Urea-Driven Epigallocatechin Gallate (EGCG) Permeation into the Ferritin Cage, an Innovative Method for Fabrication of Protein-Polyphenol Co-assemblies

Possibility and challenge of plant-derived ferritin cages encapsulated polyphenols in the precise nutrition field

Polyphenols have attracted extensive attention due to their rich functional activities, such as antioxidant, anti-inflammatory and anti-tumor. However, the low solubility and poor stability limit their bioavailability and functional activities. Plant-derived ferritin cages have a unique hollow cage structure that can embed polyphenols to improve their unfavorable properties. Therefore, it is essential to adequately elaborate and summarize plant-derived ferritin cages to maximize their potential benefits in nutritional interventions. This review focuses on the fundamental properties of plant-derived ferritin cages, including the preparation process, purification technology, identification methods, and structural and functional properties. The relevant research on ferritin cages in polyphenol delivery has been summarized, including the delivery of water/lipid soluble polyphenols, modification of ferritin cages, and the interaction between polyphenols and ferritin cages. The research progress, shortcomings and prospects of plant-derived ferritin cages in precise nutrition are introduced. In addition, the relevant research on ferritin in immune response and protein engineering is also discussed to provide the theoretical basis for applying plant-derived ferritin cages in many frontier fields.

The application of ferritin in transporting and binding diverse metal ions

The ferritin cage can not only load iron ions in its inner cavity, but also has the capacity to carry other metal ions, thus constructing a new biological nano-transport system. The nanoparticles formed by ferritin and minerals can be used as ingredients of mineral supplements, which overcome the shortcomings of traditional mineral ingredients such as low bioavailability. Moreover, ferritin can be used to remove heavy metal ions from contaminated food. Silver and palladium nanoparticles formed by ferritin are also applied as anticancer agents. Ferritin combined with metal ions can be also used to detect harmful substances. This review aims to provide a comprehensive overview of ferritin's function in transporting and binding metal ions, and discusses the limitations and future prospects, which offers valuable insights for the application of ferritin in mineral supplements, food detoxifiers, anticancer agents, and food detections.

Advancements of the Molecular Directed Design and Structure-Activity Relationship of Ferritin Nanocage

Ferritin nanocages possess remarkable structural properties and biological functions, making them highly attractive for applications in functional materials and biomedicine. This comprehensive review presents an overview of the molecular characteristics, extraction and identification of ferritin, ferritin receptors, as well as the advancements in the directional design of high-order assemblies of ferritin and the applications based on its unique structural properties. Specifically, this Review focuses on the regulation of ferritin assembly from one to three dimensions, leveraging the symmetry of ferritin and modifications on key interfaces. Furthermore, it discusses targeted delivery of nutrition and drugs through facile loading and functional modification of ferritin. The aim of this Review is to inspire the design of micro/nano functional materials using ferritin and the development of nanodelivery vehicles for nutritional fortification and disease treatment.

Self-assembly embedding of curcumin by alkylated rice bran protein

Lysine-rich rice bran protein (RBP) can be used as raw material for alkylation modification to improve the self-assembly performance of protein. The results of 1H NMR, degree of alkylation, and DSC analysis showed that the alkyl chain was successfully attached to the RBP. The surface hydrophobicity and absolute ζ-potential increased. The three-dimensional structure of the alkylated RBP (ARBP) become more porous and ARBP-2 was selected as the material for embedding curcumin. The XRD results revealed that curcumin induced self-aggregation of ARBP-2 and the inclusion of curcumin was attained. The maximum encapsulation efficiency of curcumin was 82.67 % and the maximum loading amount was 171.37 g/100 g RBP. The results of atomic force microscopy (AFM), particle size, and polydispersity index (PDI) analyses revealed that the particles in the system were aggregated after curcumin was added. Curcumin was well protected by encapsulation in the self-assembled particles. Thus, this study provides a new strategy for the embedding and delivery of curcumin.

Multifaceted Applications of Ferritin Nanocages in Delivering Metal Ions, Bioactive Compounds, and Enzymes: A Comprehensive Review

Ferritin, a distinctive iron-storage protein, possesses a unique cage-like nanoscale structure that enables it to encapsulate and deliver a wide range of biomolecules. Recent advances prove that ferritin can serve as an efficient 8 nm diameter carrier for various bioinorganic nutrients, such as minerals, bioactive polyphenols, and enzymes. This review offers a comprehensive summary of ferritin's structural features from different sources and emphasizes its functions in iron supplementation, calcium delivery, single- and coencapsulation of polyphenols, and enzyme package. Additionally, the influence of innovative food processing technologies, including manothermosonication, pulsed electric field, and atmospheric cold plasma, on the structure and function of ferritin are examined. Furthermore, the limitations and prospects of ferritin in food and nutritional applications are discussed. The exploration of ferritin as a multifunctional protein with the capacity to load various biomolecules is crucial to fully harnessing its potential in food applications.

