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Miao Z, Qin L, Zhou Z, Zhou M, Fu H, Zhang L, Zhou J. Zwitterion-Modified Nanogel Responding to Temperature and Ionic Strength: A Dissipative Particle Dynamics Simulation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:13678-13687. [PMID: 37713407 DOI: 10.1021/acs.langmuir.3c01875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/17/2023]
Abstract
The self-assembly and stimuli-responsive properties of nanogel poly(n-isopropylacrylamide) (p(NIPAm)) and zwitterion-modified nanogel poly(n-isopropylacrylamide-co-sulfobetainemethacrylate) (p(NIPAm-co-SBMA)) were explored by dissipative particle dynamics simulations. Simulation results reveal that for both types of nanogel, it is beneficial to form spherical nanogels at polymer concentrations of 5-10%. When the chain length (L) elongates from 10 to 40, the sizes of the nanogels enlarge. As for the p(NIPAm) nanogel, it shows thermoresponsiveness; when it switches to the hydrophilic state, the nanogel swells, and vice versa. The zwitterion-modified nanogel p(NIPAm-co-SBMA) possesses thermoresponsiveness and ionic strength responsiveness concurrently. At 293 K, both hydrophilic p(NIPAm) and superhydrophilic polysulfobetaine methacrylate (pSBMA) could appear on the outer surface of the nanogel; however, at 318 K, superhydrophilic pSBMA is on the outer surface to cover the hydrophobic p(NIPAm) core. As the temperature rises, the nanogel shrinks and remains antifouling all through. The salt-responsive property can be reflected by the nanogel size; the volumes of the nanogels in saline systems are larger than those in salt-free systems as the ionic condition inhibits the shrinkage of the zwitterionic pSBMA. This work exhibits the temperature-responsive and salt-responsive behavior of zwitterion-modified-pNIPAm nanogels at the molecular level and provides guidance in antifouling nanogel design.
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Affiliation(s)
- Zhaohong Miao
- School of Chemistry and Chemical Engineering, Guangdong Provincial Key Lab for Green Chemical Product Technology, South China University of Technology, Guangzhou 510640, P. R. China
| | - Lanlan Qin
- School of Chemistry and Chemical Engineering, Guangdong Provincial Key Lab for Green Chemical Product Technology, South China University of Technology, Guangzhou 510640, P. R. China
| | - Zhaoxi Zhou
- School of Chemistry and Chemical Engineering, Guangdong Provincial Key Lab for Green Chemical Product Technology, South China University of Technology, Guangzhou 510640, P. R. China
| | - Meng Zhou
- School of Chemistry and Chemical Engineering, Guangdong Provincial Key Lab for Green Chemical Product Technology, South China University of Technology, Guangzhou 510640, P. R. China
| | - Heqing Fu
- School of Chemistry and Chemical Engineering, Guangdong Provincial Key Lab for Green Chemical Product Technology, South China University of Technology, Guangzhou 510640, P. R. China
| | - Lizhi Zhang
- School of Chemistry and Chemical Engineering, Guangdong Provincial Key Lab for Green Chemical Product Technology, South China University of Technology, Guangzhou 510640, P. R. China
| | - Jian Zhou
- School of Chemistry and Chemical Engineering, Guangdong Provincial Key Lab for Green Chemical Product Technology, South China University of Technology, Guangzhou 510640, P. R. China
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Rudov AA, Portnov IV, Bogdanova AR, Potemkin II. Structure of swollen hollow polyelectrolyte nanogels with inhomogeneous cross-link distribution. J Colloid Interface Sci 2023; 640:1015-1028. [PMID: 36921382 DOI: 10.1016/j.jcis.2023.02.090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 01/31/2023] [Accepted: 02/16/2023] [Indexed: 02/23/2023]
Abstract
HYPOTHESIS Recently, it has become possible to synthesize hollow polyelectrolyte nano- and microgels. The shell permeability can be controlled by external stimuli, while the cavity can serve as a storage place for guest molecules. However, there is a lack of a detailed understanding at the molecular level regarding the role of the network topology, inhomogeneities of the distribution of cross-links, and the impact of the electrostatics on the structural response of hollow microgel to external stimuli. To bridge these gaps, molecular dynamics (MD) of computer simulations are used. EXPERIMENTS Here, we propose a fresh methodology to create realistic hollow microgel particles in silico. The technique involves a gradual change in the average local length of subchains depending on the distance to the center of mass of the microgel particles resulting in the microgels with a non-uniform distribution of cross-linking species. In particular, a series of microgels with (i) a highly cross-linked inner part of the shell and gradually decreased cross-linker concentration towards the periphery, (ii) microgels with loosely cross-linked inner and outer parts, as well as (iii) microgels with a more-or-less homogeneous structure, have been created and validated. Counterions and salt ions are taken into account explicitly, and electrostatic interactions are described by the Coulomb potential. FINDINGS Our studies reveal a strong dependence of the microgel swelling response on the network topology. Simple redistribution of cross-links plays a significant role in the structure of the microgels, including cavity size, microgel size, fuzziness, and extension of the inner and outer parts of the microgels. Our results indicate the possibilities of qualitative justification of the structure of the hollow microgels in the experiments by measuring the relative change in the size of the sacrificial core to the size of the cavity and by estimation of a power law function, [Formula: see text] , of the hydrodynamic radius of the hollow microgels as a function of added salt concentration.
