Linoleic acid binding properties of ovalbumin nanoparticles

Reduction in the antigenicity of beta-lactoglobulin in whole milk powder via supercritical CO2 treatment

Cow milk allergy is a common phenomenon experienced in early childhood (<5 yr of age) with an average occurrence rate of roughly 2.5%. The most prevalent allergen in cow milk is believed to be β-LG. The objective of this study was to evaluate the use of hydrophobic supercritical CO2 (ScCO2) to modify the chemical structure β-LG, thus impairing its recognition by antibodies. Whole milk powder (WMP) was selected because of its closest compositional resemblance to bovine fluid milk and its applications in reconstitution and in the beverage (infant, toddler, and adult), confectionary, bakery, and meat industries. For this study, WMP was treated with food-grade CO2 at temperatures of 50, 63, and 75°C under operating pressures of 100, 150, 200, 250, and 300 bar. Proteins in WMP were examined using SDS-PAGE, western blot, and ELISA. Orbitrap Fusion liquid chromatography-tandem MS (LC-MS/MS) and periodic staining was performed to confirm post-translational modifications in β-LG. Functional properties of WMP before and after treatment were assessed by its solubility index, oil holding capacity, emulsion capacity and stability, zeta potential, particle size, and color analysis. SDS-PAGE of treated samples yielded fuzzy bands (variable mobility of molecules due to different molecular weights results in ill-defined bands) indicative of an increase in molecular weight, presumably due to chemical change in the protein, and demonstrated a maximum of 71.13 ± 0.29% decrease in the band intensity of β-LG under treatment conditions of 75°C/300 bar for 30 min. These changes were small with samples treated with heat only. Lighter, diffused bands were observed using western blot analysis. The ELISA tests proved that ScCO2 treatment specifically and significantly affected the antigenicity of β-LG with a reduction of 42.9 ± 2.83% and 54.75 ± 2.43% at 63°C/200 bar and 75°C/300 bar, respectively. Orbitrap fusion detected the presence of fatty acids and sugar moieties bound to β-LG and the latter was confirmed by periodic staining. Functional properties of ScCO2-treated milk powder yielded a decrease in solubility index and an increase in emulsion capacity of WMP was observed under ScCO2 treatment at 75°C/300 bar, with small and insignificant changes at other treatments producing a decrease in antigenicity. Color changes were small for most samples, except at 63°C/200 bar, where a significant increase in yellowness was observed. Zeta potential and particle size measurements indicated that most changes were temperature driven. This study demonstrates 2 approaches to mitigate β-LG antigenicity via fatty acid binding and lactosylation using hydrophobic ScCO2.

Docosahexaenoic acid-mediated milk protein treated by ultrasound-assisted pH shifting for enhanced astaxanthin delivery and processed cheese application

Whey protein isolate (WPI)-based nanodelivery systems have recently attracted an increasing amount of attention. Despite this, research focusing on milk protein concentrate (MPC) and micellar casein (MCC) as carriers loaded in hydrophobic compounds is lacking. This study investigated the mediated effect of docosahexaenoic acid (DHA) in 3 different milk proteins for the embedding of astaxanthin (ASTA) after ultrasound-assisted pH-shifting treatment. We then evaluated the application of milk protein carriers in cheese processing by comparing MPC, MCC, and WPI. The particle size, polydispersity index, and zeta potential results of the milk protein-DHA complex suggested that the addition of 0.36 μmol/mL DHA optimized the delivery of milk protein to ASTA. All 3 DHA-mediated milk proteins induced an improvement in encapsulation efficiency and antioxidant properties of ASTA. Furthermore, the DHA-mediated MPC and MCC played a stronger role in improving the bioaccessibility and thermal and storage stability of ASTA than those without DHA. Tests conducted to examine the application in cheese production indicated that MCC carrier had a positive effect on the texture of cheeses. However, the delivery effect was dependent on the milk protein variety, and MCC exhibited the best protection ability of ASTA, followed by MPC and WPI. The simulated digestion and storage stability results of cheese further confirmed that the protein encapsulation mediated by DHA was more conducive to ASTA absorption. These findings suggested that the DHA-mediated milk protein complexes studied here may be suitable hydrophilic delivery carriers for the hydrophobic nutrient ASTA, potentially playing different roles in improving its storage stability and bioaccessibility.

