Special Issue "Stimuli-Responsive Hydrogels and Microgels"

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Biomaterials".

Deadline for manuscript submissions: 31 July 2021.

Special Issue Editor

Prof. Dr. Silvia Corezzi
E-Mail Website
Guest Editor
Department of Physics and Geology, University of Perugia, 06123 Perugia, Italy
Interests: dynamics of disordered materials (liquids, glasses, polymers); supercooled liquids and glasses; chemical and physical vitrification; gelation; microgels; thermoresponsive polymers; aggregation kinetics of soft materials; hydration properties of biomolecules; molecular dynamics simulation

Special Issue Information

Dear Colleagues,

Hydrogels are hydrophilic cross-linked polymer networks immersed in water or an aqueous medium. Owing to their highly hydrophilic nature they swell and retain considerable amounts of water, to an extent controlled by the cross-link density, the polymer/water compatibility, and the presence of electrical charges. Their nature of hydrated and “soft” materials imparts excellent biocompatibility, which makes them valuable in many biomedical applications in the fields of drug delivery, tissue engineering, implants, cell culture, and more. Beyond macroscopic gels, advances in synthetic methods have enabled the preparation of gel particles of colloidal size (microgels), whose behavior when immersed in a liquid combines useful aspects of conventional macrogels with useful properties of colloidal suspensions, introducing tunable features and new functionalities. One of the biggest driving forces for research on these materials (both macro- and microgels) is that they can be made responsive, meaning they can swell and deswell, or self-assemble and dissociate, in response to external stimuli like pH, temperature, ionic strength, mechanical forces, presence of specific chemicals, and magnetic and electric fields. Such “smart” materials are nowadays employed for a myriad of applications.

Although stimuli-responsive gels have been studied for decades, they are continuing to inspire researchers to find new formulations that better meet the challenges associated with specific applications in medicine and various industries, as well as to understand their physical properties and related behavior. Regarding microgels, they have become a highly active topic of research not only for applied studies, where they introduced new concepts for smart drug release and rheological control, but also for fundamental studies, where they constitute an ideal “soft” colloidal system useful for gaining new insights into biomimetic behaviors and phenomena like glass formation.

This Special Issue is open to contributions on all aspects of recent progress in the attractive field of stimuli-responsive hydrogels and microgels, including synthesis, characterization, physical properties, and dynamical behavior and applications that exploit their features. Original research papers, brief communication reports, as well as review articles, whether experimental or theoretical, are all welcome.

It is my pleasure to invite you to contribute to this Special Issue.

Dr. Silvia Corezzi
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Materials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Hydrogels
  • Microgels
  • Soft materials
  • Stimuli-responsive polymers
  • Materials physics
  • Colloid science
  • Gelation
  • Swelling
  • Volume phase transition
  • Drug delivery
  • pH-responsive
  • Thermoresponsive
  • Chemically-responsive

Published Papers (2 papers)