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Affiliation(s)
- Andrey A Rudov
- Physics Department, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Ivan V Portnov
- Physics Department, Lomonosov Moscow State University, Moscow, Russian Federation; A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Moscow 119991, Russian Federation
| | - Alisa R Bogdanova
- Physics Department, Lomonosov Moscow State University, Moscow, Russian Federation
| | - Igor I Potemkin
- Physics Department, Lomonosov Moscow State University, Moscow, Russian Federation.
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Zhou H, Xie W, Guo A, Chen B, Hu S, Zheng M, Yu H, Tian H, Li L. Temperature sensitive nanogels for real-time imaging during transcatheter arterial embolization. Des Monomers Polym 2023; 26:31-44. [PMID: 36684709 PMCID: PMC9858417 DOI: 10.1080/15685551.2022.2164445] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Several vascular embolization materials are commonly used in clinical practice, however, having application defects of varying degrees, such as poor intraoperative imaging and easy recanalization of embolized blood vessels, they are challenging for application during Transcatheter arterial embolization (TAE). Thus, an intraoperative visible vascular embolization material with good embolization effect and biocompatibility can improve transcatheter arterial embolization clinical efficacy to some extent. Our study aimed to synthesize a novel vascular embolization material that can achieve complete embolization of arterial trunks and peripheral vessels, namely poly (N-isopropyl acrylamide)-co-acrylic acid nanogel (NIPAM-co-AA). Iohexol 200 mg/mL was co-assembled with 7 wt% NIPAM-co-AA nanogel to create an intelligent thermosensitive radiopaque nanogel (INCA), which achieves a good intraoperative imaging effect and is convenient for transcatheter arterial bolus injection due to its good fluidity and temperature-sensitive sol-gel phase transition. The normal rabbit kidney embolism model further confirmed that INCA could effectively use Digital subtraction angiography (DSA) to achieve intraoperative imaging, and real-time monitoring of the embolization process could avoid mis-embolization and leakage. Meanwhile, in a 42-day study, INCA demonstrated an excellent embolization effect on the right renal artery of New Zealand white rabbits, with no vascular recanalization and ischemic necrosis and calcification remaining. As a result, this radiopaque thermosensitive nanogel has the potential to be an intelligent thermosensitive medical vascular embolization material, providing dual benefits in TAE intraoperative imaging and long-term postoperative embolization while effectively addressing the shortcomings and challenges of commonly used clinical vascular embolization agents.
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Affiliation(s)
- Hongfu Zhou
- School of Biomedical Engineering and Imaging, Xianning Medical College, Hubei University of Science and Technology, Xianning, PR China
| | - Wenjing Xie
- School of Pharmacy, Xianning Medical College, Hubei University of Science and Technology, Xianning, PR China
| | - Anran Guo
- School of Pharmacy, Xianning Medical College, Hubei University of Science and Technology, Xianning, PR China
| | - Bin Chen
- Department of Radiology, Xianning Central Hospital, the First Affiliated Hospital of Hubei University of Science and Technology, Xianning, P.R. China
| | - Sanming Hu
- School of Biomedical Engineering and Imaging, Xianning Medical College, Hubei University of Science and Technology, Xianning, PR China
| | - Min Zheng
- School of Biomedical Engineering and Imaging, Xianning Medical College, Hubei University of Science and Technology, Xianning, PR China
| | - Houqiang Yu
- Department of Mathematics and Statistics, Hubei University of Science and Technology, Xianning, PR China
| | - Hongan Tian
- Department of Radiology, Xianning Central Hospital, the First Affiliated Hospital of Hubei University of Science and Technology, Xianning, P.R. China,CONTACT Hongan Tian Department of Radiology, Xianning Central Hospital, the First Affiliated Hospital of Hubei University of Science and Technology, Xianning, PR China
| | - Ling Li
- School of Biomedical Engineering and Imaging, Xianning Medical College, Hubei University of Science and Technology, Xianning, PR China,Ling Li School of Biomedical Engineering and Imaging, Xianning Medical College, Hubei University of Science and Technology, Xianning, PR China
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Hofzumahaus C, Strauch C, Schneider S. Monte Carlo simulations of weak polyampholyte microgels: pH-dependence of conformation and ionization. SOFT MATTER 2021; 17:6029-6043. [PMID: 34076026 DOI: 10.1039/d1sm00433f] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We performed Metropolis Monte Carlo simulations to investigate the impact of varying acid and base dissociation constants on the pH-dependent ionization and conformation of weak polyampholyte microgels under salt-free conditions and under explicit consideration of the chemical ionization equilibria of the acidic and basic groups and their electrostatic interaction. Irrespective of their relative acid and base dissociation constant, all of the microgels undergo a pH-dependent charge reversal from positive to negative with a neutral charge at the isoelectric point. This charge reversal is accompanied by a U-shaped swelling transition of the microgels with a minimum of their size at the point of charge neutrality. The width of the U-shaped swelling transition, however, is found to depend on the chosen relative acid and base dissociation constants through which the extent of the favorable electrostatic intramolecular interaction of the ionized acidic and basic groups is altered. The pH-dependent swelling transition of the microgels is found to become broader, the stronger the intramolecular electrostatic interaction of the oppositely charged ionized species is. In addition, the intramolecular charge compensation of the acidic and basic groups of the microgels allows their counterions to abandon the microgel and the associated gain in translational entropy further amplifies the broadening of the pH-dependent swelling transition. The analysis of the radial ionization profiles of the acidic and basic groups of the differently composed microgels reveals a variety of radial ionization patterns with a dependence on the overall charge of the microgels.