Protein and Peptide-Based Nanotechnology for Enhancing Stability, Bioactivity, and Delivery of Anthocyanins

Anthocyanin, a unique natural polyphenol, is abundant in plants and widely utilized in biomedicine, cosmetics, and the food industry due to its excellent antioxidant, anticancer, antiaging, antimicrobial, and anti-inflammatory properties. However, the degradation of anthocyanin in an extreme environment, such as alkali pH, high temperatures, and metal ions, limits its physiochemical stabilities and bioavailabilities. Encapsulation and combining anthocyanin with biomaterials could efficiently stabilize anthocyanin for protection. Promisingly, natural or artificially designed proteins and peptides with favorable stabilities, excellent biocapacity, and wide sources are potential candidates to stabilize anthocyanin. This review focuses on recent progress, strategies, and perspectives on protein and peptide for anthocyanin functionalization and delivery, i.e., formulation technologies, physicochemical stability enhancement, cellular uptake, bioavailabilities, and biological activities development. Interestingly, due to the simplicity and diversity of peptide structure, the interaction mechanisms between peptide and anthocyanin could be illustrated. This work sheds light on the mechanism of protein/peptide-anthocyanin nanoparticle construction and expands on potential applications of anthocyanin in nutrition and biomedicine.

Ferritin nanocages: a versatile platform for nanozyme design

Nanozymes are a class of nanomaterials with enzyme-like activities and have attracted increasing attention due to their potential applications in biomedicine. However, nanozyme design incorporating the desired properties remains challenging. Natural or genetically engineered protein scaffolds, such as ferritin nanocages, have emerged as a promising platform for nanozyme design due to their unique protein structure, natural biomineralization capacity, self-assembly properties, and high biocompatibility. In this review, we highlight the intrinsic properties of ferritin nanocages, especially for nanozyme design. We also discuss the advantages of genetically engineered ferritin in the versatile design of nanozymes over natural ferritin. Additionally, we summarize the bioapplications of ferritin-based nanozymes based on their enzyme-mimicking activities. In this perspective, we mainly provide potential insights into the utilization of ferritin nanocages for nanozyme design.

Ferritin nanocages as efficient nanocarriers and promising platforms for COVID-19 and other vaccines development

BACKGROUND

The development of safe and effective vaccines against SARS-CoV-2 and other viruses with high antigenic drift is of crucial importance to public health. Ferritin is a well characterized and ubiquitous iron storage protein that has emerged not only as a useful nanoreactor and nanocarrier, but more recently as an efficient platform for vaccine development.

SCOPE OF REVIEW

This review discusses ferritin structure-function properties, self-assembly, and novel bioengineering strategies such as interior cavity and exterior surface modifications for cargo encapsulation and delivery. It also discusses the use of ferritin as a scaffold for biomedical applications, especially for vaccine development against influenza, Epstein-Barr, HIV, hepatitis-C, Lyme disease, and respiratory viruses such as SARS-CoV-2. The use of ferritin for the synthesis of mosaic vaccines to deliver a cocktail of antigens that elicit broad immune protection against different viral variants is also explored.

MAJOR CONCLUSIONS

The remarkable stability, biocompatibility, surface functionalization, and self-assembly properties of ferritin nanoparticles make them very attractive platforms for a wide range of biomedical applications, including the development of vaccines. Strong immune responses have been observed in pre-clinical studies against a wide range of pathogens and have led to the exploration of ferritin nanoparticles-based vaccines in multiple phase I clinical trials.

GENERAL SIGNIFICANCE

The broad protective antibody response of ferritin nanoparticles-based vaccines demonstrates the usefulness of ferritin as a highly promising and effective approaches for vaccine development.

Ferritin-based nanomedicine for disease treatment

Ferritin is an endogenous protein which is self-assembled by 24 subunits into a highly uniform nanocage structure. Due to the drug-encapsulating ability in the hollow inner cavity and abundant modification sites on the outer surface, ferritin nanocage has been demonstrated great potential to become a multi-functional nanomedicine platform. Its good biocompatibility, low toxicity and immunogenicity, intrinsic tumor-targeting ability, high stability, low cost and massive production, together make ferritin nanocage stand out from other nanocarriers. In this review, we summarized ferritin-based nanomedicine in field of disease diagnosis, treatment and prevention. The different types of drugs to be loaded in ferritin, as well as drug-loading methods were classified. The strategies for site-specific and non-specific functional modification of ferritin were investigated, then the application of ferritin for disease imaging, drug delivery and vaccine development were discussed. Finally, the challenges restricting the clinical translation of ferritin-based nanomedicines were analyzed.

