Tuning the Phytoglycogen Size and Aggregate Structure with Solvent Quality: Influence of Water–Ethanol Mixtures Revealed by X-ray and Light Scattering Techniques

Abstract

Phytoglycogen (PG) is a hyperbranched polysaccharide with promising properties for biomedical and pharmaceutical applications. Herein, we explore the size and structure of sweet corn PG nanoparticles and their aggregation in water–ethanol mixtures up to the ethanol mole fraction x EtOH = 0.364 in dilute concentrations using small-angle X-ray scattering (SAXS) and dynamic light scattering (DLS) measurements. Between 0 ≤ x EtOH ≤ 0.129, the conformation of PG contracts gradually decreasing up to ca. 80% in hydrodynamic volume, when measured shortly after ethanol addition. For equilibrated PG dispersions, SAXS suggests a lower PG volume decrease between 19 and 67% at the corresponding x EtOH range; however, the inflection point of the DLS volume contraction coincides with the onset of reduced colloidal stability observed with SAXS. Up to x EtOH = 0.201, the water–ethanol mixtures yield labile fractal and globular aggregates, as evidenced by their partial breakup under mild ultrasonic treatment, demonstrated by the decrease in their hydrodynamic size. Between 0.235 ≤ x EtOH ≤ 0.364, PG nanoparticles form larger, more cohesive globular aggregates that are less affected by ultrasonic shear forces.

The sweetest polymer nanoparticles: opportunities ahead for glycogen in nanomedicine

“…14 The nanoparticles exhibit poor solubility in organic solvents (e.g., limited solubility in dimethyl sulfoxide and N,N-dimethylformamide), but very soluble in most aqueous systems. Glycogen precipitates readily in alcohol solvents, where in ethanol/water mixtures (35% v/v ethanol) phytoglycogen undergoes an approximate 80% decrease in volume, 15 before aggregating at higher ethanol fractions. Due to its high molecular weight, glycogen can also be dialysed with ease to purify, allowing for green purification strategies.…”

Unveiling the flavone-solubilizing effects of α-glucosyl rutin and hesperidin: probing structural differences through NMR and SAXS analyses

“…Recently, the solubilization mechanism of hydrophobic compounds via either micelles of surfactants or supramolecular self-assembly was revealed by small-angle scattering techniques. [44][45][46][47] This study investigated the difference in the solubilizing effects of two α-glucosyl materials, namely, Rutin-G and Hsp-G, on flavone, a representative flavonoid skeleton, 41 based on the interactions of flavone with each α-glucosyl material, as determined using NMR spectroscopy. If the mechanism of solubility enhancement in flavonoids could be determined at the molecular level using NMR techniques, 48 functional food materials containing hydrophobic flavonoids could be more easily developed.…”

“…Recently, the solubilization mechanism of hydrophobic compounds via either micelles of surfactants or supramolecular self-assembly was revealed by small-angle scattering techniques. 44–47…”