Remarkable Enhancement of Antioxidant Activity of the Ovalbumin-EGCG Conjugate through a Novel Preceding Selective Protection Grafting Strategy

Conventional radical grafting of proteins with catechins consumed the most antioxidant-active hydroxyls during grafting, thus failing to effectively retain antioxidant activity in conjugates. In this study, a novel strategy of selective protection of the most reactive hydroxyls before grafting was developed to preserve the most reactive hydroxyls and effectively retain antioxidant activity in conjugates. Selective protection of the most reactive hydroxyls of (-)-epigallocatechin-3-gallate (EGCG) was successfully realized in a yield of 87% applying trimethyl orthopropionate and catalytic calcium triflate at 40 °C. The novel ovalbumin (OVA)-EGCG conjugate with 93% grafting ratio was prepared by radical grafting with the selectively protected EGCG and subsequent deprotection. Substantially enhanced antioxidant performance of the novel OVA-EGCG conjugate in liposomes was unveiled with notably reduced curcumin degradation and leakage. The strategy and approaches developed in this study will be valuable to effectively improve the antioxidant activities of protein-catechin grafting conjugates.

Modulating the texture of heat-set gels of phosphorylated walnut protein isolates through Glucono-δ-lactone acidification

The gelation of walnut protein isolates has not been extensively studied, mainly due to their inherent poor dispersity. This study investigated the gelation of alkaline-extracted walnut protein isolates (AWPI) and phosphorylated walnut protein isolates (PWPI) induced by heat treatment with glucono-δ-lactone (GDL) acidification, focusing on the impact of GDL concentrations on microstructure, rheology, and texture of the resulting gels. The PWPI gel exhibited lower hardness but a smoother structure than the AWPI gel. Notably, acidification with GDL (0.6-1.2%) significantly increased the stiffness of PWPI gels, increasing storage modulus and yield stress 10-50 times, while weakening AWPI gels. Varying concentrations of GDL effectively modulated the microstructure of the PWPI gels, leading to the altered texture (from a soft-solid state to a well-self-supporting stiff-solid gel) and water holding capacity (from approximately 46% to 85%). Additionally, hydrophobic interactions and disulfide bonds were identified as the primary forces involved in the gels.

Influence of linoleic acid on the immunodetection of shrimp (Litopenaeus vannamei) tropomyosin and the mechanism investigation via multi-spectroscopic and molecular modeling techniques

The effect of linoleic acid (LA) on the IgG/IgE recognition, in vitro digestibility and immunodetection of shrimp tropomyosin (TM) was investigated. Subsequently, the simultaneous binding of LA-TM was explored using multi-spectroscopic and molecular modeling techniques. Our findings reveled that the addition of LA significantly reduced TM's IgG/IgE immunoreactivity, digestibility, and immunodetection. Further analysis using multi-spectroscopic and molecular modeling techniques indicated that while TM's secondary structure remained largely unchanged, its 3-D structure showed significant alterations such as increased particle size and hydrophobic surface area, and a higher number of buried hydrophobic residues exposed due to the binding of LA to TM. These structural changes rendered it difficult for target antibodies and digestive enzymes to interact with related epitopes and cleavage sites buried inside the molecule. The results obtained in this study provide valuable insights into the molecular mechanism of poor immunodetection caused by food matrix interference.

Allergenicity, assembly and applications of ovalbumin in egg white: a review

Ovalbumin (OVA), the most abundant protein in egg whites, has been widely used in various industries. Currently, the structure of OVA has been clearly established, and the extraction of high-purified OVA has become feasible. However, the allergenicity of OVA is still a serious problem because it can cause severe allergic reactions and may even be life-threatening. The structure and allergenicity of the OVA can be altered by many processing methods. In this article, a detailed description on the structure and a comprehensive overview on the extraction protocols and the allergenicity of OVA was documented. Additionally, the information on assembly and potential applications of OVA was summarized and discussed in detail. Physical treatment, chemical modification, and microbial processing can be applied to alter the IgE-binding capacity of OVA by changing its structure and linear/sequential epitopes. Furthermore, research indicated that OVA could assemble with itself or other biomolecules into various forms (particles, fibers, gels, and nanosheets), which expanded its application in the food field. OVA also shows excellent application prospects, including food preservation, functional food ingredients and nutrient delivery. Therefore, OVA demonstrates significant investigation value as a food grade ingredient.