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Affiliation(s)
- C Hofzumahaus
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, D-52056 Aachen, Germany.
| | - C Strauch
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, D-52056 Aachen, Germany.
| | - S Schneider
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, D-52056 Aachen, Germany.
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Pérez-Chávez NA, Albesa AG, Longo GS. Thermodynamic Theory of Multiresponsive Microgel Swelling. Macromolecules 2021. [DOI: 10.1021/acs.macromol.0c02885] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Néstor A. Pérez-Chávez
- Instituto de Investigaciones Fisicoquímicas, Teóricas y Aplicadas (INIFTA), UNLP-CONICET, La Plata 1900, Argentina
| | - Alberto G. Albesa
- Instituto de Investigaciones Fisicoquímicas, Teóricas y Aplicadas (INIFTA), UNLP-CONICET, La Plata 1900, Argentina
| | - Gabriel S. Longo
- Instituto de Investigaciones Fisicoquímicas, Teóricas y Aplicadas (INIFTA), UNLP-CONICET, La Plata 1900, Argentina
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Casalini T. Not only in silico drug discovery: Molecular modeling towards in silico drug delivery formulations. J Control Release 2021; 332:390-417. [PMID: 33675875 DOI: 10.1016/j.jconrel.2021.03.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 02/28/2021] [Accepted: 03/02/2021] [Indexed: 12/18/2022]
Abstract
The use of methods at molecular scale for the discovery of new potential active ligands, as well as previously unknown binding sites for target proteins, is now an established reality. Literature offers many successful stories of active compounds developed starting from insights obtained in silico and approved by Food and Drug Administration (FDA). One of the most famous examples is raltegravir, a HIV integrase inhibitor, which was developed after the discovery of a previously unknown transient binding area thanks to molecular dynamics simulations. Molecular simulations have the potential to also improve the design and engineering of drug delivery devices, which are still largely based on fundamental conservation equations. Although they can highlight the dominant release mechanism and quantitatively link the release rate to design parameters (size, drug loading, et cetera), their spatial resolution does not allow to fully capture how phenomena at molecular scale influence system behavior. In this scenario, the "computational microscope" offered by simulations at atomic scale can shed light on the impact of molecular interactions on crucial parameters such as release rate and the response of the drug delivery device to external stimuli, providing insights that are difficult or impossible to obtain experimentally. Moreover, the new paradigm brought by nanomedicine further underlined the importance of such computational microscope to study the interactions between nanoparticles and biological components with an unprecedented level of detail. Such knowledge is a fundamental pillar to perform device engineering and to achieve efficient and safe formulations. After a brief theoretical background, this review aims at discussing the potential of molecular simulations for the rational design of drug delivery systems.
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Affiliation(s)
- Tommaso Casalini
- Department of Chemistry and Applied Bioscience, Institute for Chemical and Bioengineering, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, Zürich 8093, Switzerland; Polymer Engineering Laboratory, Institute for Mechanical Engineering and Materials Technology, University of Applied Sciences and Arts of Southern Switzerland (SUPSI), Via la Santa 1, Lugano 6962, Switzerland.
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7
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Pérez-Mas L, Martín-Molina A, Quesada-Pérez M. Coarse-grained Monte Carlo simulations of nanogel-polyelectrolyte complexes: electrostatic effects. SOFT MATTER 2020; 16:3022-3028. [PMID: 32129421 DOI: 10.1039/d0sm00173b] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Coarse-grained Monte-Carlo simulations of nanogel-polyelectrolyte complexes have been carried out. The results presented here capture two phenomena reported in experiments with real complexes: (i) the reduction in size after absorbing just a few chains and (ii) the charge inversion detected through electrophoretic mobility data. Our simulations reveal that charge inversion occurs if the polyelectrolyte charge is large enough. In addition, the distribution of chains inside the nanogel strongly depends on whether charge inversion takes place. It should also be stressed that the chain topology has little influence on most of the properties studied here.
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Affiliation(s)
- Luis Pérez-Mas
- Departamento de Física, Escuela Politécnica Superior de Linares, Universidad de Jaén, 23700, Linares, Jaén, Spain.
