Physicochemical Properties and the Gelation Process of Supramolecular Hydrogels: A Review

Abstract

Supramolecular polysaccharide-based hydrogels have attracted considerable research interest recently due to their high structural functionality, low toxicity, and potential applications in foods, cosmetics, catalysis, drug delivery, tissue engineering and the environment. Modulation of the stability of hydrogels is of paramount importance, especially in the case of stimuli-responsive systems. This review will update the recent progress related to the rational design of supramolecular hydrogels with the objective of understanding the gelation process and improving their physical gelation properties for tailored applications. Emphasis will be given to supramolecular host-guest systems with reference to conventional gels in describing general aspects of gel formation. A brief account of the structural characterization of various supramolecular hydrogels is also provided in order to gain a better understanding of the design of such materials relevant to the nature of the intermolecular interactions, thermodynamic properties of the gelation process, and the critical concentration values of the precursors and the solvent components. This mini-review contributes to greater knowledge of the rational design of supramolecular hydrogels with tailored applications in diverse fields ranging from the environment to biomedicine.

Natural biopolymer‐based hydrogels for use in food and agriculture

“…Hydrogels were first reported in the 1960s by Wichterle and Lim and they are defined as three‐dimensional, hydrophilic, polymer networks swollen with water . Hydrogels have numerous applications in medicine, agriculture, cosmetics, and the food industry . They are also used in personal care products, filters for water purification, separation membranes, etc …”

Properties of Water Bound in Hydrogels

“…The HG hydrophilicity is owed to a number of water-solubilizing groups: –OH, –COOH, –COO − , >C=O, >CHNH 2 , –CONH 2 , –SO 3 H, etc., in the polymer network. Water plays an important role in hydrogels by supporting their integrity, solubility and diffusion of substances, which is important for biomedical, biotechnological and environmental applications [1,2,3,4,5,6,7]. The water content and therefore the HG volume can change due to swelling/shrinking influenced by external conditions, such as temperature, pH, ionic strength, solvent nature, etc.…”

Advances in the Application of Supramolecular Hydrogels for Stem Cell Delivery and Cartilage Tissue Engineering

“…Recently, supramolecular hydrogels have received much attention as novel reversible cross-linking scaffold materials. They have inherent progressive features such as natural dynamic tissue simulation, injectability, self-healing, and adjustable mechanical behavior, providing great advantages in three-dimensional cell culture and tissue regeneration application (Du et al, 2015;Karoyo and Wilson, 2017;Shigemitsu and Hamachi, 2017;Hu et al, 2018). These properties are based on the dynamic nature of their composition, as well as the supramolecular bonding motifs from non-covalent supramolecular interactions such as hydrogen bonding, hydrophobic interactions, host-guest complexation, electrostatic interaction and metal-ligand coordination to crosslink (McCune et al, 2020).…”