Fucoidan hydrogels induced by κ-carrageenan: Rheological, thermal and structural characterization

New insights on health benefits, interactions with food components and potential application of marine-derived sulfated polysaccharides: A review

Sulfated polysaccharides refer to polysaccharides containing sulfate groups on sugar units. In nature, sulfated polysaccharides are widely distributed in marine organisms, and the variation in sulfation sites, monosaccharide composition, and branched chain distribution among different species results in differences in the physicochemical properties and biological activities. From the latest perspective, this review summarized the types, structural characteristics, and potential health benefits of sulfated polysaccharides in marine foods. In recent years, marine-derived sulfated polysaccharides have been widely used as stabilizers and antimicrobial agents applied in nutraceutical delivery systems and food packaging, which depend on their interactions with food components. Hence, we outlined the non-covalent/covalent interactions of marine-derived sulfated polysaccharides with food components (e.g., proteins, polysaccharides, and polyphenols) as well as the application in food industry. Additionally, the prospects and potential development for sulfated polysaccharides are concluded, aiming to provide a deep understanding of marine-derived sulfated polysaccharides to promote the industrial application in food health.

Development of dissolving microneedles loaded with fucoidan for enhanced anti-aging activity: An in vivo study in mice animal model

Skin aging occurs naturally as essential skin components gradually decline, leading to issues such as fine lines, wrinkles, and pigmentation. Fucoidan, a natural bioactive compound, holds potential for addressing these age-related concerns. However, its hydrophilic nature and substantial molecular weight hinder its absorption into the skin. In this study, we utilized polyvinyl pyrrolidone K30 (PVP) and polyvinyl alcohol (PVA) as polymers to fabricate dissolving microneedles loaded with fucoidan (DMN-F). The DMN-F formulations were examined for physical characteristics, stability, permeability, toxicity, and efficacy in animal models. These formulations exhibited consistent polymer blends with a conical structure and uniform cone-shaped design. Microneedle structure and penetration capability gradually decreased with increasing fucoidan concentration, with storage recommended at approximately 33 % relative humidity (RH). Ex vivo studies showed that DMN-F efficiently delivered up to 95.03 ± 2.36 % of the total fucoidan concentration into the skin. In vivo investigations revealed that DMN-F effectively reduced wrinkles, improved skin elasticity, maintained moisture levels, and increased epidermal thickness. Histological images provided additional evidence of DMN-F's positive effects on these aging parameters. The results confirm that the DMN-F formulation effectively delivers fucoidan into the skin, allowing it to treat and mitigate signs of aging.

Polyelectrolyte complex formation of alginate and chito oligosaccharide is influenced by their proportion and alginate molecular weight

Sodium alginate (SA) and chito oligosaccharide (COS) are widely used food additives in the food industry, and exploring their interaction to form polyelectrolyte complexes (PECs) may provide insights into food development. In the present study, the effects of viscosity-average molecular weight (Mv) and relative amounts of SA on the formation of sodium alginate/chito oligosaccharide polyelectrolyte (SCP) complexes were investigated. The results showed that the electrostatic interaction between -COOH and -NH2 and the hydrogen bonding between OH, were attributed to the formation of the SCP complexes. Then the formation and properties of SCP complexes were greatly dependent on the Mv and the relative amount of SA. SA with Mv of ≥2.16 × 106 Da could form spherical SCP complexes, while the SA/COS ratio (w/w) ≥ 0.8 was not conducive to the formation of SCP complexes. Moreover, the SCP complexes were more stable in the gastric environment than in the intestinal condition. In addition, 1.73 × 107 Da was the optimal Mv of SA for SCP complexes formation. This study contributed to a comprehensive understanding of the interaction between SA and COS, and shed light on the potential application of SA and COS formulation to develop new food products.

