A systematic study of the adsorption of a methylthio on different sites of silver nanoparticles of 13, 55, 147, and 309 atoms with icosahedral symmetry as well as on the (111) surface is performed using density functional theory. Ab initio molecular dynamics were used to obtain the adsorption energies, atomic positions, and electronic properties of the lowest-energy configurations. Different adsorption sites and orientations of the molecule were tested. The electronic density of states also shows a size dependence, in which a transition from discrete to more band-like structure is found. Adsorption of a second methylthio is also studied. It was observed that final structures, adsorption energies, and electronic density of states strongly depended on the nanoparticle size and thus on the atomic coordination number, where bridge configurations had the lowest total energy and the highest adsorption energy for all sizes except Ag 13 .
Honeycomb plasmonic lattices are characterized by a 2-particle unit cell. The difference between the intrasublattice and intersublattice coupling is distinctive of non-Bravais lattices. Although the two particles are identical the two types of coupling may be different.
A method to manipulate the multipolar plasmonic response of a nanostructure in the quasi-static limit is introduced. The theoretical method puts on the same footing geometry, dielectric properties, and incident field and proceeds in two steps: it optimizes the geometry of the nanostructure to maximize the intensity of the scattering crosssection spectrum. This is done by calculating the coupling strengths of the different modes of the system to the external field, which the method naturally provides. Then, it exploits the symmetry of the incident electromagnetic field to enhance or suppress specific orders, which, in turn, tunes the field enhancement. We demonstrate the method by using a plasmonic dimer of nanospheres.
We present a numerical calculation of the heat transport in a Bragg mirror configuration made of materials that do not obey Fourier’s law of heat conduction. The Bragg mirror is made of materials that are described by the Cattaneo-Vernotte equation. By analyzing the Cattaneo-Vernotte equation’s solutions, we define the thermal wave surface impedance to design highly reflective thermal Bragg mirrors. Even for mirrors with a few layers, very high reflectance is achieved (>90%). The Bragg mirror configuration is also a system that makes evident the wave-like nature of the solution of the Cattaneo-Vernotte equation by showing frequency pass-bands that are absent if the materials obey the usual Fourier’s law.
We
analyze the time-harmonic heating of a non-Fourier medium by
spherical nanoparticles via the photothermal effect. The nanoparticle
is embedded in a medium with thermal properties similar to those reported
for organic tissue that does not obey Fourier’s law of heat
conduction but rather the Cattaneo–Vernotte equation. By assuming
the nanoparticle is illuminated with an intensity-modulated laser,
we show that the temperature profile outside the nanoparticle oscillates
and, at specific separations, can have a temperature 16% lower than
predicted using Fourier’s law of heat conduction.
We had previously synthetized a macromolecular prodrug consisting of oxidized Alginate and dopamine (AlgOx-Da) for a potential application in Parkinson disease (PD). Methods: In the present work, we aimed at gaining an insight into the interactions occurring between AlgOx-Da and SH-SY5Y neuronal cell lines in view of further studies oriented towards PD treatment. With the scope of ascertaining changes in the external and internal structure of the cells, multiple methodologies were adopted. Firstly, fluorescently labeled AlgOx-Da conjugate was synthetized in the presence of fluorescein 5(6)-isothiocyanate (FITC), providing FITC-AlgOx-Da, which did not alter SH-SY5Y cell viability according to the sulforhodamine B test. Furthermore, the uptake of FITC-AlgOx-Da by the SH-SY5Y cells was studied using scanning near-field optical microscopy and assessments of cell morphology over time were carried out using atomic force microscopy. Results: Notably, the AFM methodology confirmed that no relevant damage occurred to the neuronal cells. Regarding the effects of DA on the intracellular reactive oxygen species (ROS) production, AlgOx-Da reduced them in comparison to free DA, while AlgOx did almost not influence ROS production. Conclusions: these findings seem promising for designing in vivo studies aiming at administering Oxidized Alginate Dopamine Conjugate for PD treatment.
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