Sculpting Silica Colloids by Etching Particles with Nonuniform Compositions

Hagemans, Fabian; Vlug, Wessel; Raffaelli, Chiara; Blaaderen, Alfons van; Imhof, Arnout

doi:10.1021/acs.chemmater.7b00687

Cited by 22 publications

(35 citation statements)

References 32 publications

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“…[ 51 ] As a further illustration, using the same experimental conditions another LC experiment was performed with rods grown at 5

^{\circ}

C followed by a segment grown at 25

^{\circ}

C, and the tip of the particle was preferentially etched as expected (Figure 7, panel b). [ 51 ] With a three‐step growth of silica rods (25

^{\circ}

C, 5

^{\circ}

C, and 25

^{\circ}

Section: Resultsmentioning

confidence: 99%

“…[ 51 ] With a three‐step growth of silica rods (25

^{\circ}

C, 5

^{\circ}

C, and 25

^{\circ}

C), silica particles with a thicker but less condensed middle part were synthesized. The in situ etching results for this kind of silica rods are shown in Figure 7, panel c. The LC‐STEM observations with the same mentioned experimental conditions agree with the previous results shown by our group [ 51 ] for ex situ etching of these particles in bulk, as the middle, less condensed segment etched preferentially. Consequently, the experimental conditions determined in this work for conducting LC‐STEM chemical etching experiments of silica rods are applicable to similar systems with a negligible effect of the electron beam as well as of the LC geometry.…”

Section: Resultsmentioning

confidence: 99%

“…[ 49,50 ] This inhomogeneous silica structure could be obtained during particle synthesis by changing the reaction temperature, precursor concentration, and/or ethanol concentration. [ 51 ] Finally we used the information obtained to explore the chemical composition of newly developed, even more complexly structured silica rod‐shaped particles known as crooked silica rods. Such crooked rods have been developed recently in our group [ 52 ] and that of others [ 53 ] as such particles can form interesting new colloidal liquid crystal phases.…”

Section: Introductionmentioning

confidence: 99%

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Low‐dose liquid cell electron microscopy investigation of the complex etching mechanism of rod‐shaped silica colloids

et al. 2020

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Understanding the chemical structure of rod-shaped silica colloidal particles is attainable by investigating their etching mechanism in solution. Liquid Cell (Scanning) Transmission Electron Microscopy (LC-(S)TEM) is a promising technique through which the etching of these particles can be observed in real time, and at the single particle level, without possible deformations induced by the surface tension of dried particles. However, the presence of high energy electrons, and the different geometry in LC experiments may alter the conditions of in situ experiments compared to their ex situ counterparts. Here we present a controlled low-dose LC-STEM study of the basic etching process of micron-sized silica rods that are immobilized on the SiN window of a liquid cell. The results show that using low-dose imaging conditions, combined with a low accumulated electron dose, and optimized flow rates of solutions allow for investigation of the chemical etching mechanism of silica colloidal particles using the LC-(S)TEM technique with negligible effects of the electron beam. A comparison of ex situ etching experiments with LC-STEM observations show that the LC geometry can play a crucial role in LC-STEM experiments where the diffusion of the etching particles is important, which should be considered during the interpretations of LC-STEM results.

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“…[ 51 ] As a further illustration, using the same experimental conditions another LC experiment was performed with rods grown at 5

^{\circ}

C followed by a segment grown at 25

^{\circ}

C, and the tip of the particle was preferentially etched as expected (Figure 7, panel b). [ 51 ] With a three‐step growth of silica rods (25

^{\circ}

C, 5

^{\circ}

C, and 25

^{\circ}

Section: Resultsmentioning

confidence: 99%

“…[ 51 ] With a three‐step growth of silica rods (25

^{\circ}

C, 5

^{\circ}

C, and 25

^{\circ}

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Low‐dose liquid cell electron microscopy investigation of the complex etching mechanism of rod‐shaped silica colloids

et al. 2020

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“…As a control study, we prepared template particles with a secondary rim in the middle according to ref ( 35 ). Nucleation and growth of MPTMS* onto these particles, in the same way as described above, resulted in a droplet enveloping the end of the template particle while terminating on the middle rim ( Figure S6 ), albeit with low particle yield.…”

