Electrostatic expansion of polyelectrolyte microgels: Effect of solvent quality and added salt

Lopez, Carlos G.; Lohmeier, Thomas; Wong, John E.; Richtering, Walter

doi:10.1016/j.jcis.2019.07.042

Cited by 26 publications

(24 citation statements)

References 75 publications

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“…For all thermos‐responsive microgels, the presence of salts can greatly affect the LCST and UCST behavior of polymers and thus needs to be considered when designing microgels for medical applications. [ 185,188 ]…”

Section: Clinical Applicationsmentioning

confidence: 99%

“…For all thermos-responsive microgels, the presence of salts can greatly affect the LCST and UCST behavior of polymers and thus needs to be considered when designing microgels for medical applications. [185,188] Light-responsive microgels are of interest for drug delivery, as an external light source can easily be focused on a specific area yielding site specific release. In principle, a variety of different wavelengths could be used and the exposure dose will impact the on-demand release kinetics of the drug.…”

Section: Stimuli-responsive Microgelsmentioning

confidence: 99%

See 1 more Smart Citation

Translating Therapeutic Microgels into Clinical Applications

Kittel

Kuehne

Laporte

2021

Adv Healthcare Materials

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Microgels are crosslinked, water‐swollen networks with a 10 nm to 100 µm diameter and can be modified chemically or biologically to render them biocompatible for advanced clinical applications. Depending on their intended use, microgels require different mechanical and structural properties, which can be engineered on demand by altering the biochemical composition, crosslink density of the polymer network, and the fabrication method. Here, the fundamental aspects of microgel research and development, as well as their specific applications for theranostics and therapy in the clinic, are discussed. A detailed overview of microgel fabrication techniques with regards to their intended clinical application is presented, while focusing on how microgels can be employed as local drug delivery materials, scavengers, and contrast agents. Moreover, microgels can act as scaffolds for tissue engineering and regeneration application. Finally, an overview of microgels is given, which already made it into pre‐clinical and clinical trials, while future challenges and chances are discussed. This review presents an instructive guideline for chemists, material scientists, and researchers in the biomedical field to introduce them to the fundamental physicochemical properties of microgels and guide them from fabrication methods via characterization techniques and functionalization of microgels toward specific applications in the clinic.

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Section: Clinical Applicationsmentioning

confidence: 99%

Section: Stimuli-responsive Microgelsmentioning

confidence: 99%

Translating Therapeutic Microgels into Clinical Applications

Kittel

Kuehne

Laporte

2021

Adv Healthcare Materials

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“…Rička and Tanaka proposed a model by combining the Flory–Rehner model with the Donnan equilibrium to describe the swelling behaviors of polyelectrolyte gels. Many experimental studies have been conducted to validate the Flory–Rehner model with the Donnan equilibrium using polyelectrolyte gels obtained via radical polymerizations, such as polyacrylamide–acrylic acid, poly( N -isopropylacrylamide), , poly( N -isopropylacrylamide- co -acrylic acid), − acrylamide-based, − poly(vinylimidazole), and poly(acrylamide- co -acrylic acid and trimethyl- N -acryloyl-3-aminopropylammonium chloride) gels . The model succeeded in describing the swelling behaviors of polyelectrolyte gels with relatively low charge density.…”

Section: Introductionmentioning

confidence: 99%

Swelling Behaviors of Hydrogels with Alternating Neutral/Highly Charged Sequences

Jian

Katashima

et al. 2020

Macromolecules

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Polyelectrolyte gels comprising fixed ions exhibit swelling behaviors because of external solution conditions. Such behaviors are usually explained by using the Flory–Rehner model that considers the Donnan equilibrium. However, this model assumes a homogeneous distribution for fixed ions; therefore, its applicability to the case of heterogeneous distributions remains unclear. Here, we successfully designed a hydrogel with alternating neutral/highly charged sequences (i.e., tetrapoly(acrylic acid)–poly(ethylene glycol) gel). The Flory–Rehner model with the Donnan equilibrium was found to predict the swelling ratio only below pH 5.6. The distance between two neighboring fixed ions is larger than the Bjerrum length. The swelling behaviors above pH 5.6, where the fixed ions are more closely located than the Bjerrum length, can be explained by considering additionally the counterion condensation in the poly(acrylic acid) units. These results indicate that the ionic interactions within the length scale of the network strand can determine the counterion condensation and that it is vital to estimate accurately the distance between neighboring fixed ions for predicting the swelling behaviors of polyelectrolyte gels.

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“…Moreover, the influence of this relationship in divalent solutions is overshadowed by the cross-linking/charged group interaction effect of divalent ions, evident in the lower mixing pressures than univalent solutions [20]. Although, a relationship between these pressures exists, it has been shown that the interactions between the energies of Flory-Rehner does not play a significant role on swelling magnitude, especially at physiological salt concentrations, and therefore, this study assumes they are independent [19,40].…”

Section: Divalent Vs Univalent Solutionsmentioning

confidence: 89%

The Importance of the Mixing Energy in Ionized Superabsorbent Polymer Swelling Models

2020

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The Flory-Rehner theoretical description of the free energy in a hydrogel swelling model can be broken into two swelling components: the mixing energy and the ionic energy. Conventionally for ionized gels, the ionic energy is characterized as the main contributor to swelling and, therefore, the mixing energy is assumed negligible. However, this assumption is made at the equilibrium state and ignores the dynamics of gel swelling. Here, the influence of the mixing energy on swelling ionized gels is quantified through numerical simulations on sodium polyacrylate using a Mixed Hybrid Finite Element Method. For univalent and divalent solutions, at initial porosities greater than 0.90, the contribution of the mixing energy is negligible. However, at initial porosities less than 0.90, the total swelling pressure is significantly influenced by the mixing energy. Therefore, both ionic and mixing energies are required for the modeling of sodium polyacrylate ionized gel swelling. The numerical model results are in good agreement with the analytical solution as well as experimental swelling tests.

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Electrostatic expansion of polyelectrolyte microgels: Effect of solvent quality and added salt

Cited by 26 publications

References 75 publications

Translating Therapeutic Microgels into Clinical Applications

Translating Therapeutic Microgels into Clinical Applications

Swelling Behaviors of Hydrogels with Alternating Neutral/Highly Charged Sequences

The Importance of the Mixing Energy in Ionized Superabsorbent Polymer Swelling Models

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