An oral gel suitable for swallowing: The effect of micronization on the gel properties and microstructure of κ-carrageenan

κ-Carrageenan (κ-Car) is an important material for preparing food gels and hydrogels. However, κ-Car gel has issues with high hardness and low water-holding capacity. Modification strategy of micronization is proposed for the first time to explore its influence on texture properties and gelling process of κ-Car gel, and to investigate the feasibility of κ-Car as a food matrix with low strength. κ-Car undergoing 60 min of micronization, the d(0.9) decreased by 79.33 %, SBET and Vtotal increased by 89.23 % and 95.27 %. The swelling rate and degree of gelling process increased significantly, and the microstructure changed from loose large pores to dense small pores resembling a "honeycomb". Importantly, the hardness of gel-60, Milk-60 and PNS-60 decreased by 72.52 %, 49.25 % and 81.37 %. In addition, WHC of gel-60, Milk-60 and PNS-60 was improved. IDDSI tests showed that κ-Car gels, milk gels and PNS gels can be categorized as level 6 (soft and bite-sized), except for PNS-60, which belongs to level 5 (crumbly and moist). Furthermore, the texture and bitter masking effect of milk gels and PNS gels were improved. In conclusion, this study demonstrated that micronization can be a novel approach to improve the gel properties of κ-Car, laying the groundwork for developing dysphagia foods.

Fucoidan alleviates the inhibition of protein digestion by chitosan and its oligosaccharides

Chitosan (CTS) and chitosan oligosaccharides (COS) have been widely applied in food industry due to their bioactivities and functions. However, CTS and COS with positive charges could interact with proteins, such as whey protein isolate (WPI), influencing their digestion. Interaction among CTS/COS, FUC, and WPI/enzymes was studied by spectroscopy, chromatography, and chemical methods in order to reveal the role of FUC in relieving the inhibition of protein digestibility by CTS/COS and demonstrate the action mechanisms. As shown by the results, the addition of FUC increased degree of hydrolysis (DH) and free protein in the mixture of CTS and WPI to 3.1-fold and 1.8-fold, respectively, while raise DH value and free protein in the mixture of COS and WPI to 6.7-fold and 1.2-fold, respectively. The interaction between amino, carboxyl, sulfate, and hydroxyl groups from carbohydrates and protein could be observed, and notably, FUC could interact with CTS/COS preferentially to prevent CTS/COS from combining with WPI. In addition, the addition of FUC could also relieve the combination of CTS to trypsin, increasing the fluorescence intensity and concentration of trypsin by 83.3 % and 4.8 %, respectively. Thus, the present study demonstrated that FUC could alleviate the inhibitory effect of CTS/COS on protein digestion.

An Effective Method to Prepare Curcumin-Loaded Soy Protein Isolate Nanoparticles Co-Stabilized by Carrageenan and Fucoidan

In this study, a novel and simple strategy is proposed based on 3D network formed by easily blending polysaccharide carrageenan (Car) and fucoidan (Fuc) without a crosslinker. The Fuc/Car dual coating effectively assists the self-assembly of soy protein-isolated (SPI)/curcumin (Cur, C) composite microcapsules (SPI/C) and achieves an excellent curcumin encapsulation efficiency (EE) up to 95.28% with a 4.16% loading capacity (LC) under optimal conditions. The resulting nanocomposites achieved a satisfying redispersibility in aqueous solution and enhanced the water solubility with a lower size dispersity index (PDI) of 0.12 and a larger zeta potential of -29.67 mV. The Fuc/Car double-layer network not only dramatically improved its thermal stability and photostability, but also provided controlled release and enhanced antioxidant activity in in vitro conditions. The underlying mechanism of the self-assembly of the curcumin-loaded nanoparticles was also addressed. The results proved the feasibility of the encapsulation of unstable hydrophobic bioactive substances (curcumin) with the dual anionic polysaccharide Fuc/Car co-stabilized SPI nanoparticles. This study paves the way for an alternative way of developing novel curcumin delivery systems and will have broad prospects in the pharmaceutical industries.

Gel properties and interactions of hydrogels constructed with low acyl gellan gum and puerarin

To develop composite hydrogels based on low acyl gellan gum (GG), the effect of puerarin (PUE) on the gel properties of GG was investigated. The results showed that the maximum storage modulus (G') of the 1.2 % GG/0.8 % PUE composite hydrogel was 377.4 Pa at 0.1 Hz, which was enhanced by 4.7-fold compared with that of 1.2 % GG. The melting temperature of this composite hydrogel increased from 74.1 °C to >80.0 °C. LF-NMR results showed that a significant amount of free water was present in the hydrogel matrix. The surface structure aggregation and the shrinkage of the honeycomb meshes in the composite hydrogel proved the cross-linking of PUE and GG. XRD, FTIR and molecular simulation results illustrated that hydrogen bonds were the most important factor controlling the interaction between GG and PUE. Thus, the GG/PUE composite hydrogel has good elasticity, thermal stability and water retention, which lays a good foundation for further application in the food industry.

