Curcumin encapsulated in the complex of lysozyme/carboxymethylcellulose and implications for the antioxidant activity of curcumin

Construction of fish scale (Cyprinus carpio L.) gelatin-fatty acid conjugate for loading curcumin: Effect of alkyl chain length on the interaction and stability

A fish scale (FS) gelatin-fatty acid conjugate (GFC) with alkyl chain lengths of 8-18 was constructed to increase the aqueous solubility of curcumin. The effect of alkyl chain length on the interaction between GFC and curcumin was characterized by dynamic light scattering (DLS), X-ray photoelectron spectroscopy (XPS), fluorescence spectroscopy (FS), and isothermal titration calorimetry (ITC). The surface hydrophobicity (from 4987 ± 223.79 to 9982 ± 262.78) and curcumin loading capacity (from 8.20 ± 0.54 to 31.18 ± 1.41 μg/mg) of the GFC exhibited significant enhancements through increasing alkyl chain lengths from 8 to 18. This was accompanied by a reduction in particle size (from 661.5 ± 28.9 to 329.7 ± 6.6 nm) and ζ-potential (from -2.7 ± 0.92 to -26.8 ± 0.27). FS and ITC confirmed that GOC shared an optimal binding constant (Ka, 2.40 × 108 L·mol-1 and 3.47 × 105 M-1) and binding site (n, 1.45 and 2.276) with curcumin among GFCs. Increasing GFC's alkyl chain length also boosted the stability of entrapped curcumin against the thermal environment and ultraviolet radiation. These results could be beneficial for gelatin-based nanocarrier development and application.

Optimization of hypobaric and ultrasonic processing of persimmon rhamnogalacturonan-I to enhance drug-digestion interactions

The biological activity of polysaccharides used for nutraceuticals/drug excipients has been a neglected area of study. This work deals with the preparation, optimization, characterization, and evaluation of persimmon (Diospyros kaki Thunb.) fruit by-products and the study of the resultant dietary fiber (DF) interaction with other compounds, using acetaminophen as a model. Processing conditions for persimmon by-products were optimized to enhance antioxidant activity, with hypobaric, ultrasonic, and drying conditions tested at three levels of time and pH. The optimized DF was evaluated through in-vitro and ex-vivo release and permeation studies. Optimal conditions included three cycles of vacuum instantaneous expansion coupled with ultrasound waves (USEX), 42 min of ultrasound assisted extraction (UAE), and a pH of 1.5. After treatments, the antioxidant capacity (AC) increased six-fold, and zeta potential (ζ) analysis indicated polysaccharide aggregation at the optimized pH. The optimized polysaccharides, mainly formed by rhamnogalacturonan-I, displayed nuclear factor erythroid 2-related factor 2 (Nrf2)-dependent activity. In-vitro drug-DF interaction studies showed higher acetaminophen release during digestion. Permeation kinetics adhered to the Korsmeyer-Peppas model in both ex-vivo and in-vitro models, suggesting complex permeation mechanisms. Results suggest that the optimized DF enhances the bioavailability and controlled release of acetaminophen, indicating its potential for use in drug delivery systems and nutraceutical applications.

Impact of Encapsulation Position in Pickering Emulsions on Color Stability and Intensity Turmeric Oleoresin

The emulsification of natural pigment is a widely utilized strategy to enhance its stability in the food industry. However, high turbidity in emulsions often causes color fading, limiting their application. Here, we developed a comprehensive Pickering emulsion (PE) system to improve the color intensity and stability of turmeric oleoresin (Tur) under various food processing conditions. Specifically, the effects of two encapsulation positions within the PE were compared: the inner oil phase (Tur-IPE) and the outer solid particle layer (Tur-OPE). Lysozyme and carboxymethyl cellulose nanoparticles (NPs) were used as natural solid particle surfactants, with their successful formation confirmed through physical property analysis and FTIR spectroscopy. The optimal oil fraction (φ) for suitable physical properties of PE was determined to be 0.2. Interestingly, Tur-OPE significantly exceeded Tur-conventional emulsions (Tur-CE) and Tur-IPE in terms of color vividness, exhibiting higher redness and lower lightness (p < 0.05). During thermal processing at 70 and 90 °C, all emulsions demonstrated significantly enhanced heat resistance, retaining 1.3 to 1.6 times more Tur, respectively, compared to unencapsulated Tur (free Tur) (p < 0.05). Furthermore, Tur's pH instability was significantly overcome by encapsulation in all emulsion systems (p < 0.05). During 4 weeks of storage period, Tur-OPE demonstrated the highest retention rates, with the half-life of Tur increasing in the following order: free Tur < Tur-CE < Tur-IPE < Tur-OPE. Thus, we highlighted the important role of encapsulation position in PEs in improving and maintaining the color stability and vividness of natural pigments under various food processing conditions.

