Highly absorbent hydrogels comprised from interpenetrated networks of alginate–polyurethane for biomedical applications

Abstract

Developing new approaches to improve the swelling, degradation rate, and mechanical properties of alginate hydrogels without compromising their biocompatibility for biomedical applications represents a potential area of research. In this work, the generation of interpenetrated networks (IPN) comprised from alginate–polyurethane in an aqueous medium is proposed to design hydrogels with tailored properties for biomedical applications. Aqueous polyurethane (PU) dispersions can crosslink and interpenetrate alginate chains, forming amide bonds that allow the structure and water absorption capacity of these novel hydrogels to be regulated. In this sense, this work focuses on studying the relation of the PU concentration on the properties of these hydrogels. The results indicate that the crosslinking of the alginate with PU generates IPN hydrogels with a crystalline structure characterized by a homogeneous smooth surface with high capacity to absorb water, tailoring the degradation rate, thermal decomposition, and storage module, not altering the native biocompatibility of alginate, providing character to inhibit the growth of E. coli and increasing also its hemocompatibility. The IPN hydrogels that include 20 wt.% of PU exhibit a reticulation index of 46 ± 4%, swelling capacity of 545 ± 13% at 7 days of incubation at physiological pH, resistance to both acidic and neutral hydrolytic degradation, mechanical improvement of 91 ± 1%, and no cytotoxicity for monocytes and fibroblasts growing for up to 72 h of incubation. These results indicate that these novel hydrogels can be used for successful biomedical applications in the design of wound healing dressings.

Novel Trends in Hydrogel Development for Biomedical Applications: A Review

“…IPN hydrogels may be preferred over polymer blends due to their improved mechanical strength, controlled swelling behavior and efficient drug loading capacity [ 259 , 261 ]. One of the most used biopolymers for IPN formation is CTS, as reported by Dragan et al (2020) [ 262 ], although there have been a large number of research papers based on IPN hydrogels synthesized with different synthetic and natural polymers, such as COL [ 263 , 264 , 265 ], GEL [ 266 , 267 , 268 ], alginate [ 267 , 269 , 270 ], polyurethane [ 264 , 265 , 270 ], PVA [ 268 , 271 ], PEG [ 272 , 273 ] and poly (aspartic acid) [ 274 ], among other candidate polymers. In this sense, there is a wide range of possibilities by means of materials and synthesis procedures that can be used for IPNs formation, owing to their outstanding physicochemical properties.…”

Utilizing Fish Skin of Ikan Belida (Notopterus lopis) as a Source of Collagen: Production and Rheology Properties

“…Changes in the microstructure of hydrogels may affect the migration of encapsulated cells and the ease of swelling allows the spreading of cells in the hydrogels around the wound. A high swelling hydrogel is also desirable due to its capabilities in preventing the breakdown of cell membranes (cell lysis) due to diffusion control of water molecules from the hydrogel-liquid interface [ 50 ]. The swelling properties correlate with the cross section of the SEM images ( Figure 2 ), where the morphological structure varies as alginate content increased.…”

Smart hydrogels based on semi‐interpenetrating polymeric networks of collagen‐polyurethane‐alginate for soft/hard tissue healing, drug delivery devices, and anticancer therapies

“…From a chemical perspective of crosslinking effects, it has been studied that the isocyanate groups of polyurethane react with the primary amino groups of collagen and with the carboxylate groups of alginate, generating urea and amide bonds, respectively. [20] The crosslinking index is important to modulate the mechanical behavior, rate of degradation and biological response of biomaterials in the hydrogel state. [9,20,21] High crosslinking indices (higher than 60%) generate completely interpenetrated polymeric surfaces that lose surface porosity and water absorption capacity, affecting the biological response of the biomaterial.…”

“…[20] The crosslinking index is important to modulate the mechanical behavior, rate of degradation and biological response of biomaterials in the hydrogel state. [9,20,21] High crosslinking indices (higher than 60%) generate completely interpenetrated polymeric surfaces that lose surface porosity and water absorption capacity, affecting the biological response of the biomaterial. [21,22] The hydrogels under study have an optimal crosslinking that could allow to evaluate their applications in multiple biomedical fields such as soft and hard tissue healing, anticancer strategies, and drug delivery devices, allowing to know what concentration of alginate is ideal to achieve this biomedical multifunctionality.…”

“…The modification of the crystalline structure plays an important role for cell-surface interactions, and it could be exploited to regulate the biomedical multifunctionality of smart hydrogels, as it has been observed in amorphous surfaces of hydrogels based on collagen-polyurethane-guar gum, [10,24] or semi-crystalline surfaces of collagen-polyurethane-starch and alginate-polyurethane, [20] where both systems are highly biocompatible with cells specialized in soft tissue repair, however, in the case of the starch system it was observed that the mechanics of the matrix is significantly improved. [9] This is desired for long-term biomedical applications, where smart hydrogels with surface mechanics that enable the biological processes involved in tissue regeneration are required.…”