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Multiscale analysis and reconstruction of chromatin and nuclear organization

poster: Ornstein-Zernike formalism to model polymeric particles for biomedical applications

speaker: Irene Adroher-Benítez (Scuola Internazionale Superiore di Studi Avanzati (SISSA))

abstract: Microgels are colloidal particles formed by crosslinked polymer chains. They can swell or shrink as a response to a wide variety of stimuli such as temperature, pH, solute concentration or solvent nature. This feature is an advantage for a wide number of biomedical applications, such as drug transport and delivery systems. With this aim, theoretical studies have been developed to study the permeation of ions and solutes inside microgels particles. One of the most relevant results of recent works is that microgel-ion interaction is not exclusively controlled by the electrostatic forces, but also a steric interaction must be taken into account. In this work we focus on the effect that this microgel-ion steric repulsive interaction has on the permeation of counterions inside heterogeneous microgel particles. For this purpose, we use a novel hybrid method that blends Ornstein-Zernike integral equations and Monte Carlo simulations. Two important properties have been obtained using both methods, namely the microgel effective net charge and the counterion radial distribution functions. On the one hand, the effective net charge strongly depends on the number of counterions that have penetrated inside the microgel particle, and represents an estimate of how efficiently the microgel bare charge has been screened. On the other hand, the calculation of ionic density profiles constitutes a novelty in the sense that we are able to predict not only the net permeation of ions inside the microgel, but also to determine the region where they become preferentially adsorbed. In addition, the effect of counterion valence and nanogel charge on the microgel swelling have been also studied.

References: A. Moncho-Jordá and I. Adroher-Benítez, Soft Matter, 2014, 10, 5810–5823. I. Adroher-Benítez, S. A. Ahualli, A. Martín-Molina, M. Quesada-Pérez and A. Moncho-Jordá, Macromolecules, 2015, 48, 4645–4656. I. Adroher-Benítez, S. A. Ahualli, D. Bastos-González, J. Ramos, J. Forcada and A. Moncho-Jordá, J. Polym. Sci. Part B Polym. Phys., 2016, 54, 2038–2049. I. Adroher-Benítez, A. Martin-Molina, S. A. Ahualli, M. Quesada-Pérez, G. Odriozola and A. Moncho-Jordá, Phys. Chem. Chem. Phys., 2017, 19, 6838–6848.

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