Novel pH-sensitive alginate hydrogel delivery system reinforced with gum tragacanth for intestinal targeting of nutraceuticals

A hybrid structure based on silk fibroin/PVA nanofibers and alginate/gum tragacanth hydrogel embedded with cardamom extract

Hybrid structures made of natural-synthetic polymers have been interested due to high biological features combining promising physical-mechanical properties. In this research, a hybrid dressing consisting of a silk fibroin (SF)/polyvinyl alcohol (PVA) nanofibers and sodium alginate (SA)/gum tragacanth (GT) hydrogel incorporating cardamom extract as an antibacterial agent was prepared. Accordingly, SF was extracted from cocoons followed by electrospinning in blend form with PVA (SF/PVA ratio: 1:1) under the voltage of 18 kV and the distances of 15 cm. The SEM images confirmed the formation of uniform, bead free fibers with the average diameter of 199 ± 28 nm. FTIR and XRD results revealed the successful extraction of SF and preparation of mixed fibrous mats. Next, cardamom oil extract-loaded SA/GT hydrogel was prepared and the nanofibrous structure was placed on the surface of hydrogel. SEM analysis depicted the uniform morphology of hybrid structure with desirable matching between two layers. TGA analysis showed desired thermal stability. The swelling ratio was found to be 1251% after 24 h for the hybrid structure and the drug was released without any initial burst. MTT assay and cell attachment results showed favorable biocompatibility and cell proliferation on samples containing extract, and antibacterial activity values of 85.35% against S. aureus and 75% against E. coli were obtained as well. The results showed that the engineered hybrid nanofibrous-hydrogel film structure incorporating cardamom oil extract could be a promising candidate for wound healing applications and skin tissue engineering.

Current trend on preparation, characterization and biomedical applications of natural polysaccharide-based nanomaterial reinforcement hydrogels: A review

The tunable properties of hydrogels have led to their widespread use in various biomedical applications such as wound treatment, drug delivery, contact lenses, tissue engineering and 3D bioprinting. Among these applications, natural polysaccharide-based hydrogels, which are fabricated from materials like agarose, alginate, chitosan, hyaluronic acid, cellulose, pectin and chondroitin sulfate, stand out as preferred choices due to their biocompatibility and advantageous fabrication characteristics. Despite the inherent biocompatibility, polysaccharide-based hydrogels on their own tend to be weak in physiochemical and mechanical properties. Therefore, further reinforcement in the hydrogel is necessary to enhance its suitability for specific applications, ensuring optimal performance in diverse settings. Integrating nanomaterials into hydrogels has proven effective in improving the overall network and performance of the hydrogel. This approach also addresses the limitations associated with pure hydrogels. Next, an overview of recent trends in the fabrication and applications of hydrogels was presented. The characterization of hydrogels was further discussed, focusing specifically on the reinforcement achieved with various hydrogel materials used so far. Finally, a few challenges associated with hydrogels by using polysaccharide-based nanomaterial were also presented.

Preparation and Properties of Attapulgite/Brucite Fiber-Based Highly Absorbent Polymer Composite

The ATP-BF-P(HEC-AA-AMPS) composite highly absorbent polymer was copolymerized with acrylic acid (AA) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) using an aqueous solution method with attapulgite (ATP) and attapulgite (ATP) as a matrix. The prepared ATP-BF-P(HEC-AA-AMPS) was characterized in terms of microstructure and tested for its water absorption capacity, water retention properties, and pH dynamic sensing ability. The results showed that the synthesized ATP-BF-P(HEC-AA-AMPS) had a rough and porous surface and a high water absorption capacity and rate, almost reaching the maximum water absorption around 20 min, and demonstrated excellent water retention performance at low and medium temperatures. ATP-BF-P(HEC-AA-AMPS) has a sensitive dynamic sensing ability in different pH solutions, with a high swelling capacity between pH 6.0 and 10.0. When the pH value exceeded 10.0, the swelling rate decreased rapidly. Additionally, the thermal stability and mechanical strength of the highly absorbent polymers were significantly improved after blending with ATP and BF.

