Structure and Hydration of Highly-Branched, Monodisperse Phytoglycogen Nanoparticles

Solubilization of Hydrophobic Astaxanthin in Water by Physical Association with Phytoglycogen Nanoparticles

Astaxanthin (AXT) is a xanthophyll carotenoid with reported health benefits. Realizing its potential as a bioactive is challenging because of its extremely poor solubility in water. We describe a method to improve the effective solubility of AXT in water through its physical association with phytoglycogen (PG), which is produced in sweet corn as compact, highly branched nanoparticles. We combine PG in water with AXT in acetone, evaporate the acetone, and lyophilize. The result is an AXT-PG complex that can be readily redispersed in water, resulting in stable aqueous dispersions. By characterizing the UV-vis absorbance due to different aggregation states of AXT in the AXT-PG complex, we determined the maximum loading of AXT onto PG to be ∼10% by mass. Our results demonstrate the promise of using PG as a solubilizing agent for hydrophobic compounds in water.

Self-Assembled Aggregated Structures of Natural Products for Oral Drug Delivery

The self-assembling aggregated structures of natural products have gained significant interest due to their simple synthesis, lack of carrier-related toxicity, and excellent biological efficacy. However, the mechanisms of their assembly and their ability to traverse the gastrointestinal (GI) barrier remain unclear. This review summarizes various intermolecular non-covalent interactions and aggregated structures, drawing on research indexed in Web of Science from 2010 to 2024. Cheminformatics analysis of the self-assembly behaviors of natural small molecules and their supramolecular aggregates reveals assembly-favorable conditions, aiding drug formulation. Additionally, the review explores the self-assembly properties of macromolecules like polysaccharides, proteins, and exosomes, highlighting their role in drug delivery. Strategies to overcome gastrointestinal barriers and enhance drug bioavailability are also discussed. This work underscores the potential of natural products in oral drug delivery and offers insights for designing more effective drug delivery systems.

Sweet corn phytoglycogen dendrimers as a lyoprotectant for dry-state protein storage

Protein biotherapeutics typically require expensive cold-chain storage to maintain their fold and function. Packaging proteins in the dry state via lyophilization can reduce these cold-chain requirements. However, formulating proteins for lyophilization often requires extensive optimization of excipients that both maintain the protein folded state during freezing and drying (i.e., "cryoprotection" and "lyoprotection"), and form a cake to carry the dehydrated protein. Here we show that sweet corn phytoglycogens, which are glucose dendrimers, can act as both a protein lyoprotectant and a cake-forming agent. Phytoglycogen (PG) dendrimers from 16 different maize sources (PG1-16) were extracted via ethanol precipitation. PG size was generally consistent at ~70-100 nm for all variants, whereas the colloidal stability in water, protein contaminant level, and maximum density of cytocompatibility varied for PG1-16. 10 mg/mL PG1, 2, 9, 13, 15, and 16 maintained the activity of various proteins, including green fluorescent protein, lysozyme, β-galactosidase, and horseradish peroxidase, over a broad range of concentrations, through multiple rounds of lyophilization. PG13 was identified as the lead excipient candidate as it demonstrated narrow dispersity, colloidal stability in phosphate-buffered saline, low protein contaminants, and cytocompatibility up to 10 mg/mL in NIH3T3 cell cultures. All dry protein-PG13 mixtures had a cake-like appearance and all frozen protein-PG13 mixtures had a Tg' of ~ -26°C. The lyoprotection and cake-forming properties of PG13 were density-dependent, requiring a minimum density of 5 mg/mL for maximum activity. Collectively these data establish PG dendrimers as a new class of excipient to formulate proteins in the dry state.

Building respirable powder architectures: utilizing polysaccharides for precise control of particle morphology for enhanced pulmonary drug delivery

INTRODUCTION

Dry powder inhaler (DPI) formulations are gaining attention as universal formulations with applications in a diverse range of drug formulations. The practical application of DPIs to pulmonary drugs requires enhancing their delivery efficiency to the target sites for various treatment modalities. Previous reviews have not explored the relation between particle morphology and delivery to different pulmonary regions. This review introduces new approaches to improve targeted DPI delivery using novel particle design such as supraparticles and metal-organic frameworks based on cyclodextrin.

AREAS COVERED

This review focuses on the design of DPI formulations using polysaccharides, promising excipients not yet approved by regulatory agencies. These excipients can be used to design various particle morphologies by controlling their physicochemical properties and manufacturing methods.

EXPERT OPINION

Challenges associated with DPI formulations include poor access to the lungs and low delivery efficiency to target sites in the lung. The restricted applicability of typical excipients contributes to their limited use. However, new formulations based on polysaccharides are expected to establish a technological foundation for the development of DPIs capable of delivering modalities specific to different lung target sites, thereby enhancing drug delivery.

Gas-Phase Functionalization of Phytoglycogen Nanoparticles and the Role of Reagent Structure in the Formation of Self-Limiting Hydrophobic Shells

A suite of acyl chloride structural isomers (C6H11OCl) was used to effect gas-phase esterification of starch-based phytoglycogen nanoparticles (PhG NPs). The surface degree of substitution (DS) was quantified using X-ray photoelectron spectroscopy, while the overall DS was quantified using 1H NMR spectroscopy. Gas-phase modification initiates at the NP surface, with the extent of surface and overall esterification determined by both the reaction time and the steric footprint of the acyl chloride reagent. The less sterically hindered acyl chlorides diffuse fully into the NP interior, while the branched isomers are restricted to the near-surface region and form self-limiting hydrophobic shells, with shell thicknesses decreasing with increasing steric footprint. These differences in substitution were also reflected in the solubility of the NPs, with water solubility systematically decreasing with increasing DS. The ability to separately control both the surface and overall degree of functionalization and thereby form thin hydrophobic shells has significant implications for the development of polysaccharide-based biopolymers as nanocarrier delivery systems.

