Interactions of glucose and polyacrylamide in solutions and gels

Abstract

The swelling of polyacrylamide (PAAm) gels increased with rising glucose concentrations, and so did the osmotic pressure of the soluble polymer and its intrinsic viscosity. A Flory-Huggins-based model for the osmotic pressure of a nonionic hydrophilic polymer in a ternary solution consisting of a main solvent, a polymer, and a nondissociating low-molecular-weight cosolute was developed and examined. The model-calculated values were in reasonably good agreement with experimental results for the water-PAAm-glucose system studied when PAAm-water and glucose-water interaction coefficients from the binary systems were used, and only the PAAm-glucose interaction coefficient was adjusted. Its negative value suggested a favorable interaction of glucose and PAAm, supporting the notion of glucose being a good cosolvent for PAAm. Isothermal titration microcalorimetry results showed no evidence for the binding of glucose to PAAm, but an exothermic interaction was indicated between glucose and PAAm. Microcalorimetrically determined enthalpic contributions to the Flory-Huggins interaction coefficients showed enthalpically favorable binary interactions, particularly the enthalpic component of the PAAm-glucose interaction coefficient ( H23 ), which was slightly negative. The enthalpically favorable interaction between glucose and PAAm may explain the increased osmotic pressure of PAAm in glucose solutions.

Saccharide‐structure effects on poly N‐isopropylacrylamide phase transition in aqueous media; Reflections on protein stability

“…They classified sugars as polar nonionic kosmotropes, characterized by exothermic heat of dilution in water. Our ITC results in the current study (not shown) and in a previous study17 also demonstrated such exothermic dilution with all the sugars studied.…”

“…Graziano16 demonstrated the analogy between temperature induced CGT process of PNIPA, an isomer of polyleucine, in aqueous solution and cold renaturation of globular proteins. We have previously reported the favorable effect of glucose on swelling of the hydrophilic polyacrylamide gel,17 a “soluting‐in” effect. The effect of saccharides on the more hydrophobic PNIPA is generally opposite; however, the mechanisms of this soluting‐out effect, and the reasons for the differences between effects of various saccharides are still obscure.…”

Soluting-in and soluting-out of water-soluble polymers in aqueous carbohydrate solutions studied by vapor pressure osmometry

“…Livney et al [4,6] studied the effect of carbohydrates on the swelling of polyacrylamide and poly(N-isopropylacrylamide) gels. They observed that the swelling of polyacrylamide gels, which are hydrophilic polymers as PEGs, increases with rising glucose concentrations and there is an enthalpically favorable interaction between glucose and polyacrylamide [4]. However, based on their results, sugars exert shrinkage and soluting-out effects on poly(N-isopropylacrylamide) gels, which are hydrophobic polymers as PPG [6].…”

“…They have received a huge interest for delivery of macromolecular drugs, vaccine development and cosmetic industry [2,3]. Carbohydrates may exert significant influence on the stability and behavior of aqueous polymeric systems in foods and in other fields of application [4][5][6]. For instance, polyethylene glycols (PEGs) are used as plasticizers in film-coating formulations for food supplements and pharmaceutical products (tablets and capsules) [7].…”

Soft condensed matter perspective on moisture transport in cooking meat

“…The presence of low molecular weight solutes in the food makes the treatment more complex. The direct effect is that the solutes contribute to the osmotic pressure, but they also have indirect effects such as salting‐in/salting‐out effects, and they can act as cosolutes, and their interaction with polymers gives extra contributions in the osmotic pressure 43…”