Ferritin nanocage based delivery vehicles: From single-, co- to compartmentalized- encapsulation of bioactive or nutraceutical compounds

Bioactive or nutraceutical ingredients have been widely used in pursuit of health and well-being. However, the environmental instability, poor solubility and bioavailability, and unspecific delivery highly limited their practical values. By virtue of the unique shell-like structure, definite disassembly/reassembly behavior, and excellent safety profile of ferritin protein, it stands out among of various nano-materials and is emerging as one of the most promising vehicles for the encapsulation and delivery of bioactive ingredients or drugs. In this review, we present a systematic overview of recent advances of ferritin-based delivery systems from single-encapsulation, co-encapsulation, to compartmentalized-encapsulation of bioactive ingredients or drugs. Different encapsulation strategies for cargo loading as well as their advantages and drawbacks have been critically reviewed. This study emphasized the importance of the construction of compartmentalized delivery systems through the usage of ferritin nanocages, which exhibit great potential for facilitating the synergistic functionality of different types of cargos. Lastly, the applications of ferritin nanocages for physicochemical improvements and functionality achievements of loaded cargos are summarized. In conclusion, ferritin protein nanocages not only are excellent nanocarriers, but also can act as"multi-seated" vehicles for co-encapsulation and compartmentalized encapsulation of different cargos simultaneously.

Chitosan binding to a novel alfalfa phytoferritin nanocage loaded with baicalein: Simulated digestion and absorption evaluation

Phytoferritin was explored as an attractive nanocarrier to encapsulate bioactive compounds due to its excellent stability and biocompatibility. In the present study, a novel phytoferritin derived from alfalfa (Medicago sativa) was successfully expressed, purified and characterized. Results confirmed that alfalfa ferritin, self-assembled by 24 subunits, formed a spherical hollow structure. Baicalein exhibits superior antioxidant properties and nutritious values, but low bioavailability and solubility limit its application. Herein, we fabricated water-soluble chitosan-ferritin-baicalein nanoparticles to overcome its drawbacks. It was calculated that one apoferritin cage could encapsulate 52 molecules of baicalein. Moreover, chitosan-ferritin-baicalein nanoparticles prolonged the release of baicalein in simulated gastrointestinal tract digestion. Caco-2 cell monolayer absorption analysis demonstrated that baicalein encapsulated within ferritin-chitosan double layers was more efficient in cellular transportation. These results indicated that alfalfa ferritin, as a novel cage-like protein, has potential application in improving the bioavailability of insoluble bioactive molecules.

Improved stability and pharmacokinetics of wogonin through loading into PASylated ferritin

Wogonin (Wog) plays an important role in human diseases, especially cancer and inflammatory diseases, but its poor solubility, unstable metabolism and low bioavailability greatly limit its application in biomedical fields. Therefore, we developed a temperature-dependent method to encapsulate wogonin into a novel ferritin-based nanocarrier. To improve the loading capacity and stability, the human H chain ferritin (HFtn) was functionalized with a repetitive polypeptide sequence composed of proline (Pro), alanine (Ala), and serine (Ser) in different residues lengths (PAS10 and PAS30). Wogonin loading and release studies demonstrated that the encapsulation efficiency and stability of the PASylated nanocarriers were significantly higher than those of the wild type. PAS-HFtn-Wog exhibited enhanced cytotoxicity to MCF-7 breast cancer cells and HepG2 liver cancer cells. Notably, the PASylated HFtn, especially PAS30-HFtn greatly prolonged the pharmacokinetics of wogonin in the mice bloodstream. Therefore, wogonin-loaded PAS-HFtn may be a promising drug candidate for cancer therapy.

Dual stabilization of Pickering emulsion with epigallocatechin gallate loaded mesoporous silica nanoparticles

Oxidation in food emulsions remains challenging to keep food quality and shelf-life. In this paper, a dual stabilization to both oil phase and antioxidant in Pickering emulsion is presented. Mesoporous silica nanospheres (MSN) were prepared to incorporate epigallocatechin gallate (EGCG), a typical plant-based antioxidant. EGCG loaded MSN were used to emulsify Litsea cubeba essential oil, a model oil, with olfactory investigation of the chemical stability. The emulsions improved the physical and chemical stabilization. The emulsions were uniformly stable with various parameters with one-month observation. Olfactory evaluation and GC-MS-O investigation reveal that the odors and odorous compounds of essential oil were well preserved in Pickering emulsions and much better than those in conventional emulsion with Tween 80. EGCG loaded MSN Pickering emulsion efficiently protect essential oil from oxidation. EGCG was also well retained in Pickering emulsion. This strategy could inspire new designs for food functional Pickering emulsions with efficient protective effect.