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Silkina EF, Molotilin TY, Maduar SR, Vinogradova OI. Ionic equilibria and swelling of soft permeable particles in electrolyte solutions. SOFT MATTER 2020; 16:929-938. [PMID: 31815270 DOI: 10.1039/c9sm01602c] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We discuss osmotic equilibria between soft permeable particles, of radius R and volume charge density ρ, and bulk electrolyte solutions of inverse Debye length κ. Existing models are based on a simplified assumption of weakly charged particles. Here we derive analytical approximations for the distribution of potentials, ions and pressure in a system, suitable even when ρ is quite large. Our theory is valid not only for "large" particles (κR≫ 1), where the central part is fully screened, but also for weakly screened "small" particles (κR≤ 1) with overlapping inner diffuse layers. Besides, we present novel coarse-grained simulations to validate the analysis and illustrate the variation of potential/ion profiles in response to changes in κR and ρ. Our simulations also allow us to argue that swelling of both "large" and "small" particles is uniform, although their inner non-uniform local pressure profiles are essentially and qualitatively different. These results are directly relevant for a variety of permeable charged objects, from polymer micro- and nanogels to more rigid porous colloids.
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Affiliation(s)
- Elena F Silkina
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31 Leninsky Prospect, 119071 Moscow, Russia.
| | - Taras Y Molotilin
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31 Leninsky Prospect, 119071 Moscow, Russia.
| | - Salim R Maduar
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31 Leninsky Prospect, 119071 Moscow, Russia.
| | - Olga I Vinogradova
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31 Leninsky Prospect, 119071 Moscow, Russia. and Department of Physics, Lomonosov Moscow State University, 119991 Moscow, Russia and DWI - Leibniz Institute for Interactive Materials, Forckenbeckstr. 50, 52056 Aachen, Germany
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9
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Maroto-Centeno JA, Quesada-Pérez M. Coarse-grained simulations of diffusion controlled release of drugs from neutral nanogels: Effect of excluded volume interactions. J Chem Phys 2020; 152:024107. [DOI: 10.1063/1.5133900] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Affiliation(s)
- José Alberto Maroto-Centeno
- Departamento de Física, Escuela Politécnica Superior de Linares, Universidad de Jaén, 23700 Linares, Jaén, Spain
| | - Manuel Quesada-Pérez
- Departamento de Física, Escuela Politécnica Superior de Linares, Universidad de Jaén, 23700 Linares, Jaén, Spain
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10
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Pérez-Mas L, Martín-Molina A, Jain RK, Quesada-Pérez M. Effect of dispersion forces on the behavior of thermosensitive nanogels: A coarse-grained simulation study. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.111101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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11
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Casalini T, Perale G. From Microscale to Macroscale: Nine Orders of Magnitude for a Comprehensive Modeling of Hydrogels for Controlled Drug Delivery. Gels 2019; 5:E28. [PMID: 31096685 PMCID: PMC6631542 DOI: 10.3390/gels5020028] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 04/14/2019] [Accepted: 05/06/2019] [Indexed: 12/21/2022] Open
Abstract
Because of their inherent biocompatibility and tailorable network design, hydrogels meet an increasing interest as biomaterials for the fabrication of controlled drug delivery devices. In this regard, mathematical modeling can highlight release mechanisms and governing phenomena, thus gaining a key role as complementary tool for experimental activity. Starting from the seminal contribution given by Flory-Rehner equation back in 1943 for the determination of matrix structural properties, over more than 70 years, hydrogel modeling has not only taken advantage of new theories and the increasing computational power, but also of the methods offered by computational chemistry, which provide details at the fundamental molecular level. Simulation techniques such as molecular dynamics act as a "computational microscope" and allow for obtaining a new and deeper understanding of the specific interactions between the solute and the polymer, opening new exciting possibilities for an in silico network design at the molecular scale. Moreover, system modeling constitutes an essential step within the "safety by design" paradigm that is becoming one of the new regulatory standard requirements also in the field-controlled release devices. This review aims at providing a summary of the most frequently used modeling approaches (molecular dynamics, coarse-grained models, Brownian dynamics, dissipative particle dynamics, Monte Carlo simulations, and mass conservation equations), which are here classified according to the characteristic length scale. The outcomes and the opportunities of each approach are compared and discussed with selected examples from literature.
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Affiliation(s)
- Tommaso Casalini
- Biomaterials Laboratory, Institute for Mechanical Engineering and Materials Technology, SUPSI-University of Applied Sciences and Arts of Southern Switzerland, Via Cantonale 2C, Galleria 2, 6928 Manno, Switzerland.
- Institute for Chemical and Bioengineering, Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, 8093 Zurich, Switzerland.
| | - Giuseppe Perale
- Biomaterials Laboratory, Institute for Mechanical Engineering and Materials Technology, SUPSI-University of Applied Sciences and Arts of Southern Switzerland, Via Cantonale 2C, Galleria 2, 6928 Manno, Switzerland.
- Department of Surgical Sciences and Integrated Diagnostics, Orthopaedic Clinic-IRCCS Ospedale Policlinico San Martino, Faculty of Biomedical Sciences, University of Genova, Largo R. Benzi 10, 16132 Genova, Italy.
