Rheological and controlled release properties of hydrogels based on mushroom hyperbranched polysaccharide and xanthan gum

A hyperbranched polysaccharide, coded as TM3a, was extracted from the Pleurotus tuber-regium sclerotia. TM3a was hybridized with xanthan gum (XG) by chemical crosslinking using sodium trimetaphosphate (STMP) to obtain new hydrogels with self-healing and release-controlled properties. The oscillatory rheological measurements indicated that chemically crosslinking was happened immediately on mixing STMP solutions into the XG-TM3a solutions, and the crosslinked network developed slightly as time increased. The resultant hydroges were disturbed into the loose structures and regrouped the microstructure in 2 min when a large and a small amplitude oscillation were applied in turn, suggesting a self-healable property. The XG-TM3a-STMP hydrogels exhibited shear-thinning behavior with yield stress. The storage modulus of the XG5-TM3a-STMP hydrogel was 445.2 Pa at 1% strain and 243.3 Pa at 100% strain, and yield stress was 160.6 Pa, which was higher than the corresponding value of the XG5-STMP hydrogel. The morphological observation indicated the aggregates of double helical XG chains exhibited directional arrangement, and were combined with the TM3a aggregates to constitute a network of hierarchical structures. The hybrid hydrogels with enhanced mechanical properties displayed good drug loading efficiencies and sustained drug release properties.