Emerging trends in nano-bioactive-mediated mitochondria-targeted therapeutic stratagems using polysaccharides, proteins and lipidic carriers

The emergence of new lifestyle disorders and pharmaco-resistant variants of diseases has necessitated the search for effective therapeutic moieties and approaches that could overcome the limitations in the existing treatment modalities. In this context, bioactives such as flavonoids, polyphenols, tannins, terpenoids and alkaloids have demonstrated promise in therapy owing to their ability to scavenge free radicals and modulate the mitochondrial function as well as regulate metabolic pathways. However, their clinical applicability is low owing to their poor bioavailability and aqueous solubility. The encapsulation of bioactives in nanodimensional particles has overcome these limitations to a large extent while simultaneously conferring additional advantages of improved circulation time, enhanced cell uptake and target specific release. A wide range of nanocarriers derived from biopolymers such as polysaccharides, lipids and proteins, have been explored for encapsulation of different bioactives and have reported significant improvement of the bioavailability and therapeutic efficacy of the encapsulated cargo. However, incorporation of cell-specific and mitochondria-specific elements on the nanocarriers has been relatively less explored. This review summarizes some of the recent attempts to treat different disorders using bioactives encapsulated in biopolymer nanostructures and few instances of mitochondria-specific delivery.

Mechanism Study of Thermally Induced Anti-Tumor Drug Loading to Engineered Human Heavy-Chain Ferritin Nanocages Aided by Computational Analysis

Diverse drug loading approaches for human heavy-chain ferritin (HFn), a promising drug nanocarrier, have been established. However, anti-tumor drug loading ratio and protein carrier recovery yield are bottlenecks for future clinical application. Mechanisms behind drug loading have not been elaborated. In this work, a thermally induced drug loading approach was introduced to load anti-tumor drug doxorubicin hydrochloride (DOX) into HFn, and 2 functionalized HFns, HFn-PAS-RGDK, and HFn-PAS. Optimal conditions were obtained through orthogonal tests. All 3 HFn-based proteins achieved high protein recovery yield and drug loading ratio. Size exclusion chromatography (SEC) and transmission electron microscopy (TEM) results showed the majority of DOX loaded protein (protein/DOX) remained its nanocage conformation. Computational analysis, molecular docking followed by molecular dynamic (MD) simulation, revealed mechanisms of DOX loading and formation of by-product by investigating non-covalent interactions between DOX with HFn subunit and possible binding modes of DOX and HFn after drug loading. In in vitro tests, DOX in protein/DOX entered tumor cell nucleus and inhibited tumor cell growth.

Shrimp ferritin greatly improves the physical and chemical stability of astaxanthin

The low stability of trans-astaxanthin (AX) not only limits its applications as a functional factor in food systems, but also affects the sensor quality of most shrimp products. Therefore, it is important to find an easy, effective way to improve the physical and chemical stability of AX. In this study, by taking advantage of the co-existence of AX and shrimp ferritin (Marsupenaeus japonicus ferritin, MjF), we investigated the interaction of AX with MjF. Results showed that AX molecules are able to bind on the outer surface of MjF to form complexes, and quantitative analyses demonstrated that one ferritin molecule is bound to ∼48 AX molecules. Consequently, such binding not only greatly enhances the water solubility, thermal stability, and photo stability of AX, but also protects AX from Fe²⁺ -induced oxidative damage, as compared to free AX. Thus, MjF could be used as a protective molecule to improve the physical and chemical stability of AX. PRACTICAL APPLICATION: Our study opens up a new avenue for improving the physicochemical properties of bioactive molecules by interacting with protein, and shrimp ferritin could be explored as a protective system for the bioactive molecules.

Ferritin: A Multifunctional Nanoplatform for Biological Detection, Imaging Diagnosis, and Drug Delivery

