Departamento de Física
URI permanente para esta comunidadhttps://hdl.handle.net/10953/33
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Examinando Departamento de Física por Materia "Coarse-grained simulations"
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Ítem Coarse-grained simulations of diffusion controlled release of drugs from neutral nanogels: Effect of excluded volume interactions(AIP Publishing, 2020-01-08) Maroto-Centeno, José-Alberto; Quesada-Pérez, ManuelThe primary goal of this work is to assess the effect of excluded volume interactions on the diffusion controlled release of drug molecules from a spherical, neutral, inert, and cross-linked device of nanometric size. To this end, coarse-grained simulations of the release process were performed. In this way, the inner structure and topology of the polymer network can be explicitly taken into account as well. Our in silico experiments reveal that the boundary condition of constant surface concentration is not appropriate for nanogels. In particular, the predictions based on the perfect sink condition clearly overestimate the fraction of drug released. In addition, these simulations provide values for the release exponent that depends on both the diameter of drug molecules and the number of drug molecules loaded in the matrix, which clearly contrasts with the classical prediction of a constant release exponent. Consequently, the widely used classification of drug release mechanisms based on this kinetic exponent must be extended to include new situations.Ítem Electrostatic hindrance to diffusion in flexible crosslinked gels: A coarse-grained simulation study(AIP Publishing, 2023-07-05) Pérez-Mas, Luis; Ramos-Tejada, María del Mar; Martín-Molina, Alberto; Maroto-Centeno, José ALberto; Quesada-Pérez, ManuelIn this work, we study how electrostatic forces slow down the diffusion of solute in flexible gels through coarse-grained simulations. The model used explicitly considers the movement of solute particles and polyelectrolyte chains. These movements are performed by following a Brownian dynamics algorithm. The effect of three electrostatic parameters characterizing the system (solute charge, polyelectrolyte chain charge, and ionic strength) is analyzed. Our results show that the behavior of both the diffusion coefficient and the anomalous diffusion exponent changes upon the reversal of the electric charge of one of the species. In addition, the diffusion coefficient in flexible gels differs significantly from that in rigid gels if the ionic strength is low enough. However, the effect of chain flexibility on the exponent of anomalous diffusion is significant even at high ionic strength (100 mM). Our simulations also prove that varying the polyelectrolyte chain charge does not have exactly the same effect as varying the solute particle charge.