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

Abstract

The pH-responsive hydrogels were obtained through successive carboxymethylation and phosphorylase elongatation of phytoglycogen and their structure and functional characterizations were investigated. Phytoglycogen (PG) was first carboxymethylated to obtain carboxymethyl phytoglycogen (CM-PG) with degree of substitution (DS) at 0.15, 0.25, 0.30, and 0.40, respectively. Iodine staining and X-ray diffraction analysis suggested that the linear glucan chains were successfully phosphorylase-elongated from the non-reducing ends at the CM-PG surface and assembled into the double helical segments, leading to formation of the hydrogel. The DS of CM-PG significantly influenced elongation of glucan chains. Specifically, fewer glucan chains were elongated for CM-PG with higher DS and the final glucan chains were shorter, resulting in lower gelation rate of chain-elongated CM-PG and lower firmness of the corresponding hydrogels. Scanning electron microscope observed that the hydrogels exhibited a porous and interconnected morphology. The swelling ratio and volume of hydrogels was low at pH 3–5 and then became larger at pH 6–8 due to electrostatic repulsion resulting from deprotonated carboxymethyl groups. Particularly, the hydrogel prepared from chain-elongated CM-PG (DS = 0.25) showed the highest sensitivity to pH. These results suggested that phosphorylase-treated CM-PG formed the pH-responsive hydrogel and that the elongation degree and the properties of hydrogels depended on the carboxymethylation degree. Thus, it was inferred that these hydrogels was a potential carrier system of bioactive substances for their targeted releasing in small intestine.

Design, characterization and applications of nanocolloidal hydrogels

“…These NPs are represented by e.g., latexes 6 or nanogels. 61 Alternatively, biosourced polymer NPs derived from proteins (e.g., lysozyme, 54 casein, 62 or gelatin 63,64 ), polysaccharides (e.g., cellulose 41 and phytoglycogen 65 ), and DNA 66 can be used as NCG building blocks, thus, paving the way for the fabrication of biocompatible and biodegradable materials. Examples of these NPs are shown in Fig.…”

Advanced dendritic glucan‐derived biomaterials: From molecular structure to versatile applications

“…This pH‐dependent behavior was mainly attributed to changes in the hydrogen bonding and electrostatic interactions when the pH was altered. Moreover, the pH‐responsive hydrogels were obtained through successive carboxymethylation and phosphorylase elongation of phytoglycogen (Hu et al., 2021). The swelling ratio and volume of hydrogels were low at pH 3−5 and then became larger at pH 6−8 due to electrostatic repulsion resulting from deprotonated carboxymethyl groups.…”

“…The introduction of Fe 3+ in the cross‐linked polymer network composed of Gly and polyacrylic acid produced hydrogels with dynamic energy dissipative coordination bonds, thus greatly increasing their mechanical and self‐healing properties (Hussain, Sayed, Liu, et al., 2018). Other dendritic glucan‐based hydrogels have also been reported to have potential as tissue engineering scaffolds (Hu et al., 2021; Jose et al., 2020; Takata et al., 2015).…”

Stimulus-Responsive Nanoconjugates Derived from Phytoglycogen Nanoparticles

“…To utilize PhG NPs in emulsion stabilization, drug solubilization, or vaccine and drug delivery, PhG NPs have been chemically modified by, for example, esterification, − cationization, − or enzyme-catalyzed reactions. − Furthermore, PhG NPs were also conjugated with fluorescein isothiocyanate for silver ion sensing or with lipoic acid for surface-facilitated catalysis and surface-enhanced Raman scattering . To functionalize PhG NPs, strong electrophiles such as epoxide groups or periodate and/or demanding reaction conditions ( e.g.…”