Nanoarchitectonics to entrap living cells in silica-based systems: encapsulations with yolk–shell and sepiolite nanomaterials

• Celia Martín-Morales,
• Jorge Fernández-Méndez,
• Pilar Aranda and
• Eduardo Ruiz-Hitzky

Beilstein J. Nanotechnol. 2023, 14, 522–534, doi:10.3762/bjnano.14.43

• sol–gel methods, as well as pre-synthesised yolk–shell bionanohybrids have been studied subsequently. Optical microscopy and SEM confirm that the silica shell microstructures provide a reduced contact between cells. The inorganic matrix increases the survival of the cells and maintains their

• hand, the use of yolk–silica shell (YS) microstructures formed by soft template synthesis was explored [30] to encapsulate living cells with a highly porous SiO2 network aiming to introduce a small interstitial space between the microorganisms and the silica matrix. The latter strategy intends to

• easily observable. This indicates that the cyanobacteria encapsulated in yolk–shell microstructures, instead of being directly attached to an inorganic surface, are floating separated by a space between cell wall and silica shell. This gap is crucial to alleviate the previously observed stress

Comprehensive review on ultrasound-responsive theranostic nanomaterials: mechanisms, structures and medical applications

• Sepand Tehrani Fateh,
• Lida Moradi,
• Elmira Kohan,
• Michael R. Hamblin and
• Amin Shiralizadeh Dezfuli

Beilstein J. Nanotechnol. 2021, 12, 808–862, doi:10.3762/bjnano.12.64

Recent progress in magnetic applications for micro- and nanorobots

• Ke Xu,
• Shuang Xu and
• Fanan Wei

Beilstein J. Nanotechnol. 2021, 12, 744–755, doi:10.3762/bjnano.12.58

• analyte. The magnetic bead (MaB) architecture is composed of a 15 nm iron oxide (Fe3O4) superparamagnetic core encased in a silica shell. The DNA strands are conjugated to the polymeric brush using a flexible linker. The brush permits passage of the nanoparticles through cell membranes, and prevents

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

• cytometry measurements performed on macrophages (RAW 264.7 cells) indicate that cells treated with amino-functionalized particles with a thicker silica shell have a higher viability than those incubated with UCNPs with a thinner silica shell, even if more particles with a thicker shell are taken up. This

• protect UCNPs surfaces from dissolution. In contrast to a more complex polymeric coating, silica surfaces can be easily functionalized with a wide range of coupling agents and biomolecules, and the interior of the silica shell can be modified by integrating dye molecules, for example. However, amorphous

• silica shells with two different thickness values were grown onto these cores to enable the investigation of a possible relation between the degree of cytotoxicity, particle size, and silica shell thickness. The particles were subsequently functionalized with N-(6-aminohexyl)-3

Unravelling the interfacial interaction in mesoporous SiO₂@nickel phyllosilicate/TiO₂ core–shell nanostructures for photocatalytic activity

• Bridget K. Mutuma,
• Xiluva Mathebula,
• Isaac Nongwe,
• Bonakele P. Mtolo,
• Boitumelo J. Matsoso,
• Rudolph Erasmus,
• Zikhona Tetana and
• Neil J. Coville

Beilstein J. Nanotechnol. 2020, 11, 1834–1846, doi:10.3762/bjnano.11.165

• [24][25]. One method to maximize the SiO2–TiO2 interaction is via the synthesis of core–shell nanostructures or nanocomposites [18][19][26][27]. Ikeda et al. [26] reported an improved photodecomposition of acetic acid by using a titania core@hollow silica shell nanostructured catalyst. Similarly, Ren

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

• microemulsion technique in 2008 [42][43]. However, for certain applications such as sensing and plasmonics, a thicker silica shell is desired that can be loaded with sensor molecules or used as spacer for the plasmonic enhancement of the emission of UCNPs by gold or silver shells [45]. Moreover, since UCNPs can