Structural homeostasis and controlled release for anthocyanin in oral film via sulfated polysaccharides complexation

Oral film is a novel functional carrier, which can provide a new pathway for the efficient absorption of anthocyanin. However, anthocyanin homeostasis in oral film is a prerequisite for achieving efficient absorption and utilization of anthocyanin. Herein, three sulfated polysaccharides, including chondroitin sulfate (CS), fucoidin (FU) and λ-carrageenan (λ-CG), were complexed with blueberry anthocyanin (BA) to prepare oral film formulations using hydroxypropyl methylcellulose (HPMC) as a film-forming matrix. The addition of three sulfated polysaccharides improved the stability of BA in content and color, which were associated with interactions between BA and polysaccharides. The BA retention rate of CS-BA/HPMC system increased 5.5-fold after 8 d of light-accelerated storage compared with the control group, showing the best homeostasis effect. CS and λ-CG enhanced the elongation at break and prolonged disintegration time of oral films. The addition of FU made the oral film denser and smoother, and had the highest BA release (75.72 %) in the simulated oral cavity system. In addition, the oral films of three sulfated polysaccharides complexed with BA showed superior antioxidant capacity. The present study provides new insights into the application of anthocyanin in film formulation carriers.

Interaction mechanism between hydroxychloroquine sulfate and collagen: Insights from multi-spectroscopy, molecular docking, and molecular dynamic simulation methods

Hydroxychloroquine sulfate (HCQ) can be used to treat various connective tissue diseases. Collagen, which is not only an important drug delivery carrier but also the main component in the connective tissue, is the focus of this study. Here, the interaction mechanism of HCQ with collagen was investigated through various spectroscopic and computational methods. It is found that HCQ binds to collagen spontaneously, primarily via hydrophobic interactions and some hydrogen bonds. The findings of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) verified that formation of HCQ-collagen complex and the amorphous structure, secondary structures, and microstructure of collagen were changed after HCQ binding. A decrease in the relaxation time of free water was observed in the collagen system when HCQ was added. Molecular docking demonstrated that HCQ was almost buried in the cavity of collagen via some hydrophobic interactions with one hydrogen bond, which conforms to the findings of the fluorescence and FTIR analyses. Molecular dynamic (MD) simulations further revealed the structural change information in the docking process. Hopefully, the information generated in this study can provide some useful insights for the research on the pharmacological mechanisms of HCQ in the treatment of the connective tissue diseases and the application of collagen as a drug carrier.

Machine Learning-Enhanced Biomass Pressure Sensor with Embedded Wrinkle Structures Created by Surface Buckling

Flexible piezoresistive sensors are core components of many wearable devices to detect deformation and motion. However, it is still a challenge to conveniently prepare high-precision sensors using natural materials and identify similar short vibration signals. In this study, inspired by microstructures of human skins, biomass flexible piezoresistive sensors were prepared by assembling two wrinkled surfaces of konjac glucomannan and k-carrageenan composite hydrogel. The wrinkle structures were conveniently created by hardness gradient-induced surface buckling and coated with MXene sheets to capture weak pressure signals. The sensor was applied to detect various slight body movements, and a machine learning method was used to enhance the identification of similar and short throat vibration signals. The results showed that the sensor exhibited a high sensitivity of 5.1 kPa-1 under low pressure (50 Pa), a fast response time (104 ms), and high stability over 100 cycles. The XGBoost machine learning model accurately distinguished short voice vibrations similar to those of individual English letters. Moreover, experiments and numerical simulations were carried out to reveal the mechanism of the wrinkle structure preparation and the excellent sensing performance. This biomass sensor preparation and the machine learning method will promote the optimization and application of wearable devices.