Ferritins are spherical iron storage proteins within cells that are composed of a combination of 24 subunits of two types, heavy-chain ferritin (HFn) and light-chain ferritin (LFn). They autoassemble naturally into a spherical hollow nanocage with an outer diameter of 12 nm and an interior cavity that is 8 nm in diameter. In recent years, with the constantly emerging safety issues and the concerns about unfavorable uniformity and indefinite in vivo behavior of traditional nanomedicines, the characteristics of native ferritin nanocages, such as the unique nanocage structure, excellent safety profile, and definite in vivo behavior, make ferritin-based formulations uniquely attractive for nanomedicine development. To date, a variety of cargo molecules, including therapeutic drugs (e.g., cisplatin, carboplatin, paclitaxel, curcumin, atropine, quercetin, gefitinib, daunomycin, epirubicin, doxorubicin, etc.), imaging agents (e.g., fluorescence dyes, radioisotopes, and MRI contrast agents), nucleic acids (e.g., siRNA and miRNA), and metal nanoparticles (e.g., Fe₃O₄, CeO₂, AuPd, CuS, CoPt, FeCo, Ag, etc.) have been loaded into the interior cavity of ferritin nanocages for a broad range of biomedical applications from in vitro biosensing to targeted delivery of cargo molecules in living systems with the aid of modified targeting ligands either genetically or chemically. We reported that human HFn could selectively deliver a large amount of cargo into tumors in vivo via transferrin receptor 1 (TfR1)-mediated tumor-cell-specific targeting followed by rapid internalization. By the use of the intrinsic tumor-targeting property and unique nanocage structure of human HFn, a broad variety of cargo-loaded HFn formulations have been developed for biological analysis, imaging diagnosis, and medicine development. In view of the intrinsic tumor-targeting property, unique nanocage structure, lack of immunogenicity, and definite in vivo behavior, human HFn holds promise to promote therapeutic drugs, diagnostic imaging agents, and targeting moieties into multifunctional nanomedicines.Since the report of the intrinsic tumor-targeting property of human HFn, we have extensively explored human HFn as an ideal nanocarrier for tumor-targeted delivery of anticancer drugs, MRI contrast agents, inorganic nanoparticles, and radioisotopes. In particular, by the use of genetic tools, we also have genetically engineered human HFn nanocages to recognize a broader range of disease biomarkers. In this Account, we systematically review human ferritins from characterizing their tumor-binding property and understanding their mechanism and kinetics for cargo loading to exploring their biomedical applications. We finally discuss the prospect of ferritin-based formulations to become next-generation nanomedicines. We expect that ferritin formulations with unique physicochemical characteristics and intrinsic tumor-targeting property will attract broad interest in fundamental drug research and offer new opportunities for nanomedicine development.

The formation of phycocyanin-EGCG complex for improving the color protection stability exposing to light

Phycocyanin (PC) is a natural pigment-protein complex in food dye applications. In this study, a phycocyanin-epigallocatechin gallate (EGCG) complex (PE) was prepared and the effects of EGCG on the structure and color stability of PC were evaluated. The fluorescence results showed that the binding number n was 62.1 ± 3.41 (EGCG/PC) and the binding constant K was 4.39 (±0.2) × 10⁵ M^-1, indicating a weak-binding interaction. Fourier transform-infrared analysis showed that EGCG caused structural changes in PC by partially uncoiling α-helix and increasing β-sheet content. The EGCG induced a PC association at a reaction molar ratio above 40:1 (EGCG/PC). Moreover, EGCG protected phycocyanobilin against color fading, making PE more stable relative to PC under 8-days storage in light. This study provides a novel scheme to stabilize PC by forming a complex with polyphenols, which will facilitate the PC application as a natural blue pigment in food.

ERK-Peptide-Inhibitor-Modified Ferritin Enhanced the Therapeutic Effects of Paclitaxel in Cancer Cells and Spheroids

Rational design of a drug delivery system with enhanced therapeutic potency is critical for efficient tumor chemotherapy. Many protein-based drug delivery platforms have been designed to deliver drugs to target sites and improve the therapeutic efficacy. In this study, paclitaxel (PTX) molecules were encapsulated within an apoferritin nanocage-based drug delivery system with the modification of an extracellular-signal-regulated kinase (ERK) peptide inhibitor at the C-terminus of ferritin (HERK). Apoferritin is an endogenous nano-sized spherical protein which has the ability to specially bind to a majority of tumor cells via interacting with transferrin receptor 1. The ERK peptide inhibitor is a peptide which can disrupt the interaction of MEK with ERK in the mitogen-activated protein kinase/ERK pathway. By combining the targeted delivery effect of ferritin and the inhibitory effect of the ERK peptide inhibitor, the newly fabricated ferritin carrier nanoparticle HERK could still be taken up by tumor cells, and it displayed higher cell cytotoxicity than the parent ferritin. After loading with PTX, HERK-PTX displayed a favorable anticancer effect in human breast cancer cells MDA-MB-231 and lung carcinoma cells A549. The remarkable inhibitory effect on MDA-MB-231 tumor spheroids was also identified. These results indicated that the constructed HERK nanocarrier is a promising multi-functional drug delivery vehicle to enhance the therapeutic effect of drugs in cancer therapy.

A single residue can modulate nanocage assembly in salt dependent ferritin

Cage forming proteins have numerous potential applications in biomedicine and biotechnology, where the iron storage ferritin is a widely used example. However, controlling ferritin cage assembly/disassembly remains challenging, typically requiring extreme conditions incompatible with many desirable cargoes, particularly for more fragile biopharmaceuticals. Recently, a ferritin from the hyperthermophile bacterium Thermotoga maritima (TmFtn) has been shown to have reversible assembly under mild conditions, offering greater potential biocompatibility in terms of cargo access and encapsulation. Like Archeoglobus fulgidus ferritin (AfFtn), TmFtn forms 24mer cages mediated by metal ions (Mg2+). We have solved the crystal structure of the wild type TmFtn and several mutants displaying different assembly/disassembly properties. These data combined with other biophysical studies allow us to suggest candidate interfacial amino acids crucial in controlling assembly. This work deepens our understanding of how these ferritin complexes assemble and is a useful step towards production of triggerable ferritins in which these properties can be finely designed and controlled.