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Martín-Molina A, Quesada-Pérez M. A review of coarse-grained simulations of nanogel and microgel particles. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.02.030] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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13
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Ramos-Tejada MDM, Quesada-Pérez M. Coarse-Grained Simulations of Nanogel Composites: Electrostatic and Steric Effects. Macromolecules 2019. [DOI: 10.1021/acs.macromol.8b02657] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- María del Mar Ramos-Tejada
- Departamento de Física, Escuela Politécnica Superior de Linares, Campus Científico-Tecnológico, 23700 Linares, Jaén, Spain
| | - Manuel Quesada-Pérez
- Departamento de Física, Escuela Politécnica Superior de Linares, Campus Científico-Tecnológico, 23700 Linares, Jaén, Spain
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Landsgesell J, Nová L, Rud O, Uhlík F, Sean D, Hebbeker P, Holm C, Košovan P. Simulations of ionization equilibria in weak polyelectrolyte solutions and gels. SOFT MATTER 2019; 15:1155-1185. [PMID: 30706070 DOI: 10.1039/c8sm02085j] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
This article recapitulates the state of the art regarding simulations of ionization equilibria of weak polyelectrolyte solutions and gels. We start out by reviewing the essential thermodynamics of ionization and show how the weak polyelectrolyte ionization differs from the ionization of simple weak acids and bases. Next, we describe simulation methods for ionization reactions, focusing on two methods: the constant-pH ensemble and the reaction ensemble. After discussing the advantages and limitations of both methods, we review the existing simulation literature. We discuss coarse-grained simulations of weak polyelectrolytes with respect to ionization equilibria, conformational properties, and the effects of salt, both in good and poor solvent conditions. This is followed by a discussion of branched star-like weak polyelectrolytes and weak polyelectrolyte gels. At the end we touch upon the interactions of weak polyelectrolytes with other polymers, surfaces, nanoparticles and proteins. Although proteins are an important class of weak polyelectrolytes, we explicitly exclude simulations of protein ionization equilibria, unless they involve protein-polyelectrolyte interactions. Finally, we try to identify gaps and open problems in the existing simulation literature, and propose challenges for future development.
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Affiliation(s)
- Jonas Landsgesell
- Institute for Computational Physics, University of Stuttgart, Allmandring 3, Stuttgart, Germany.
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15
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Hofzumahaus C, Hebbeker P, Schneider S. Monte Carlo simulations of weak polyelectrolyte microgels: pH-dependence of conformation and ionization. SOFT MATTER 2018; 14:4087-4100. [PMID: 29569677 DOI: 10.1039/c7sm02528a] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
In this study, we investigated the effect of pH on single weak acidic polyelectrolyte microgels under salt-free conditions with (i) varying microgel concentration, (ii) varying content of acidic groups and (iii) different crosslinking densities using Monte Carlo simulations under explicit consideration of the protonation/deprotonation reaction. We assessed both global properties, such as the degree of ionization, the degree of swelling and the counterion distribution, and local properties such as the radial network ionization profile and the ionization along the polymer chains as a function of pH. We found a pronounced suppression of the pH-dependent ionization of the microgels, as compared to the ideal titration behavior and a shift of the titration curve to a higher pH originating in the proximity of acidic groups in the microgel. In contrast to macroscopic gels, counterions can leave the microgel, resulting in an effective charge of the network, which hinders the ionization. A decreasing microgel concentration leads to an increased effective charge of the microgel and a more pronounced shift of the titration curve. The number of acidic groups showed only a weak effect on the ionization behavior of the microgels. For two different microgels with different crosslinking densities, similar scaling of the gel size was observed. A distinct transition from an uncharged and unswollen to a highly charged and expanded polymer network was observed for all investigated microgels. The degree of swelling mainly depends on the degree of ionization. An inhomogeneous distribution of the degree of ionization along the radial profile of the microgel was found.
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Affiliation(s)
- C Hofzumahaus
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, D-52056 Aachen, Germany.
| | - P Hebbeker
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, D-52056 Aachen, Germany.
| | - S Schneider
- Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, D-52056 Aachen, Germany.
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Quesada-Pérez M, Maroto-Centeno JA, Martín-Molina A, Moncho-Jordá A. Direct determination of forces between charged nanogels through coarse-grained simulations. Phys Rev E 2018; 97:042608. [PMID: 29758622 DOI: 10.1103/physreve.97.042608] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Indexed: 06/08/2023]
Abstract
In this work, electrostatic forces between charged nanogels are explored through coarse-grained simulations. These simulations allow us to explicitly consider the complex topology of these nanoparticles and provide reliable force values to examine highly charged nanogels of a few tens of nanometers. The results obtained here clearly reveal that the electrostatic interactions between these nanoparticles are not governed by the net charge of the nanogel, which includes not only the charge of the polymer network but also the charge of ions inside. Thus two theoretical procedures for predicting effective charges are also proposed and investigated. Both provide predictions of the same order and capture the behavior found for the effective charge obtained from simulations.