Plant-Derived Biomaterials and Their Potential in Cardiac Tissue Repair

Cardiovascular disease remains the leading cause of mortality worldwide. The inability of cardiac tissue to regenerate after an infarction results in scar tissue formation, leading to cardiac dysfunction. Therefore, cardiac repair has always been a popular research topic. Recent advances in tissue engineering and regenerative medicine offer promising solutions combining stem cells and biomaterials to construct tissue substitutes that could have functions similar to healthy cardiac tissue. Among these biomaterials, plant-derived biomaterials show great promise in supporting cell growth due to their inherent biocompatibility, biodegradability, and mechanical stability. More importantly, plant-derived materials have reduced immunogenic properties compared to popular animal-derived materials (e.g., collagen and gelatin). In addition, they also offer improved wettability compared to synthetic materials. To date, limited literature is available to systemically summarize the progression of plant-derived biomaterials in cardiac tissue repair. Herein, this paper highlights the most common plant-derived biomaterials from both land and marine plants. The beneficial properties of these materials for tissue repair are further discussed. More importantly, the applications of plant-derived biomaterials in cardiac tissue engineering, including tissue-engineered scaffolds, bioink in 3D biofabrication, delivery vehicles, and bioactive molecules, are also summarized using the latest preclinical and clinical examples.

Role of metal chlorides in the gelation and properties of fucoidan/κ-carrageenan hydrogels

Metal ions play a crucial role in forming hydrogels, and their effects on fucoidan (FUC): κ-carrageenan (KC) mixed gels were investigated. The results indicated that the FUC: KC mixed gels (FC) were promoted by K⁺ and Ca²⁺ but destroyed by Fe³⁺. The gel strength of FC was enhanced by K⁺ and Ca²⁺, with G' and G″ being highest at 50 mmol/L KCl and 25 mmol/L CaCl₂, respectively. Water mobility was weakened after the addition of KCl and CaCl₂ in accordance with the decrease in T₂₃ relaxation time (free water, 100-1000 ms). After addition of KCl and CaCl₂, the FC groups presented a typical three-dimensional network structure in contrast to the lamellar, disordered, and broken structure of FUC. Moreover, the FT-IR spectrum certified the enhancement of hydrogen bonds and the occurrence of electrostatic interactions during gel formation by the red-shift of the OH stretching vibration of the Ca²⁺ group and the blue-shift of the COS vibrations. The XRD results confirmed that the binding of Ca²⁺ to FC was tighter than that of K⁺ at the same charge content. These results provide a theoretical basis for understanding the interaction mechanism of FC with metal ions.

Fucoidan in Pharmaceutical Formulations: A Comprehensive Review for Smart Drug Delivery Systems

Fucoidan is a heterogeneous group of polysaccharides isolated from marine organisms, including brown algae and marine invertebrates. The physicochemical characteristics and potential bioactivities of fucoidan have attracted substantial interest in pharmaceutical industries in the past few decades. These polysaccharides are characterized by possessing sulfate ester groups that impart negatively charged surfaces, low/high molecular weight, and water solubility. In addition, various promising bioactivities have been reported, such as antitumor, immunomodulatory, and antiviral effects. Hence, the formulation of fucoidan has been investigated in the past few years in diverse pharmaceutical dosage forms to be able to reach their site of action effectively. Moreover, they can act as carriers for various drugs in value-added drug delivery systems. The current work highlights the attractive biopharmaceutical properties of fucoidan being formulated in oral, inhalable, topical, injectable, and other advanced formulations treating life-quality-affecting diseases. Therefore, the present work points out the current status of fucoidan pharmaceutical formulations for future research transferring their application from in vitro and in vivo studies to clinical application and market availability.

Effect of physiological pH on the molecular characteristics, rheological behavior, and molecular dynamics of κ-carrageenan/casein

Introduction

During gastrointestinal digestion, κ-carrageenan (κ-CGN) undergoes physicochemical changes, which associated with the risk of colitis.

Methods

To understand the effect of physiological pH on the conformational transition and binding stability of κ-CGN and κ-carrageenan/casein (κ-CC), we conducted experiments at pH 3.0 (gastric environment) and pH 7.0 (intestinal environment). We evaluated zeta potential, free sulfate group content, Fourier transform infrared spectroscopy, thermodynamic properties, microstructure, and molecular mechanism.