Succinylated ferritin as a novel nanocage-like vehicle of polyphenol: Structure, stability, and absorption analysis

Ferritin, a protein with an 8-nm cage structure, can encapsulate and deliver bioactive molecules. In this study, succinylation was adopted to modify plant ferritin to fabricate succinylated red been ferritin (SRBF) at pH 8.0. The SRBF was retained as a cage-like shape (12 nm diameter), while its secondary structure was altered, rendering higher negative charge accompanies by decreased surface hydrophobicity. The SRBF also demonstrated favorable property of reversible assembly regulated by pH-transitions (pH 2.0/7.0), thus enabled successful encapsulation of epigallocatechin gallate (EGCG) for fabrication of EGCG-loaded SRBF complexes with a diameter of ~12 nm. Succinylation enhanced the thermal stabilities of ferritin and the embedded EGCG. Moreover, SRBF markedly improved the transport efficiency of EGCG in Caco-2 monolayers relative to EGCG and that encapsulated in unmodified ferritin. These findings have extended the succinylation reaction for the cage-like protein modification, and facilitated the usage of ferritin variant in delivery of bioactive molecules.

Towards Green Nanoscience: From extraction to nanoformulation

The use of nanotechnology has revolutionized many biotechnological sectors, from bioengineering to medicine, passing through food and cosmetic fields. However, their clinic and industrial application has been into the spotlight due to their safety risk and related side effects. As a result, Green Nanoscience/Nanotechnology emerged as a strategy to prevent any associated nanotoxicity, via implementation of sustainable processes across the whole lifecycle of nanoformulation. Notwithstanding its success across inorganic nanoparticles, the green concept for organic nanoparticle elaboration is still at its infancy. This, coupled with the organic nanoparticles being the most commonly used in biomedicine, highlights the need to implement specific green principles for their elaboration. In this review, we will discuss the possible green routes for the proper design of organic nanoparticles under the umbrella of Green Nanoscience: from the extraction of nanomaterials and active compounds to their final nanoformulation.

A review of the interaction between anthocyanins and proteins

Anthocyanins have good physiological functions, but they are unstable. The interaction between anthocyanins and proteins can improve the stability, nutritional and functional properties of the complex. This paper reviews the structural changes of complex of anthocyanins interacting with proteins from different sources. By circular dichroism (CD) spectroscopy, it was found that the contents of α-helix (from 15.90%-42.40% to 17.60%-52.80%) or β-sheet (from 29.00%-50.00% to 29.40%-57.00%) of the anthocyanins-proteins complex increased. Fourier transform infrared spectroscopy showed that the regions of amide I (from 1627.87-1641.41 cm^-1 to 1643.34-1651.02 cm^-1) and amide II (from 1537.00-1540.25 cm^-1 to 1539.00-1543.75 cm^-1) of anthocyanins-proteins complex were shifted. Fluorescence spectroscopy showed that the fluorescence intensity of the complex decreased from 150-5100 to 40-3900 a.u. The thermodynamic analysis showed that there were hydrophobic interactions, electrostatic and hydrogen bonding interactions between anthocyanins and proteins. The kinetic analysis showed that the half-life and activation energy of the complex increased. The stability, antioxidant, digestion, absorption, and emulsification of the complex were improved. This provides a reference for the study and application of anthocyanins and proteins interactions.

Ferritin Nanocage: A Versatile Nanocarrier Utilized in the Field of Food, Nutrition, and Medicine

Compared with other nanocarriers such as liposomes, mesoporous silica, and cyclodextrin, ferritin as a typical protein nanocage has received considerable attention in the field of food, nutrition, and medicine owing to its inherent cavity size, excellent water solubility, and biocompatibility. Additionally, ferritin nanocage also serves as a versatile bio-template for the synthesis of a variety of nanoparticles. Recently, scientists have explored the ferritin nanocage structure for encapsulation and delivery of guest molecules such as nutrients, bioactive molecules, anticancer drugs, and mineral metal ions by taking advantage of its unique reversible disassembly and reassembly property and biomineralization. In this review, we mainly focus on the preparation and structure of ferritin-based nanocarriers, and regulation of their self-assembly. Moreover, the recent advances of their applications in food nutrient delivery and medical diagnostics are highlighted. Finally, the main challenges and future development in ferritin-directed nanoparticles’ synthesis and multifunctional applications are discussed.