From Nature-Sourced Polysaccharide Particles to Advanced Functional Materials

Polysaccharides constitute over 90% of the carbohydrate mass in nature, which makes them a promising feedstock for manufacturing sustainable materials. Polysaccharide particles (PSPs) are used as effective scavengers, carriers of chemical and biological cargos, and building blocks for the fabrication of macroscopic materials. The biocompatibility and degradability of PSPs are advantageous for their uses as biomaterials with more environmental friendliness. This review highlights the progresses in PSP applications as advanced functional materials, by describing PSP extraction, preparation, and surface functionalization with a variety of functional groups, polymers, nanoparticles, and biologically active species. This review also outlines the fabrication of PSP-derived macroscopic materials, as well as their applications in soft robotics, sensing, scavenging, water harvesting, drug delivery, and bioengineering. The paper is concluded with an outlook providing perspectives in the development and applications of PSP-derived materials.

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

There is considerable interest in the development of advanced biomaterials with improved or novel functionality for diversified applications. Dendritic glucans, such as phytoglycogen and glycogen, are abundant biomaterials with highly branched three-dimensional globular architectures, which endow them with unique structural and functional attributes, including small size, large specific surface area, high water solubility, low viscosity, high water retention, and the availability of numerous modifiable surface groups. Dendritic glucans can be synthesized by in vivo biocatalysis reactions using glucosyl-1-phosphate as a substrate, which can be obtained from plant, animal, or microbial sources. They can also be synthesized by in vitro methods using sucrose or starch as a substrate, which may be more suitable for large-scale industrial production. The large numbers of hydroxyl groups on the surfaces of dendritic glucan provide a platform for diverse derivatizations, including nonreducing end, hydroxyl functionalization, molecular degradation, and conjugation modifications. Due to their unique physicochemical and functional attributes, dendritic glucans have been widely applied in the food, pharmaceutical, biomedical, cosmetic, and chemical industries. For instance, they have been used as delivery systems, adsorbents, tissue engineering scaffolds, biosensors, and bioelectronic components. This article reviews progress in the design, synthesis, and application of dendritic glucans over the past several decades.

Harnessing the polymer-particle duality of ultra-soft nanogels to stabilise smart emulsions

Micro- and nanogels are widely used to stabilise emulsions and simultaneously implement their responsiveness to the external stimuli. One of the factors that improves the emulsion stability is the nanogel softness. Here, we study how the softest nanogels that can be synthesised with precipitation polymerisation of N-isopropylacrylamide (NIPAM), the ultra-low crosslinked (ULC) nanogels, stabilise oil-in-water emulsions. We show that ULC nanogels can efficiently stabilise emulsions already at low mass concentrations. These emulsions are resistant to droplet flocculation, stable against coalescence, and can be easily broken upon an increase in temperature. The resistance to flocculation of the ULC-stabilised emulsion droplets is similar to the one of emulsions stabilised by linear pNIPAM. In contrast, the stability against coalescence and the temperature-responsiveness closely resemble those of emulsions stabilised by regularly crosslinked pNIPAM nanogels. The reason for this combination of properties is that ULC nanogels can be thought of as colloids in between flexible macromolecules and particles. As a polymer, ULC nanogels can efficiently stretch at the interface and cover it uniformly. As a regularly crosslinked nanogel particle, ULC nanogels protect emulsion droplets against coalescence by providing a steric barrier and rapidly respond to changes in external stimuli thus breaking the emulsion. This polymer-particle duality of ULC nanogels can be exploited to improve the properties of emulsions for various applications, for example in heterogeneous catalysis or in food science.

Opposites Attract: Electrostatically Driven Loading of Antimicrobial Peptides into Phytoglycogen Nanocarriers

Antimicrobial peptides, such as GL13K, have a high binding selectivity toward bacterial membranes, while not affecting healthy mammalian cells at therapeutic concentrations. However, delivery of these peptides is challenging since they are susceptible to proteolytic hydrolysis and exhibit poor cellular uptake. A protective nanocarrier is thus proposed to overcome these obstacles. We investigate the potential to employ biodegradable phytoglycogen nanoparticles as carriers for GL13K using a simple loading protocol based on electrostatic association rather than chemical conjugation, eliminating the need for control of chemical cleavage for release of the peptide in situ. Both the native (quasi-neutral) and carboxymethylated (anionic) phytoglycogen were evaluated for their colloidal stability, loading capacity, and release characteristics. We show that the anionic nanophytoglycogen carries a greater cationic GL13K load and exhibits slower release kinetics than native nanophytoglycogen. Isotope exchange measurements demonstrate that the antimicrobial peptide is entrapped in the pores of the dendritic-like macromolecule, which should provide the necessary protection for delivery. Importantly, the nanoformulations are active against a Pseudomonas aeruginosa clinical isolate at concentrations comparable to those of the free peptide and representative, small molecule antibiotics. The colloidal nanocarrier preserves peptide stability and antimicrobial activity, even after long periods of storage (at least 8 months).

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

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.

Binding Affinity of Concanavalin A to Native and Acid-Hydrolyzed Phytoglycogen Nanoparticles

Phytoglycogen (PG) is a polysaccharide produced in the kernels of sweet corn as soft, highly branched, compact nanoparticles. Its tree-like or dendritic architecture, combined with a high-safety profile, makes PG nanoparticles attractive for use in biological applications, many of which rely on the association or binding of small biomolecules. We have developed a methodology to functionalize surface plasmon resonance (SPR) sensor surfaces with PG nanoparticles, and we demonstrate the utility of the PG-functionalized SPR sensor by measuring the binding affinity of the tetrameric concanavalin A (ConA) protein to both native PG nanoparticles and smaller, softer acid-hydrolyzed PG nanoparticles. We measure comparable values of the equilibrium association constant K for native and acid-hydrolyzed PG, with a slightly smaller value for the acid-hydrolyzed particles that we attribute to unfavorable lateral interactions between the tetrameric subunits of ConA due to the increase in surface curvature of the smaller acid-hydrolyzed PG particles. We also use infrared reflection-absorption spectroscopy (IRRAS) to show that ConA maintains a large fraction of its native conformation, and thus its bioactivity, upon binding to PG, representing an important step toward the realization of PG as a novel bioactive delivery vehicle.