Towards understanding the interaction between ultrasound-pretreated β-lactoglobulin monomer with resveratrol

Increasingly, studies are using ultrasound to elevate the functional properties of proteins, so the interaction between phenolic compounds and proteins induced by ultrasound needs to be further understood. β-Lactoglobulin (β-LG) at pH 8.1, which exists mainly as monomers, was ultrasound treated at 20 kHz ultrasonic intensity and 30% amplitude for 0-5 min and subsequently interacted with resveratrol. Fluorescence data showed that ultrasound pretreatment improved binding constant (K_a ) from (1.62 ± 0.45) × 10⁵ to (9.43 ± 0.55) × 10⁵  M^-1 and binding number from 1.13 ± 0.09 to 1.28 ± 0.11 in a static quenching mode. Fluorescence resonance energy transfer (FRET) analysis indicated that resveratrol bound to the surface hydrophobic pocket of native and treated proteins with no obvious changes in energy transfer efficiency (E) and Föster's distance (r). Thermodynamic parameters indicated that ultrasonication shifted the main driving force from the hydrophobic force for native and 1-min treated β-LG to van der Waals forces and hydrogen bonding for both 3-min and 5-min treated proteins. Ultrasonication and resveratrol addition generated significant differences in surface hydrophobicity and the surface charge of the protein (P < 0.05), whereas they had little influence on the secondary structure of β-LG. Compared with the native β-LG/resveratrol complex, ultrasound-treated protein complexes showed significantly stronger 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) scavenging capacity (P < 0.05), and kept relatively stable after 180-min irradiation. Data provided by this study can lead to a better comprehension of the structure and molecular events occurring during the complexing process between an ultrasound-pretreated protein with polyphenol.

Bioactive compounds: Application of albumin nanocarriers as delivery systems

Enriched products with bioactive compounds (BCs) show the capacity to produce a wide range of possible health effects. Most BCs are essentially hydrophobic and sensitive to environmental factors; so, encapsulation becomes a strategy to solve these problems. Many globular proteins have the intrinsic ability to bind, protect, encapsulate, and introduce BCs into nutraceutical or pharmaceutical matrices. Among them, albumins as human serum albumin (HSA), bovine serum albumin (BSA), ovalbumin (OVA) and α-lactalbumin (ALA) are widely abundant, available, and applied in many industrial sectors, becoming promissory materials to encapsulate BCs. Therefore, this review focuses on researches about the main groups of natural origin BCs (namely phenolic compounds, lipids, vitamins, and carotenoids), the different types of nanostructures based on albumins to encapsulate them and the main fields of application for BCs-loaded albumin systems. In this context, phenolic compounds (catechins, quercetin, and chrysin) are the most extensively BCs studied and encapsulated in albumin-based nanocarriers. Other extensively studied subgroups are stilbenes and curcuminoids. Regarding lipids and vitamins; terpenes, carotenoids (β-carotene), and xanthophylls (astaxanthin) are the most considered. The main application areas of BCs are related to their antitumor, anti-inflammatory, and antioxidant properties. Finally, BSA is the most used albumin to produced BCs-loaded nanocarriers.

FTIR study of synthesized ovalbumin nanoparticles

Ovalbumin particles are reduced to nano size using heat treatment techniques. Their structural patterns in their native state and in their pH denatured state were attempted. Denaturation is also a part of conformation and hence conformations due to pH and glucose were analyzed using FTIR spectroscopy. The interactions behind these conformations are unraveled and the role of glucose as cosolvent in restricting the denaturation is also revealed from the observed secondary structures of ovalbumin. Further, the characterization of these synthesized nano particles reveals the extent of their applications. The obtained results indicate that consideration of ovalbumin nanoparticles seems to favor a very clear trend of protein denaturation and the observed structural modifications are the result of development of non-covalent interactions by the cosolvent molecules.

