Formation, stability and in vitro digestion of curcumin loaded whey protein/ hyaluronic acid nanoparticles: Ethanol desolvation vs. pH-shifting method

Preparation and characterization of tilapia protein isolate - Hyaluronic acid complexes using a pH-driven method for improving the stability of tilapia protein isolate emulsion

This study aimed to investigate the non-covalent complexation between hyaluronic acid (HA) and tilapia protein isolate (TPI) on the stability of oil-in-water (O/W) TPI emulsion. The results showed that HA binds to TPI through electrostatic, hydrophobic, and hydrogen bonding interactions, forming homogeneous hydrophilic TPI-HA complexes. The binding of HA promoted the structural folding of TPI and altered its secondary structure during pH neutralization. The TPI-HA complexes presented significantly improved EAI and ESI (P < 0.05) when the HA concentration was 0.8 % (w/v). Emulsion characterization showed that HA promoted the transfer of TPI to the O/W interface, forming an emulsion with excellent stability, which, combined with the high surface charge and strong spatial site resistance effect of HA, improved TPI emulsion stability. Therefore, non-covalent complexation with HA is an effective strategy to improve the stability of TPI emulsion.

Physicochemical Properties, Stability, and Functionality of Non-Covalent Ternary Complexes Fabricated with Pea Protein, Hyaluronic Acid and Chlorogenic Acid

The aim of this study was to prepare and characterize stable non-covalent ternary complexes based on pea protein (PP, 0.5%), hyaluronic acid (HA, 0.125%), and chlorogenic acid (CA, 0~0.03%). The ternary complexes were comprehensively evaluated for physicochemical attributes, stability, emulsifying capacities, antioxidant properties, and antimicrobial efficacy. PP-HA binary complexes were first prepared at pH 7, and then CA was bound to the binary complexes, as verified by fluorescence quenching. Molecular docking elucidated that PP interacted with HA and CA through hydrogen bonding, hydrophobic and electrostatic interactions. The particle size of ternary complexes initially decreased, then increased with CA concentration, peaking at 0.025%. Ternary complexes demonstrated good stability against UV light and thermal treatment. Emulsifying activity of complexes initially decreased and then increased, with a turning point of 0.025%, while emulsion stability continued to increase. Complexes exhibited potent scavenging ability against free radicals and iron ions, intensifying with higher CA concentrations. Ternary complexes effectively inhibited Staphylococcus aureus and Escherichia coli, with inhibition up to 0.025%, then decreasing with CA concentration. Our study indicated that the prepared ternary complexes at pH 7 were stable and possessed good functionality, including emulsifying properties, antioxidant activity, and antibacterial properties under certain concentrations of CA. These findings may provide valuable insights for the targeted design and application of protein-polysaccharide-polyphenol complexes in beverages and dairy products.

Maintained particulate integrity of soy protein nanoparticles during gastrointestinal digestion via genipin crosslinking enhancing stability and bioavailability of curcumin

Poor stability during gastrointestinal digestion is a major challenge for the applications of protein-based nanoparticles as oral delivery systems. In this work, genipin was used to crosslink the partially enzymatic hydrolyzed soy protein nanoparticles, aiming to improve their performance in gastrointestinal tract as delivery carrier. Results showed that the obtained genipin-crosslinked soy protein nanoparticles (GSPNPs) were still spherically monodisperse with a diameter around 60 nm. Encapsulation with GSPNPs significantly improved the solubility of curcumin (Cur) and its stability against UV light as well as long-term storage. Compared to those un-crosslinked nanoparticles, particles crosslinked by genipin had a more compact structure less sensitive to ionic effect and digestive enzymes, showing enhanced digestion stability. The well-maintained nanoparticulate structure of GSPNPs further contributed to the enhanced bioaccessibility and facilitated absorption by epithelial cells. Furthermore, in vivo experiment on rats showed that Cur encapsulated in GSPNPs exhibited a slowed down and sustained absorption manner with an 8.11-fold improvement in its bioavailability. These suggested that GSPNPs could be a promising nanocarrier to enhance the bioavailability of functional factors.