• release rare earth metal and fluoride ions to some extent into the surrounding medium [46], which can cause toxic effects, a thick silica shell could act as protective coating [46]. For silica shells grown onto iron oxide NPs using an inverse microemulsion, it was shown that the thickness of the shell

• nm by a similar procedure [23]. In this work, we present an approach for growing a silica shell with an adjustable thickness between 5 and 250 nm onto oleate-coated NaYF4:Yb3+/Er3+ UCNP. This coating procedure comprises the growth of a silica shell via a reverse microemulsion method to shell

Polydopamine-coated Au nanorods for targeted fluorescent cell imaging and photothermal therapy

• Boris N. Khlebtsov,
• Andrey M. Burov,
• Timofey E. Pylaev and
• Nikolai G. Khlebtsov

Beilstein J. Nanotechnol. 2019, 10, 794–803, doi:10.3762/bjnano.10.79

• obtain a loading efficiency of 103 R123 molecules per one composite AuNRs-PDA-R123-folate particle. This number is comparable with the typical estimations of the loading capacity for AuNRs coated with a mesoporous silica shell [45] (several thousands of dye molecules per particle). In our case, a smaller

Colloidal chemistry with patchy silica nanoparticles

• Pierre-Etienne Rouet,
• Cyril Chomette,
• Laurent Adumeau,
• Etienne Duguet and
• Serge Ravaine

Beilstein J. Nanotechnol. 2018, 9, 2989–2998, doi:10.3762/bjnano.9.278

• mixture was left to react for 2 h, and was centrifuged at 9000 rpm for 30 min (twice) in order to eliminate undesired reactants. The AuNPs@PEG-SH nanoparticles were redispersed in absolute ethanol. To coat the gold nanoparticles with a silica shell, 15 mL of the Au nanoparticles dispersion were mixed

• under continuous magnetic stirring with a solution of deionized water and ammonia, at a volume ratio of 93.8/5/1.2 for absolute ethanol, water and ammonia, respectively. 18.3 μL of TEOS were added and the reaction mixture was stirred for 12 h at 20 ± 2 °C. Upon completion of the growth of silica shell

• chains at the bottom of the dimples; (5) growth of a silica shell around gold nanoparticles; (6) grafting of carboxylic acid groups at the silica surface of the nanospheres; (7) locking of carboxylated satellites within the aminated dimples through amide bonding. a) Silica surface modification with

Circular dichroism of chiral Majorana states

• Javier Osca and
• Llorenç Serra

Beilstein J. Nanotechnol. 2018, 9, 1194–1199, doi:10.3762/bjnano.9.110

• allowed measuring the extinction spectrum of a single silica shell-coated silver nanoparticle excited with varying polarizations [29]. Energy eigenvalues close to zero energy as a function of ΔB. Panels a) and b) are for a square of dimensions Lx = Ly = 10LU, while c) and d) correspond to a rectangle of

Bright fluorescent silica-nanoparticle probes for high-resolution STED and confocal microscopy

• Isabella Tavernaro,
• Christian Cavelius,
• Henrike Peuschel and
• Annette Kraegeloh

Beilstein J. Nanotechnol. 2017, 8, 1283–1296, doi:10.3762/bjnano.8.130

• hypothesise that the differences in the decrease of fluorescence intensities can be explained by the varying thicknesses of the silica shells of the particles. Using the C-dots method, dye-doped silica nanoparticles with a dye-rich core and a pure silica shell are obtained [39]. In contrast, the two other

• methods lead to a significant distribution of the fluorescent dye in the particle matrix and consequently to a reduced shielding. To examine the hypothesis, an additional silica shell without dye molecules was applied on the FD45_Atto647N particles (FD45_Atto647N_NFSS). Next, the photostability of these

• particles and the fully dyed FD60_Atto647N was compared (Figure S21, Supporting Information File 1). As a result, a higher photostability can be achieved through an additional pure silica shell, since the fluorescence intensity of FD45_Atto647N_NFSS tends to be reduced slower compared to the fully dyed