Molecular structure modification of ovalbumin through controlled glycosylation with dextran for its emulsibility improvement

Ovalbumin (OVA) is a high nutritious protein, but the poor emulsibility limited its application. The present study glycosylated OVA with dextran (Dex) by controlled wetheating (60-90 °C for 3 h). Temperature was an inductive factor for glycosylation degree (DG and browning intensity), and higher temperature could accelerate the reaction. Variations in molecular structure of OVA were analyzed by SDS-PAGE, FTIR, fluorescence spectroscopy and UV spectroscopy, which verified successes in the generation of glycoconjugate with more flexible structure. Emulsifying activity index (EAI) and emulsion stability index (ESI) for the emulsion of OVA-Dex glycoconjugates were significantly enhanced with the increasing of glycosylation temperature. Moreover, confocal laser scanning results revealed that the emulsion exhibited smaller size and more uniform distribution, and slower transmission profiles were checked by LUMiSizer centrifugal analysis as well, confirming the emulsibility improvement of OVA. Thus, controlled glycosylation reaction is an available method to improve the emulsifying properties of OVA.

Utilization of diverse protein sources for the development of protein-based nanostructures as bioactive carrier systems: A review of recent research findings (2010-2021)

Consumer awareness of the relationship between health and nutrition has caused a substantial increase in the demand for nutraceuticals and functional foods containing bioactive compounds (BACs) with potential health benefits. However, the direct incorporation of many BACs into commercial food and beverage products is challenging because of their poor matrix compatibility, chemical instability, low bioavailability, or adverse impact on food quality. Advanced encapsulation technologies are therefore being employed to overcome these problems. In this article, we focus on the utilization of plant and animal derived proteins to fabricate micro and nano-particles that can be used for the oral delivery of BACs such as omega-3 oils, vitamins and nutraceuticals. This review comprehensively discusses different methods being implemented for fabrications of protein-based delivery vehicles, types of proteins used, and their compatibility for the purpose. Finally, some of the challenges and limitations of different protein matrices for encapsulation of BACs are deliberated upon. Various approaches have been developed for the fabrication of protein-based microparticles and nanoparticles, including injection-gelation, controlled denaturation, and antisolvent precipitation methods. These methods can be used to construct particle-based delivery systems with different compositions, sizes, surface hydrophobicity, and electrical characteristics, thereby enabling them to be used in a wide range of applications.

Nanocomplexes based on egg white protein nanoparticles and bioactive compounds as antifungal edible coatings to extend bread shelf life

This work is aimed to obtain nanocomplexes based on egg white protein nanoparticles (EWPn) and bioactive compounds (BC), carvacrol (CAR), thymol (THY) and trans-cinnamaldehyde (CIN), and evaluate their application as antifungal edible coatings on preservative-free breads. The nanocomplex formation was studied through stoichiometry, affinity, colloidal behavior, morphology, and encapsulation efficiency (EE, %). Rounded-shape nanocomplexes with particle sizes < 100 nm were obtained. The EE values were similar for all BC (>83%). Furthermore, the in vitro antifungal activity of the nanocomplexes was verified using the Aspergillus niger species. The nanocomplexes were applied as coatings onto the crust of preservative-free breads, which were stored for 7 days (at 25 °C). The coatings had no impact on the physicochemical properties of the bread loaves (moisture, a_w, texture, and color). Finally, the coatings based on EWPn-THY and EWPn-CAR nanocomplexes showed higher antifungal efficacy, extending the bread shelf life after 7 days.

