAW biosensor phase and amplitude signals was investigated in real-time. The influence of organic molecules is studied in two different systems: First, citric acid in

• carbonate surface interactions seem to be less well controlled at flow rates higher than 50 µL/min. One can assume that, at higher flow rates, the interaction of calcium and/or (bi)carbonate does not reach the maximum capacity of the sensor surface. Calcium carbonate and citric acid interactions In order to