Gastric Emptying of Maltodextrin versus Phytoglycogen Carbohydrate Solutions in Healthy Volunteers: A Quasi-Experimental Study

Preoperative carbohydrate beverages have been shown to be beneficial in improving patient outcomes. There have been several investigations into the safety of maltodextrin as a preoperative carbohydrate. Although alternative preoperative carbohydrate sources have been proposed, there have been few investigations into the safety and gastric emptying of novel carbohydrate beverages. The present study aimed to compare the gastric emptying of phytoglycogen and maltodextrin to evaluate safety for use as presurgical carbohydrate beverages. In a quasi-experimental design, ten healthy participants orally consumed either a 12.5% maltodextrin or a 12.5% phytoglycogen solution. Gamma scintigraphy was used to evaluate gastric emptying at baseline at 45, 90, and 120 min. Serum insulin and serum glucose were measured at baseline at 15, 30, 45, 60, 90, and 120 min. Gastric volume was significantly lower in the phytoglycogen group at 45 min (p = 0.01) and 90 min (p = 0.01), but this difference lost significance at 120 min (p = 0.17). There were no significant differences between treatments for serum insulin or serum glucose at any time point. This study indicates that the gastric emptying of phytoglycogen is comparable to maltodextrin at 120 min after ingestion, opening the opportunity for the study of alternative carbohydrates for utilization as preoperative carbohydrates.

How Softness Matters in Soft Nanogels and Nanogel Assemblies

Softness plays a key role in determining the macroscopic properties of colloidal systems, from synthetic nanogels to biological macromolecules, from viruses to star polymers. However, we are missing a way to quantify what the term "softness" means in nanoscience. Having quantitative parameters is fundamental to compare different systems and understand what the consequences of softness on the macroscopic properties are. Here, we propose different quantities that can be measured using scattering methods and microscopy experiments. On the basis of these quantities, we review the recent literature on micro- and nanogels, i.e. cross-linked polymer networks swollen in water, a widely used model system for soft colloids. Applying our criteria, we address the question what makes a nanomaterial soft? We discuss and introduce general criteria to quantify the different definitions of softness for an individual compressible colloid. This is done in terms of the energetic cost associated with the deformation and the capability of the colloid to isotropically deswell. Then, concentrated solutions of soft colloids are considered. New definitions of softness and new parameters, which depend on the particle-to-particle interactions, are introduced in terms of faceting and interpenetration. The influence of the different synthetic routes on the softness of nanogels is discussed. Concentrated solutions of nanogels are considered and we review the recent results in the literature concerning the phase behavior and flow properties of nanogels both in three and two dimensions, in the light of the different parameters we defined. The aim of this review is to look at the results on micro- and nanogels in a more quantitative way that allow us to explain the reported properties in terms of differences in colloidal softness. Furthermore, this review can give researchers dealing with soft colloids quantitative methods to define unambiguously which softness matters in their compound.

Antimicrobial effects of thymol-loaded phytoglycogen/zein nanocomplexes against foodborne pathogens on fresh produce

In this study, thymol-loaded hydrophobically modified phytoglycogen/zein nanocomplexes with a particle size around 100 nm were developed for improving microbial safety of fresh produce. The antimicrobial activities, including the determination of minimum inhibitory and bactericidal concentration, growth kinetic curves, and inhibition zone of the nanocomplexes against foodborne pathogens (Listeria monocytogenes, Salmonella enteritidis, and Escherichia coli) were evaluated. The results showed that the antimicrobial activities of the nanocomplexes were significantly stronger than that of free thymol control (without encapsulation), and the antimicrobial efficacy remained unchanged after storage at 4 °C for 60 days. The morphological results from atomic force microscope revealed that small micellar blebs were formed at the surface of bacteria after treatment with nanocomplexes and the gradual disappearance of the cell boundary indicated the occurrence of cytolysis. The potential applications of this nanocomplex as disinfectant agent in wash water were evaluated on different types of fresh produce (lettuce, cantaloupe, and strawberries). Notably, the nanocomplexes also demonstrated efficacy in biofilm removal. Findings from this study clearly demonstrated that the thymol-loaded nanocomplexes hold promising potential for the disinfection of fresh produce to improve their microbial safety and quality.

Phytoglycogen Encapsulation of Lanthanide-Based Nanoparticles as an Optical Imaging Platform with Therapeutic Potential

Lanthanide-based upconverting nanoparticles (UCNPs) are largely sought-after for biomedical applications ranging from bioimaging to therapy. A straightforward strategy is proposed here using the naturally sourced polymer phytoglycogen to coencapsulate UCNPs with hydrophobic photosensitizers as an optical imaging platform and light-induced therapeutic agents. The resulting multifunctional sub-micrometer-sized luminescent beads are shown to be cytocompatible as carrier materials, which encourages the assessment of their potential in biomedical applications. The loading of UCNPs of various elemental compositions enables multicolor hyperspectral imaging of the UCNP-loaded beads, endowing these materials with the potential to serve as luminescent tags for multiplexed imaging or simultaneous detection of different moieties under near-infrared (NIR) excitation. Coencapsulation of UCNPs and Rose Bengal opens the door for potential application of these microcarriers for collagen crosslinking. Alternatively, coloading UCNPs with Chlorin e6 enables NIR-light triggered generation of reactive oxygen species. Overall, the developed encapsulation methodology offers a straightforward and noncytotoxic strategy yielding water-dispersible UCNPs while preserving their bright and color-tunable upconversion emission that would allow them to fulfill their potential as multifunctional platforms for biomedical applications.

Effect of Starch Primers on the Fine Structure of Enzymatically Synthesized Glycogen-like Glucan

Glycogen-like glucan (GnG) is a unique hyperbranched polysaccharide nanoparticle which is drawing increasing attention due to its biodegradability and abundant short branches that can be functionalized. Because starch and GnG are both composed of glucose residues and have similar glucosidic bonds, GnG could be fabricated by sucrose phosphorylase, α-glucan phosphorylase, and branching enzymes from starch primers and sucrose. In this study, high-amylose starch, normal starch, and waxy corn starch were used as primers to synthesize GnG, and their impact on the fine structure of GnG was investigated. Structural analysis indicated that with increasing content of amylopectin in the starch primer, the proportion of short chains in GnG decreased, and the degree of β-amylolysis and α-amylolysis was enhanced. Amylose in the primer contributed to a compact and homogeneous structure of GnG, while amylopectin triggered the formation of branch points with a more open distribution. These findings provide a new strategy for regulating the fine structure of GnG.

