Phytoglycogen Nanoparticles: Nature-Derived Superlubricants

Abstract

Phytoglycogen nanoparticles (PhG NPs), a single-molecule highly branched polysaccharide, exhibit excellent water retention, due to the abundance of close-packed hydroxyl groups forming hydrogen bonds with water. Here we report lubrication properties of close-packed adsorbed monolayers of PhG NPs acting as boundary lubricants. Using direct surface force measurements, we show that the hydrated nature of the NP layer results in its striking lubrication performance, with two distinct confinement-controlled friction coefficients. In the weak-to moderate-confinement regime, when the NP layer is compressed down to 8% of its original thickness under a normal pressure of up to 2.4 MPa, the NPs lubricate the surface with a friction coefficient of 10 −3 . In the strong-confinement regime, with 6.5% of the original layer thickness under a normal pressure of up to 8.1 MPa, the friction coefficient was 10 −2 . Analysis of the water content and energy dissipation in the confined NP film reveals that the lubrication is governed by synergistic contributions of unbound and bound water molecules, with the former contributing to lubrication properties in the weak-to moderate-confinement regime and the latter being responsible for the lubrication in the strong-confinement regime. These results unravel mechanistic insights that are essential for the design of lubricating systems based on strongly hydrated NPs.

Stimulus-Responsive Nanoconjugates Derived from Phytoglycogen Nanoparticles

“…The combination of the therapeutic effect and lubrication may provide synergy for the treatment of shearinduced arthritis. Together with excellent lubrication properties of PhG NPs, which were demonstrated in our earlier work, 20 the results reported in the present study stimulate further exploration of biomedical applications of nanoconjugates of PhG NPs, with a potential effect of the endogenous albumin in synovial fluids on the release of MTX considered for in vivo studies. Intra-articular injection of PhG NP-BSA-MTX nanoconjugates may provide an alternative treatment for osteoarthritis due to their lubricating properties and the stimuli-responsive release of the antiarthritic drug.…”

“…The hyperbranched nature and high density of hydroxyl groups of PhG NPs facilitate their hydrogen bonding with water and result in strong water retention and orientation and ordering of water molecules within the NPs . Importantly, recently, our group has shown that highly hydrated PhG NPs confined between two solid surfaces exhibit excellent lubrication properties …”

“…19 Importantly, recently, our group has shown that highly hydrated PhG NPs confined between two solid surfaces exhibit excellent lubrication properties. 20 To utilize PhG NPs in emulsion stabilization, drug solubilization, or vaccine and drug delivery, PhG NPs have been chemically modified by, for example, esterification, 21−23 cationization, 24−26 or enzyme-catalyzed reactions. 27−29 thermore, PhG NPs were also conjugated with fluorescein isothiocyanate for silver ion sensing 30 or with lipoic acid for surface-facilitated catalysis and surface-enhanced Raman scattering.…”

Hyaluronic Acid-Modified Nanoplatforms as a Vector for Targeted Delivery of Autophagy-Related Gene to the Endometriotic Lesions in Mice

“…These (PEI-SA/DNA) HA particles exhibited a uniform distribution with an average diameter of 179 nm (Figures 2B-D). While these particles appeared smaller in TEM images, this is likely attributable to the drying of these samples during the sample preparation procedure, given that the presence of a layer that is hydrated in aqueous solutions results in larger apparent particle sizes upon DLS-based analysis (Adibnia et al, 2021).…”

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

“…14,15 These properties imbue PG with a globular shape, with a hydrodynamic diameter between 20 and 25 nm, 13,16,17 which, together with its soft colloidal character, have motivated recent studies to employ it as an optical probe, 18 a drug delivery vehicle, 19,20 a solubilizer, 21−24 and a lubricant. 25 Although glycogen and PG have been the subject of smallangle neutron scattering (SANS) and small-angle X-ray scattering (SAXS) studies that have elucidated its properties in water, 26−28 PG aggregation behavior in poor solvent conditions has not been investigated with small-angle scattering techniques. Although the stability of PG in water is influenced by its branching degree 29 and one can precipitate PG with high-volume-percentage ethanol 30,31 or a surfactant such as sodium dodecyl sulfate, 32 the characteristics of PG at low and moderate ethanol concentrations are still poorly understood.…”