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

• procedures, which are typically limited to dimensions in the nanometer range, the suggested process of LPEI mediated immobilization of silica nanotubes onto carbon fibers allows covering the surface with an amorphous silica shell that can reach an extent of several micrometers in thickness. In addition to

• the new approach of polyamine mediated silica deposition onto carbon fibers, the presented method by means of LPEI immobilization is able to introduce a silica shell with a nanostructured surface. This preparation route gives access to a new hybrid material that combines the properties of both the

Hierarchically structured nanoporous carbon tubes for high pressure carbon dioxide adsorption

• Julia Patzsch,
• Deepu J. Babu and
• Jörg J. Schneider

Beilstein J. Nanotechnol. 2017, 8, 1135–1144, doi:10.3762/bjnano.8.115

• at 20 W for one minute. Synthesis of silica@polystyrene composite tubes (2) and silica@carbon composite tubes (3) Analogous to our previous work [38], a modified Stoeber method was used to coat the plasma-treated, and thus oxo-functionalized, PS fibres with a silica shell. In a typical reaction, the

• used to remove the silica shell of the silica@carbon composite (3). The as-obtained carbon tubes were washed with water and dried at 80 °C. The obtained carbon tubes (4) were finally treated at 1300 °C or 1600 °C for 1 h. Synthesis of silicon carbide tubes (5) The silica@carbon composite (3) sample was

• tubes 4 and the silicon carbide tubes 5 which both require the removal of the silica shell. The electrospun PS fibres have an average diameter of about 2.5 µm as revealed by the SEM images (Figure 2a). A homogeneous coverage of silica spheres of 200 nm diameter obtained from the Stoeber process is

From iron coordination compounds to metal oxide nanoparticles

• Mihail Iacob,
• Carmen Racles,
• Codrin Tugui,
• George Stiubianu,
• Adrian Bele,
• Liviu Sacarescu,
• Daniel Timpu and
• Maria Cazacu

Beilstein J. Nanotechnol. 2016, 7, 2074–2087, doi:10.3762/bjnano.7.198

• , suggesting that the iron oxide nanoparticles are covered with silica. The formation of a silica shell on the surface of the iron oxide nanoparticles in NPC3 might be the reason for such a difference of size between nanoparticles obtained in a similar way from the cluster with Si (29 nm) and without Si (≈200

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

• :Yb3+/Er3+ nanoparticles at temperatures above 300 °C was confirmed by both ED and XRD. Upconversion luminescence under excitation at 980 nm was observed in the luminescence spectra of OM–NaYF4:Yb3+/Er3+ nanoparticles. Finally, the OM–NaYF4:Yb3+/Er3+ nanoparticles were coated with a silica shell to

• . However, the nanoparticles must disperse in aqueous media for biological applications. To disperse the no. 4 NaYF4:Yb3+/Er3+ nanoparticles in water, they were coated with a thin silica shell using a microemulsion technique. TMOS and Igepal CO-520 were used as a precursor and an emulsifier, respectively

• . Compared with the initial 10 nm OM–NaYF4:Yb3+/Er3+ nanoparticles, the TEM micrograph (Figure 9) showed that the size of the NaYF4:Yb3+/Er3+&SiO2 particles had increased to 17 nm due to the presence of the silica shell on the surface. The NaYF4:Yb3+/Er3+&SiO2 nanoparticles had a clear core–shell structure

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

• was carried out to determine the silica shell thickness of TMV–KD10 particles after different reaction times. 3 µL of mineralized TMV particles in solution were incubated on a 400-mesh formvar, carbon-covered copper grid for 5 min. The droplet was removed with five droplets of ultrapure water and air

• for SEM (for details, refer to text). Time-resolved monitoring of silica shell growth on TMV–KD10 templates: TEM analysis of non-stained specimens, after the reaction times indicated above. Total average diameters (Ø ± standard deviations) of mineralized TMV–KD10-hybrids were determined from 11–15

Structure and mechanism of the formation of core–shell nanoparticles obtained through a one-step gas-phase synthesis by electron beam evaporation

