title: Study of the contribution of the state of water to the gel properties of a photocrosslinked polyacrylic acid hydrogel using magnetic resonance imaging.
abstract: Photocrosslinked polyacrylic acid (PAA-HEMA) hydrogels are a promising candidate for use in dermatological patch adhesives. To gain further knowledge about the properties of this gel, we investigated the T1 relaxation time and the diffusion coefficient (D) of water in the hydrogels using magnetic resonance (MR) imaging. Hydrogels with different formulations and process factors were prepared and tested. The observed data were analyzed by ANOVA, which clarified the mode of action of the formulation and process factors based on these MR parameters. Various gel properties (i.e., gel fraction, swelling capacity, gel strength, and water-retention ability) were also measured, followed by a Bayesian network (BN) analysis. The BN allowed us to summarize well the relationships between the formulation and process factors, MR parameters, and gel properties. T1 was associated with the swelling and water-retention properties of the hydrogel, whereas D was associated with gel formation and gel strength. Furthermore, this study clarified that T1 and D mostly represented the hydration and water-compartmentalization effects of the hydrogel, respectively. In conclusion, the state of water seems to play an important role in the properties of the PAA-HEMA hydrogel.
authors.affiliation: Department of Pharmaceutics, Hoshi University, Shinagawa, Tokyo 142-8501, Japan. Electronic address: onuki@hoshi.ac.jp.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Onuki
authors.affiliation: Department of Pharmaceutics, Hoshi University, Shinagawa, Tokyo 142-8501, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Hasegawa
authors.affiliation: Department of Pharmaceutics, Hoshi University, Shinagawa, Tokyo 142-8501, Japan.
authors.forename: Chihiro
authors.initials: C
authors.lastname: Kida
authors.affiliation: Department of Pharmaceutics, Hoshi University, Shinagawa, Tokyo 142-8501, Japan.
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Obata
authors.affiliation: Department of Pharmaceutics, Hoshi University, Shinagawa, Tokyo 142-8501, Japan.
authors.forename: Kozo
authors.initials: K
authors.lastname: Takayama
mesh_terms: D000269:Adhesives; D000704:Analysis of Variance; D001499:Bayes Theorem; D002626:Chemistry, Pharmaceutical; D004058:Diffusion; D020100:Hydrogels; D008279:Magnetic Resonance Imaging; D008956:Models, Chemical; D011102:Polyhydroxyethyl Methacrylate / Q000737:chemistry*; D013678:Technology, Pharmaceutical / Q000379:methods*; D014867:Water / Q000737:chemistry*
chemical_list: D000269:Adhesives; D020100:Hydrogels; D014867:Water; D011102:Polyhydroxyethyl Methacrylate
keywords: Bayesian network; MRI; diffusion coefficient; hydration; hydrogels; imaging methods; multivariate analysis; relaxation time; state of water