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Overview of the Manifold VNPs Used in Nanotechnology
Published in Nicole F Steinmetz, Marianne Manchester, Viral Nanoparticles, 2019
Nicole F Steinmetz, Marianne Manchester
Examples of each group are shown in Fig. 2.1. Many viruses currently in use for nanotechnology have icosahedral symmetry (see Section 2.1.2.1). Approximately 20 different viruses are currently being studied and exploited as VNPs for nanotechnology 13 of which are non-enveloped with icosahedral symmetry. Four are non-enveloped rod-shaped, and three are enveloped. Some reasons for the lowered incidence of enveloped VNPs in the nanotech literature are as follows: (i) production of non-enveloped VNPs are more feasible compared with generating enveloped VNPs; (ii) non-enveloped VNPs are in general more stable; and (iii) use of non-enveloped non-mammalian VNPs can be regarded as safe from a human health perspective compared to working with potentially infectious enveloped mammalian VNPs.
Magnetic Structures of 2D and 3D Nanoparticles
Published in Jean-Claude Levy, Magnetic Structures of 2D and 3D Nanoparticles, 2018
Here we want to focus first on cluster magical properties. These structural properties do not depend strongly on the nature of the interaction when leading to dense structures since they mainly depend on geometry. Starting with very small clusters, the most stable structures are the more symmetric ones. That is a good introduction to magical clusters and so magical numbers. So for four atoms the regular tetrahedron is stable [119]. For seven atoms the most stable configuration is a regular planar pentagon surrounded by two atoms on the top and the bottom [119]. This unusual fivefold symmetry is found also in the icosahedron of 13 atoms [35] where the icosahedral symmetry group Yh contains 120 symmetry operations, more than the octahedral group Oh, the largest crystalline symmetry group which contains 48 symmetry operations. Then from that, cluster sizes 7 or 13 up to the largest sizes which favor crystalline symmetry, icosahedral symmetry is expected to occur as a rich local symmetry. According to this remark, a large cluster structure with this icosahedral symmetry was built from a variational minimization of energy [105]. An interesting feature of this cluster shown is in Fig. 1.4: this icosahedral symmetry is present everywhere in the cluster at the expense of defects such as holes or voids of different sizes [105].
Onion-Like Inorganic Fullerenes from a Polyhedral Perspective
Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2020
Ch. Chang, A. B. C. Patzer, D. Sülzle, H. Bauer
A ‘fullerene’ is a polyhedron made from exactly 12 pentagons and any number of hexagons. Furthermore, they have rotational icosahedral symmetry and exactly three faces meet at each vertex. They are not necessarily achiral, therefore they might come in pairs of enantiomorphs. Icosa-hedral symmetry ensures that the pentagons are all always regular (all edges equal), although many of the hexagons may not be (semi-regular edges being alternatingly equal). Typically, but not infallibly, all of the vertices lie on a common sphere. The fullerene with only pentagonal faces is the Platonic dodecahedron and that with 20 hexagonal faces and 60 vertices is an Archimedean solid, the truncated icosahedron.
HIV-1 immature virion network and icosahedral capsids self-assembly with patchy spheres
Published in Molecular Physics, 2023
Brian Ignacio Machorro-Martínez, Anthony B. Gutiérrez, Jacqueline Quintana, Julio C. Armas-Pérez, Paola Mendoza-Espinosa, Gustavo A. Chapela
The next few references use different scaffolds to obtain closed structures with icosahedral symmetry with great success. Zandi et al. [48] used a LJ potential to perform MC simulations of two different kinds of capsomers, pentamers and hexamers, by varying well depth of each species. Simulations are carried out on the surface of a sphere where the molecules are allowed to change from pentamer to hexamer and vise versa. They obtain structures with T = 1, 3, 4 and 7, among others. Chen et al. [49] performing MC simulations studied a rigid cone-shaped model with 4 to 17 overlapped spheres, with various angles. These particles, interacting with LJ and square well potentials, are initially located on the surface of a hull sphere and allow to move on it. They report the formation of clusters of icosahedral symmetry corresponding to T = 1, 3, 7 and 13 virus structures. Pak et al. [50] used a coarse grain model with 161 beads per Gag, interacting through a long-range 12-6 LJ potential with a modified soft core are used to produce an open hexagonal lattice with the aid of a cell membrane and RNA. Various types of MD simulations with the LAMMPS [51] package are performed. They report the self-assembly of a hexagonal open network, formed on the cell membrane used as a scaffold. Guo et al. [52] Performed reaction-diffusion simulations on a coarse-grained model containing 6 sites over the surface of a sphere to assembly a hexagonal HIV open network.
Comparison of enzyme immunoassay, latex agglutination and polyacrylamide gel electrophoresis for diagnosis of rotavirus in children
Published in Egyptian Journal of Basic and Applied Sciences, 2020
Safaa Mohamad El-Ageery, Rabab Ali, Noha Tharwat Abou El-Khier, Shirien Amin Rakha, Mayada Sabry Zeid
Rotavirus is the main etiological pathogen causing diarrhea in children aged under 5 years. It is concerned in many episodes of gastroenteritis worldwide, and yearly thousands of deaths, mostly in developing countries [1] . Rotavirus is one of the Reoviridae family, and it was initially recognized by electron microscopy (EM) [2]. The virus has non-enveloped icosahedral symmetry associated with three protein layers. The viral genome is composed of 11 double-stranded RNA segments encoding six structural proteins VP1-4, VP6 and VP7 and six nonstructural proteins NSP1-6 [3]. Among these structural proteins, the VP6 contains the antigenic determinants, classifying the virus into seven serogroups of A to G, with group A being the most frequent cause of childhood diarrhea [4] .
Metal nanoclusters: from fundamental aspects to electronic properties and optical applications
Published in Science and Technology of Advanced Materials, 2023
Rodophe Antoine, Michel Broyer, Philippe Dugourd
These new experimental beam techniques, associated with mass spectrometry and laser spectroscopy, paved the way to the study of electronic, optical, magnetic, catalytic properties of isolated clusters as a function of sizes. Two main results were obtained, first a general trend for an evolution as a function of radius R of the cluster, and secondly specific effects observed for well-defined number of atoms (each atom counts). However, if molecular beams are well-fitted for the detailed study, in gas phase, of clusters, the produced clusters are very fragile and available in very small quantities. They are also very difficult to deposit on surfaces or in matrices and then to characterize at solid state level, for example by X-ray diffraction. In that sense, the discovery of the fullerene C60 was instructive: in 1985, Kroto, Smalley et al. observed an intense peak in mass spectra corresponding to C60 [15]. They showed by varying beam conditions that this molecule was really stable. They proposed the now well-known and elegant cage structure of icosahedral symmetry (Buckminsterfullerene). But they did not succeed to synthesize a sufficient amount of C60 by molecular beam and mass spectrometry techniques. Finally in 1991, Krätschmer et al. [16] synthesized a solid fullerite made by the crystal arrangement of C60, by condensing graphite vapor from an electric arc in an inert gas. The obtained powder was then purified by solvents, and the structure proposed by Smalley et al. was confirmed by X-ray diffraction. But the example of C60 (and of a few other carbon fullerenes) was unique and could not be generalized to metal clusters such as Au8 or others, in particular due to their high reactivity.