Application of chitosan as nano carrier in the treatment of inflammatory bowel disease

Inflammatory bowel disease (IBD), encompassing ulcerative colitis (UC) and Crohn's disease (CD), is characterized by persistent and recurrent gastrointestinal inflammation. Conventional IBD therapies often involve the use of antibiotics, NSAIDs, biological agents, and immunomodulators. While these medications can mitigate acute inflammatory symptoms, their long-term efficacy is frequently compromised due to cumulative toxic effects. In recent years, significant attention has shifted toward nanoparticle (NP)-based therapies as potential alternatives for IBD management. Various drug delivery strategies, including those targeting microbiota interactions, ligand-receptor binding, pH sensitivity, biodegradability, pressure response, and specific charge and size parameters, have been explored and optimized in animal studies. This review provides a comprehensive overview of the current landscape of chitosan NP-mediated drug delivery systems for IBD treatment. Additionally, it will discuss the prevailing challenges and propose future research directions to advance chitosan NP-based therapeutic strategies for IBD.

Mix and Shake: A Mild Way to Drug-Loaded Lysozyme Nanoparticles

Biocompatible nanoparticles as drug carriers can improve the therapeutic efficiency of hydrophobic drugs. However, the synthesis of biocompatible and biodegradable polymeric nanoparticles can be time-consuming and often involves toxic solvents. Here, a simple method for protein-based stable drug-loaded particles with a narrow polydispersity is introduced. In this process, lysozyme is mixed with hydrophobic drugs (curcumin, ellipticine, and dasatinib) and fructose to prepare lysozyme-based drug particles of around 150 nm in size. Fructose is mixed with the drug to generate nanoparticles that serve as templates for the lysozyme coating. The effect of lysozyme on the physicochemical properties of these nanoparticles is studied by transmission electron microscopy (TEM) and scattering techniques (e.g., dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS)). We observed that lysozyme significantly stabilized the curcumin fructose particles for 7 days. Moreover, additional drugs, such as ellipticine and dasatinib, can be loaded to form dual-drug particles with narrow polydispersity and spherical morphology. The results also reveal that lysozyme dual ellipticine/dasatinib curcumin particles enhance the cytotoxicity and uptake on MCF-7 cells, RAW 264.7 cells, and U-87 MG cells due to the larger and rigid hydrophobic core. In summary, lysozyme in combination with fructose and curcumin can serve as a powerful combination to form protein-based stable particles for the delivery of hydrophobic drugs.

Pectin-coated whey protein isolate/zein self-aggregated nanoparticles as curcumin delivery vehicles: Effects of heating, pH, and adding sequence

In this work, pectin was employed as a coating material to fabricate zein/whey protein isolate (WPI)/pectin complex nanoparticles via a pH-adjusted and heat-induced electrostatic adsorption process for potential oral administration applications of curcumin. Factors such as the order of raw material addition, heating temperature and pH, and zein concentration were comprehensively examined. In addition to electrostatic interactions, Fourier transform infrared and fluorescence spectroscopy indicated that hydrophobic interactions and hydrogen bonds were also involved in the development of complex nanoparticles. The complex nanoparticles obtained not only improved the antioxidant activity of curcumin in aqueous phase, but also contributed to its controlled release under gastrointestinal conditions. Our findings revealed that the heating pH and adding sequence of raw materials had a notable impact on the properties of complex nanoparticles, and that pectin coating had an exceptional stabilizing effect on complex nanoparticles under gastrointestinal circumstances. This study provides novel insights and perspectives for the preparation of polysaccharide-protein complex nanoparticles, signifying the potential use of zein/WPI/pectin complex nanoparticles as delivery vehicles in the functional food and pharmaceutical industries.

