Hybrid thermoresponsive graft constructs of fungal polysaccharide β-glucan: Physico-chemical and immunomodulatory properties

We describe a family of thermoresponsive hybrid biodegradable peptidoglycan-like polymers, beta-glucan-graftpoly(2-isopropyl-2-oxazoline-co-2-butyl-2-oxazoline)s, in the context of their physical, chemical and biological properties. Four polymer samples, differing in the polyoxazoline graft length (500-5000 Da), were synthesized using beta-glucan extracted from Auricularia auricula-judae, which is known for its anticancer and immunomodulatory activities. The thermoresponsive behaviour of the prepared polymers were thoroughly studied using dynamic light scattering, fluorescence and magnetic resonance measurements, demonstrating an easy adjustment of the cloud point temperature by the graft length. Moreover, all samples show nontoxicity in vitro. The assay of oxidative burst of the polymorphonuclears established that the polymer immunostimulatory properties are not significantly influenced by their graft length considering the same amount of beta-glucan. Thus, we showed that the desired immunostimulatory properties are not decreased by the polyoxazoline grafting of beta-glucan, even they are not influenced by the graft length of the polyoxazoline chains. Therefore, for the intended application the final graft length can be chosen considering the polymer thermoresponsive properties only, while not influencing their immunostimulatory properties.