Stabilization mechanisms and digestion properties of Pickering emulsions prepared with tempo-oxidized hyaluronic acid/chitosan nanoparticles: From the perspective of oxidation degree

In this study, the stabilization mechanism and digestion behavior of Pickering emulsion prepared by a combination of chitosan (CS) and TEMPO-oxidized hyaluronic acid (HA) were investigated. Conductometric titration was used to determine the degree of oxidation and carboxylate content of TEMPO-oxidized HA. The results showed that the degree of oxidation increased proportionally with increasing oxidation time, and the electrostatic and hydrogen bonding interactions with CS were significantly enhanced. The results of FTIR and TEM showed the formation of CS/oxidized HA nanoparticles (CS/oxidized-HANPs). In addition, the contact angle of CS/oxidized-HANPs is closed to 77°, thereby providing higher desorption energy at the interface. Rheological results showed that the Pickering emulsion exhibited a gel-like network structure and higher viscosity. In vitro digestion results suggested that the quercetin (Que) bioaccessibility of the CS/oxidation HANps-stabilized Pickering emulsion with an oxidation time of 20 min was better than that of the conventional emulsion prepared with CS alone. The research is expected to develop novel polysaccharide-based Pickering emulsion delivery systems for functional compounds.

Enhanced bioavailability of curcumin amorphous nanocomposite prepared by a green process using modified starch

Curcumin (Cur), a bioactive compound extracted from plants, has attracted widespread attention due to its multiple pharmacological activities. However, the low bioavailability due to the inherent limitations in water solubility, chemical stability, and permeability poses great challenges for realizing its clinical potentials. In the current study, octenyl succinic anhydride-modified starch (OSA-S), a renewable and biodegradable biopolymer, was employed to fabricate Cur amorphous composite nanoparticles (Cur/OSA-S NPs) through a solvent-free pH-driven method with the aim to enhance Cur's bioavailability by improving its solubility and stability. Cur/OSA-S NPs, with mean sizes of about 128.9 ± 8.6 nm, encapsulation efficiencies of about 90.0 %, and the drug loading capacities around 51.0 ± 0.2 %, were successfully prepared. Cur was found to be dispersed within the composite nanoparticles in amorphous state as confirmed by the XRD and DSC characterizations. In addition, Cur/OSA-S NPs offers excellent storage, thermal and light stability, excellent re-dispersibility, and approximately 92 times better solubility than the original Cur. Furthermore, studies of dissolution and the parallel artificial membrane permeability assay (PAMPA) confirmed enhanced dissolution rates and in vitro permeabilities of Cur/OSA-S NPs. Cancer cell viability and uptake experiments revealed that Cur/OSA-S NPs possessed more potent inhibitory effects on cancer cell proliferation compared to the raw Cur. The results obtained from the current study demonstrated the effectiveness of OSA-S for manufacturing Cur amorphous composite nanoparticles with enhanced solubility, stability, and permeability, which might be valuable for further development of Cur based products for treatment of various diseases.

Stability, Digestion, and Cellular Transport of Soy Isoflavones Nanoparticles Stabilized by Polymerized Goat Milk Whey Protein

Soy isoflavones (SIF) are bioactive compounds with low bioavailability due to their poor water solubility. In this study, we utilized polymerized goat milk whey protein (PGWP) as a carrier to encapsulate SIF with encapsulation efficiency of 89%, particle size of 135.53 nm, and zeta potential of -35.16 mV. The PGWP-SIF nanoparticles were evaluated for their stability and in vitro digestion properties, and their ability to transport SIF was assessed using a Caco-2 cell monolayer model. The nanoparticles were resistant to aggregation when subjected to pH changes (pH 2.0 to 8.0), sodium chloride addition (0-200 mM), temperature fluctuations (4 °C, 25 °C, and 37 °C), and long-term storage (4 °C, 25 °C, and 37 °C for 30 days), which was mainly attributed to the repulsion generated by steric hindrance effects. During gastric digestion, only 5.93% of encapsulated SIF was released, highlighting the nanoparticles' resistance to enzymatic digestion in the stomach. However, a significant increase in SIF release to 56.61% was observed during intestinal digestion, indicating the efficient transport of SIF into the small intestine for absorption. Cytotoxicity assessments via the MTT assay showed no adverse effects on Caco-2 cell lines after encapsulation. The PGWP-stabilized SIF nanoparticles improved the apparent permeability coefficient (Papp) of Caco-2 cells for SIF by 11.8-fold. The results indicated that using PGWP to encapsulate SIF was an effective approach for delivering SIF, while enhancing its bioavailability and transcellular transport.