Double-Interface Binding of Two Bioactive Compounds with Cage-Like Ferritin

Ferritin is a cage-like carrier protein with multiple interfaces, allowing for the encapsulation and delivery of biologically active molecules. In this study, hesperetin was covalently conjugated to the outer surface of ferritin to fabricate hesperetin covalently modified ferritin (HFRT) at pH 9.0. This conjugation resulted in a binding equivalent of hesperetin to ferritin of 12.33 ± 0.56 nmol/mg. After covalent binding, the free amino content of HFRT decreased and the secondary and tertiary structures of HFRT were changed relative to the structure of control ferritin. In addition, HFRT successfully retained the cage-like structure of ferritin and exhibited reversible self-assembly property regulated by pH shifts. Taking advantage of this property, quercetin was encapsulated into the inner surface of HFRT with an encapsulation ratio of 14.0 ± 1.36% (w/w). The modification with hesperetin improved the digestive stability of ferritin and enhanced the stability of encapsulated quercetin against thermal treatment compared to unmodified ferritin. This study explored the functions of the double interfaces of ferritin by covalent and non-covalent binding of two different bioactive compounds. The results can help guide the functionalization of the ferritin cage as a nanocarrier in food application.

Coencapsulation and Stability Evaluation of Hydrophilic and Hydrophobic Bioactive Compounds in a Cagelike Phytoferritin

Enrichment of multiple bioactive components with different characters into one food substrate simultaneously is a challenge. In this study, the hydrophilic epigallocatechin gallate (EGCG) and the hydrophobic quercetin were simultaneously enriched in the cavity of phytoferritin from red bean seed deprived of iron (apoRBF), a cagelike protein. The interactions of apoRBF with EGCG and quercetin were evaluated by UV/visible absorption, fluorescence, and circular dichroism technologies. By combination of the reversible assembly and urea induced approaches, both EGCG and quercetin were successfully coencapsulated in apoRBF to fabricate four kinds of apoRBF-EGCG-quercetin nanocomplexes FEQ (FEQ1, FEQ2, FEQ3, and FEQ4) with good solubility in aqueous solution. All FEQ samples maintained the typically spherical morphology of ferritin cage with a diameter around 12 nm. Among the four FEQ samples, the FEQ1 prepared by involving a pH 2.0/6.7 transition scheme was more effective in encapsulating EGCG and quercetin molecules than that by the urea induced method. Furthermore, all FEQs facilitated the stability of EGCG and quercetin molecules relative to free ones, and simultaneous coencapsulation of EGCG and quercetin could significantly improve the quercetin stability as compared with that of the free one and quercetin-loaded ferritin (p < 0.05), respectively. This work provides a new scheme to design and fabricate the ferritin based carrier for encapsulation of multiple bioactive components, and it is beneficial for the intensification of multifunction in one food substrate.

Proanthocyanidin Encapsulated in Ferritin Enhances Its Cellular Absorption and Antioxidant Activity

Proanthocyanidins (PAs) possess superior antioxidant properties and nutritious value, however, low bioavailability and stability limit their applications. Here, we developed a novel method to encapsulate PA dimers successfully into horse spleen apoferritin (apoHSF) using a disassembly/reassembly method based on pH change. The PA-HSF nanoparticles were characterized using fluorescence spectroscopy, transmission electron microscopy, circular dichroism, and high-performance liquid chromatography. One apoferritin cage could approximately encapsulate 25.6 molecules of the PA dimer. The results showed that the encapsulation of the PA dimers protected it from the damage of oxidants and temperature below room temperature would be an appropriate condition for HSF-578 solution storage. Moreover, HepG2 cell monolayer absorption and adhesion analyses indicated that the PA dimers encapsulated within apoHSF cages were more efficient in transport. In addition, it was indicated that the PA-HSF nanoparticles had higher cellular antioxidant activity. The novel strategy provided in this study indicates that the protein cage structures like ferritin have potential to be applied in the field of food nutrition.

Influence of Manothermosonication on the Physicochemical and Functional Properties of Ferritin as a Nanocarrier of Iron or Bioactive Compounds

Ferritin is a multisubunit protein with a hollow interior interface and modifiable surfaces. In this study, the manothermosonication (MTS) technology was applied to apo-red bean seed ferritin (apoRBF) to produce the MTS-treated apoRBF (MTFS). MTS treatment (200 kPa, 50 °C, and 40 s) maintained the spherical morphology of apoRBF (12 nm), but reduced the content of α-helix structure and increased the content of random coil structure, and correspondingly decreased the ferritin stability. The MTS treatment also affected the ferritin's iron storage function by decreasing its iron oxidative deposition activity and increasing the iron release activity. Importantly, the disassembly and reassembly properties of the MTFS induced by pH changes were retained, which facilitated its usage in encapsulation of tea polyphenol-epigallocatechin gallate (EGCG) into the ferritin by a relatively benign pH conversion routine (pH 3.0/6.8). In addition, the water solubility of the MTFS was increased, leading to the improved encapsulation efficiency of the EGCG molecules. This study will facilitate the ferritin modification and functionalization by MTS to design a protein variant to be used as new scaffold for iron and bioactive compounds.