Effects of Different Molecular Weight Oxidized Dextran as Crosslinkers on Stability and Antioxidant Capacity of Curcumin-Loaded Nanoparticles

Curcumin is a polyphenolic compound that has been widely investigated for its health benefits. However, the clinical relevance of curcumin is limited due to its low water solubility and inefficient absorption. Therefore, curcumin is often encapsulated in nanocarriers to improve its delivery and function. In this study, composite nanoparticles composed of stearic acid-modified chitosan (SA-CS) and sodium caseinate (NaCas) were formed using sodium periodate-oxidized dextran with different molecular weights as a crosslinking agent. The effects of oxidized dextran (Odex) with different molecular weights on the composite nanoparticles were compared. The optimal SA-CS/NaCas/Odex composite nanoparticle (NPO) was obtained using an Odex (150 kDa)-to-SA-CS mass ratio of 2:1. Its size, polydispersity index (PDI), and zeta potential (ZP) were 130.2 nm, 0.149, and 25.4 mV, respectively. The particles were highly stable in simulated gastric fluid (SGF) in vitro, and their size and PDI were 172.3 nm and 0.263, respectively. The encapsulation rate of NPO loaded with curcumin (Cur-NPO) was 93% under optimal ultrasonic conditions. Compared with free curcumin, the sustained release of Cur-NPO significantly reduced to 17.9%, and free-radical-scavenging ability improved to 78.7%. In general, the optimal prepared NPO exhibited good GI stability and has potential applications in the formulation of orally bioactive hydrophobic drugs.

Development and In Vitro Analysis of Layer-by-Layer Assembled Membranes for Potential Wound Dressing: Electrospun Curcumin/Gelatin as Middle Layer and Gentamicin/Polyvinyl Alcohol as Outer Layers

Nanofibrous membranes made of hydrogels have high specific surface areas and are suitable as drug carriers. Multilayer membranes fabricated by continuous electrospinning could delay drug release by increasing diffusion pathways, which is beneficial for long-term wound care. In this experiment, polyvinyl alcohol (PVA) and gelatin were used as membrane substrates, and a sandwich PVA/gelatin/PVA structure of layer-by-layer membranes was prepared by electrospinning under different drug loading concentrations and spinning times. The outer layers on both sides were citric-acid-crosslinked PVA membranes loaded with gentamicin as an electrospinning solution, and the middle layer was a curcumin-loaded gelatin membrane for the study of release behavior, antibacterial activity, and biocompatibility. According to the in vitro release results, the multilayer membrane could release curcumin slowly; the release amount was about 55% less than that of the single layer within 4 days. Most of the prepared membranes showed no significant degradation during immersion, and the phosphonate-buffered saline absorption rate of the multilayer membrane was about five to six times its weight. The results of the antibacterial test showed that the multilayer membrane loaded with gentamicin had a good inhibitory effect on Staphylococcus aureus and Escherichia coli. In addition, the layer-by-layer assembled membrane was non-cytotoxic but detrimental to cell attachment at all gentamicin-carrying concentrations. This feature could be used as a wound dressing to reduce secondary damage to the wound when changing the dressing. This multilayer wound dressing could be applied to wounds in the future to reduce the risk of bacterial infection and help wounds heal.

Multifunctional hydrogels based on chitosan, hyaluronic acid and other biological macromolecules for the treatment of inflammatory bowel disease: A review

Hydrogel is a three-dimensional network polymer material rich in water. It is widely used in the biomedical field because of its unique physical and chemical properties and good biocompatibility. In recent years, the incidence of inflammatory bowel disease (IBD) has gradually increased, and the disadvantages caused by traditional drug treatment of IBD have emerged. Therefore, there is an urgent need for new treatments to alleviate IBD. Hydrogel has become a potential therapeutic platform. However, there is a lack of comprehensive review of functional hydrogels for IBD treatment. This paper first summarizes the pathological changes in IBD sites. Then, the action mechanisms of hydrogels prepared from chitosan, sodium alginate, hyaluronic acid, functionalized polyethylene glycol, cellulose, pectin, and γ-polyglutamic acid on IBD were described from aspects of drug delivery, peptide and protein delivery, biologic therapies, loading probiotics, etc. In addition, the advanced functions of IBD treatment hydrogels were summarized, with emphasis on adhesion, synergistic therapy, pH sensitivity, particle size, and temperature sensitivity. Finally, the future development direction of IBD treatment hydrogels has been prospected.

Effects of the molecular weight of hyaluronan on the conformation and release kinetics of self-assembled 5-fluorouracil-loaded lysozyme-hyaluronan colloidal nanoparticles

