Energy scaling law for nanostructured materials

The equilibrium binding energy is an important factor in the design of materials and devices. However, it presents great computational challenges for materials built up from nanostructures. Here we investigate the binding-energy scaling law from first-principles calculations. We show that the equilibrium binding energy per atom between identical nanostructures can scale up or down with nanostructure size. From the energy scaling law, we predict finite large-size limits of binding energy per atom. We find that there are two competing factors in the determination of the binding energy: Nonadditivities of van der Waals coefficients and center-to-center distance between nanostructures. To uncode the detail, the nonadditivity of the static multipole polarizability is investigated. We find that the higher-order multipole polarizability displays ultra-strong intrinsic nonadditivity, no matter if the dipole polarizability is additive or not.Comment: 13 pages, 4 figures, 7 table

Co-exposure of the organic nanomaterial fullerene C60 with benzo[a]pyrene in Danio rerio (zebrafish) hepatocytes: Evidence of toxicological interactions

Compounds from the nanotechnology industry, such as carbon-based nanomaterials, are strong candidates to contaminate aquatic environments because their production and disposal have exponentially grown in a few years. Previous evidence shows that fullerene C60, a carbon nanomaterial, can facilitate the intake of metals or PAHs both in vivo and in vitro, potentially amplifying the deleterious effects of these toxicants in organisms. The present work aimed to investigate the effects of fullerene C60 in a Danio rerio (zebrafish) hepatocyte cell lineage exposed to benzo[a]pyrene (BaP) in terms of cell viability, oxidative stress parameters and BaP intracellular accumulation. Additionally, a computational docking was performed to investigate the interaction of the fullerene C60 molecule with the detoxificatory and antioxidant enzyme πGST. Fullerene C60 provoked a significant (p 0.05) alter the enzyme activity when added to GST purified extracts from the zebrafish hepatocyte cells. These results show that fullerene C60 can increase the intake of BaP into the cells, decreasing cell viability and impairing the detoxificatory response by phase II enzymes, such as GST, and this latter effect should be occurring at the transcriptional level.Fil: Ribas Ferreira, Josencler L.. Universidade Federal do Rio Grande do Sul; BrasilFil: Lonné, María Noelia. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: França, Thiago A.. Universidade Federal do Rio Grande do Sul; BrasilFil: Maximilla, Naiana R.. Universidade Federal do Rio Grande do Sul; BrasilFil: Lugokenski, Thiago H.. Universidade Federal de Santa Maria. Departamento de Química; BrasilFil: Costa, Patrícia G.. Universidade Federal do Rio Grande do Sul; BrasilFil: Fillmann, Gilberto. Universidade Federal do Rio Grande do Sul; BrasilFil: Soares, Félix A.. Universidade Federal de Santa Maria. Departamento de Química; BrasilFil: de la Torre, Fernando Roman. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Luján. Departamento de Ciencias Básicas; ArgentinaFil: Monserrat, José María. Universidade Federal do Rio Grande do Sul; Brasil. Instituto Nacional de Ciência e Tecnologia de Nanomateriais de Carbono; Brasi

Modeling charge transport in C60-based self-assembled monolayers for applications in field-effect transistors

We have investigated the conductance properties of C60-containing self-assembled monolayers (SAMs), which are used in organic field-effect transistors, employing a combination of molecular-dynamics simulations, semiempirical electronic structure calculations and Landauer transport theory. The results reveal the close relation between the transport characteristics and the structural and electronic properties of the SAM. Furthermore, both local pathways of charge transport in the SAMs and the influence of structural fluctuations are analyzed.Comment: 10 figure

Nanomaterials for Healthcare Biosensing Applications

In recent years, an increasing number of nanomaterials have been explored for their applications in biomedical diagnostics, making their applications in healthcare biosensing a rapidly evolving field. Nanomaterials introduce versatility to the sensing platforms and may even allow mobility between different detection mechanisms. The prospect of a combination of different nanomaterials allows an exploitation of their synergistic additive and novel properties for sensor development. This paper covers more than 290 research works since 2015, elaborating the diverse roles played by various nanomaterials in the biosensing field. Hence, we provide a comprehensive review of the healthcare sensing applications of nanomaterials, covering carbon allotrope-based, inorganic, and organic nanomaterials. These sensing systems are able to detect a wide variety of clinically relevant molecules, like nucleic acids, viruses, bacteria, cancer antigens, pharmaceuticals and narcotic drugs, toxins, contaminants, as well as entire cells in various sensing media, ranging from buffers to more complex environments such as urine, blood or sputum. Thus, the latest advancements reviewed in this paper hold tremendous potential for the application of nanomaterials in the early screening of diseases and point-of-care testing

Raman scattering in C_{60} and C_{48}N_{12} aza-fullerene: First-principles study

We carry out large scale {\sl ab initio} calculations of Raman scattering activities and Raman-active frequencies (RAFs) in ${\rm C}_{48}{\rm N}_{12}$ aza-fullerene. The results are compared with those of ${\rm C}_{60}$. Twenty-nine non-degenerate polarized and 29 doubly-degenerate unpolarized RAFs are predicted for ${\rm C}_{48}{\rm N}_{12}$. The RAF of the strongest Raman signal in the low- and high-frequency regions and the lowest and highest RAFs for ${\rm C}_{48}{\rm N}_{12}$ are almost the same as those of ${\rm C}_{60}$. The study of ${\rm C}_{60}$ reveals the importance of electron correlations and the choice of basis sets in the {\sl ab initio} calculations. Our best calculated results for ${\rm C}_{60}$ with the B3LYP hybrid density functional theory are in excellent agreement with experiment and demonstrate the desirable efficiency and accuracy of this theory for obtaining quantitative information on the vibrational properties of these molecules.Comment: submitted to Phys.Rev.

Magnetically operated nanorelay based on two single-walled carbon nanotubes filled with endofullerenes Fe@C20

Structural and energy characteristics of the smallest magnetic endofullerene Fe@C20 have been calculated using the density functional theory approach. The ground state of Fe@C20 is found to be a septet state, and the magnetic moment of Fe@C20 is estimated to be 8 Bohr magnetons. Characteristics of an (8,8) carbon nanotube with a single Fe@C20 inside are studied in the framework of the semiempirical approach. The scheme of a magnetic nanorelay based on cantilevered nanotubes filled with magnetic endofullerenes is elaborated. The proposed nanorelay is turned on as a result of bending of nanotubes by a magnetic force. Operational characteristics of such a nanorelay based on (8,8) and (21,21) nanotubes fully filled with Fe@C20 are estimated and compared to the ones of a nanorelay made of a (21,21) nanotube fully filled with experimentally observed (Ho3N)@C80 with the magnetic moment of 21 Bohr magnetons. Room temperature operation of (21,21) nanotube based nanorelays is shown.Comment: 18 pages, 9 figure