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Affiliation(s)
- Manuel Quesada-Pérez
- Departamento de Física, Escuela Politécnica Superior de Linares, Universidad de Jaén, 23700, Linares, Jaén, Spain
| | - José Alberto Maroto-Centeno
- Departamento de Física, Escuela Politécnica Superior de Linares, Universidad de Jaén, 23700, Linares, Jaén, Spain
| | - Alberto Martín-Molina
- Departamento de Física Aplicada, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
- Instituto Carlos I de Física Teórica y Computacional, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
| | - Arturo Moncho-Jordá
- Departamento de Física Aplicada, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
- Instituto Carlos I de Física Teórica y Computacional, Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
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17
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Sean D, Landsgesell J, Holm C. Computer Simulations of Static and Dynamical Properties of Weak Polyelectrolyte Nanogels in Salty Solutions. Gels 2017; 4:E2. [PMID: 30674778 PMCID: PMC6318681 DOI: 10.3390/gels4010002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Revised: 12/21/2017] [Accepted: 12/23/2017] [Indexed: 12/02/2022] Open
Abstract
We investigate the chemical equilibria of weak polyelectrolyte nanogels with reaction ensemble Monte Carlo simulations. With this method, the chemical identity of the nanogel monomers can change between neutral or charged following the acid-base equilibrium reaction HA ⇌ A- + H⁺. We investigate the effect of changing the chemical equilibria by modifying the dissociation constant K a . These simulations allow for the extraction of static properties like swelling equilibria and the way in which charge-both monomer and ionic-is distributed inside the nanogel. Our findings reveal that, depending on the value of K a , added salt can either increase or decrease the gel size. Using the calculated mean-charge configurations of the nanogel from the reaction ensemble simulation as a quenched input to coupled lattice-Boltzmann molecular dynamics simulations, we investigate dynamical nanogel properties such as the electrophoretic mobility μ and the diffusion coefficient D.
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Affiliation(s)
- David Sean
- Institute for computational physics, University of Stuttgart, Allmandring 3, 70569 Stuttgart, Germany.
| | - Jonas Landsgesell
- Institute for computational physics, University of Stuttgart, Allmandring 3, 70569 Stuttgart, Germany.
| | - Christian Holm
- Institute for computational physics, University of Stuttgart, Allmandring 3, 70569 Stuttgart, Germany.
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18
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Orakdogen N, Sanay B. Tailoring the physico-chemical properties and elasticity of poly(hydroxy-functional methacrylate)-based cationically charged gel beads: Combined hydrophobicity and mechanical durability through frozen droplets. Eur Polym J 2017. [DOI: 10.1016/j.eurpolymj.2017.09.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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19
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Abstract
The morphology of core-shell microgels under different swelling conditions and as a function of the core-shell thickness ratio is systematically characterized by mesoscale hydrodynamic simulations. With increasing hydrophobic interaction of the shell polymers, we observe drastic morphological changes from a core-shell structure to an inverted microgel, where the core is turned to the outside, or a microgel with a patchy surface of core polymers directly exposed to the environment. We establish a phase diagram of the various morphologies. Moreover, we characterize the polymer and microgel conformations. For sufficiently thick shells, the changes of the shell size upon increasing hydrophobic interactions are well described by the Flory-Rehner theory. Additionally, this theory provides a critical line in the phase diagram separating core-shell structures from the distinct two other phases. The appearing new phases provide a novel route to nano- and microscale functionalized materials.
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Affiliation(s)
- Ali Ghavami
- Theoretical Soft Matter and
Biophysics, Institute for Advanced Simulation, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Roland G. Winkler
- Theoretical Soft Matter and
Biophysics, Institute for Advanced Simulation, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
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20
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Polymer Conformations in Ionic Microgels in the Presence of Salt: Theoretical and Mesoscale Simulation Results. Polymers (Basel) 2017; 9:polym9010015. [PMID: 30970691 PMCID: PMC6431964 DOI: 10.3390/polym9010015] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 12/22/2016] [Accepted: 12/29/2016] [Indexed: 11/17/2022] Open
Abstract
We investigate the conformational properties of polymers in ionic microgels in the presence of salt ions by molecular dynamics simulations and analytical theory. A microgel particle consists of coarse-grained linear polymers, which are tetra-functionally crosslinked. Counterions and salt ions are taken into account explicitly, and charge-charge interactions are described by the Coulomb potential. By varying the charge interaction strength and salt concentration, we characterize the swelling of the polyelectrolytes and the charge distribution. In particular, we determine the amount of trapped mobile charges inside the microgel and the Debye screening length. Moreover, we analyze the polymer extension theoretically in terms of the tension blob model taking into account counterions and salt ions implicitly by the Debye–Hückel model. Our studies reveal a strong dependence of the amount of ions absorbed in the interior of the microgel on the electrostatic interaction strength, which is related to the degree of the gel swelling. This implies a dependence of the inverse Debye screening length κ on the ion concentration; we find a power-law increase of κ with the Coulomb interaction strength with the exponent 3/5 for a salt-free microgel and an exponent 1/2 for moderate salt concentrations. Additionally, the radial dependence of polymer conformations and ion distributions is addressed.