Novel Pickering emulsion stabilized by glycosylated whey protein isolate: Characterization, stability, and curcumin bioaccessibility

Pickering emulsions prepared from protein-polysaccharide complexes have attracted increasing attention. In this study, whey protein isolates (WPI) were modified with oligochitosan using transglutaminase (TGase)-type to fabricate Pickering emulsions, and loaded with curcumin. The curcumin/protein ratio of 1:25 and oil phase fraction (φ = 17 %) are the most optimal condition for emulsions stabilization, and particle size of glycosylated WPI emulsion was 31.70 μm. Glycosylated WPI emulsion had the highest encapsulation efficiency (96.64 %) of curcumin. Microstructure analysis showed that glycosylated WPI had small droplets covered by dense interface layers. The modified WPI emulsions exhibited optimal emulsifying properties and emulsion stability, which effectively inhibited the premature water-oil stratification in emulsion. In vitro digestion results showed that WPI-oligochitosan complexes enhanced curcumin bioaccessibility (40.34 %). The antioxidant activity of glycosylated WPI emulsions was significantly increased. The results of this study provide helpful references for applying glycosylated WPI-stabilized Pickering emulsions, which can be used as transport carriers of curcumin.

Development of Novel Nanocarriers by Ultrasound and Ethanol-Assisted Soy Protein Isolate: Enhancing the Resistance of Lutein to Environmental Stress

The aim of this work was to investigate the effects of the processing sequence of ultrasound and ethanol on the physicochemical properties of soy protein isolate (SPI), which were further evaluated for the morphology and stability of SPI-lutein coassembled nanoparticles. The results showed that the sequence of ultrasound followed by ethanol treatment was the optimal one. The samples were subjected to ultrasonication followed by subunit disassembly and reassembly induced by 40% (v/v) ethanol, with the resulting molecular unfolding and subsequent aggregation being attributed to intramolecular hydrogen bonds. The recombined nanoparticles had smaller particle size (142.43 ± 2.91 nm) and turbidity (0.16 ± 0.01), and the exposure of more hydrophobic groups (H0 = 6221.00 ± 130.20) induced a shift of SPI structure toward a more ordered direction. The homogeneous and stable particle provided excellent stability for the loading of lutein. The bioaccessibility (from 25.48 ± 2.35 to 65.85 ± 1.78%) and release rate of lutein were modulated in gastrointestinal digestion experiments. Our discoveries provide a new perspective for the development of combined physicochemical modification of proteins as nanocarriers in functional foods.

Combination of Machine Learning and Raman Spectroscopy for Determination of the Complex of Whey Protein Isolate with Hyaluronic Acid

Macromolecules and their complexes remain interesting topics in various fields, such as targeted drug delivery and tissue regeneration. The complex chemical structure of such substances can be studied with a combination of Raman spectroscopy and machine learning. The complex of whey protein isolate (WPI) and hyaluronic acid (HA) is beneficial in terms of drug delivery. It provides HA properties with the stability obtained from WPI. However, differences between WPI-HA and WPI solutions can be difficult to detect by Raman spectroscopy. Especially when the low HA (0.1, 0.25, 0.5% w/v) and the constant WPI (5% w/v) concentrations are used. Before applying the machine learning techniques, all the collected data were divided into training and test sets in a ratio of 3:1. The performances of two ensemble methods, random forest (RF) and gradient boosting (GB), were evaluated on the Raman data, depending on the type of problem (regression or classification). The impact of noise reduction using principal component analysis (PCA) on the performance of the two machine learning methods was assessed. This procedure allowed us to reduce the number of features while retaining 95% of the explained variance in the data. Another application of these machine learning methods was to identify the WPI Raman bands that changed the most with the addition of HA. Both the RF and GB could provide feature importance data that could be plotted in conjunction with the actual Raman spectra of the samples. The results show that the addition of HA to WPI led to changes mainly around 1003 cm-1 (correspond to ring breath of phenylalanine) and 1400 cm-1, as demonstrated by the regression and classification models. For selected Raman bands, where the feature importance was greater than 1%, a direct evaluation of the effect of the amount of HA on the Raman intensities was performed but was found not to be informative. Thus, applying the RF or GB estimators to the Raman data with feature importance evaluation could detect and highlight small differences in the spectra of substances that arose from changes in the chemical structure; using PCA to filter out noise in the Raman data could improve the performance of both the RF and GB. The demonstrated results will make it possible to analyze changes in chemical bonds during various processes, for example, conjugation, to study complex mixtures of substances, even with small additions of the components of interest.

