Effect of different silica coatings on the toxicity of upconversion nanoparticles on RAW 264.7 macrophage cells

• Cynthia Kembuan,
• Helena Oliveira and
• Christina Graf

Beilstein J. Nanotechnol. 2021, 12, 35–48, doi:10.3762/bjnano.12.3

• : cytotoxicity; ion release; RAW 264.7 macrophage cell line; silica coating; upconversion nanoparticles; Introduction Upconversion nanoparticles (UCNPs) convert excitation radiation with long wavelengths to a short-wavelength emission. Since biological molecules do not have an upconversion mechanism, imaging

• silica is a porous material. A typical Stöber silica has a pore size of around 1–4 nm [35][36]; therefore, a thin silica coating shell cannot completely inhibit the dissolution of UCNPs [37]. The thickness of silica shells on UCNPs can be easily adjusted over a wide range [38]. Lathinen et al. have shown

• that even a thin silica coating shell of <2 nm or of 5 nm can already reduce the luminescence quenching of UCNPs in an aqueous dispersion [19]. Besides, several studies revealed that silica-coated UCNPs have a low toxicity in vitro and in vivo compared with other nanoparticles [7][11][39]. Amorphous

Influence of the magnetic nanoparticle coating on the magnetic relaxation time

• Mihaela Osaci and
• Matteo Cacciola

Beilstein J. Nanotechnol. 2020, 11, 1207–1216, doi:10.3762/bjnano.11.105

• applicability of the magnetic nanoparticles. In this regard, the optimized microemulsion method can be used to obtain a homogenous silica coating on Fe3−xO4 nanoparticles [14]. This method controls the thickness of the coating layer, enabling a higher average separation among particles when compared to the

Coating of upconversion nanoparticles with silica nanoshells of 5–250 nm thickness

• Cynthia Kembuan,
• Maysoon Saleh,
• Bastian Rühle,
• Ute Resch-Genger and
• Christina Graf

Beilstein J. Nanotechnol. 2019, 10, 2410–2421, doi:10.3762/bjnano.10.231

• -core particles are obtained. This strategy can be easily transferred to other nanomaterials for the design of plasmonic nanoconstructs and sensor systems. Keywords: reverse microemulsion; silica coating; stepwise growth; thick shells; upconversion nanoparticles; Introduction Lanthanide-based

• Stöber growth. All spectra show the typical green and red Er3+ emission bands of NaYF4:(Yb,Er) UCNPs [62][63][64]. The silica coating only slightly alters the relative spectral distribution of the UCL spectra. The most pronounced effect is the slight reduction of the green emission bands at 520 and 540

• as -OH groups from ethanol and maybe also from silanol or silanolate groups of the silica network. The increase in non-radiative relaxation processes by surface quenching effects caused for example by Igepal CO-520 after silica coating can lead to a decrease of the UCL intensity [66]. The

Preparation of thick silica coatings on carbon fibers with fine-structured silica nanotubes induced by a self-assembly process

• Benjamin Baumgärtner,
• Hendrik Möller,
• Thomas Neumann and
• Dirk Volkmer

Beilstein J. Nanotechnol. 2017, 8, 1145–1155, doi:10.3762/bjnano.8.116

• carbon fibers with a silica shell is presented in this work. By immobilizing linear polyamines on the carbon fiber surface, the high catalytic activity of polyamines in the sol–gel-processing of silica precursors is used to deposit a silica coating directly on the fiber’s surface. The surface

• linear poly(ethylenimine), silica shells of several micrometers in thickness can be obtained and their morphology is easily controlled by a considerable number of synthesis parameters. A unique feature is the hierarchical biomimetic structure of the silica coating which surrounds the embedded carbon

• wet-chemical silica coating method. Due to the high catalytic activity of the polyamine with regards to the silica polycondensation, a diminished TMOS concentration of as low as 3 vol % is sufficient for silicification. Increasing the reaction time beyond 40 min up to 24 h does not increase the amount

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

• agglomeration, while the lipophilic surface of the MWCNT has sufficiently high affinity to the cell membrane for permanent connections. Chen subjected pristine MWCNT to LBL (layer-by-layer) non-covalent functionalizations with the polyelectrolyte poly(allylamine hydrochloride) (PAH) followed by silica coating

Cantilever bending based on humidity-actuated mesoporous silica/silicon bilayers

• Christian Ganser,
• Gerhard Fritz-Popovski,
• Roland Morak,
• Parvin Sharifi,
• Benedetta Marmiroli,
• Barbara Sartori,
• Heinz Amenitsch,
• Thomas Griesser,
• Christian Teichert and
• Oskar Paris

Beilstein J. Nanotechnol. 2016, 7, 637–644, doi:10.3762/bjnano.7.56

• , Aldrich) in a 1 mM solution in ethanol for 8 h. This hydrophobization was necessary to deposit silica only on the non-hydrophobic side of the cantilever and so that its reflective coating could still be used. The precursor solution for the mesoporous silica coating was prepared in a three-step process