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21
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Dimde M, Neumann F, Reisbeck F, Ehrmann S, Cuellar-Camacho JL, Steinhilber D, Ma N, Haag R. Defined pH-sensitive nanogels as gene delivery platform for siRNA mediated in vitro gene silencing. Biomater Sci 2017; 5:2328-2336. [DOI: 10.1039/c7bm00729a] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An advanced cationic carrier system which combines high transfection efficiency with low cytotoxicity and a control over the release of the encapsulated genetic material by the reduction of the multivalent architecture upon pH triggered degradation was developed.
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Affiliation(s)
- Mathias Dimde
- Institute of Chemistry and Biochemistry
- Freie Universität Berlin
- Berlin 14195
- Germany
| | - Falko Neumann
- Institute of Chemistry and Biochemistry
- Freie Universität Berlin
- Berlin 14195
- Germany
| | - Felix Reisbeck
- Institute of Chemistry and Biochemistry
- Freie Universität Berlin
- Berlin 14195
- Germany
| | - Svenja Ehrmann
- Institute of Chemistry and Biochemistry
- Freie Universität Berlin
- Berlin 14195
- Germany
- Forschungszentrum für Elektronenmikroskopie
| | | | - Dirk Steinhilber
- Institute of Chemistry and Biochemistry
- Freie Universität Berlin
- Berlin 14195
- Germany
| | - Nan Ma
- Institute of Chemistry and Biochemistry
- Freie Universität Berlin
- Berlin 14195
- Germany
- Institute of Biomaterial Science and Berlin-Brandenburg Center for Regenerative Therapies Helmholtz-Zentrum Geesthacht
| | - Rainer Haag
- Institute of Chemistry and Biochemistry
- Freie Universität Berlin
- Berlin 14195
- Germany
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22
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Adroher-Benítez I, Martín-Molina A, Ahualli S, Quesada-Pérez M, Odriozola G, Moncho-Jordá A. Competition between excluded-volume and electrostatic interactions for nanogel swelling: effects of the counterion valence and nanogel charge. Phys Chem Chem Phys 2017; 19:6838-6848. [DOI: 10.1039/c6cp08683g] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The equilibrium distribution of monovalent and trivalent ions within a thermo-responsive charged nanogel is investigated using Monte Carlo simulations and Ornstein–Zernike equations.
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Affiliation(s)
- Irene Adroher-Benítez
- Departamento de Física Aplicada
- Facultad de Ciencias
- Universidad de Granada
- 18001 Granada
- Spain
| | - Alberto Martín-Molina
- Departamento de Física Aplicada
- Facultad de Ciencias
- Universidad de Granada
- 18001 Granada
- Spain
| | - Silvia Ahualli
- Departamento de Física Aplicada
- Facultad de Ciencias
- Universidad de Granada
- 18001 Granada
- Spain
| | - Manuel Quesada-Pérez
- Departamento de Física
- Escuela Politécnica Superior de Linares
- Universidad de Jaeén
- 23700 Linares
- Spain
| | - Gerardo Odriozola
- Área de Física de Procesos Irreversibles
- División de Ciencias Básicas e Ingeniería
- Universidad Autónoma Metropolitana
- 02200 México CD de México
- Mexico
| | - Arturo Moncho-Jordá
- Departamento de Física Aplicada
- Facultad de Ciencias
- Universidad de Granada
- 18001 Granada
- Spain
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23
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Maldonado-Valderrama J, Del Castillo-Santaella T, Adroher-Benítez I, Moncho-Jordá A, Martín-Molina A. Thermoresponsive microgels at the air-water interface: the impact of the swelling state on interfacial conformation. SOFT MATTER 2016; 13:230-238. [PMID: 27427242 DOI: 10.1039/c6sm01375a] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Poly(N-vinylcaprolactam) (PVCL) is a new temperature-responsive type of polymer microgel with improved biocompatibility as compared to more commonly used poly(N-isopropylacrylamide) (PNIPAM). Both polymers swell at low temperatures and collapse at high ones, showing a volume phase transition temperature (VPTT) around the physiological temperature. Exploring the interfacial characteristics of thermoresponsive microgels is important due to their potential application in emulsion based systems with tailored stabilities and controlled degradation profiles. In this work, we study the properties of charged PVCL particles at the air-water interface by a combination of adsorption, dilatational rheology and Langmuir monolayers. Although PVCL particles adsorb spontaneously at the air-water interface in both, swollen and collapsed conformations, the interfacial properties show significant differences depending on the swelling state. In particular, the total amount of adsorbed microgels and the rigidity of the monolayer increase as the temperature increases above the VPTT, which is connected to the more compact morphology of the microgels in this regime. Dilatational rheology data show the formation of a very loose adsorbed layer with low cohesivity. In addition, collapsed microgels yield a continuous increase of the surface pressure, whereas swollen microgels show a phase transition at intermediate compressions caused by the deformation of the loose external polymer shell of the particles. We also provide a qualitative interpretation for the surface pressure behavior in terms of microgel-microgel effective pair potentials, and correlate our experimental findings to recent rescaling models that take into account the importance of the internal polymer degrees of freedom in the rearrangement of the conformation of the microgel particles at the interface.