Results and Discussion

Our results revealed that the helical conformation of κ-CGN and κ-CC were more ordered and stable, and sulfate group exposure both lower in the intestinal environment (pH 7.0). However, in gastric environment (pH 3.0), the charge density of κ-CGN decreased, accompanied by random curling conformation and free sulfate group content increased. In contrast, the intermolecular interactions between κ-CGN and casein increased in gastric acid environments due to casein flocculation and secondary structure folding, and significantly reduced the exposure of free sulfate groups of κ-CGN. Our research results provide an important theoretical basis for elucidating the molecular mechanism and structure-activity relationship of κ-CGN under casein matrix to protect the mucosal barrier and inhibit colitis, and are of great significance for guiding and expanding the safe application of κ-CGN, thus assisting food nutrition to be absorbed.

Eco-Friendly Extraction, Structure, and Gel Properties of ι-Carrageenan Extracted Using Ca(OH)2

An eco-friendly method for ι-carrageenan extraction from seaweed Eucheuma denticulatum through boiling and using a low concentration of Ca(OH)2 is reported. Compared to the traditional method of ι-carrageenan extraction using NaOH, the reported method using Ca(OH)2 had the advantages of using 93.3% less alkali and 86.8% less water, having a 25.0% shorter total extraction time, a 17.6% higher yield, and a 43.3% higher gel strength of the product. In addition, we evaluated the gel properties and structures of ι-carrageenan products extracted by Ca(OH)2 (Ca-IC) and NaOH (Na-IC). The Fourier transform infrared spectroscopy results showed that the structures of Ca-IC and Na-IC did not change remarkably. The results of the thermogravimetric analysis and differential scanning calorimetry showed that Ca-IC had the same thermal stability as Na-IC. The results of the textural analysis showed that Ca-IC had a higher hardness and better chewiness compared to Na-IC. Rheological results indicated that Ca-IC and Na-IC exhibited shear-thinning and non-Newtonian fluid properties, whereas the viscosity of Ca-IC was less than that of Na-IC. In conclusion, this new method of ι-carrageenan extraction using Ca-IC is markedly better and yields higher quality carrageenan than the conventional method of using Na-IC.

Algal Polysaccharides-Based Hydrogels: Extraction, Synthesis, Characterization, and Applications

Hydrogels are three-dimensional crosslinked hydrophilic polymer networks with great potential in drug delivery, tissue engineering, wound dressing, agrochemicals application, food packaging, and cosmetics. However, conventional synthetic polymer hydrogels may be hazardous and have poor biocompatibility and biodegradability. Algal polysaccharides are abundant natural products with biocompatible and biodegradable properties. Polysaccharides and their derivatives also possess unique features such as physicochemical properties, hydrophilicity, mechanical strength, and tunable functionality. As such, algal polysaccharides have been widely exploited as building blocks in the fabrication of polysaccharide-based hydrogels through physical and/or chemical crosslinking. In this review, we discuss the extraction and characterization of polysaccharides derived from algae. This review focuses on recent advances in synthesis and applications of algal polysaccharides-based hydrogels. Additionally, we discuss the techno-economic analyses of chitosan and acrylic acid-based hydrogels, drawing attention to the importance of such analyses for hydrogels. Finally, the future prospects of algal polysaccharides-based hydrogels are outlined.

Chitosan and Whey Protein Bio-Inks for 3D and 4D Printing Applications with Particular Focus on Food Industry

The application of chitosan (CS) and whey protein (WP) alone or in combination in 3D/4D printing has been well considered in previous studies. Although several excellent reviews on additive manufacturing discussed the properties and biomedical applications of CS and WP, there is a lack of a systemic review about CS and WP bio-inks for 3D/4D printing applications. Easily modified bio-ink with optimal printability is a key for additive manufacturing. CS, WP, and WP-CS complex hydrogel possess great potential in making bio-ink that can be broadly used for future 3D/4D printing, because CS is a functional polysaccharide with good biodegradability, biocompatibility, non-immunogenicity, and non-carcinogenicity, while CS-WP complex hydrogel has better printability and drug-delivery effectivity than WP hydrogel. The review summarizes the current advances of bio-ink preparation employing CS and/or WP to satisfy the requirements of 3D/4D printing and post-treatment of materials. The applications of CS/WP bio-ink mainly focus on 3D food printing with a few applications in cosmetics. The review also highlights the trends of CS/WP bio-inks as potential candidates in 4D printing. Some promising strategies for developing novel bio-inks based on CS and/or WP are introduced, aiming to provide new insights into the value-added development and commercial CS and WP utilization.