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Research

Open AccessArticle
Effect of the Cross-Linking Density on the Swelling and Rheological Behavior of Ester-Bridged β-Cyclodextrin Nanosponges
Materials 2021, 14(3), 478; https://doi.org/10.3390/ma14030478 - 20 Jan 2021
Cited by 1 | Viewed by 450
Abstract
The cross-linking density influences the physicochemical properties of cyclodextrin-based nanosponges (CD-NSs). Although the effect of the cross-linker type and content on the NSs performance has been investigated, a detailed study of the cross-linking density has never been performed. In this contribution, nine ester-bridged [...] Read more.
The cross-linking density influences the physicochemical properties of cyclodextrin-based nanosponges (CD-NSs). Although the effect of the cross-linker type and content on the NSs performance has been investigated, a detailed study of the cross-linking density has never been performed. In this contribution, nine ester-bridged NSs based on β-cyclodextrin (β-CD) and different quantities of pyromellitic dianhydride (PMDA), used as a cross-linking agent in stoichiometric proportions of 2, 3, 4, 5, 6, 7, 8, 9, and 10 moles of PMDA for each mole of CD, were synthesized and characterized in terms of swelling and rheological properties. The results, from the swelling experiments, exploiting Flory–Rehner theory, and rheology, strongly showed a cross-linker content-dependent behavior. The study of cross-linking density allowed to shed light on the efficiency of the synthesis reaction methods. Overall, our study demonstrates that by varying the amount of cross-linking agent, the cross-linked structure of the NSs matrix can be controlled effectively. As PMDA βCD-NSs have emerged over the years as a highly versatile class of materials with potential applications in various fields, this study represents the first step towards a full understanding of the correlation between their structure and properties, which is a key requirement to effectively tune their synthesis reaction in view of any specific future application or industrial scale-up. Full article
(This article belongs to the Special Issue Stimuli-Responsive Hydrogels and Microgels)
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Open AccessArticle
TEMPO-Nanocellulose/Ca2+ Hydrogels: Ibuprofen Drug Diffusion and In Vitro Cytocompatibility
Materials 2020, 13(1), 183; https://doi.org/10.3390/ma13010183 - 02 Jan 2020
Cited by 9 | Viewed by 1119
Abstract
Stable hydrogels with tunable rheological properties were prepared by adding Ca2+ ions to aqueous dispersions of 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO)-oxidized and ultra-sonicated cellulose nanofibers (TOUS-CNFs). The gelation occurred by interaction among polyvalent cations and the carboxylic units introduced on TOUS-CNFs during the oxidation [...] Read more.
Stable hydrogels with tunable rheological properties were prepared by adding Ca2+ ions to aqueous dispersions of 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO)-oxidized and ultra-sonicated cellulose nanofibers (TOUS-CNFs). The gelation occurred by interaction among polyvalent cations and the carboxylic units introduced on TOUS-CNFs during the oxidation process. Both dynamic viscosity values and pseudoplastic rheological behaviour increased by increasing the Ca2+ concentration, confirming the cross-linking action of the bivalent cation. The hydrogels were proved to be suitable controlled release systems by measuring the diffusion coefficient of a drug model (ibuprofen, IB) by high-resolution magic angle spinning (HR-MAS) nuclear magnetic resonance (NMR) spectroscopy. IB was used both as free molecule and as a 1:1 pre-formed complex with β-cyclodextrin (IB/β-CD), showing in this latter case a lower diffusion coefficient. Finally, the cytocompatibility of the TOUS-CNFs/Ca2+ hydrogels was demonstrated in vitro by indirect and direct tests conducted on a L929 murine fibroblast cell line, achieving a percentage number of viable cells after 7 days higher than 70%. Full article
(This article belongs to the Special Issue Stimuli-Responsive Hydrogels and Microgels)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Tentative Title: Cells encapsulation and drug diffusion in TEMPO-nanocellulose hydrogels
Authors: Andrea Fiorati; Nicola Contessi Negrini; Elena Baschenis; Monica Ferro; Lina Altomare;Alberto Giacometti Schieroni; Daniele Piovani; Raniero Mendich; Franca Castiglione; Andrea Mele Carlo Punta; Lucio Melone
Emails: ;; ; ; ; ; ; ;

Tentative Title: Lipid-based hydrogels: a sustainable and targeted drug delivery system
Authors: Caterina Branca*, Valeria Conti Nibali, Valentino Romano, Ulderico Wanderlingh and Giovanna D'Angelo.
Emails: ; ; ; ;

Tentative Title: Determination of crosslinking density and monomer composition of pyromellitic β-cyclodextrin-based nanosponges: a multiple-method approach
Authors: Gjylije Hoti, Fabrizio Caldera, Silvia Lucia Appleton, Alberto Rubin Pedrazzo, Yousef Khazaei Monfared and Francesco Trotta
Emails: (G.H.); (F.C.); (S.L.A.); (A.R.P.); (Y.K.M.); (F.T.)
Affiliation: Department of Inorganic, Physical and Materials Chemistry, NIS Centre of Excellence and INSTM, University of Torino, Via P. Giuria 7, 10125 Torino, Italy

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