Genistein loaded in self-assembled bovine serum albumin nanovehicles and their effects on mouse mammary adenocarcinoma cells

Antitumor activity of plant-derived flavonoids has been researched during recent decades. Among them, genistein (Gen) stands out for showing cytotoxic activity against breast cancer cells. However, its low water solubility, limited bioavailability, and fast metabolism hinder its administration in chemopreventive therapies. To overcome these obstacles, bovine serum albumin nanovehicles (BSAnp) were obtained by a heat-induced self-assembly process at 70 °C and two aqueous medium pH (9.0 and 11.0) and assayed for the Gen loading. Thus, in this work, Gen loading in BSAnp was studied by spectroscopic techniques and compared with the one obtained for its stereoisomer, chrysin (Chrys). Results revealed that Gen binds to BSAnp via fluorescence quenching mechanism forming inclusion complexes. Compared to Chrys, Gen binding to BSAnp involved more molecules, whereas the association constant was similar for both flavonoids. In general, flavonoid loading in protein systems was strongly affected by the combined effects of BSA conformational state (native vs. aggregated), nanovehicle size, and flavonoid chemical structure. To evaluate the antitumor properties freeze-dried powders were obtained, and they were assayed in vitro after reconstitution by XTT technique and Annexin V-FITC flow cytometry against mouse mammary adenocarcinoma F3II cells. Gen-loaded BSAnp produced a significant decrease in cell viability compared with unloaded BSAnp systems, being the highest cytotoxic effects found for the lowest sized Gen-loaded BSAnp. The leading cytotoxicity mechanism for Gen-loaded systems was apoptosis. Summarizing, it can be concluded that BSAnp constitute versatile nanovehicles for potential flavonoid incorporation in pharmaceutical and nutraceutical matrices.

Effects of tea polyphenols on physicochemical and antioxidative properties of whey protein coating

Effects of tea polyphenols (TP) incorporation on physicochemical and antioxidative properties of whey protein isolate (WPI) coating were studied. Two WPI coating solutions were prepared by heating WPI solutions (pH 8, 90 °C) for 30 min and then TP was incorporated. TP addition could increase the negative zeta potential of 5% solution. The surface hydrophobicity index of both solutions was increased and intrinsic fluorescence intensity decreased greatly after addition of TP. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis (2 ethylbenzothiazoline-6-sulfonate) (ABTS) radical scavenging capacities of both solutions increased with increasing TP. Compared with apple pieces coated with whey protein only, those with TP containing whey protein coatings showed lower browning index and slight changes in weight loss during 24 h storage. Data indicated that TP could influence the physicochemical properties and improve the antioxidant activity of WPI coating solutions and can be used to retard the enzymatic browning of fruit during storage.

Protein Nanoparticle Charge and Hydrophobicity Govern Protein Corona and Macrophage Uptake

Protein nanoparticles are biomaterials composed entirely of proteins, with the protein sequence and structure determining the nanoparticle physicochemical properties. Upon exposure to physiological or environmental fluids, it is likely that protein nanoparticles, like synthetic nanoparticles, will adsorb proteins and this protein corona will be dependent on the surface properties of the protein nanoparticles. As there is little understanding of this phenomenon for engineered protein nanoparticles, the purpose of this work was to create protein nanoparticles with variable surface hydrophobicity and surface charge and establish the effect of these properties on the mass and composition of the adsorbed corona, using the fetal bovine serum as a model physiological solution. Albumin, cationic albumin, and ovalbumin cross-linked nanoparticles were developed for this investigation and their adsorbed protein coronas were isolated and characterized by gel electrophoresis and nanoliquid chromatography mass spectrometry. Distinct trends in corona mass and composition were identified for protein nanoparticles based on surface charge and surface hydrophobicity. Proteomic analyses revealed unique protein corona patterns and identified distinct proteins that are known to affect nanoparticle clearance in vivo. Further, the protein corona influenced nanoparticle internalization in vitro in a macrophage cell line. Altogether, these results demonstrate the strong effect protein identity and properties have on the corona formed on nanoparticles made from that protein. This work builds the foundation for future study of protein coronas on the wide array of protein nanoparticles used in nanomedicine and environmental applications.

Chrysin-loaded bovine serum albumin particles as bioactive nanosupplements

Freeze-dried Chrys-loaded BSAnp retained their properties after reconstitution and induced apoptosis on breast cancer cells. BSAnp-70-11 (smallest sized) was the most cytotoxic system with a gastrointestinal release of 14% Chrys.

