3D design of self-assembled nanoporous colloids

Sokolov, Igor; Kievsky, Yaroslav

doi:10.1016/s0167-2991(05)80240-x

Cited by 18 publications

(10 citation statements)

References 45 publications

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“…Over time, seafloor Fe deposits typically experience diagenetic recrystallization, which obscures the distinct twisted and branching morphological traits that link filament growth to biomineralization by Fe-oxidizing bacteria. Furthermore, abiotic processes have been advocated to explain some of the common textural features in hydrothermal Si-Fe deposits, including dendrites and moss agates (Hopkinson, Roberts, Herrington, & Wilkinson, 1998;Little et al, 2004) and twisted and striated silica filaments (Park, Lee, Cheon, & Park, 2001;Sokolev & Kievsky, 2005), as well as tubes with particulate iron interiors (García-Ruiz, Nakouzi, Kotopoulou, Tamborrino, & Steinbock, 2017) have been generated experimentally by using entirely abiotic processes. Thus, one of the key remaining challenges in the search for microbial Fe oxidation in the rock record is to confidently distinguish true iron biominerals, from abiotic chemical precipitates, in Fe deposits that have experienced diagenetic alteration.…”

Section: Introductionmentioning

confidence: 99%

On the biogenicity of Fe‐oxyhydroxide filaments in silicified low‐temperature hydrothermal deposits: Implications for the identification of Fe‐oxidizing bacteria in the rock record

et al. 2019

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Microaerophilic Fe(II)‐oxidizing bacteria produce biomineralized twisted and branched stalks, which are promising biosignatures of microbial Fe oxidation in ancient jaspers and iron formations. Extracellular Fe stalks retain their morphological characteristics under experimentally elevated temperatures, but the extent to which natural post‐depositional processes affect fossil integrity remains to be resolved. We examined siliceous Fe deposits from laminated mounds and chimney structures from an extinct part of the Jan Mayen Vent Fields on the Arctic Mid‐Ocean Ridge. Our aims were to determine how early seafloor diagenesis affects morphological and chemical signatures of Fe‐oxyhydroxide biomineralization and how extracellular stalks differ from abiogenic features. Optical and scanning electron microscopy in combination with focused ion beam‐transmission electron microscopy (FIB‐TEM) was used to study the filamentous textures and cross sections of individual stalks. Our results revealed directional, dendritic, and radial arrangements of biogenic twisted stalks and randomly organized networks of hollow tubes. Stalks were encrusted by concentric Fe‐oxyhydroxide laminae and silica casings. Element maps produced by energy dispersive X‐ray spectroscopy (EDS) in TEM showed variations in the content of Si, P, and S within filaments, demonstrating that successive hydrothermal fluid pulses mediate early diagenetic alteration and modify the chemical composition and surface features of stalks through Fe‐oxyhydroxide mineralization. The carbon content of the stalks was generally indistinguishable from background levels, suggesting that organic compounds were either scarce initially or lost due to percolating hydrothermal fluids. Dendrites and thicker abiotic filaments from a nearby chimney were composed of nanometer‐sized microcrystalline iron particles and silica and showed Fe growth bands indicative of inorganic precipitation. Our study suggests that the identification of fossil stalks and sheaths of Fe‐oxidizing bacteria in hydrothermal paleoenvironments may not rely on the detection of organic carbon and demonstrates that abiogenic filaments differ from stalks and sheaths of Fe‐oxidizing bacteria with respect to width distribution, ultrastructure, and textural context.

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Section: Introductionmentioning

confidence: 99%

On the biogenicity of Fe‐oxyhydroxide filaments in silicified low‐temperature hydrothermal deposits: Implications for the identification of Fe‐oxidizing bacteria in the rock record

et al. 2019

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“…However, if the process of condensation is fast, the developed internal stresses may result in fracture of silica material near the surface, i.e., lead to cracks seen on spongy shapes and chipping out the particle's material. As was shown [20,53], the strain due to silica condensation can reach 70%. This alone can explain the observed spongy cracks.…”

Section: Resultsmentioning

confidence: 67%

“…This leads to the development of differential mechanical stresses near the particle surface due to the different rates of condensation of silicic acid inside and near the particle surface [47,52]. When this process is slow, the mechanical stresses may relax resulting in the overall complex morphologies of silica particles as was described in [20,53].…”

Section: Resultsmentioning

confidence: 98%

“…The synthesis procedure is a modified self-assembly previously reported in [20,47]. The following molar ratio of the reactants 100H 2 O:8HCl:0.11CTACl:0.13TEOS: 9.5HCONH 2 was used.…”

Section: Synthesismentioning

confidence: 99%

“…A nontrivial micron shapes can also define specific photonic properties [18,19]. It was previously found that cationic surfactants form and mineralize in the presence of metastable semi/metal oxides to a well-ordered nanostructure that can extend up to a few hundred microns [1,20]. These shapes can extend up to a few hundred microns and form mesoporous thin films, [21][22][23][24][25] spheres, [26][27][28], curved shaped solids, [29,30] tubes, [31,32], rods and fibers, [33][34][35] membranes, [36] and monoliths [37] has been reported.…”

Section: Introductionmentioning

confidence: 99%

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Self-assembly of multi-hierarchically structured spongy mesoporous silica particles and mechanism of their formation

Kalaparthi

Palantavida

Mordvinova

et al. 2017

Journal of Colloid and Interface Science

Self Cite

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Here we report on self-assembly of novel multi-hierarchically structured meso(nano)porous colloidal silica particles which have cylindrical pores of 4-6nm, overall size of ∼10μm and "cracks" of 50-200nm. These cracks make particles look like micro-sponges. The particles were prepared through a modified templated sol-gel self-assembly process. The mechanism of assembly of these particles is investigated. Using encapsulated fluorescent dye, we demonstrate that the spongy particles are advantageous to facilitate dye diffusion out of particles. This multi-hierarchically geometry of particles can be used to improve the particle design for multiple applications to control drug release, rate of catalysis, filtration, utilization of particles as hosts for functional molecules (e.g., enzymes), etc.

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Pharmaceutical Nanosystems: Manufacture, Characterization, and Safety

Chowdhury

2010

Pharmaceutical Sciences Encyclopedia

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Nano‐pharmaceutical systems generally imply products that may in their own right or in combination with another moiety bring about therapeutic benefit. Nanosystems can be classified in a number of ways, for example, according to their elemental composition, according to size, structure, and function, or according to a structure‐function relationship. This article focuses on the manufacture, characterization, and safety of pharmaceutical nanosystems.

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3D design of self-assembled nanoporous colloids

Cited by 18 publications

References 45 publications

On the biogenicity of Fe‐oxyhydroxide filaments in silicified low‐temperature hydrothermal deposits: Implications for the identification of Fe‐oxidizing bacteria in the rock record

On the biogenicity of Fe‐oxyhydroxide filaments in silicified low‐temperature hydrothermal deposits: Implications for the identification of Fe‐oxidizing bacteria in the rock record

Self-assembly of multi-hierarchically structured spongy mesoporous silica particles and mechanism of their formation

Pharmaceutical Nanosystems: Manufacture, Characterization, and Safety

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