The effect of polyol co-solvents on the gelation properties of polyvinyl alcohol-based hydrogels for cell immobilization

Hydrogel materials have a variety of applications, ranging from biomedical materials and drug delivery systems, to their employment as immobilization matrices in bioprocessing applications. Polyvinyl alcohol (PVA) is a synthetic, water-soluble, and biocompatible polymer. Due to its physical properties when gelled, this polymer has been highlighted as a suitable candidate for application in the bioprocessing industry as an immobilization matrix for microorganisms. This study investigates the effects of using various polyols as co-solvent on the gelation of PVA-based hydrogels formed at ambient conditions, and their resulting properties. In addition to glycerol, previously known for its capabilities to improve gelation when used as co-solvent, polyols including erythritol (C₄H₁₀O₄), xylitol (C₅H₁₂O₅), and sorbitol (C₆H₁₄O₆) were investigated. Key physical properties of the resulting PVA-based hydrogels were investigated, including: transparency; tensile and compressive strengths; diffusion coefficients; rates of gelation; and method of gelation. It was determined that the hydrogels are formed through physical crosslinking rather than chemical crosslinking. The glycerol-PVA hydrogels tended to exhibit more suitable properties for application in the immobilization of photosynthetic organisms, although the differences in properties between the glycerol-PVA, xylitol-PVA, and sorbitol-PVA hydrogels were comparable and often not significantly different after rehydration. This investigation showed that through the addition of simple polyols, solid PVA-based hydrogels could be formed at ambient conditions without the requirement of cytotoxic chemicals, harsh gelation conditions, or unfavorable intermediate chemicals.