Lysozyme (LYS) and hyaluronan with low (HA1: 3 kDa), medium (HA2: 120 kDa), and high (HA3: 1200 kDa) molecular weights were used to fabricate lysozyme-hyaluronan colloidal nanoparticles using a green self-assembly method. Fourier transform infrared spectroscopy indicated that hydrogen bonding, hydrophobic and electrostatic interactions promoted the formation of the colloidal nanoparticles. The hydrophobic area of prepared colloidal nanoparticles was quantified using a pyrene fluorescent probe, and the results showed that the LYS-HA3 nanoparticles had the strongest hydrophobic capacity. Furthermore, 5-fluorouracil (5-Fu) was used to evaluate encapsulation performance, demonstrating that the LYS-HA3 nanoparticles had the highest encapsulation ability (>90 %). All prepared 5-Fu-loaded lysozyme-hyaluronan (5-Fu@LYS-HA) colloidal nanoparticles exhibited excellent long-term storage stability at 4 °C for 60 days. Cellular uptake and in vitro release results indicated that the LYS-HA2 nanoparticles exhibited the highest cellular uptake efficiency, and the LYS-HA3 nanoparticles had the best slow-release effect, while the release process was mainly controlled by the combination of Fickian diffusion and structural relaxation, respectively. This study demonstrates the influence of molecular weight on the conformational and structural properties of colloidal nanoparticles, which has implications for the design of insoluble drug self-assembly systems.

Understanding of physicochemical properties and antioxidant activity of ovalbumin-sodium alginate composite nanoparticle-encapsulated kaempferol/tannin acid

In this research, ovalbumin (OVA) and sodium alginate (SA) were used as the materials to prepare an OVA–SA composite carrier, which protected and encapsulated the hydrophobic kaempferol (KAE) and the hydrophilic tannic acid (TA) (OVA–SA, OVA–TA–SA, OVA–KAE–SA, and OVA–TA–KAE–SA). Results showed that the observation of small diffraction peaks in carriers proved the successful encapsulation of KAE/TA. The protein conformation of the composite nanoparticles changed. OVA–TA–SA composite nanoparticles had the highest α-helix content and the fewest random coils, so the protein structure of it had the strongest stability. OVA–TA–KAE–SA composite nanoparticles had the strongest system stability and thermal stability, which might be due to the synergistic effect of the two polyphenols, suggesting the encapsulation of KAE/TA increased the system stability and the thermal stability of OVA–SA composite nanoparticles. Additionally, the composite nanoparticles were endowed with antioxidant ability and antibacterial ability (against Staphylococcus aureus and Escherichia coli) in the order OVA–TA–SA > OVA–TA–KAE–SA > OVA–KAE–SA based on the difference in antibacterial diameter (D, mm) and square (S, mm²), indicating that polyphenols enhanced the antibacterial and antioxidant ability of OVA–SA composite nanoparticles, and the enhancement effect of TA was stronger than that of KAE. These results provide a theoretical basis for the application of OVA–SA composite nanoparticles in the delivery of bioactive compounds.

Ovalbumin (OVA) and sodium alginate (SA) were used as materials to prepare an OVA–SA composite carrier, which encapsulated the hydrophobic kaempferol (KAE) and the hydrophilic tannic acid (TA) (OVA–SA, OVA–TA–SA, OVA–KAE–SA, and OVA–TA–KAE–SA).

Influence of polyphenol-metal ion-coated ovalbumin/sodium alginate composite nanoparticles on the encapsulation of kaempferol/tannin acid

In this research, ovalbumin (OVA) and sodium alginate (SA) were used as the materials to prepare OVA-SA composite carriers, which protected and encapsulated the hydrophobic kaempferol (KAE) and the hydrophilic tannic acid (TA). To achieve the purpose of targeted delivery, the TA-Fe³⁺ coating film was prepared. Results showed that the observation of small diffraction peaks in carriers proved the formation of TA/Fe³⁺ coating film on the surface of four composite nanoparticles (pOVA, pOVA-SA, pOVA-KAE-SA, and pOVA-KAE-TA-SA). The protein structure of the composite nanoparticles coated with TA/Fe³⁺ changed, and the order of the changes was pOVA-KAE > pOVA > pOVA-KAE-SA > pOVA-KAE-TA-SA > pOVA-SA. This phenomenon is due to the fact that the chromophore -C=O and the auxo-chromophore -OH are in the opposite position in the benzene ring of TA, and the two substituents have opposite effects and synergize, resulting in the different degrees of redshift of the composite nanoparticle λ_max. Additionally, pOVA-SA had the highest α-helix content and the lowest random coils, conferring the protein structure the strongest stability. The coating of TA/Fe³⁺ increased the system stability and the thermal stability of the composite nanoparticles. Additionally, the carriers were endowed with antioxidant activity, and their antibacterial ability against Staphylococcus aureus and Escherichia coli was pOVA-KAE-TA-SA > pOVA-KAE-SA > pOVA-KAE > pOVA-SA > pOVA based on the difference in antibacterial diameter (D, mm) and square (S, mm²). pOVA-KAE-TA-SA had the strongest antioxidant activity and antibacterial ability, which improved the bioavailability of TA/KAE. These results provide a theoretical basis for the application of OVA-SA composite nanoparticles in the delivery of bioactive compounds.