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Affiliation(s)
- J Maldonado-Valderrama
- Departamento de Física Aplicada, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
| | - T Del Castillo-Santaella
- Departamento de Física Aplicada, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
| | - I Adroher-Benítez
- Departamento de Física Aplicada, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
| | - A Moncho-Jordá
- Departamento de Física Aplicada and Instituto Carlos I de Física Teórica y Computacional, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain.
| | - A Martín-Molina
- Departamento de Física Aplicada, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
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24
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25
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Rizzi LG, Levin Y. Influence of network topology on the swelling of polyelectrolyte nanogels. J Chem Phys 2016; 144:114903. [DOI: 10.1063/1.4943981] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- L. G. Rizzi
- Departamento de Física, Universidade Federal de Viçosa, 36570-900 Viçosa, MG, Brazil
- Instituto de Física, Universidade Federal do Rio Grande do Sul, CP 15051, 91501-970 Porto Alegre, RS, Brazil
| | - Y. Levin
- Instituto de Física, Universidade Federal do Rio Grande do Sul, CP 15051, 91501-970 Porto Alegre, RS, Brazil
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26
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González-Mozuelos P. Effective electrostatic interactions among charged thermo-responsive microgels immersed in a simple electrolyte. J Chem Phys 2016; 144:054902. [DOI: 10.1063/1.4941324] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- P. González-Mozuelos
- Departamento de Física, Cinvestav del I. P. N., Av. Instituto Politécnico Nacional 2508, Mexico, Distrito Federal, C. P. 07360, Mexico
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27
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Universal conformational properties of polymers in ionic nanogels. Sci Rep 2016; 6:19836. [PMID: 26830457 PMCID: PMC4735297 DOI: 10.1038/srep19836] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 12/18/2015] [Indexed: 11/23/2022] Open
Abstract
Polyelectrolyte gels are known to undergo significant conformational changes in response to external stimuli such as pH, temperature, or the dielectric constant. Specifically, an increase of the degree of ionization associated with an increasing number of counterions leads to swelling of the network. For a macroscopically large gel, which is electrostatically neutral in its interior, swelling is no longer governed by electrostatic interactions, but rather by the osmotic pressure of counterions. However, this electrostatic neutrality is typically violated for nanogels, because counterions are free to leave a gel particle. Although nanogel-swelling exhibits similar features as swelling of micro- and macrogels, another mechanism has to be relevant. Here, we use molecular dynamics simulations and scaling theory to unravel the structural properties of nanogels upon changing the electrostatic interactions. We demonstrate that the swelling of nanogels is governed by screened electrostatic interactions without a relevant contribution by the counterion osmotic pressure.
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28
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Moncho-Jordá A, Dzubiella J. Swelling of ionic microgel particles in the presence of excluded-volume interactions: a density functional approach. Phys Chem Chem Phys 2016; 18:5372-85. [DOI: 10.1039/c5cp07794j] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
In this work a new density functional theory framework is developed to predict the salt-concentration dependent swelling state of charged microgels and the local concentration of monovalent ions inside and outside the microgel.
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Affiliation(s)
- Arturo Moncho-Jordá
- Departamento de Física Aplicada
- Facultad de Ciencias
- Universidad de Granada
- 18071 Granada
- Spain
| | - Joachim Dzubiella
- Institut für Weiche Materie und Funktionale Materialien
- Helmholtz-Zentrum Berlin
- 14109 Berlin
- Germany
- Institut für Physik, Humboldt-Universität zu Berlin
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29
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Košovan P, Richter T, Holm C. Modeling of Polyelectrolyte Gels in Equilibrium with Salt Solutions. Macromolecules 2015. [DOI: 10.1021/acs.macromol.5b01428] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Peter Košovan
- Department
of Physical and Macromolecular Chemistry, Faculty of Science, Charles University in Prague, Hlavova 8 128 00 Praha 2, Czech Republic
| | - Tobias Richter
- Institute
for Computational Physics, University Stuttgart, Allmandring 3 70569 Stuttgart, Germany
| | - Christian Holm
- Institute
for Computational Physics, University Stuttgart, Allmandring 3 70569 Stuttgart, Germany
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30
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Adroher-Benítez I, Ahualli S, Martín-Molina A, Quesada-Pérez M, Moncho-Jordá A. Role of Steric Interactions on the Ionic Permeation Inside Charged Microgels: Theory and Simulations. Macromolecules 2015. [DOI: 10.1021/acs.macromol.5b00356] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- Irene Adroher-Benítez
- Departamento
de Física Aplicada, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
| | - Silvia Ahualli
- Departamento
de Física, Escuela Politécnica Superior de Linares, Universidad de Jaén, 23700 Linares, Jaén, Spain
| | - Alberto Martín-Molina
- Departamento
de Física Aplicada, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
| | - Manuel Quesada-Pérez
- Departamento
de Física, Escuela Politécnica Superior de Linares, Universidad de Jaén, 23700 Linares, Jaén, Spain
| | - Arturo Moncho-Jordá
- Departamento
de Física Aplicada, Facultad de Ciencias, Universidad de Granada, Campus Fuentenueva S/N, 18071 Granada, Spain
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