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    Dual covalent and ionic crosslinked xanthan gum–PVA hydrogel films for enhanced drug release performance
    (2025-11-01) ;
    Napradit, Sasipa
    ;
    Sintoppun, Tanaporn
    ;
    Yamaguchi, Masayuki
    This study presents the development and characterization of dual crosslinked xanthan gum–polyvinyl alcohol (XP) hydrogel films for potential use in controlled drug delivery applications. Hydrogel films were synthesized using glutaraldehyde for covalent crosslinking and Cu<sup>2+</sup> ions for ionic crosslinking, with varying polymer ratios and crosslinker concentrations. The swelling behavior and gel content were evaluated in both distilled water at 25 °C and simulated body fluid (SBF) at 37 °C, revealing that dual crosslinking significantly enhanced structural integrity and swelling resistance, with gel content reaching up to 98%. Thermal analysis using DSC and DMA confirmed increased glass transition temperatures, indicating reduced polymer chain mobility due to denser crosslinking networks. Mechanical tests showed that the films possessed high tensile strength (60–62 MPa), with stiffness increasing alongside Cu<sup>2+</sup> concentration and xanthan content. Cytocompatibility was validated through MTT assays on Vero cells, with all formulations exceeding 80% viability, thus classified as non-cytotoxic according to ISO 10993-5:2009 guidelines. Drug release studies using para-acetylaminophenol demonstrated sustained release behavior, achieving 50% release over 6 h in SBF. Kinetic analysis revealed that the release followed zero-order kinetics (R² = 0.9986) and case-II transport (n = 1.0396), indicating that release was governed by matrix swelling and erosion. These findings highlight the potential of XP dual crosslinked hydrogels as effective and biocompatible platforms for sustained drug delivery, particularly in wound care applications.
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    Enhancing Structural Stability and Drug Release Control in Xanthan Gum–Poly(vinyl alcohol) Hydrogel Films via Ferric Ion Crosslinking
    (2026-05-01) ;
    Napradit, Sasipa
    ;
    Sintoppun, Tanaporn
    ;
    Yamaguchi, Masayuki
    This study investigates the development and characterization of xanthan gum/poly(vinyl alcohol) (XP) hydrogel films crosslinked with ferric ions via a dipping method for controlled oral drug delivery. The effects of ferric ion crosslinking on the physicochemical and mechanical properties of the films were systematically evaluated through swelling behavior, gel content, thermal and mechanical analyses, cytotoxicity testing, and in vitro drug release profiling using para-acetylaminophenol as a model drug under simulated digestive conditions. Crosslinking with ferric ions significantly enhanced the structural integrity of the films by reducing water uptake and improving gel stability in both simulated gastric (SGF) and intestinal fluids (SIF). Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) revealed restricted polymer chain mobility due to ionic interactions within the network. Mechanical testing showed increased tensile strength and Young’s modulus with higher crosslinking density. Cytotoxicity assays confirmed excellent biocompatibility, with high cell viability observed across all formulations. The films enabled controlled release of para-acetylaminophenol under simulated gastrointestinal conditions, with drug release kinetics suggesting a combination of diffusion-controlled and erosion-mediated mechanisms. These findings support the potential of Fe<sup>3+</sup>-crosslinked XP hydrogel films as stable and biocompatible carriers for sustained oral drug delivery.
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    Surface improvement on water and oil affinities and absorption rate of PVA/Tung oil-coated paperboard and fiberboard
    (2016-03-01)
    Jianprasert, Apichaya
    ;
    ;
    Yamaguchi, Masayuki
    A novel coating material on paperboard and fiberboard from poly(vinyl alcohol) (PVA) modified with Tung oil was developed. The PVA/Tung oil coating was cured at several conditions: 25, 40, 50, and 60°C, in the presence of two types of catalysts, i.e., thermal catalyst using potassium persulfate (KPS) and redox catalyst using KPS and sodium thiosulfate. The chemical crosslinked structure of PVA/Tung oil-coating films was confirmed by FTIR. The result indicated the decrease in the double bonds of Tung oil by crosslinking reaction, especially at 60°C. In comparison with the same curing temperature, the films with redox catalyst showed more reduction in the number of double bonds of Tung oil. DMA results of the PVA/Tung oil-coating materials with redox catalyst showed the lowering of the heights of both β transition peak of Tung oil and α transition peak of PVA. FTIR and DMA results confirmed the more efficient crosslinking reaction of redox catalytic system than that of the thermal catalytic system. The water resistance and mechanical properties of these coating materials exhibited better values as projected to higher curing temperature and redox catalyst. SEM images showed the smooth surface of PVA/Tung oil covered on the paperboards with ~72 µm in thickness. The contact angle of water or oil drop and dynamic change in contact angle on the surfaces of PVA/Tung oil-coated paperboards and fiberboards were investigated. The results show the contact angles for both water and oil were lower than those of the uncoated ones, indicating the improvement of water and oil affinities of the PVA/Tung oil-coating materials. The dynamic changes in contact angle of the coated ones also decreased, suggesting the reduction in water and oil absorption rates of these coated substrates.