Maillard-Type Protein-Polysaccharide Conjugates and Electrostatic Protein-Polysaccharide Complexes as Delivery Vehicles for Food Bioactive Ingredients: Formation, Types, and Applications

Due to their combination of featured properties, protein and polysaccharide-based carriers show promising potential in food bioactive ingredient encapsulation, protection, and delivery. The formation of protein–polysaccharide complexes and conjugates involves non-covalent interactions and covalent interaction, respectively. The common types of protein–polysaccharide complex/conjugate-based bioactive ingredient delivery systems include emulsion (conventional emulsion, nanoemulsion, multiple emulsion, multilayered emulsion, and Pickering emulsion), microcapsule, hydrogel, and nanoparticle-based delivery systems. This review highlights the applications of protein–polysaccharide-based delivery vehicles in common bioactive ingredients including polyphenols, food proteins, bioactive peptides, carotenoids, vitamins, and minerals. The loaded food bioactive ingredients exhibited enhanced physicochemical stability, bioaccessibility, and sustained release in simulated gastrointestinal digestion. However, limited research has been conducted in determining the in vivo oral bioavailability of encapsulated bioactive compounds. An in vitro simulated gastrointestinal digestion model incorporating gut microbiota and a mucus layer is suggested for future studies.

Recent Developments of Carboxymethyl Cellulose

Carboxymethyl cellulose (CMC) is one of the most promising cellulose derivatives. Due to its characteristic surface properties, mechanical strength, tunable hydrophilicity, viscous properties, availability and abundance of raw materials, low-cost synthesis process, and likewise many contrasting aspects, it is now widely used in various advanced application fields, for example, food, paper, textile, and pharmaceutical industries, biomedical engineering, wastewater treatment, energy production, and storage energy production, and storage and so on. Many research articles have been reported on CMC, depending on their sources and application fields. Thus, a comprehensive and well-organized review is in great demand that can provide an up-to-date and in-depth review on CMC. Herein, this review aims to provide compact information of the synthesis to the advanced applications of this material in various fields. Finally, this article covers the insights of future CMC research that could guide researchers working in this prominent field.

Insight into the effect of charge regulation on the binding mechanism of curcumin to myofibrillar protein

Myofibrillar proteins (MPs), as a food-grade material, have the potential to improve the solubility and bioavailability of curcumin. However, the interaction mechanism between MPs and curcumin under charge regulation induced by alkaline pH and NaCl was unclear. In this study, the binding between curcumin and MPs at pH 12 was confirmed by the fluorescence quenching under different NaCl concentration (0, 0.3, 0.6 and 0.9 mol/L). Further kinetic experiments showed, MPs possessed a higher affinity to bind curcumin in the presence of NaCl, especially at 0.6 M NaCl. Followed pH shifting from 12 to 7 does not affect UV-Vis absorption spectra of protein-curcumin dispersions. The secondary structure of MPs was not affected by binding with curcumin. Formation of this stable complex can be explained by hydrophobic other than electrostatic interaction. Therefore, the presence of NaCl facilitated exposure of hydrophobic pocket to improve the binding affinity between curcumin and MPs due to the importance of hydrophobic interaction.

Building an aprismatic enamel-like layer on a demineralized enamel surface by using carboxymethyl chitosan and lysozyme-encapsulated amorphous calcium phosphate nanogels

OBJECTIVES

The purpose of this study was to prepare carboxymethyl chitosan (CMC) and lysozyme nanogels that could encapsulate amorphous calcium phosphate (ACP) for achieving its controlled delivery, thus forming an aprismatic enamel-like layer on the demineralized enamel surface.

METHODS

CMC/LYZ-ACP nanogels were developed, and the controlled delivery of ACP from the nanogels was induced by the presence of NaCl. The nanogel morphologies at various NaCl concentrations was measured by transmission electron microscopy (TEM). The particle sizes and zeta potentials (ζ-potential) of the samples were determined using a combined dynamic light scattering/particle electrophoresis instrument. Comparing the remineralization effect of the CMC/LYZ-ACP nanogels on the demineralized enamel surface with that of a fluoride treatment, the remineralization effect was examined by nanoindentation tests, X-ray diffraction (XRD), confocal laser scanning microscopy (CLSM), and scanning electron microscopy (SEM).