A review on plant polysaccharide based on drug delivery system for construction and application, with emphasis on traditional Chinese medicine polysaccharide

Carbohydrate polymers with unique chemical composition, molecular weight and functional chemical groups show multiple potentials in drug delivery. Most carbohydrate polymers such as plant polysaccharides exhibit advantages of biodegradability, ease of modification, low immunogenicity and low toxicity. They can be conjugated, cross-linked or functionally modified, and then used as nanocarrier materials. Polysaccharide drug delivery system can avoid the phagocytosis of the reticuloendothelial system, prevent the degradation of biomolecules, and increase the bioavailability of small molecules, thus exerting effective therapeutic effects. Therefore, they have been fully explored. In this paper, we reviewed the construction methods of drug delivery systems based on carbohydrate polymers (astragalus polysaccharide, angelica polysaccharide, lycium barbarum polysaccharide, ganoderma lucidum polysaccharide, bletilla polysaccharide, glycyrrhiza polysaccharide, and epimedium polysaccharides, etc). The application of polysaccharide drug delivery systems to deliver small molecule chemotherapeutic drugs, gene drugs, and metal ion drugs was also briefly introduced. At the same time, the role of the polysaccharide drug delivery system in tumor treatment, targeted therapy, and wound healing was discussed. In addition, the research of polysaccharide delivery systems based on the therapeutic efficacy of traditional Chinese medicine was also summarized and prospected.

Transition in the Glassy Dynamics of Melts of Acid-Hydrolyzed Phytoglycogen Nanoparticles

The deformability, responsiveness, and tunability of soft nanoparticles (NPs) offer unique opportunities to learn about their complex properties and the interactions between particles. In the present study, we provide new insights into the physical properties of phytoglycogen (PG) NPs, which are soft, compact particles with a dendritic architecture that are produced in the kernels of sweet corn. In particular, we study PG NPs modified using acid hydrolysis, which not only reduces their diameter but also alters their stiffness, internal structure, and the interactions between particles in aqueous dispersions. We used steady shear rheology to determine the dependence of the relative zero-shear viscosity η_r of aqueous dispersions of acid-hydrolyzed PG NPs on the effective volume fraction ϕ_eff, which indicated a reduction in stiffness of the particles relative to that of native PG NPs. We quantified this difference by analyzing the nature of the colloidal glasses formed at high ϕ_eff. We measured a smaller value of the fragility index m for acid-hydrolyzed PG NP glasses than that for native PG NP glasses, indicating that acid-hydrolyzed PG NPs form stronger glasses and are therefore softer than native PG NPs. Unlike the native PG NPs, we observed a distinctive change in the character of the glass transition of the acid-hydrolyzed PG NPs as ϕ_eff was increased above ϕ_eff∼1: a crossover in the dependence of η_r on ϕ_eff from Vogel-Fulcher-Tammann behavior to a more gradual, Arrhenius-like behavior. By expressing the steady shear and oscillatory rheology data in terms of generalized Péclet numbers, we obtained collapse of the data onto master curves. We interpret this result in terms of the acid-hydrolyzed PG NPs predominantly interpenetrating neighboring particles at large ϕ_eff, for which fluctuations of the outer chains enhance the mobility of the particles and make α-relaxation times τ_α experimentally accessible.

Stimulus-Responsive Nanoconjugates Derived from Phytoglycogen Nanoparticles

Plant-derived phytoglycogen nanoparticles (PhG NPs) have the advantages of size uniformity, dispersibility in water, excellent lubrication properties, and lack of cytotoxicity; however, their chemical functionalization may lead to loss of NP structural integrity. Here, we report a straightforward approach to the generation of PhG NP conjugates with biologically active molecules. Hydrogen bonding of bovine serum albumin with electroneutral PhG NPs endows them with additional ligand binding affinity and enables the electrostatically governed attachment of methotrexate (MTX), a therapeutic agent commonly used in the treatment of cancer and arthritis diseases, to the protein-capped NPs. We showed stimuli-responsive release of MTX from the PhG-based nanoconjugates under physiological cues such as temperature and ionic strength. The results of this study stimulate future exploration of biomedical applications of nanoconjugates of PhG NPs.

Oral delivery of a dsRNA-Phytoglycogen nanoparticle complex enhances both local and systemic innate immune responses in rainbow trout

Salmonids are one of the most farmed fish species worldwide. These aquatic vertebrates rely heavily on their innate immune responses as the first line of defense to defend themselves against invading pathogens. Although commercial vaccines are available against some viral and bacterial pathogens affecting salmonids, their protective efficacy varies. Using a prophylactic inducer of local and systemic innate immune responses to limit infection could have significant implications in salmonid aquaculture. A potent inducer of innate immune responses in fish is double-stranded RNA (dsRNA), a molecule that all viruses make during their replicative cycle. Polyinosinic: polycytidylic acid (polyI:C) is a synthetic dsRNA commonly used to induce type I interferons (IFNs), interferon stimulated genes (ISGs) as well as an antiviral state in vertebrate species. Based on in vitro data it was hypothesized that both local and systemic innate immune responses, in salmonids, would be enhanced by orally delivering high molecular weight polyI:C (HMW polyI:C) using cationic phytoglycogen nanoparticles (NPs) as a delivery method. The present study investigates this hypothesis using two feed delivery methods. In the first in vivo study, to ensure an equal distribution of dose, individual rainbow trout (Oncorhynchus mykiss) were orally gavaged with feed moistened with a solution containing HMW-NP (polyI:C complexed with cationic phytoglycogen nanoparticles) or HMW polyI:C alone. In a second in vivo experiment, to better mimic a more realistic feeding scenario, rainbow trout were fed feed pellets to which HMW, or HMW-NP was added. The expression of IFN1 and ISGs (vig-3, Mx1) were quantified using real-time PCR in the intestine (local response) and head kidney (systemic response). The results of these studies indicate that HMW-NP induced a higher level of IFN1 and ISG expression in the intestine and head kidney compared to the HMW fed fish. The results of this study could lead to new advances in therapeutics for the aquaculture industry by utilizing the innate immune response against invading pathogens using an orally delivered stimulant.