Food gels: principles, interaction mechanisms and its microstructure

Food hydrogels are important materials having great scientific interest due to biocompatibility, safety and environment-friendly characteristics. In the food industry, hydrogels are widely used due to their three-dimensional crosslinked networks. Furthermore, they have attracted great attention due to their wide range of applications in the food industry, such as fat replacers, encapsulating agents, target delivery vehicles, and many more. In addition to basic and recent knowledge on food hydrogels, this review exclusively focuses on sensorial perceptions, nutritional significance, body interactions, network structures, mechanical properties, and potential hydrogel applications in food and food-based matrices. Additionally, this review highlights the structural design of hydrogels, which provide the forward-looking idea for future applications of food hydrogels (e.g., 3D or 4D printing).

The Release of Grape Pomace Phenolics from Alginate-Based Microbeads during Simulated Digestion In Vitro: The Influence of Coatings and Drying Method

Grape pomace is a byproduct of wineries and a sustainable source of bioactive phenolic compounds. Encapsulation of phenolics with a well-chosen coating may be a promising means of delivering them to the intestine, where they can then be absorbed and exert their health-promoting properties, including antioxidant, anti-inflammatory, anticancer, cardioprotective, and antimicrobial effects. Ionic gelation of grape pomace extract with natural coatings (sodium alginate and its combination with maltodextrins, gelatin, chitosan, gums Tragacanth and Arabic) was performed, and the resulting hydrogel microbeads were then air-, vacuum-, and freeze-dried to prevent spoilage. Freeze-drying showed advantages in preserving the geometrical parameters and morphology of the microbeads compared to other drying techniques. A good relationship was found between the physicochemical properties of the dried microbeads and the in vitro release of phenolics. Freeze-dried microbeads showed the highest cumulative release of phenols in the intestinal phase (23.65-43.27 mgGAE/gMB), while the most suitable release dynamics in vitro were observed for alginate-based microbeads in combination with gelatin, gum Arabic, and 1.5% (w/v) chitosan. The results highlight the importance of developing encapsulated formulations containing a natural source of bioactive compounds that can be used in various functional foods and pharmaceutical products.

Recent research advances on oral colon-specific delivery system of nature bioactive components: A review

Oral colon-specific delivery system (OCDS) is a targeted approach that aims to directly deliver bioactive compounds directly to the colon following oral administration, thereby enhancing the colonic release of bioactive substances and minimizing adverse reactions. The effectiveness of bioactive substances in the colon hinges on the degree of release, which are affected by various factors including pH, mucosal barrier, delivery time and so on. Therefore, this review provides a comprehensive overview of the key factors affecting oral colon-specific release of bioactive components firstly. Considering the oral safety, this review then mainly focuses on the types of carriers with edible OCDS and preparation strategies for OCDS. Finally, several preparation strategies for loading typical natural bioactive ingredients into oral safe OCDS are reviewed, along with future development prospects.

Tailoring the Swelling-Shrinkable Behavior of Hydrogels for Biomedical Applications

Hydrogels with tailor-made swelling-shrinkable properties have aroused considerable interest in numerous biomedical domains. For example, as swelling is a key issue for blood and wound extrudates absorption, the transference of nutrients and metabolites, as well as drug diffusion and release, hydrogels with high swelling capacity have been widely applicated in full-thickness skin wound healing and tissue regeneration, and drug delivery. Nevertheless, in the fields of tissue adhesives and internal soft-tissue wound healing, and bioelectronics, non-swelling hydrogels play very important functions owing to their stable macroscopic dimension and physical performance in physiological environment. Moreover, the negative swelling behavior (i.e., shrinkage) of hydrogels can be exploited to drive noninvasive wound closure, and achieve resolution enhancement of hydrogel scaffolds. In addition, it can help push out the entrapped drugs, thus promote drug release. However, there still has not been a general review of the constructions and biomedical applications of hydrogels from the viewpoint of swelling-shrinkable properties. Therefore, this review summarizes the tactics employed so far in tailoring the swelling-shrinkable properties of hydrogels and their biomedical applications. And a relatively comprehensive understanding of the current progress and future challenge of the hydrogels with different swelling-shrinkable features is provided for potential clinical translations.