RESULTS

CMC/LYZ-ACP nanogels were negatively charged spherical structures with a particle size of approximately 300 nm. At high concentrations of NaCl (0.15 M), ACP was dissociated from the disassembled nanogels and transformed into hydroxyapatite (HAP). Groups treated with the CMC/LYZ-ACP nanogels showed the regeneration of an aprismatic enamel-like layer on an acid-etched enamel surface, which provided increased mechanical properties (P < 0.05) and a high impermeability (P < 0.01) compared to those of the fluoride-treated group.

CONCLUSIONS

This research provides a new idea for the stable and controllable delivery of ACP from CMC/LYZ-ACP nanogels, which can form an aprismatic enamel-like layer in situ on the surface of demineralized enamel. In regard to further clinical development, this material and method may be promising for treating early enamel caries.

Elaboration and characterization of curcumin-loaded soy soluble polysaccharide (SSPS)-based nanocarriers mediated by antimicrobial peptide nisin

Curcumin was recently attracted great interest owing to its multiple bioactivities; however, the use of curcumin was hindered by its poor solubility and stability. In this study, curcumin-nisin-soy soluble polysaccharide nanoparticles (Cur-Nisin-SSPS-NPs, size = 118.76 nm) have been successfully elaborated to improve the application of curcumin. The formation of Cur-Nisin-SSPS-NPs was mediated by amphiphilic and positively charged nisin: SSPS encapsulated nisin, which was mainly driven by electrostatic attraction. And nisin-SSPS complex encapsulated curcumin mainly through hydrophobic interactions between nisin and curcumin. The encapsulation efficiency of curcumin (91.66%) in this novel nanocarriers was significantly higher than that in nanoparticles prepared by a single SSPS (31.82%) or nisin (41.69%), most likely because more hydrophobic regions of nisin were exposed after interacting with SSPS through electrostatic interaction. Consequently, this facile and green nanocarriers improved the solubility/dispersibility and stability of curcumin and nisin, as well as endowed SSPS-based nanoparticles with antioxidant and antimicrobial activities.

pH-shifting encapsulation of curcumin in egg white protein isolate for improved dispersity, antioxidant capacity and thermal stability

Curcumin (Cur) has many functions, such as antioxidant and anti-inflammatory. However, its poor solubility and thermal stability at aqueous solutions limit its application in the food industry. In this study, egg white protein isolate (EPI) was complexed with Cur via a pH-shifting method. The effects of ultimate pH (from 5.0 to 7.0) on the physicochemical properties of the complex were studied. Cur could reach 84.4% encapsulation efficiency at pH 6.0. Meanwhile, the EPI complex could remain stable at pH 7.0 after 30 days and protect Cur from thermal degradation, thereby improving the Cur retention rate with the increasing ultimate pH. Compared with those of EPI and free Cur, the antioxidant capacity of the complex was enhanced effectively. The EPI-Cur complex was certified using UV-vis and fluorescence spectra. The fluorescence results indicated that Cur and EPI are combined through a static quenching and with a strong affinity of 1.8 × 10⁵ M^-1 at pH 6.0. In summary, this work provides a biocompatible and straightforward method for the development of nanoparticles based on egg white protein isolates, which can be used as a promising carrier for insoluble nutritional compounds.

Carboxymethyl chitosan microspheres loaded hyaluronic acid/gelatin hydrogels for controlled drug delivery and the treatment of inflammatory bowel disease

A major drawback of oral treatment of inflammatory bowel disease (IBD) is the non-specific distribution of drugs during long-term treatment. Despite its effectiveness as an anti-inflammatory drug, curcumin (CUR) is limited by its low bioavailability in IBD treatment. Herein, a pH-sensitive composite hyaluronic acid/gelatin (HA/GE) hydrogel drug delivery system containing carboxymethyl chitosan (CC) microspheres loaded with CUR was fabricated for IBD treatment. The composition and structure of the composite system were optimized and the physicochemical properties were characterized using infrared spectroscopy, X-ray diffraction, swelling, and release behavior studies. In vitro, the formulation exhibited good sustained release property and the drug release rate was 65% for 50 h. In vivo pharmacokinetic experiments indicated that high level of CUR was maintained in the colon tissue for more than 24 h; it also played an anti-inflammatory role by evaluating the histopathological changes through hematoxylin and eosin (H&E), myeloperoxidase (MPO), and immunofluorescent staining. Additionally, the formulation substantially inhibited the level of the main pro-inflammatory cytokines of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) secreted by macrophages, compared to the control group. The pharmacodynamic experiment showed that the formulation group of CUR@gels had the best therapeutic effect on colitis in mice. The composite gel delivery system has potential for the effective delivery of CUR in the treatment of colitis. This study also provides a reference for the design and preparation of a new oral drug delivery system with controlled release behavior.