Are Plant-Based Carbohydrate Nanoparticles Safe for Inhalation? Investigating Their Interactions with the Pulmonary Surfactant Using Langmuir Monolayers

Nanoparticle carriers show promise for drug delivery, including by inhalation, where the first barrier for uptake in the lungs is the monolayer pulmonary surfactant membrane that coats the air/alveoli interface and is critical to breathing. It is imperative to establish the fate of potential nanocarriers and their effects on the biophysical properties of the pulmonary surfactant. To this end, the impact of the nanoparticle surface charge on the lateral organization, thickness, and recompressibility of Langmuir monolayers of model phospholipid-only and phospholipid-protein mixtures was investigated using native and modified forms of nanophytoglycogen, a carbohydrate-based dendritic polymer extracted from corn as monodisperse nanoparticles. We show that the native (quasi-neutral) and anionic nanophytoglycogens have little impact on the phase behavior and film properties. By contrast, cationic nanophytoglycogen alters the film morphology and increases the hysteresis associated with the work of breathing due to its electrostatic interaction with the anionic phospholipids in the model systems. These findings specifically highlight the importance of surface charge as a selection criterion for inhaled nanoformulations.

Dose-Response Oxidation of Ingested Phytoglycogen during Exercise in Endurance-Trained Men

BACKGROUND

Phytoglycogen (PHY; PhytoSpherix; Mirexus Biotechnologies), a highly branched polysaccharide extracted from sweet corn, has considerable potential for exercise oxidation due to its low viscosity in water, high water retention, and exceptional stability.

OBJECTIVES

Using gas chromatography-isotope ratio mass spectrometry, we investigated dose-response oxidation of ingested PHY during prolonged, moderate-intensity exercise.

METHODS

Thirteen men (≥1 y endurance-training experience, ≥6 d·wk-1, ∼1-1.5 h·d-1; age, 25.7 ± 5.5 y; mass, 79.3 ± 10.0 kg;  V̇O2max, 59.9 ± 5.5 mL·kg-1·min-1; means ± SDs) cycled for 150 min (50% maximal watt output) while ingesting PHY concentrations of 0.0% (0.0 g·min-1), 3.6% (0.5 g·min-1), 7.2% (1.0 g·min-1), 10.8% (1.5 g·min-1), or 14.4% (2 g·min-1) in water (2100 mL) (n = 7-10/dose). Substrate oxidation was determined using stable-isotope methods and indirect calorimetry.

RESULTS

PHY oxidation plateaued between 60 and 150 min of exercise and increased (P < 0.001) from 0.49 to 0.72 g·min-1 with 0.5- and 1.0-g·min-1 doses without further increases (0.76 and 0.73 g·min-1; P > 0.05) with 1.5 or 2 g·min-1. Peak PHY oxidation (0.84 ± 0.04 g·min-1) occurred in the final 30 min of exercise with 2 g·min-1. Exercise blood glucose was greater (5.1 mmol·L-1) with 1.0-, 1.5-, and 2-g·min-1 doses compared with that of 0.5 (4.7 mmol·L-1) or 0.0 g·min-1 (4.2 mmol·L-1) (P < 0.0001). Gastrointestinal distress was minimal except with 2 g·min-1 (P < 0.001).

CONCLUSIONS

In male endurance athletes, PHY oxidation plateaued at 0.72-0.76 g·min-1 during 150 min of cycling at 50% Wmax (peak oxidation of 0.84 g·min-1 occurred during the final 30 min). This trial was registered at clinicaltrials.gov as NCT02909881.

Ultrasound-Assisted Microencapsulation of Soybean Oil and Vitamin D Using Bare Glycogen Nanoparticles

Ultrasonically synthesized core-shell microcapsules can be made of synthetic polymers or natural biopolymers, such as proteins and polysaccharides, and have found applications in food, drug delivery and cosmetics. This study reports on the ultrasonic synthesis of microcapsules using unmodified (natural) and biodegradable glycogen nanoparticles derived from various sources, such as rabbit and bovine liver, oyster and sweet corn, for the encapsulation of soybean oil and vitamin D. Depending on their source, glycogen nanoparticles exhibited differences in size and 'bound' proteins. We optimized various synthetic parameters, such as ultrasonic power, time and concentration of glycogens and the oil phase to obtain stable core-shell microcapsules. Particularly, under ultrasound-induced emulsification conditions (sonication time 45 s and sonication power 160 W), native glycogens formed microcapsules with diameter between 0.3 μm and 8 μm. It was found that the size of glycogen as well as the protein component play an important role in stabilizing the Pickering emulsion and the microcapsules shell. This study highlights that native glycogen nanoparticles without any further tedious chemical modification steps can be successfully used for the encapsulation of nutrients.

Reduction of antibiotic-induced biofilm accumulation of Pseudomonas aeruginosa by quaternized phytoglycogen

Biofilms are oft cited as a factor in the unwanted persistence and recalcitrance of microbial life and a strong research initiative exists to identify, understand, and target vulnerabilities. Phytoglycogen is a biodegradable nanoparticulate biomaterial that is purified from crop plants. Importantly, the highly branched glucan structure provides a scaffold on which to construct novel polymers. Functionalized phytoglycogen (FP) was synthesized using green chemistry principles. Screening of several molecules identified a form of quaternized phytoglycogen which reduced biofilm formation and accretion by Pseudomonas aeruginosa. Exposing P. aeruginosa to modified phytoglycogen and antibiotic in combination not only substantively reduced biofilms, but also prevented increased biofilm formation, a biological response to suboptimal antibiotic concentrations. Treatment of pregrown biofilms with sub-minimum inhibitory concentration antibiotic alone also led to increased proliferation, whereas FP-antibiotic combinations prevented or reduced the extent of this. Swimming, swarming and twitching motility, all critical for biofilm development, were negatively affected by FP. This work supports phytoglycogen as a promising foundational molecule for novel polymers, including those with anti-biofilm function. Critically, in addition to published reports on how suboptimal antibiotic concentrations promote biofilm formation, we demonstrated a similar effect upon pre-existing biofilms, indicating a further route for the failure of antibiotic therapies.