Evaluation of multicomplex systems on pomegranate concentrate loaded alginate hydrogels by low-field NMR relaxometry: physicochemical characterization and controlled release study

Alginate (ALG) and various gums are potential biomaterials to be employed in hydrogel designs for both food and biomedical applications. This study evaluated a multicomplex design by combining food grade polymers to examine their polymer-polymer interactions and design an oral delivery system for pomegranate concentrate (PC). ALG was replaced with gum tragacanth (GT), xanthan (XN) and their equal combinations (GT:XN) at 50% ratio in hydrogel fabrication. In addition to CaCI2 in binding solution, honey (H) and chitosan (CH) were also used during physical crosslinking. Relaxation time constants in NMR indicated poor ability of GT for water entrapment especially in the presence of honey (S2H). They also confirmed FTIR results indicating similar trends. Strong negative correlations were observed between T2 and texture results. GT replacement of ALG especially in the use of single CaCI2 (S2) promoted higher PC release up to 80% in digestive media compared to XN substitution (S3). This study promoted use of LF NMR as an indicator for polymer mixture characterization in complex gels. ALG based gels could be modified by replacing ALG with different kinds of gums and with use of different binding solutions to regulate target compound release in food and pharmaceutical fields.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-023-05730-2.

A review on tragacanth gum: A promising natural polysaccharide in drug delivery and cell therapy

Tragacanth is an abundant natural gum extracted from wounds created in some plants and is dried for use in various applications from industry to biomedicines. It is a cost-effective and easily accessible polysaccharide with desirable biocompatibility and biodegradability, drawing much attention for use in new biomedical applications such as wound healing and tissue engineering. Moreover, this anionic polysaccharide with a highly branched structure has been used as an emulsifier and thickening agent in pharmaceutical applications. In the following, this gum has been interested as an appealing biomaterial for producing engineering tools in drug delivery. Furthermore, the biological properties of tragacanth gum have made it a favorable biomaterial in cell therapies, especially for bone tissue engineering. This review aims to discuss the recent studies on this natural gum as a potential carrier for different drugs and cells.

Development of alginate-based hydrogels: Crosslinking strategies and biomedical applications

Natural polysaccharide-based hydrogels have drawn much concern in the biomedical fields. Among them, alginate, a natural polyanionic polysaccharide, has become one of the research hotspots, because of its abundant source, biodegradability, biocompatibility, solubility, modification flexibility, and other characteristics or physiological functions. Recently, through adopting various physical or chemical crosslinking strategies, selecting suitable crosslinking or modification reagents, precisely controlling the reaction conditions, or introducing organic or inorganic functional materials, a variety of alginate-based hydrogels with excellent performance have been continuously developed, considerably expanding the breadth and depth of their applications. Here, various crosslinking strategies in the preparation of alginate-based hydrogels are comprehensively introduced. The representative application progress of alginate-based hydrogels in drug carrier, wound dressing and tissue engineering is also summarized. Meanwhile, the application prospects, challenges and development trends of alginate-based hydrogels are discussed. It is expected to provide guidance and reference for the further development of alginate-based hydrogels.

Polyphenol Release and Antioxidant Activity of the Encapsulated Antioxidant Crude Extract from Cold Brew Spent Coffee Grounds under Simulated Food Processes and an In Vitro Static Gastrointestinal Model

An ionic gelation technique based on an alginate-calcium-based encapsulation process was prepared as the delivery matrix for antioxidant crude extracts from cold brew spent coffee grounds (350 mg/mL). All the encapsulated samples were treated with different simulated food processes, namely pH 3, pH 7, low-temperature long-time (LTLT) pasteurization, and high-temperature short-time (HTST) pasteurization, to evaluate the stability of the encapsulated matrices. The results showed that alginate (2%, w/v)/maltodextrin (2%, w/v) (CM), and alginate (2%, w/v)/inulin (5%, w/v) (CI) could enhance encapsulation efficiency (89.76 and 85.78%, respectively) and provide lower swelling behavior after being treated using the simulated food processes. Both CM and CI could control the release of antioxidants during the gastric phase (2.28-3.98 and 2.52-4.00%, respectively) and gradual release in the intestinal phase (6.80-11.78 and 4.16-12.72%, respectively) compared to pure alginate (CA). In addition, pasteurization treatment at pH 7.0 produced the highest accumulated release of total phenolic content (TPC) and antioxidant activity (DPPH) after digestion in the in vitro gastrointestinal system compared to the other simulated food processes. The thermal process resulted in a greater release of compounds from the encapsulated matrix during the gastric phase. On the other hand, the treatment with pH 3.0 resulted in the lowest accumulated release of TPC and DPPH (5.08 and 5.12%, respectively), which indicated phytochemical protection.