Fabrication of resveratrol-loaded soy protein isolate-glycyrrhizin nanocomplex for improving bioavailability via pH-responsive hydrogel properties

Resveratrol (RES) is a functional polyphenol that suffers from low water solubility and poor bioavailability. A novel RES-loaded soy protein isolate-dipotassium glycyrrhizinate (SPI-DG) nanocomplex (RES@SPI-DG) was designed and evaluated in this study. RES@SPI-DG was prepared using a simple but novel self-assembly ultrasonic-assisted pH-driven method. The interactions between RES and SPI-DG were non-covalent bonds, including hydrophobic interactions, hydrogen bonds, and van der Waals interactions. RES@SPI-DG exhibited high encapsulation efficiency (97.60 ± 0.38 %) and loading capacity (8.74 ± 0.03 %) of RES with a uniform small size (68.39 ± 1.10 nm). RES in RES@SPI-DG was in an amorphous state and demonstrated a 24-h apparent solubility 482.53-fold higher than bare RES. RES@SPI-DG also showed strong in vitro antioxidant properties. The pH-responsive hydrogel character of SPI-DG makes it an effective intestine-targeted delivery system that could retard the release of RES in a simulated stomach and accelerate it in a simulated intestine. In animal experiments, the bioavailability of RES@SPI-DG was 5.17 times higher than that of bare RES, and the biodistribution was also significantly improved. RES@SPI-DG demonstrated a strong hepatoprotective effect against overdose acetaminophen-induced liver injury. The SPI-DG complex might be a promising nano-platform for enhancing the bioavailability and efficacy of hydrophobic polyphenols such as RES.

Zein/hyaluronic acid nanoparticle stabilized Pickering emulsion for astaxanthin encapsulation

Pickering emulsions have attracted considerable attention owing to the stability and functionality. In this study, zein/hyaluronic acid (ZH) nanoparticles were prepared and applied for stabilizing astaxanthin encapsulated Pickering emulsions. By non-covalent interaction between Zein and hyaluronic acid (HA), the conformation of zein changed and therefore improved the wettability of ZH nanoparticles. Unlike the spherical zein nanoparticles, ZH nanoparticles possessed a cross-linked structure with rough surface. Confocal laser scanning microscopy indicated that the nanoparticles accumulated at the oil-water interface. The Pickering emulsion stabilized by ZH nanoparticles exhibited high viscoelasticity and a solid-like behavior, as well as excellent stability during the storage. In vitro digestion results revealed that the presence of HA coating prevented the emulsion from pepsin hydrolysis and achieved efficient delivery of astaxanthin. This work confirmed that Pickering emulsion stabilized by ZH nanoparticles could be used as an effective deliver system for bioactive substances.

Extraction, identification and application of gliadin from gluten: Impact of pH on physicochemical properties of unloaded- and lutein-loaded gliadin nanoparticles

In the present study, high purity gliadin was extracted from gluten by the marginally modified Osborne method and the effect of different pHs in the aqueous ethanol on the physicochemical properties of unloaded gliadin nanoparticles (UGNs) and lutein-loaded gliadin nanoparticles (LGNs) was investigated. The results revealed that the formation of UGNs and LGNs at diverse pHs was driven by a conjunction of hydrogen bonding, electrostatic interactions and hydrophobic effects, but their dominant roles varied at different pHs. pH also significantly impacted the surface hydrophobicity, secondary structure and aromatic amino acid microenvironment of UGNs and LGNs. LGNs at pH 5.0 and at pH 9.0 exhibited better loading capacity and could reach 9.7884 ± 0.0006 % and 9.7360 ± 0.0017 %, respectively. These two samples also had greater photostability and thermal stability. Half-lives of LGNs at pH 5.0 were 2.185 h and 54.579 h, respectively. Half-lives of LGNs at pH 9.0 were 2.937 h and 49.159 h, respectively. LGNs at pH 5.0 and LGNs at pH 9.0 also had higher bioaccessibility of lutein, with 15.98 ± 0.04 % and 15.27 ± 0.03 %, respectively. These findings yielded precious inspirations for designing innovative lutein delivery system.