Environmentally friendly antibiofilm strategy based on cationized phytoglycogen nanoparticles

Biofilm tolerance to antibiotics has led to the search for new alternatives in treating biofilms. The use of metallic nanoparticles has been a suggested strategy against biofilms, but their potential environmental toxicity and high cost of synthesizing have limited their applications. In this study, we investigate the potential of polysaccharidic phytoglycogen nanoparticles extracted from corn, in treating cyanobacterial biofilms, which are the source of toxins and pollution in aquatic environments. Our results revealed that the surface of cyanobacterial cells was dominated by the negatively charged functional groups such as carboxylic and phosphoric groups. The native phytoglycogen (PhX) nanoparticles were dominated with non-charged groups, such as hydroxyl groups, and the cationized phytoglycogen (PhXC) nanoparticles showed positively charged surfaces due to the presence of quaternary ammonium cations. Our results indicated that, as opposed to PhX, PhXC strongly inhibited biofilm formation when dispersed in the culture medium. PhXC also eradicated the already grown cyanobacterial biofilms. The antibiofilm properties of PhXC were attributed to its strong electrostatic interactions with the cyanobacterial cells, which could inhibit cell/cell and cell/substrate interactions and nutrient exchange with the media. This class of antibacterial polysaccharide nanoparticles may provide a novel cost-effective and environment-friendly strategy for treating biofilm formation by a broad spectrum of bacteria.

Characterization of the volume fraction of soft deformable microgels by means of small-angle neutron scattering with contrast variation

The volume occupied by colloids in a suspension - namely the volume fraction - is the thermodynamic variable that determines the phase behavior of these systems. While for hard incompressible spheres this quantity is well defined, for soft compressible colloids such as microgels - polymeric crosslinked networks swollen in a good solvent - the determination of the real volume occupied by these particles in solution is particularly challenging. This fact depends on two aspects: first the surface and, therefore, the volume of the microgels is hard to define properly given their external fuzziness; second, microgels can osmotically deswell, deform or interpenetrate their neighbors, i.e. change their shape and size depending on the solution concentration. Here, the form factors of few hydrogenated microgels embedded in a matrix of deuterated but otherwise identical microgels are measured using small-angle neutron scattering with contrast variation. From the analysis of the scattering data, the variation of the volume of the microgels as a function of concentration is obtained and used to calculate the real microgel volume fraction in solution. Soft neutral microgels are shown to facet already at low concentrations while in contrast, harder microgels maintain their shape and change their volume.

Force Spectroscopy Mapping of the Effect of Hydration on the Stiffness and Deformability of Phytoglycogen Nanoparticles

Phytoglycogen is a naturally occurring glucose polymer that is produced by sweet corn in the form of compact nanoparticles with a dendritic or tree-like architecture. The soft and porous nature of the nanoparticles, combined with their biodegradability and lack of toxicity, makes them ideal for a broad range of applications in personal care, nutrition, and biomedicine. To fully exploit these applications, it is necessary to understand the complex properties of the soft, hydrated nanoparticles in detail. In the present study, we have used atomic force microscopy (AFM) force spectroscopy to collect high-resolution force-distance maps of a large number of individual phytoglycogen nanoparticles, providing unique insights into the morphology and mechanical stiffness of the nanoparticles at the single-particle level. Our measurements performed in water on nanoparticles covalently bonded to gold surfaces revealed an inner branched structure and high deformability of the nanoparticles at modest values of the applied force. These measurements also allowed us to determine the spatial distribution of Young's modulus values within individual nanoparticles. Drying of the nanoparticles resulted in a dramatic increase in Young's modulus, quantifying the effect of hydration on their mechanical stiffness. We obtained excellent agreement between AFM and osmotic pressure measurements of the mechanical properties of hydrated phytoglycogen nanoparticles; the ratio of the average Young's modulus measured using AFM to the bulk modulus measured using osmotic pressure was in close agreement with that expected for a material with Poisson's ratio ν = 0. The soft, deformable nature of phytoglycogen nanoparticles revealed by our measurements provides new insights at the single-nanoparticle level and suggests their suitability for biomedical applications such as transdermal and targeted drug delivery.

SANS quantification of bound water in water-soluble polymers across multiple concentration regimes

Contrast-variation small-angle neutron scattering (CV-SANS) is a widely used technique for quantifying hydration water in soft matter systems, but it is predominantly applied in the dilute regime or for systems with a well-defined structure factor. Here, CV-SANS was used to quantify the number of hydration water molecules associating with three water-soluble polymers with different critical solution temperatures and types of water-solute interactions in dilute, semidilute, and concentrated solution through the exploration of novel methods of data fitting and analysis. Multiple SANS fitting workflows with varying levels of model assumptions were evaluated and compared to give insight into SANS model selection. These fitting pathways ranged from general, model-free algorithms to more standard form and structure factor fitting. In addition, Monte Carlo bootstrapping was evaluated as a method to estimate parameter uncertainty through simulation of technical replicates. The most robust fitting workflow for dilute solutions was found to be form factor fitting without CV-SANS (i.e. polymer in 100% D2O). For semidilute and concentrated solutions, while the model-free approach can be mathematically defined for CV-SANS data, the addition of a structure factor imposes physical constraints on the optimization problem, suggesting that the optimal fitting pathway should include appropriate form and structure factor models. The measured hydration numbers were consistent with the number of tightly bound water molecules associated with each monomer unit, and the concentration dependence of the hydration number was largely governed by the chemistry-specific interactions between water and polymer. Polymers with weaker water-polymer interactions (i.e. those with fewer hydration water molecules) were found to have more bound water at higher concentrations than those with stronger water-polymer interactions due to the increase in the number of forced water-polymer contacts in the concentrated system. This SANS-based method to count hydration water molecules can be applied to polymers in any concentration regime, which will lead to improved understanding of water-polymer interactions and their impact on materials design.

