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

In vitro and in vivo interactions of selected nanoparticles with rodent serum proteins and their consequences in biokinetics

• Wolfgang G. Kreyling,
• Stefanie Fertsch-Gapp,
• Martin Schäffler,
• Blair D. Johnston,
• Nadine Haberl,
• Christian Pfeiffer,
• Jörg Diendorf,
• Carsten Schleh,
• Stephanie Hirn,
• Manuela Semmler-Behnke,
• Matthias Epple and
• Wolfgang J. Parak

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

• . Therefore, we studied the role of five different surface modifications on monodisperse AuNP of 5 nm core diameter (i.e., the diameter as determined by transmission electron microscopy). As surface ligands we chose: citric acid (as supplied by the manufacturer), bis(p-sulfonatophenyl)phenylphosphine, a thiol

Synthesis of hydrophobic photoluminescent carbon nanodots by using L-tyrosine and citric acid through a thermal oxidation route

• Venkatesh Gude

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

• Venkatesh Gude Department of Chemistry, Assam University-Silchar, Assam, 788011, India 10.3762/bjnano.5.164 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

• ]. The as-prepared CNDs are hydrophilic in nature. There are some synthetic routes by using citric acid and some surface passivating agents like L-lysine [15], ethanolamine [20], betaine [21] to obtain hydrophilic CNDs through thermal oxidation in air. Amino acids like histidine, arginine, threonine, and

• commonly available laboratory equipment. The CNDs were prepared by using citric acid and L-tyrosine precursors through a thermal oxidation process in air at two temperatures 220 °C and 300 °C, and they exhibit characteristic emission properties. The two chosen temperatures are below the melting point of L

Glassy carbon electrodes modified with multiwalled carbon nanotubes for the determination of ascorbic acid by square-wave voltammetry

• Sushil Kumar and
• Victoria Vicente-Beckett

Beilstein J. Nanotechnol. 2012, 3, 388–396, doi:10.3762/bjnano.3.45

• ) analysed by HPLC were excellent (95–101%). Fresh fruit juices may contain a number of organic acids (e.g., citric acid) and sugars (e.g., glucose, fructose and sucrose), which could cause potential interferences. However no such interferences were evident in the analyses. Comparison of the SWV method with

Manipulation of gold colloidal nanoparticles with atomic force microscopy in dynamic mode: influence of particle–substrate chemistry and morphology, and of operating conditions

• Samer Darwich,
• Karine Mougin,
• Akshata Rao,
• Enrico Gnecco,
• Shrisudersan Jayaraman and
• Hamidou Haidara

Beilstein J. Nanotechnol. 2011, 2, 85–98, doi:10.3762/bjnano.2.10

• is essentially affected by electrostatic interactions arising from residues from the synthesis (citric acid) that may be adsorbed on the particles. It is thus normal, in the absence of both physical contact and notable intermolecular forces between the particles, that their mobility is independent of

• nanogold particles, HAuCl4·3H2O supplied by ABCR, Karlsruhe, Germany. The suspension was stabilized with citric acid trisodium salt (Aldrich), which, by reducing HAuCl4, imparts the negative charge of the citrate ions to the gold nano-particle surface [27][28]. The average size of these nanogold particles

• reduce the citric acid concentration. The nanoparticles were then purified from excess surfactant and other reactants by dialysis for one week. Finally, the dialyzed solution was centrifuged and particles were re-dispersed in tetrahydrofuran. 300 µL of the appropriate thiol (methyl- or hydroxyl