Characteristics of insoluble soybean fiber (ISF) concentrated emulsions: Effects of pretreatment on ISF and freeze-thaw stability of emulsions

The properties of emulsions could be affected by the interactions between the components and network stabilization effect, which are commonly adjusted by changes in pH, ionic strength and temperature. In this work, insoluble soybean fiber (ISF) obtained via homogenization after alkaline treatment was pretreated firstly and then resultant emulsions were freeze-thawed. Heating pretreatment reduced droplet size, enhanced viscosity and viscoelasticity as well as subsequent stability of ISF concentrated emulsions, while both acidic pretreatment and salinized pretreatment decreased the viscosity and weakened the stability. Furthermore, ISF emulsions exhibited a good freeze-thaw performance which was further improved by secondary emulsification. Heating promoted the swelling of ISF and strengthened the gel-like structure of emulsions while salinization and acidization weakened the electrostatic interactions and caused the destabilization. These results indicated that pretreatment of ISF significantly influenced the concentrated emulsion properties, providing guidance for the fabrication of concentrated emulsions and related food with designed characteristics.

Improvement of delivery properties of soybean 7S protein by high-pressure homogenization: In the case of curcumin

In this study, curcumin@high-pressure homogenization-soybean 7S protein/nanoparticles (CUR@HPH-7S-NPs) were prepared by an anti-solvent method. The physicochemical properties results showed at a CUR concentration of 4 mg/mL, CUR@HPH-7S-NPs had better size, encapsulation efficiency (EE), and zeta-potential values of 151.9 nm, 88.80 %, and -23.1 mV, respectively. Fourier transforms infrared (FTIR) and endogenous fluorescence spectroscopy results indicated CUR bound to HPH-7S through hydrophobic interactions, and the force between HPH-7S and CUR molecules was greater than that between untreated 7S protein and CUR. Furthermore, the pH stability results showed the size of CUR@HPH-7S-NPs was barely affected by pH away from adjacent area of the isoelectric point of 7S protein. The physical thermal stability and bio-accessibility results suggested that HPH-7S was more effective in delaying the degradation, had more physical thermal stability, and had a significant improvement in the bio-accessibility of CUR than that of untreated 7S protein. What's more, the antioxidant activity results showed at a CUR equivalent concentration of 40 μg/mL, the DPPH and ABTS radical scavenging activity of CUR@HPH-7S-NPs was 85.10 % and 96.64 %, respectively, both of which were significantly higher than that of free CUR. Finally, this study aimed to provide a theoretical basis for the delivery of other hydrophobic bioactive substances.

Protein-polysaccharide-based delivery systems for enhancing the bioavailability of curcumin: A review

In recent years, a wide attention has been paid to curcumin in medicine due to its excellent physiological activities, including anti-inflammatory, antioxidant, antibacterial, and nerve damage repair. However, the low solubility, poor stability, and rapid metabolism of curcumin make its bioavailability low, which affects its development and application. As a unique biopolymer structure, protein-polysaccharide (PRO-POL)-based delivery system has the advantages of low toxicity, biocompatibility, biodegradability, and delayed release. Many scholars have investigated PRO-POL -based delivery systems to improve the bioavailability of curcumin. In this paper, we focus on the interactions between different proteins (e.g. casein, whey protein, soybean protein isolate, pea protein, zein, etc.) and polysaccharides (chitosan, sodium alginate, hyaluronic acid, pectin, etc.) and their effects on complexes diameter, surface charge, encapsulation drive, and release characteristics. The mechanism of the PRO-POL-based delivery system to enhance the bioavailability of curcumin is highlighted. In addition, the application of PRO-POL complexes loaded with curcumin is summarized, aiming to provide a reference for the construction and application of PRO-POL delivery systems.