Silica-coated upconversion lanthanide nanoparticles: The effect of crystal design on morphology, structure and optical properties

• Uliana Kostiv,
• Miroslav Šlouf,
• Hana Macková,
• Alexander Zhigunov,
• Hana Engstová,
• Katarína Smolková,
• Petr Ježek and
• Daniel Horák

Beilstein J. Nanotechnol. 2015, 6, 2290–2299, doi:10.3762/bjnano.6.235

• particles can be dispersed in the aqueous biological media. Charged or polar moieties, such as amphiphilic (co)polymers [24], lipids [25] and silica [26], are therefore attached to the particle surface. The silica coating imparts many useful properties to the nanoparticles, including additional

Peptide-equipped tobacco mosaic virus templates for selective and controllable biomineral deposition

• Klara Altintoprak,
• Axel Seidenstücker,
• Alexander Welle,
• Sabine Eiben,
• Petia Atanasova,
• Nina Stitz,
• Alfred Plettl,
• Joachim Bill,
• Hartmut Gliemann,
• Holger Jeske,
• Dirk Rothenstein,
• Fania Geiger and
• Christina Wege

Beilstein J. Nanotechnol. 2015, 6, 1399–1412, doi:10.3762/bjnano.6.145

• sequence types on structure-directing TMV nanorods. This allows for the systematic investigation of their influence on silica coating reactions via ethanol-containing TEOS on this viral backbone for the first time. Genetically modified TMV particles (TMVLys) with an accessible amino group on every CP

• since the viral CPs are known to be N-terminally acetylated [89] and thereby might act as repetitive charge-relay systems on the viral surface. However, we could not detect any silica coating on TMV–Lys templates under the conditions applied. This may be due to the surrounding amino acids in the CP

• of otherwise non-stained samples. This template was therefore selected for a twelve day time course experiment to investigate the growth kinetics of its mineral shells, and if the thickness of the silica coating might be controlled via the TEOS incubation time. Total widths of randomly selected, low

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

• trimethylammonium bromide (CTAB), butanol and hexane as surfactant, co-surfactant and oil phase, respectively. The silica coating of the Gd2(CO3)3:Tb complex was done by using tetraethylorthosilicate (TEOS) under ammonical conditions. The synthesized NPs were characterized by HRTEM, EDX and FTIR. The size of the

• centrifuged NPs with TEOS to form LSMO@SiF@Si-w. The secondary silica coating was expected to increase the stability of synthesized NPs. The excitation and the emission maxima of LSMO@SiF@Si-u were found to be at 492 and 514 nm, respectively. Further studies suggested that the excitation peak of LSMO@SiF@Si-u

• chloride salts of rare earth and lanthanide metals, namely yttrium (Y), ytterbium (Yb) and erbium (Er) in presence of EDTA solution. The silica coating of these NPs was done by hydrolysis of TEOS and APS followed by conjugation of streptavidin on the silica surface. The TEM micrographs revealed that the

Synergic combination of the sol–gel method with dip coating for plasmonic devices

• Cristiana Figus,
• Maddalena Patrini,
• Francesco Floris,
• Lucia Fornasari,
• Paola Pellacani,
• Gerardo Marchesini,
• Andrea Valsesia,
• Flavia Artizzu,
• Daniela Marongiu,
• Michele Saba,
• Franco Marabelli,
• Andrea Mura,
• Giovanni Bongiovanni and
• Francesco Quochi

Beilstein J. Nanotechnol. 2015, 6, 500–507, doi:10.3762/bjnano.6.52

• fine-tuning of the silica layer thickness on the plasmonic structure were studied. Control of the silica coating thickness was achieved through a combined approach involving sol–gel and dip-coating techniques. The silica films were characterized using spectroscopic ellipsometry, contact angle

• measurements, atomic force microscopy and dispersive spectroscopy. The effect of the use of silica layers on the optical properties of the plasmonic structures was evaluated. The obtained results show that the silica coating enables surface protection of the plasmonic structures, preserving their stability for

• plasmonic nanostructure for sensing applications were investigated. Results and Discussion Silica coating control In order to investigate the effect of the silica layer coating on the optical response of the plasmonic structure, the first step is to understand the role that the main parameters play on the

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

• -employed, aminosilane used in many applications. Ciofani et al. used APTES as an agent for silica coating to functionalize BNNTs [15]. For cellular uptake studies, a fluorescent dye, Oregon Green 488 carboxylic acid, succinimidyl ester was covalently bound to the functionalized BNNTs. The NIH/3T3

Rapid degradation of zinc oxide nanoparticles by phosphate ions

• Rudolf Herrmann,
• F. Javier García-García and
• Armin Reller

Beilstein J. Nanotechnol. 2014, 5, 2007–2015, doi:10.3762/bjnano.5.209

• zinc phosphate, which does not lead to precipitation and equilibrium shifts. In the light of these results it seems essential to ensure a tight coating by a chemically resistant material before applying ZnO-NP for, e.g., medical or cosmetic purposes. Silica coating can suppress photocatalytic activity