Phytoglycogen Nanoparticles: Nature-Derived Superlubricants

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.

Phytoglycogen Nanoparticle Delivery System for Inorganic Selenium Reduces Cytotoxicity without Impairing Selenium Bioavailability

Purpose

Selenium is an essential trace element that supports animal health through the antioxidant defense system by protecting cells from oxidative-related damage. Using inorganic selenium species, such as sodium selenite (Na Sel), as a food supplement is cost-effective; however, its limitation as a nutritional supplement is its cytotoxicity. One strategy to mitigate this problem is by delivering inorganic selenium using a nanoparticle delivery system (SeNP).

Methods

Rainbow trout intestinal epithelial cells, bovine turbinate cells and bovine intestinal myofibroblasts were treated with soluble Na Sel or SeNPs. Two SeNP formulations were tested; SeNP-Ionic where inorganic selenium was ionically bound to cationic phytoglycogen (PhG) NPs, and SeNP-Covalent, where inorganic selenium was covalently bound to PhG NPs. Selenium-induced cytotoxicity along with selenium bioavailability were measured.

Results

SeNPs (SeNP-Ionic or SeNP-Covalent) substantially reduced cytotoxicity in all cell types examined compared to similar doses of soluble inorganic selenium. The SeNP formulations did not affect selenium bioavailability, as selenium-induced glutathione peroxidase (GPx) activity and GPx1 transcript levels were similarly elevated whether cells were treated with soluble Na Sel or SeNPs. This was the case for all three cell types tested.

Conclusion

Nanoparticle-assisted inorganic selenium delivery, which demonstrated equal bioavailability without causing deleterious cytotoxic side effects, has potential applications for safely supplementing animal diets with inorganic selenium at what are usually toxic doses.

Biopolymer-Based Nanotechnology Approaches To Deliver Bioactive Compounds for Food Applications: A Perspective on the Past, Present, and Future

Food nanotechnology is an emerging and rapidly evolving field that encompasses an extremely broad range of disciplines and has found various applications in different food sectors. The objective of this perspective is to update the current knowledge on the nanotechnology-based approaches to prepare delivery vehicles for bioactive compounds. Research progress on the development of nanoparticles made from food biopolymers (i.e., protein and polysaccharide) is particularly highlighted. In addition, two types of most recently developed nanoscale delivery systems, i.e., protein-polysaccharide complex and lipid-biopolymer hybrid nanoparticles, are introduced, and their relevant applications are discussed. Finally, suggestions for future research directions on developing safe, effective, and edible nanoscale delivery vehicles for food applications are provided.

Encapsulation of Phloretin in a Ternary Nanocomplex Prepared with Phytoglycogen-Caseinate-Pectin via Electrostatic Interactions and Chemical Cross-Linking

In this study, we chemically modified a phytoglycogen structure to introduce negative surface charge via carboxymethylation (CMPG) and then prepared CMPG-based ternary nanocomplex particles through electrostatic interactions with sodium caseinate (core) and chemical cross-linking with pectin (shell). The chemical cross-linking process by glutaradehyde was systematically optimized under various temperatures and durations. The cross-linked ternary nanocomplex was comprehensively characterized, and our results showed that it had a size of 86 nm with a spherical shape, smooth surface, homogeneous distribution, and negative surface charge. The chemical cross-linking process significantly improved colloidal stability of the nanocomplex under simulated gastrointestinal fluids with digestive enzymes. The as-prepared nanocomplex exhibited exceptional capability to encapsulate phloretin, a natural dihydrochalcone, as a model lipophilic bioactive compound. The nanocomplex not only showed a slow and sustained kinetic release of phloretin under simulated gastrointestinal fluids but also dramatically enhanced its antioxidant activity under an aqueous environment compared to pure phloretin dissolved in ethanol. Findings from this work revealed the promising features of the as-prepared ternary nanocomplex as a potential oral delivery system for lipophilic bioactive compounds.

Protein Component of Oyster Glycogen Nanoparticles: An Anchor Point for Functionalization

Biosourced nanoparticles have a range of desirable properties for therapeutic applications, including biodegradability and low immunogenicity. Glycogen, a natural polysaccharide nanoparticle, has garnered much interest as a component of advanced therapeutic materials. However, functionalizing glycogen for use as a therapeutic material typically involves synthetic approaches that can negatively affect the intrinsic physiological properties of glycogen. Herein, the protein component of glycogen is examined as an anchor point for the photopolymerization of functional poly(N-isopropylacrylamide) (PNIPAM) polymers. Oyster glycogen (OG) nanoparticles partially degrade to smaller spherical particles in the presence of protease enzymes, reflecting a population of surface-bound proteins on the polysaccharide. The grafting of PNIPAM to the native protein component of OG produces OG-PNIPAM nanoparticles of ∼45 nm in diameter and 6.2 MDa in molecular weight. PNIPAM endows the nanoparticles with temperature-responsive aggregation properties that are controllable and reversible and that can be removed by the biodegradation of the protein. The OG-PNIPAM nanoparticles retain the native biodegradability of glycogen. Whole blood incubation assays revealed that the OG-PNIPAM nanoparticles have a low cell association and inflammatory response similar to that of OG. The reported strategy provides functionalized glycogen nanomaterials that retain their inherent biodegradability and low immune cell association.

Glycogen as a Building Block for Advanced Biological Materials

Biological nanoparticles found in living systems possess distinct molecular architectures and diverse functions. Glycogen is a unique biological polysaccharide nanoparticle fabricated by nature through a bottom-up approach. The biocatalytic synthesis of glycogen has evolved over time to form a nanometer-sized dendrimer-like structure (20-150 nm) with a highly branched surface and a dense core. This makes glycogen markedly different from other natural linear or branched polysaccharides and particularly attractive as a platform for biomedical applications. Glycogen is inherently biodegradable, nontoxic, and can be functionalized with diverse surface and internal motifs for enhanced biofunctional properties. Recently, there has been growing interest in glycogen as a natural alternative to synthetic polymers and nanoparticles in a range of applications. Herein, the recent literature on glycogen in the material-based sciences, including its use as a constituent in biodegradable hydrogels and fibers, drug delivery vectors, tumor targeting and penetrating nanoparticles, immunomodulators, vaccine adjuvants, and contrast agents, is reviewed. The various methods of chemical functionalization and physical assembly of glycogen nanoparticles into multicomponent nanodevices, which advance glycogen toward a functional therapeutic nanoparticle from nature and back again, are discussed in detail.