Encapsulation and release behavior of curcumin based on nanoemulsions-filled alginate hydrogel beads

To provide the bilateral advantages of emulsions and hydrogels, a facile approach was used to fabricate nanoemulsions filled hydrogel beads through combining the method of self-emulsification and sodium alginate (SA) ionic gelation. The encapsulation and release behavior of curcumin (Cur) were further investigated. The results indicated that Cur packaged nanoemulsions were with the size of 24.26 ± 0.22 nm. The nanoemulsions filled SA hydrogel beads were spherical shell with the diameter of 0.46 ± 0.02 mm. For Cur, the EE and LC of emulsion filled SA hydrogel beads were 99.15 ± 0.85% and 7.25 ± 3.16 mg/g respectively. The release behavior could be regulated by external pH condition. The release behavior at pH 9.0 displayed a higher release rate than that at pH 7.0. Cur released behavior well followed the Hixcon-Crowell model which indicated that Cur was released in a diffusion-controlled model. Comparatively investigation of microstructure using field emission scanning electron microscope (FE-SEM) further investigates the corrosion behavior of SA gel beads during Cur release. The worth-while endeavor provided a practical combined technique of emulsions and ionic gelation to fabricate hybrid hydrogel beads that have potential in delivery system for hydrophobic composition.

Comparison of structural and physicochemical properties of lysozyme/carboxymethylcellulose complexes and microgels

Proteins and polysaccharides can be used to assemble colloidal delivery systems suitable for industrial applications, such as functional foods, supplements, pharmaceuticals, and personal care products. The purpose of this work was to compare the physicochemical and structural properties of colloidal delivery systems prepared from lysozyme and carboxymethyl cellulose (CMC) at different biopolymer ratios, pH values, and salt levels. Specifically, the performance of unheated ("complexes") and heated ("microgels") lysozyme-CMC systems were compared. Isothermal turbidity-pH titrations indicated that the critical pH value for complex formation was lower for microgels than for complexes. Complexes were prone to dissociation when the pH or ionic strength was altered due to weakening of electrostatic interactions between the CMC and lysozyme. Conversely, microgels remained intact when the pH or ionic strength was altered, exhibiting swelling or shrinkage rather than dissociation. These results have important implications for the selection of the most appropriate protein/polysaccharide systems to achieve specific functional requirements. Complexes may be more suitable for pH- or salt-based triggered release whereas microgels may be more suitable for sustained release.

Macro- and Microphase Separated Protein-Polyelectrolyte Complexes: Design Parameters and Current Progress

Protein-containing polyelectrolyte complexes (PECs) are a diverse class of materials, composed of two or more oppositely charged polyelectrolytes that condense and phase separate near overall charge neutrality. Such phase-separation can take on a variety of morphologies from macrophase separated liquid condensates, to solid precipitates, to monodispersed spherical micelles. In this review, we present an overview of recent advances in protein-containing PECs, with an overall goal of defining relevant design parameters for macro- and microphase separated PECs. For both classes of PECs, the influence of protein characteristics, such as surface charge and patchiness, co-polyelectrolyte characteristics, such as charge density and structure, and overall solution characteristics, such as salt concentration and pH, are considered. After overall design features are established, potential applications in food processing, biosensing, drug delivery, and protein purification are discussed and recent characterization techniques for protein-containing PECs are highlighted.

Immobilization of β-galactosidase by complexation: Effect of interaction on the properties of the enzyme

In the present work, we aimed to explore the molecular binding between alginate and β-galactosidase, as well as the effect of this interaction on the activity retention, thermal stability, and kinetic properties of the enzyme. The impact of pH and enzyme/alginate ratio on physicochemical properties (turbidity, morphology, particle size distribution, ζ-potential, FTIR, and isothermal titration calorimetry) was also evaluated. The ratio of biopolymers and pH of the system directly affected the critical pH of complex formation; however, a low alginate concentration (0.1 wt%) could achieve an electrical charge equivalence at pH 3.4 with 93.72% of yield. The binding between β-galactosidase and alginate was an equilibrium between enthalpic and entropic contributions, which promoted changes in the structure of the enzyme. Nevertheless, this conformational modification was reversible after the dissociation of the complex, which allowed the enzyme to regain its activity. These findings will likely broaden functional applications of enzyme immobilization.