• Andrey V. Nomoev,
• Sergey P. Bardakhanov,
• Makoto Schreiber,
• Dashima G. Bazarova,
• Nikolai A. Romanov,
• Boris B. Baldanov,
• Bair R. Radnaev and
• Viacheslav V. Syzrantsev

Beilstein J. Nanotechnol. 2015, 6, 874–880, doi:10.3762/bjnano.6.89

• particles are thought to be due to local fluctuations in the vapour concentration of Cu and Si. Fluctuations in local vapour concentrations can easily occur from the carrier gas flow and convection currents in the Cu–Si liquid being evaporated. As the thickness of the silica shell is relatively constant

• compared to the particle sizes, this suggests that the silica shell stops the growth of the core Cu. Thus areas containing higher Si concentrations would form smaller core–shell particles while in areas with lower Si concentrations, the Cu core would grow larger before the growth was halted by the shell

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

• ions Gd3+ and Eu3+/Tb3+ inside silica NPs through Stöber’s process. In addition, the silica spheres were modified with a pyridine–based aromatic linkage which in turn was found to increase the quantum yield emission of Eu3+/Tb3+ ions present inside the silica shell. The silica NPs grafted with 3

• suggested that the particle relaxivity was in direct correlation with the number of Gd3+ ions covalently linked to the silica shell. The in vivo studies further revealed that these silica-coated MRI probes enhance the MRI signal intensity in the bladder with no observable effects on the health of the animal

• biochemical assays also confirmed low toxicity of Mn3O4@SiO2(RB)–PEG–Apt NPs. Again, Schladt et al. [24] designed PEG-functionalized silica-shell-coated manganese oxide NPs. Further the surface of these NPs was modified by using fluorescent APS–Atto 465. These nanocomposites were characterized by UV–vis and

The effect of surface charge on nonspecific uptake and cytotoxicity of CdSe/ZnS core/shell quantum dots

• Vladimir V. Breus,
• Anna Pietuch,
• Marco Tarantola,
• Thomas Basché and
• Andreas Janshoff

Beilstein J. Nanotechnol. 2015, 6, 281–292, doi:10.3762/bjnano.6.26

• ]. Various functionalization strategies have been employed in order to increase the stability of the surface ligand shell and to reduce the cytotoxicity of QDs, such as the use of cross-linked polymer coatings [10][12][13] or encapsulation in a silica shell [14][15][16]. These approaches, however, also

Caveolin-1 and CDC42 mediated endocytosis of silica-coated iron oxide nanoparticles in HeLa cells

• Nils Bohmer and
• Andreas Jordan

Beilstein J. Nanotechnol. 2015, 6, 167–176, doi:10.3762/bjnano.6.16

• oxide nanoparticles (SPIONs) SPIONs were provided and characterized by MagForce AG. SPIONs with an iron oxide core of 15 nm and a silica shell of 5 nm were modified by coupling the respective functional groups as an ethoxy- or rather methoxysilane to the free hydroxy groups of the surface (Figure 2

• incubated for 24 h with SPIONs (50 µg Fe/mL) which were either caboxylated, PEGylated or which had no further modifications on their silica shell. Uptake of nanoparticles was measured by dissolution of cell pellets and nanoparticles in concentrated hydrochloric acid, followed by quantitative determination

• of the iron content by a photometric assay and ICP. Bare SPIONs with silica shell Non-transfected control cells internalized 39.2 ± 1.5 pg Fe/cell in 24 h, while cells with a knockdown of Caveolin-1 contained only 28.4 ± 1.0 pg Fe/cell. Hence, knockdown of Caveolin-1 decreased endocytosis of

Synthesis and characterization of fluorescence-labelled silica core-shell and noble metal-decorated ceria nanoparticles

• Rudolf Herrmann,
• Markus Rennhak and
• Armin Reller

Beilstein J. Nanotechnol. 2014, 5, 2413–2423, doi:10.3762/bjnano.5.251

• -derived BPD dye can be immobilized in a polyorganosiloxane network which in turn could be isolated by a silica shell. This is indeed possible. We modified existing procedures [24][25][26][27] for the slow co-hydrolysis of methyltrimethoxysilane and dimethyldiethoxysilane in the presence of BPD in micelles