Photopolymerized Starchstarch Nanoparticle (SNP) network hydrogels

Starch is an attractive biomaterial given its low cost and high protein repellency, but its use in forming functional hydrogels is limited by its high viscosity and crystallinity. Herein, we demonstrate the use of fully amorphous starch nanoparticles (SNPs) as functional hydrogel building blocks that overcome these challenges. Methacrylation of SNPs enables hydrogel formation via photopolymerization, with the low viscosity of SNPs enabling facile preparation of pre-gel suspensions of up to 35 wt% SNPs relative to <10 wt% with linear starch. Small angle neutron scattering indicates a significantly different microstructure in SNP-based hydrogels compared to linear starch-based hydrogels due to the balance between inter- and intra-particle crosslinks, consistent with SNPs forming denser and stiffer hydrogels. Functionalized SNPs are highly cytocompatible at degree of substitution values <0.25 and, once gelled, can effectively repel cell adhesion. The physicochemical versatility and biological functionality of SNP-based hydrogels offer potential in various applications.

Characterizing the Physical Properties and Cell Compatibility of Phytoglycogen Extracted from Different Sweet Corn Varieties

Owing to its unique structure and properties, the glucose dendrimer phytoglycogen is gaining interest for medical and biotechnology applications. Although many maize variants are available from commercial and academic breeding programs, most applications rely on phytoglycogen extracted from the common maize variant, sugary1. Here we characterized the solubility, hydrodynamic diameter, water-binding properties, protein contaminant concentration, and cytotoxicity of phytoglycogens from different maize sources, A632su1, A619su1, Wesu7, and Ia453su1, harboring various sugary1 mutants. A619su1-SW phytoglycogen was cytotoxic while A632su1-SW phytoglycogen was not. A632su1-Pu phytoglycogen promoted cell growth, whereas extracts from A632su1-NE, A632su1-NC, and A632su1-CM were cytotoxic. Phytoglycogen extracted from Wesu7su1-NE using ethanol precipitation was cytotoxic. Acid-treatment improved Wesu7 phytoglycogen cytocompatibility. Protease-treated Wesu7 extracts promoted cell growth. Phytoglycogen extracted from Ia453su1 21 days after pollination (“Ia435su1 21DAP”) was cytotoxic, whereas phytoglycogen extracted at 40 days (“Ia435su1 40DAP”) was not. In general, size and solubility had no correlation with cytocompatibility, whereas protein contaminant concentration and water-binding properties did. A632su1-CM had the highest protein contamination among A632 mutants, consistent with its higher cytotoxicity. Likewise, Ia435su1 21DAP phytoglycogen had higher protein contamination than Ia435su1 40DAP. Conversely, protease-treated Wesu7 extracts had lower protein contamination than the other Wesu7 extracts. A632su1-NE, A632su1-NC, and A632su1-CM had similar water-binding properties which differed from those of A632su1-Pu and A632su1-SW. Likewise, water binding differed between Ia435su1 21DAP and Ia435su1 40DAP. Collectively, these data demonstrate that maize phytoglycogen extracts are not uniformly cytocompatible. Rather, maize variant, plant genotype, protein contaminants, and water-binding properties are determinants of phytoglycogen cytotoxicity.

Flow properties reveal the particle-to-polymer transition of ultra-low crosslinked microgels

Exploiting soft, adaptive microgels as building blocks for soft materials with controlled and predictable viscoelastic properties is of great interest for both industry and fundamental research. Here the flow properties of different poly(N-isopropylacrylamide) (pNIPAM) microgels are compared: regularly crosslinked versus ultra-low crosslinked (ULC) microgels. The latter are the softest microgels that can be produced via precipitation polymerization. The viscosity of ULC microgel suspensions at low concentrations can be described with models typically used for hard spheres and regularly crosslinked microgels. In contrast, at higher concentrations, ULC microgels show a much softer behavior compared to regularly crosslinked microgels. The increase of the storage modulus with concentration discloses that while for regularly crosslinked microgels the flow properties are mainly determined by the more crosslinked core, for ULC microgels the brush-like interaction is dominant at high packing fractions. Both the flow curves and the increase of the storage modulus with concentration indicates that ULC microgels can form glass and even reach an apparent jammed state despite their extreme softness. In contrast, the analysis of oscillatory frequency sweep measurements show that when approaching the glass transition the ultra-low crosslinked microgels behave as the regularly crosslinked microgels. This is consistent with a recent study showing that in this concentration range the equilibrium phase behavior of these ULC microgels is the one expected for regularly crosslinked microgels.

Molecular origins of bulk viscosity in liquid water

The shear viscous response of water is closely associated with changes in network connectivity on the sub ps timescale. The bulk viscous response is shown here to be associated with local density fluctuations and rotational motion around 1–3 ps.

Nanoengineering multifunctional hybrid interfaces using adhesive glycogen nanoparticles

Amphiphilic phytoglycogen nanoparticles are used as building blocks for engineering multifunctional hybrid films with catalytic and sensing properties.

Translocation of soft phytoglycogen nanoparticles through solid-state nanochannels

Phytoglycogen nanoparticles are soft, naturally-derived nanomaterials with a highly uniform size near 35 nm. Their interior is composed of a highly-branched polysaccharide core that contains more than 200% of its dry mass in water. In this work, we measure the translocation of phytoglycogen particles by observing blockade events they create when occluding solid-state nanochannels with diameters between 60 and 100 nm. The translocation signals are interpreted using Poisson-Nernst-Planck calculations with a "hardness parameter" that describes the extent to which solvent can penetrate through the interior of the particles. Theory and experiment were found to be in quantitative agreement, allowing us to extract physical characteristics of the particles on a per particle basis.