Section: Resultsmentioning

confidence: 99%

Regiospecific Nucleation and Growth of Silane Coupling Agent Droplets onto Colloidal Particles

et al. 2017

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Nucleation-and-growth processes are used extensively in the synthesis of spherical colloids, and more recently regiospecific nucleation-and-growth processes have been exploited to prepare more complex colloids such as patchy particles. We demonstrate that surface geometry alone can be made to play the dominant role in determining the final particle geometry in such syntheses, meaning that intricate chemical surface patternings are not required. We present a synthesis method for “lollipop”-shaped colloidal heterodimers (patchy particles), combining a recently published nucleation-and-growth technique with our recent findings that particle geometry influences the locus of droplet adsorption onto anisotropic template particles. Specifically, 3-methacryloxypropyl trimethoxysilane (MPTMS) is nucleated and grown onto bullet-shaped and nail-shaped colloids. The shape of the template particle can be chosen such that the MPTMS adsorbs regiospecifically onto the flat ends. In particular, we find that particles with a wider base increase the range of droplet volumes for which the minimum in the free energy of adsorption is located at the flat end of the particle compared with bullet-shaped particles of the same aspect ratio. We put forward an extensive analysis of the synthesis mechanism and experimentally determine the physical properties of the heterodimers, supported by theoretical simulations. Here we numerically optimize, for the first time, the shape of finite-sized droplets as a function of their position on the rod-like silica particle surface. We expect that our findings will give an impulse to complex particle creation by regiospecific nucleation and growth.

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“…It was later possible to etch rod-like particles into cone-like particles using ammonium hydroxide (Hagemans et al 2016). This work was further extended to show that spheres and rods could be etched into dumbbells and biconcave silica rings sandwiched between two silica spheres (Hagemans et al 2017). Silica 'matchstick' colloids have also been reported (Longbottom et al 2015).…”

Section: Other Methodsmentioning

confidence: 99%

Dye-doped silica nanoparticles: synthesis, surface chemistry and bioapplications

et al. 2020

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Background: Fluorescent silica nanoparticles have been extensively utilised in a broad range of biological applications and are facilitated by their predictable, wellunderstood, flexible chemistry and apparent biocompatibility. The ability to couple various siloxane precursors with fluorescent dyes and to be subsequently incorporated into silica nanoparticles has made it possible to engineer these fluorophores-doped nanomaterials to specific optical requirements in biological experimentation. Consequently, this class of nanomaterial has been used in applications across immunodiagnostics, drug delivery and human-trial bioimaging in cancer research. Main body: This review summarises the state-of-the-art of the use of dye-doped silica nanoparticles in bioapplications and firstly accounts for the common nanoparticle synthesis methods, surface modification approaches and different bioconjugation strategies employed to generate biomolecule-coated nanoparticles. The use of dye-doped silica nanoparticles in immunoassays/biosensing, bioimaging and drug delivery is then provided and possible future directions in the field are highlighted. Other non-cancerrelated applications involving silica nanoparticles are also briefly discussed. Importantly, the impact of how the protein corona has changed our understanding of NP interactions with biological systems is described, as well as demonstrations of its capacity to be favourably manipulated. Conclusions: Dye-doped silica nanoparticles have found success in the immunodiagnostics domain and have also shown promise as bioimaging agents in human clinical trials. Their use in cancer delivery has been restricted to murine models, as has been the case for the vast majority of nanomaterials intended for cancer therapy. This is hampered by the need for more human-like disease models and the lack of standardisation towards assessing nanoparticle toxicity. However, developments in the manipulation of the protein corona have improved the understanding of fundamental bio-nano interactions, and will undoubtedly assist in the translation of silica nanoparticles for disease treatment to the clinic.

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Sculpting Silica Colloids by Etching Particles with Nonuniform Compositions

Cited by 22 publications

References 32 publications

Low‐dose liquid cell electron microscopy investigation of the complex etching mechanism of rod‐shaped silica colloids

Low‐dose liquid cell electron microscopy investigation of the complex etching mechanism of rod‐shaped silica colloids

Regiospecific Nucleation and Growth of Silane Coupling Agent Droplets onto Colloidal Particles

Dye-doped silica nanoparticles: synthesis, surface chemistry and bioapplications

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