Enhancing the Gastrointestinal Stability of Curcumin by Using Sodium Alginate-Based Nanoemulsions Containing Natural Emulsifiers

Curcumin presents interesting biological activities but low chemical stability, so it has been incorporated into different emulsion-based systems in order to increase its bioaccessibility. Many strategies are being investigated to increase the stability of these systems. Among them, the use of polysaccharides has been seen to highly improve the emulsion stability but also to modulate their digestibility and the release of the encapsulated compounds. However, the effect of these polysaccharides on nanoemulsions depends on the presence of other components. Then, this work aimed to study the effect of alginate addition at different concentrations (0-1.5%) on the gastrointestinal fate and stability of curcumin-loaded nanoemulsions formulated using soybean lecithin or whey protein as emulsifiers. Results showed that, in the absence of polysaccharides, whey protein was more effective than lecithin in preventing curcumin degradation during digestion and its use also provided greater lipid digestibility and higher curcumin bioaccessibility. The addition of alginate, especially at ≥1%, greatly prevented curcumin degradation during digestion up to 23% and improved the stability of nanoemulsions over time. However, it reduced lipid digestibility and curcumin bioaccessibility. Our results provide relevant information on the use of alginate on different emulsifier-based nanoemulsions to act as carriers of curcumin.

Hybrid gum tragacanth/sodium alginate hydrogel reinforced with silver nanotriangles for bacterial biofilm inhibition

Biomaterial associated bacterial infections are indomitable to treatment due to the rise in antibiotic resistant strains, thereby triggering the need for new antibacterial agents. Herein, composite bactericidal hydrogels were formulated by incorporating silver nanotriangles (AgNTs) inside a hybrid polymer network of Gum Tragacanth/Sodium Alginate (GT/SA) hydrogels. Physico-chemical examination revealed robust mechanical strength, appreciable porosity and desirable in vitro enzymatic biodegradation of composite hydrogels. The antibacterial activity of AgNT-hydrogel was tested against planktonic and biofilm-forming Gram-negative (Escherichia coli and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) bacteria. For all the strains, AgNT-hydrogel showed a dose-dependent decrease in bacterial growth. The addition of AgNT-hydrogels (40-80 mg ml^-1) caused 87% inhibition of planktonic biomass and up to 74% reduction in biofilm formation. Overall, this study proposes a promising approach for designing antibacterial composite hydrogels to mitigate various forms of bacterial infection.

Multitasking smart hydrogels based on the combination of alginate and poly(3,4-ethylenedioxythiophene) properties: A review

Poly(3,4-ethylenedioxythiophene) (PEDOT), a very stable and biocompatible conducting polymer, and alginate (Alg), a natural water-soluble polysaccharide mainly found in the cell wall of various species of brown algae, exhibit very different but at the same complementary properties. In the last few years, the remarkable capacity of Alg to form hydrogels and the electro-responsive properties of PEDOT have been combined to form not only layered composites (PEDOT-Alg) but also interpenetrated multi-responsive PEDOT/Alg hydrogels. These materials have been found to display outstanding properties, such as electrical conductivity, piezoelectricity, biocompatibility, self-healing and re-usability properties, pH and thermoelectric responsiveness, among others. Consequently, a wide number of applications are being proposed for PEDOT-Alg composites and, especially, PEDOT/Alg hydrogels, which should be considered as a new kind of hybrid material because of the very different chemical nature of the two polymeric components. This review summarizes the applications of PEDOT-Alg and PEDOT/Alg in tissue interfaces and regeneration, drug delivery, sensors, microfluidics, energy storage and evaporators for desalination. Special attention has been given to the discussion of multi-tasking applications, while the new challenges to be tackled based on aspects not yet considered in either of the two polymers have also been highlighted.