Comparison of dry- and wet-heat induced changes in physicochemical properties of whey protein in absence or presence of inulin

Changes in whey protein (10%, w/v) induced by dry-heating (60 °C for 5 days at a relative humidity of 63%), wet-heating (85 °C for 30 min) or the two-combined heating in absence or presence of inulin (8%, w/v) were studied. Mixture of whey protein and inulin showed significantly higher absorbance at 290 nm than whey protein alone in all heating conditions while only dry-heated samples showed significantly increased absorbance value at 420 nm (p < 0.05). Whey protein after heating showed significantly lower zeta potential and inulin decreased the value of all heated samples further (p < 0.05) except for samples after dry-heating. Heating decreased the free sulfhydryl group content of whey protein samples while presence of inulin decreased further (p < 0.05). Dry-heating decreased while wet-heating increased the surface hydrophobicity of whey protein. Inulin had no effect on the surface hydrophobicity of heated whey protein under dry-heating but decreased under wet-heating.

Magnetically controlled protein nanocontainers as a drug depot for the hemostatic agent

PURPOSE

Currently, there is a number of successfully implemented local hemostatic agents for external bleedings in forms of wound dressings and other topical materials. However, little has been done in the field of intravenous hemostatic agents. Here, we propose a new procedure to fabricate biocompatible protein nanocontainers (NCs) for intravenous injection allowing magneto-controllable delivery and short-term release of the hemostatic agent ε-aminocaproic acid (EACA).

METHODS

The nanocontainers were synthesized by the desolvation method from bovine serum albumin (BSA) using methanol without any further crosslinking. Polyethylene glycol (PEG) was used both as a stabilization agent and for size control. Characterization of nanocontainers was performed by the transmission and scanning electron microscopy, dynamic light scattering, X-ray diffraction, and FTIR spectroscopy. Cytotoxicity was estimated using MTT assay. The dopant release from nanocontainers was measured spectrophotometrically using rhodamine B as a model molecule. The specific hemostatic activity was assessed by analyzing clot lysis and formation curve (CloFAL). Moreover, the ability for magneto targeting was estimated using the original flow setup made of a syringe pump and silicon contours.

RESULTS

Fabricated nanocontainers had an average size of 186±24 nm and were constructed from building blocks-nanoparticles with average size ranged from 10 to 20 nm. PEG shell was also observed around nanocontainers with thickness 5-10 nm. NCs were proved to be completely non-cytotoxic even at concentrations up to 8 mg BSA/mL. Uptake capacity was near 36% while release within the first day was 17%. The analysis of the CloFAL curve showed the ability of NCs to inhibit the clot lysis successfully, and the ability of magneto targeting was confirmed under flow conditions.

CONCLUSION

The ability of synthesized NCs to deliver and release the therapeutic drug, as well as to accumulate at the desired site under the action of the magnetic field was proved experimentally.

Simulated gastrointestinal digestion of inclusion complexes based on ovalbumin nanoparticles and conjugated linoleic acid

Ovalbumin delivery system of conjugated linoleic acid resists in vitro gastrointestinal digestion with high percentages of bioactive retention.

Preparation of Complexes between Ovalbumin Nanoparticles and Retinoic Acid for Efficient Induction of Tolerogenic Dendritic Cells

The induction of antigen-specific immunotolerance has been gathering attention concerning the therapy of allergy and autoimmune diseases. Tolerogenic dendritic cells (tDCs) play crucial roles in immunotolerance therapy because they induce anergic responses for auto-reactive helper T cells, and also enhance differentiation to regulatory T cells to maintain tolerance against auto-antigens. All-trans retinoic acid (ATRA) is one of the representative molecules used to induce tDCs. We have proposed a simple formulation of ovalbumin nanoparticles complexed with ATRA (OVA/RA NPs). OVA/RA NPs were taken up by DCs and successfully induced phenotypes of tDCs.

Enhancing the photostability and bioaccessibility of resveratrol using ovalbumin–carboxymethylcellulose nanocomplexes and nanoparticles

The objective of this study was to investigate the impact of encapsulating resveratrol in ovalbumin (OVA)–carboxymethylcellulose (CMC) nanocomplexes or nanoparticles on its photostability and bioaccessibility.