Fabrication, Structure and Functional Characterizations of pH-Responsive Hydrogels Derived from Phytoglycogen

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Phytoglycogen (PG) is a natural polysaccharide with potential for biomaterial applications.
• Developing pH-responsive materials is crucial for targeted drug delivery.
• Controlling hydrogel properties through chemical modification is an active research area.

Purpose of the Study:

• To synthesize and characterize pH-responsive hydrogels from carboxymethyl phytoglycogen (CM-PG).
• To investigate the influence of the degree of substitution (DS) during carboxymethylation on hydrogel properties.
• To evaluate the potential of these hydrogels as carriers for bioactive substances.

Main Methods:

• Phytoglycogen was modified via carboxymethylation to create CM-PG with varying DS.
• Phosphorylase-catalyzed elongation of glucan chains on CM-PG was performed.
• Hydrogel structure and morphology were analyzed using iodine staining, X-ray diffraction, and scanning electron microscopy.
• pH-responsive swelling behavior was assessed across a range of pH values.

Main Results:

• Successful synthesis of CM-PG and subsequent phosphorylase-elongated hydrogels was achieved.
• The DS of CM-PG significantly impacted glucan chain elongation, gelation rate, and hydrogel firmness.
• Hydrogels exhibited porous, interconnected structures and demonstrated pH-responsive swelling, with increased volume at higher pH (6-8).
• The hydrogel derived from CM-PG with DS = 0.25 showed the highest pH sensitivity.

Conclusions:

• Phosphorylase-treated CM-PG forms effective pH-responsive hydrogels.
• Hydrogel properties, including responsiveness, are tunable by controlling the carboxymethylation degree.
• These pH-responsive hydrogels show promise as targeted delivery systems for bioactive substances, particularly for release in the small intestine.