On the Origin of Helical Mesostructures

Yang, Sui; Zhao, Lingzhi; Yu, Chengzhong; Zhou, Xufeng; Tang, Jiawei; Yuan, Pei; Chen, Daoyong; Zhao, Dongyuan

doi:10.1021/ja0619049

Cited by 203 publications

(242 citation statements)

References 27 publications

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“…2 are very similar to the TEM textures of rods formed by mesoporous silica with helical twist [23][24][25][26] . An interesting feature of both systems is that the families of parallel fringes can be bent.…”

Section: Resultssupporting

confidence: 65%

Helical nanofilaments of bent-core liquid crystals with a second twist

et al. 2014

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The B4 phase of bent-core liquid crystals has been shown to be an assembly of twisted layers stacked to form helical nanofilaments. Interestingly, some of them have structural colours that cannot be explained by the nanofilaments alone. Here cryogenic-transmission electron microscopy observations on 40-120 nm films of four bent-core liquid crystal materials show that the filaments are present even in contact with a carbon substrate with only minor deformation, thus representing bulk properties. We find that the subsequent arrays of nanofilaments are not parallel to each other, but rotate by an angle of 35-40°with respect to each other. This doubly twisted structure can explain the structural colour. Being principally different from the packing of molecules in the twist grain boundary and blue phases, the double-twist structure of helical nanofilaments expands the rich word of nanostructured organic materials.

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Section: Resultssupporting

confidence: 65%

Helical nanofilaments of bent-core liquid crystals with a second twist

et al. 2014

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“…The final modification with PVP ( Figure 4B) resulted in further bands at 1607 and 1414 cm −1 corresponding to the pyridine groups [65]. After modification with PVP, the specific BET surface area dropped to 110 m 2 g −1 and the pore volume to 0.1 cm 3 g −1…”

Section: Modified Nanoporous Silica Nanoparticlesmentioning

confidence: 99%

pH-responsive release of chlorhexidine from modified nanoporous silica nanoparticles for dental applications

Fullriede¹,

Abendroth²,

Ehlert

et al. 2016

BioNanoMaterials

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Abstract:A pH-sensitive stimulus-response system for controlled drug release was prepared by modifying nano porous silica nanoparticles (NPSNPs) with poly(4-vinylpyridine) using a bismaleimide as linker. At physiological pH values, the polymer serves as gate keeper blocking the pore openings to prevent the release of cargo molecules. At acidic pH values as they can occur during a bacterial infection, the polymer strains become protonated and straighten up due to electrostatic repulsion. The pores are opened and the cargo is released. The drug chlorhexidine was loaded into the pores because of its excellent antibacterial properties and low tendency to form resistances. The release was performed in PBS and diluted hydrochloric acid, respectively. The results showed a considerably higher release in acidic media compared to neutral solvents. Reversibility of this pHdependent release was established. In vitro tests proved good cytocompatibility of the prepared nanoparticles. Antibacterial activity tests with Streptococcus mutans and Staphylococcus aureus revealed promising perspectives of the release system for biofilm prevention. The developed polymer-modified silica nanoparticles can serve as an efficient controlled drug release system for long-term delivery in biomedical applications, such as in treatment of biofilm-associated infections, and could, for example, be used as medical implant coating or as components in dental composite materials.

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“…An issue of more contemporary interest, though, is the onset of mesoscopic or macroscopic twist in systems for which the self-assembling objects have no underlying handedness. Experimental systems that exhibit such behaviour include helically mesostructured silica nanofibres templated by achiral surfactants [1,2], twisted ribbons of self-assembled tetrahedral cadmium telluride nanoparticles [3], certain fibre-forming dendrimer systems [4] and achiral benzene triesters [5].…”

Section: Introductionmentioning

confidence: 99%

Hierarchical self-assembly of chiral fibres from achiral particles

2012

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We investigate, by molecular dynamics simulation, the behaviour of discotic particles in a solvent of Lennard-Jones spheres. When chromonic disc -sphere interactions are imposed on these systems, three regimes of self-assembly are observed. At moderate temperatures, numerous short threads of discs develop, but these threads remain isolated from one another. Quenching to low temperatures, alternatively, causes all of the discs to floc into a single extended aggregate which typically comprises several distinct sections and contains numerous packing defects. For a narrow temperature range between these regimes, however, defect-free chiral fibres are found to freely self-assemble. The spontaneous chirality of these fibres results from frustration between the hexagonal packing and interdigitation of neighbouring threads, the pitch being set by the particle shape. This demonstration of aggregate-wide chirality emerging owing to packing alone is pertinent to many biological and synthetic hierarchically self-assembling systems.

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On the Origin of Helical Mesostructures

Cited by 203 publications

References 27 publications

Helical nanofilaments of bent-core liquid crystals with a second twist

Helical nanofilaments of bent-core liquid crystals with a second twist

pH-responsive release of chlorhexidine from modified nanoporous silica nanoparticles for dental applications

Hierarchical self-assembly of chiral fibres from achiral particles

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