• formed by 4-dodecylbenzenesulfonic acid. When the formation of the polyorganosiloxane core incorporating BPD is complete (≈5 d), a first thin silica shell is added by further reaction with tetraethoxysilane (TEOS) during three days. At this stage the NP can be isolated from the reaction mixture [5]. The

• . Conclusion We have reviewed the preparation and characterization of particles having a fluorescent polyorganosiloxane core containing perylenediimide dye and a silica shell which can be further modified with reactive thiol groups. The number of thiol groups per nanoparticle can be determined by a

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

• scanning transmission X-ray microscopy (STXM) studies on human skin, which allowed us to visualize silica-shell/gold-core particles in the size range of 94–298 nm on superficial layers of the stratum corneum and in hair follicle openings at the single particle level (Figure 1c, see [4] for further details

Inorganic Janus particles for biomedical applications

• Isabel Schick,
• Steffen Lorenz,
• Dominik Gehrig,
• Stefan Tenzer,
• Wiebke Storck,
• Karl Fischer,
• Dennis Strand,
• Frédéric Laquai and
• Wolfgang Tremel

Beilstein J. Nanotechnol. 2014, 5, 2346–2362, doi:10.3762/bjnano.5.244

• particles are diluted in biological media [102]. On the contrary, the encapsulation of isotropic nanoparticles in a silica shell was established, which is advantageous because of the extraordinary stability of silica and its well-known surface chemistry that allows further functionalization. Furthermore

• , the silica shell preserves the intrinsic materials properties, such as magnetic or plasmonic characteristics, but it minimizes the release of toxic ions from the nanoparticle surface and a direct contact with cells. Due to its higher packing density as compared to an organic ligand coating, it also

• formation of the iron oxide component. Wu et al. pointed out that a thiol passivation of the surface is crucial for retaining the Janus character due to the two different surfaces [38]. This was demonstrated by complete encapsulation of Au@Fe3O4 as well as Ag@Fe2O3 nanoparticles with a silica shell [103

Hybrid spin-crossover nanostructures

• Carlos M. Quintero,
• Gautier Félix,
• Iurii Suleimanov,
• José Sánchez Costa,
• Gábor Molnár,
• Lionel Salmon,
• William Nicolazzi and
• Azzedine Bousseksou

Beilstein J. Nanotechnol. 2014, 5, 2230–2239, doi:10.3762/bjnano.5.232

• by means of an intermediate decorated silica shell [23]. Briefly, SCO@SiO2 particles were synthetized using the reverse micelle technique by mixing two microemulsions: one containing the triazole ligand and the other the iron(II) salt, using Triton and TEOS (tetraethoxysilane) as tensioactive and

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

• account when assessing the biological effects or the toxicology of zinc oxide nanoparticles. Keywords: degradation; phosphate; silica shell; zinc oxide nanoparticles; zinc phosphate; Introduction Crystalline nanoparticles of the semiconductor zinc oxide (ZnO-NP) show a broad fluorescence band in the

• silicon but no zinc or phosphorus. The degradation of the zinc oxide core of the coated particles is therefore complete. The silica shell (thickness 3–6 nm) is obviously not sufficiently compact to prevent the access of water to the ZnO core. Silica NP and shells formed by the Stöber process have a

Optimizing the synthesis of CdS/ZnS core/shell semiconductor nanocrystals for bioimaging applications

• Li-wei Liu,
• Si-yi Hu,
• Ying Pan,
• Jia-qi Zhang,
• Yue-shu Feng and
• Xi-he Zhang

Beilstein J. Nanotechnol. 2014, 5, 919–926, doi:10.3762/bjnano.5.105

• ][19]. There are many reports about the surface modification of QDs in the literature, for example, by functionalizing QDs with small molecules, e.g., sulfanylpropanoic acid, coating QDs with a silica shell, and encapsulating QDs within micelle polymer nanoparticles. Amongst the most-studied