Drug diffusion in neutral and ionic hydrogels assembled from acetylated galactoglucomannan

Abstract

In this study, hydrogels based on acetylated galactoglucomannan (AcGGM)-a hemicellulose present in softwood-were synthesized and examined for their properties in drug-release systems using two model substances of different molecular weight, size, and polarity (caffeine and vitasyn blue). Neutral hydrogels were produced from functionalized AcGGM using hydroxyethyl methacrylate (HEMA) coupled via carbonyldiimidazole (CDI) and a co-monomer in a radical-initiated polymerization. Through a second modification reaction between the HEMA-modified AcGGM (M-AcGGM-methacrylated AcGGM) and maleic anhydride, a ''double-modified'' AcGGM (CM-AcGGM-carboxylated M-AcGGM) was successfully formed that could be cross-linked to form ionic hydrogels by the very same polymerization method. The neutral hydrogels showed drug release kinetics that could be easily regulated by changing the relative amount of the methacrylated AcGGM and its corresponding degree of methacrylation. The drug release rate and the Fickian swelling decreased with an increase in these two aforementioned parameters. The ionic hydrogels showed quicker release kinetics and higher swelling capabilities than the corresponding nonionic gels did, especially at neutral conditions. Under acidic conditions, the release speed was lowered as expected because of protonation of carboxylic functionalities. Based on the findings we conclude that these novel hemicellulose-containing hydrogels have future prospects in drug release formulations, e.g., in a later stage of development for application in oral drug administration technology.

Hemicellulose-Based Hydrogels Present Status and Application Prospects: A Brief Review

“…Hemicellulose esterification with maleic anhydride in DMSO was performed by Voepel et al (Voepel et al, 2009). In this study, hemicellulose separated from pulp of spruce grafted with maleic acid to produce the matrix of ionic hydrogel.…”

Functionalized Polymers from Lignocellulosic Biomass: State of the Art

“…Purified hemicelluloses have fewer commercial applications than cellulose and lignin, but in recent years, interest in production of value-added products, such as xylitol [192][193][194][195][196], packaging films [197][198][199] and hydrogels [200][201][202][203][204][205][206][207][208][209] based on hemicelluloses has increased. Xylitol is used for sweetening owing to its dietetic and anticariogenic properties.…”

“…A series of hydrogels based on acetylated galactoglucomannan (AcGGM) was successfully synthesized and evaluated for drug delivery systems applications [200,201]. The modified AcGGM was radically crosslinked to form hydrogels, using a redox initiation and photo initiation in water and DMSO, respectively.…”

“…Furthermore, neutral hydrogels were produced from functionalized AcGGM using 2-hydroxyethylmethacrylate (HEMA) coupled via carbonyldiimidazole (CDI) and a co-monomer in a radical-initiated polymerization. Through a second modification reaction between the HEMA-modified AcGGM (M-AcGGM-methacrylated AcGGM) and maleic anhydride, a "double-modified" AcGGM (CM-AcGGM-carboxylated M-AcGGM) was successfully formed that could be cross-linked to form ionic hydrogels by the very same polymerization method [201]. In neutral hydrogels the drug (caffeine and vitasyn blue) release rate and the Fickian swelling decreased with an increase in the relative amount of the methacrylated AcGGM and its corresponding degree of methacrylation.…”

“…This effect explains the release results obtained from the buffered neutral conditions which gave a slower release in comparison to the corresponding nonbuffered conditions. These novel hemicellulose-containing hydrogels have future prospects in oral drug administration technology [201].…”