Alginate Hydrogels with Tuneable Properties

Construction of a non-toxic interpenetrating network hydrogel drug carrier supported by carbon microspheres and nanocellulose

To develop a stable hydrogel drug carrier with excellent biocompatibility, biodegradability and low toxicity, a green biomass-based hydrogel was prepared as a methylene blue (MB) drug carrier model using cellulose and sodium alginate (SA) polysaccharide. The addition of nanocellulose (CNF) and hydrothermally prepared carbon microspheres to the hydrogel network formed by SA undergoing chelation with Ca2+ enhanced the multifaceted properties of the drug carrier. Additionally, the prepared SA-CNFgelCS0.1 could withstand a pressure of 8.64 N and showed good compressive and elastic properties. Meanwhile, its encapsulation rate and drug loading capacity could reach 95.5 % and 19.36 mg/g, respectively. The drug release rate reached 43.4 % at 100 h in PBS solution simulating the pH value of the gastric environment, indicating good pH-responsiveness and long-lasting release ability during the drug-carrying release process. The release mechanism of the drug carrier to MB was investigated by different release kinetic models, which was in accordance with the first-order kinetic model. SA-CNFgelCS0.1 at high concentration also did not affect the number of pancreatic cell survival and showed a high degree of biocompatibility. In addition to that, SA-CNFgelCS0.1 can reach 100 % degradation rate in 18 days, which has no burden on the environment during use. The present study offers a novel approach to the synthesis of a biomass drug-carrying model with enhanced performance. Furthermore, this drug carrier provides a promising foundation for the development of oral MB as a potential treatment for gastrointestinal diseases and other chronic condition.

Effect of sodium alginate block type on the physicochemical properties and curcumin release behavior of quaternized chitosan-oxidized sodium alginate Schiff base hydrogels

Controlling bioactive ingredients release by modulating the 3D network structure of cross-linked hydrogels is important for functional food development. Hereby, oxidized sodium alginate (OSA) with varying aldehyde contents was formed by periodate oxidation of sodium alginate (SA) with different β-d-mannuronic acid (M) and α-l-guluronic acid (G) ratios (M/G = 1:2, 1:1, and 2:1) and its structure was characterized. Moreover, hydrogels were prepared via Schiff base and electrostatic interactions between quaternized chitosan (QCS) and OSA. The properties of hydrogels such as microstructure, thermal stability, swelling and controlled release were investigated. The results showed that OSA with M/G = 1:2 had the highest content of aldehyde groups, and the hydrogel formed by it and QCS had higher thermal stability and a denser network structure with the lowest equilibrium swelling rate, which could better control the release of curcumin. Additionally, it had good self-healing and can recover rapidly after the rupture of its network structure.

Synthesis and characterization of silk-poly(guluronate) hybrid polymers for the fabrication of dual crosslinked, mechanically dynamic hydrogels

The rapid ionic crosslinking of alginate has been actively studied for biomedical applications including hydrogel scaffolds for tissue engineering, injectable gels, and 3D bioprinting. However, the poor structural stability of ionic crosslinks under physiological conditions limits the widespread applications of these hydrogels. Moreover, the lack of cell adhesion to the material combined with the inability of proteases to degrade alginate further restrict utility as hydrogel scaffolds. Blends of alginate with silk fibroin have been proposed for improved structural and mechanical properties, but potential phase separation between the hydrophobic protein and the hydrophilic polysaccharide remains an issue. In this study, we demonstrated the synthesis of a hybrid biopolymer composed of a silk backbone with side chains of poly(guluronate) isolated from alginate to introduce rapid ionic crosslinking on enzymatically crosslinked silk-based hydrogels for on-demand and reversible stiffening and softening properties. Dual crosslinked macro- and microgels of silk fibroin-poly(guluronate) (SF-PG) hybrid polymers displayed dynamic morphology with reversible shrinking and swelling behavior. SF-PG hydrogel discs demonstrated dynamic mechanics with compressive moduli ranging from less than 5 kPa to over 80 kPa and underwent proteolytic degradation unlike covalently crosslinked alginate controls. SF-PG gels supplemented with gelatin substituted with tyramine or both tyramine and PG also supported the attachment and survival of murine fibroblasts, suggesting potential uses of these new hydrogels in mammalian cell culture to investigate cellular responses to dynamic mechanics or modeling of diseases defined by matrix mechanics, such as fibrosis and cancer.