Biocompatible Polyelectrolyte Complex Nanoparticles from Lactoferrin and Pectin as Potential Vehicles for Antioxidative Curcumin

Polyelectrolyte complex nanoparticles (PEC NPs) were fabricated via electrostatic interactions between positively charged heat-denatured lactoferrin (LF) particles and negatively charged pectin. The obtained PEC NPs were then utilized as curcumin carriers. PEC NPs were prepared by mixing 1.0 mg/mL solutions of heat-denatured LF and pectin at a mass ratio of 1:1 (w/w) in the absence of NaCl at pH 4.50. PEC NPs that were prepared under optimized conditions were spherical in shape with a particle size of ∼208 nm and zeta potential of ∼-32 mV. Hydrophobic curcumin was successfully encapsulated into LF/pectin PEC NPs with high encapsulation efficiency (∼85.3%) and loading content (∼13.4%). The in vitro controlled release and prominent antioxidant activities of curcumin from LF/pectin PEC NPs were observed. The present work provides a facile and fast method to synthesize nanoscale food-grade delivery systems for the improved water solubility, controlled release, and antioxidant activity of hydrophobic curcumin.

Smart nanocomposite hydrogels based on azo crosslinked graphene oxide for oral colon-specific drug delivery

A safe and efficient nanocomposite hydrogel for colon cancer drug delivery was synthesized using pH-sensitive and biocompatible graphene oxide (GO) containing azoaromatic crosslinks as well as poly (vinyl alcohol) (PVA) (GO-N=N-GO/PVA composite hydrogels). Curcumin (CUR), an anti-cancer drug, was encapsulated successfully into the hydrogel through a freezing and thawing process. Fourier transform infrared spectroscopy, scanning electron microscopy and Raman spectroscopy were performed to confirm the formation and morphological properties of the nanocomposite hydrogel. The hydrogels exhibited good swelling properties in a pH-sensitive manner. Drug release studies under conditions mimicking stomach to colon transit have shown that the drug was protected from being released completely into the physiological environment of the stomach and small intestine. In vivo imaging analysis, pharmacokinetics and a distribution of the gastrointestinal tract experiment were systematically studied and evaluated as colon-specific drug delivery systems. All the results demonstrated that GO-N=N-GO/PVA composite hydrogels could protect CUR well while passing through the stomach and small intestine to the proximal colon, and enhance the colon-targeting ability and residence time in the colon site. Therefore, CUR loaded GO-N=N-GO/PVA composite hydrogels might potentially provide a theoretical basis for the treatment of colon cancer with high efficiency and low toxicity.

A novel redox-sensitive system based on single-walled carbon nanotubes for chemo-photothermal therapy and magnetic resonance imaging

Recently, nanomaterials with multiple functions, such as drug carrier, magnetic resonance imaging (MRI) and optical imaging, and photothermal therapy, have become more and more popular in cancer research. In this work, a novel redox-sensitive system constructed from hyaluronic acid (HA), single-walled carbon nanotubes (SWCNTs), doxorubicin (DOX), and gadolinium (Gd) was successfully developed. Herein, HA-modified SWCNTs (SWCNTs-HA) was first synthesized, and then DOX was conjugated with HA by disulfide bond (SWCNTs-HA-ss-DOX). Finally, MRI contrast agents, Gd³⁺-ion loading occurred through the sidewall defects of SWCNTs, whose cytotoxicity could be sequestered within the SWCNTs. In vitro release of DOX showed that this system accomplished much faster drug release under reducing condition. Confocal microscopy analysis confirmed that Gd/SWCNTs-HA-ss-DOX were capable of simultaneously delivering DOX and SWCNTs into Michigan Cancer Foundation-7 cells via HA receptor-mediated endocytosis followed by rapid transport of cargoes into the cytosol. Enhanced cytotoxicity of Gd/SWCNTs-HA-ss-DOX further proved that the sensitive system was more potent for intracellular drug delivery as compared with the insensitive control. Meanwhile, tumor cell killing potency was improved when Gd/SWCNTs-HA-ss-DOX were combined with near-infrared irradiation, with IC₅₀ of 0.61 µg/mL at 48 hours. In vivo investigation demonstrated that Gd/SWCNTs-HA-ss-DOX could effectively accumulate in tumor sites and possessed the greatest synergistic antitumor efficacy, especially under the 808 nm laser irradiation. More importantly, this system could be used as a contrast agent for MRI to identify the location and extent of tumor tissues. These results suggested that Gd/SWCNTs-HA-ss-DOX might be a promising system for targeting chemo-photothermal therapy and MRI diagnosis in future clinical anticancer applications.