Novel Soy β-Conglycinin Core-Shell Nanoparticles As Outstanding Ecofriendly Nanocarriers for Curcumin

The development of high-performance nanocarriers for nutraceuticals or drugs has become one of the topical research subjects in the functional food fields. In this work, we for the first time propose a novel and ecofriendly process to obtain a kind of nanostructured soy β-conglycinin (β-CG; a major soy storage globulin) as outstanding nanocarriers for poorly soluble bioactives (e.g., curcumin), by a urea-assisted disassembly and reassembly strategy. At urea concentrations > 4 M, the structure of β-CG gradually dissociated into its separate subunits (α, α', and β) and even denatured (depending on the type of subunits); after dialysis to remove urea, the dissociated subunits would reassemble into a kind of core-shell nanostructured particles, in which aggregated β-subunits acted as the core while the shell layer was mainly composed of α- and α'-subunits. The core-shell nanoparticles were favorably formed at protein concentrations of 1.0-2.0 wt %. Curcumin crystals were directly introduced into the β-CG solution at high urea concentrations (e.g., 8 M) and would preferentially interact with the denatured β-subunits. As a consequence, almost all of the curcumin molecules were encapsulated in the core part of the reassembled core-shell nanoparticles. The loading amount of curcumin in these nanoparticles could reach 18 g of curcumin per 100 g of protein, which far exceeds those reported previously. The encapsulated curcumin exhibited a high water solubility, extraordinary thermal stability, and improved bioaccessibility, as well as a sustained release behavior. The findings provide a novel strategy to fabricate a kind of high-encapsulation-performance, organic solvent-free, and biocompatible nanocarrier for hydrophobic nutraceuticals and drugs.

Nanochemoprevention with therapeutic benefits: An updated review focused on epigallocatechin gallate delivery

Epigallocatechin gallate (EGCG) is a natural phenolic compound found in many plants, especially in green tea, which is a popular and restorative beverage with many claimed health benefits such as antioxidant, anti-cancer, anti-microbial, anti-diabetic, and anti-obesity activities. Despite its great curative potential, the poor bioavailability of EGCG restricts its clinical applcation. However, nanoformulations of EGCG are emerging as new alternatives to traditional formulations. This review focuses on the nanochemopreventive applications of various EGCG nanoparticles such as lipid-based, polymer-based, carbohydrate-based, protein-based, and metal-based nanoparticles. EGCG hybridized with these nanocarriers is capable of achieving advanced functions such as targeted release, active targeting, and enhanced penetration, ultimately increasing the bioavailability of EGCG. In addition, this review also summarizes the challenges for the use of EGCG in therapeutic applications, and suggests future directions for progress.

Interaction between rice bran albumin and epigallocatechin gallate and their physicochemical analysis

Epigallocatechin gallate (EGCG) is sensitive to heat thus its application in food industry is limited. In this work, rice bran albumin protein (RAP) was used as a carrier for EGCG. RAP-EGCG complexes (RAPE) were prepared with the binding number n of 0.0505:1 (EGCG: RAP, w/w) and binding constant K of (0.74 ± 0.002) × 10⁴ M^-1, which suggests that hydrogen bond/van der Waals forces played important roles in such binding. FTIR analysis demonstrated that EGCG could induce the secondary structure changes of RAP above the ratio of 1.92:1 (EGCG:RAP, w/w). Dynamic light scattering and scanning electron microscope results showed that EGCG could trigger RAP association. Furthermore, the EGCG stability in RAPE was significantly improved than that of free EGCG in 10-60 °C. The antioxidant ability of EGCG in RAPE was partially retained. These findings prove that RAP is a potential carrier for polyphenols and is beneficial for mechanism investigation between protein and polyphenols.

Food-grade Encapsulation Systems for (-)-Epigallocatechin Gallate

(-)-Epigallocatechin gallate (EGCG) has attracted significant research interest due to its health-promoting effects such as antioxidation, anti-inflammation and anti-cancer activities. However, its instability and poor bioavailability have largely limited its efficacy and application. Food-grade materials such as proteins, carbohydrates and lipids show biodegradability, biocompatibility and biofunctionality properties. Food-grade encapsulation systems are usually used to improve the bioavailability of EGCG. In the present paper, we provide an overview of materials and techniques used in encapsulating EGCG, in which the adsorption mechanisms of food-grade systems during in vitro digestion are reviewed. Moreover, the potential challenges and future work using food-grade encapsulates for delivering EGCG are also discussed.

Chitosan binding onto the epigallocatechin-loaded ferritin nanocage enhances its transport across Caco-2 cells

The binding of chitosan to epigallocatechin-encapsulated ferritin enhances epigallocatechin transport across Caco-2 cells through the transferrin receptor 1 (TfR1)-mediated absorption pathway.