Pickering emulsion hydrogel based on alginate-gellan gum with carboxymethyl chitosan as a pH-responsive controlled release delivery system

Pickering emulsion hydrogels (PEHs) were developed as a pH-responsive, controlled-release delivery system to address the limitations of Pickering emulsions in some harsh processing or gastrointestinal conditions. Specifically, the PEHs were fabricated based on alginate and various concentrations of gellan gum (GG) with carboxymethyl chitosan (CMCS) matrix. The encapsulation efficiency (EE), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) results proved the successful encapsulation. Furthermore, the hydrogels remained stable in the presence of destabilizing ions (Na⁺ or phosphate ions) and high osmotic pressure mediums. The texture profile analysis (TPA) characteristics and Young's modulus of the 0.8 % GG (w/v) PEHs were superior to the others. The PEHs prevented the emulsions from being released at pH 2.0, while the emulsions were entirely released at pH 7.4 in vitro, with the rate of release controlled by CMCS and the degree by GG concentration. This work facilitates the delivery of Pickering emulsions with excellent stability and pH-responsive controlled release for hydrophobic actives in food applications.

Biological activity of multicomponent bio-hydrogels loaded with tragacanth gum

Producing hydrogels capable of mimicking the biomechanics of soft tissue remains a challenge. We explore the potential of plant-based hydrogels as polysaccharide tragacanth gum and antioxidant lignin nanoparticles in bioactive multicomponent hydrogels for tissue engineering. These natural components are combined with TEMPO-oxidized cellulose nanofibrils, a material with known shear thinning behavior. Hydrogels presented tragacanth gum (TG) concentration-dependent rheological properties suitable for extrusion 3D printing. TG enhanced the swelling capacity up to 645 % and the degradation rate up to 1.3 %/day for hydrogels containing 75 % of TG. Young's moduli of the hydrogels varied from 5.0 to 11.6 kPa and were comparable to soft tissues like skin and muscle. In vitro cell viability assays revealed that the scaffolds were non-toxic and promoted proliferation of hepatocellular carcinoma HepG2 cells. Therefore, the plant-based hydrogels designed in this work have a significant potential for tissue engineering.

Effect of Gum Tragacanth-Sodium Alginate Active Coatings Incorporated With Epigallocatechin Gallate and Lysozyme on the Quality of Large Yellow Croaker at Superchilling Condition

This research was done to investigate the synergistic interactions of the gum tragacanth (GT)–sodium alginate (SA) active coatings, incorporated with epigallocatechin gallate and lysozyme, on the quality of large yellow croaker (Larimichthys crocea) during superchilling storage at −3°C. Results showed that the GT-SA active coatings, containing epigallocatechin gallate [EGCG (E), 0.32% w/v], and lysozyme [LYS (L), 0.32% w/v] have reduced the total viable count, psychrophilic bacteria, and Pseudomonas spp. by about 1.55 log CFU/g, 0.49 log CFU/g, and 1.64 log CFU/g compared to the control at day 35. The GT-SA active coatings containing EGCG and LYS were effective in lowering the formations of off-odor compounds such as total volatile basic nitrogen (TVB-N), malondialdehyde (MDA), and off-favor amino acid (histidine). The solid phase microextraction gas chromatography-mass spectrometer (SPME-GC/MS) was applied to characterize and to quantify the volatile compounds of large yellow croaker samples during superchilling storage, while the relative content of the fishy flavor compounds (including 1-octen-3-ol and acetoin) was significantly reduced in the active coatings treated samples. Furthermore, the GT-SA active coatings containing EGCG and LYS treatments was found to be more effective in retarding the migration of water based on magnetic resonance imaging (MRI) results and in maintaining the organoleptic quality of large yellow croaker in superchilling storage at −3°C according to the sensory evaluation results. The results showed that the GT-SA active coating containing EGCG and LYS was effective to be used as a fish preservative to improve the quality and to prolong the shelf life of large yellow croaker in a superchilling storage for at least 7 days.

Sodium alginate/soybean protein-epigallocatechin-3-gallate conjugate hydrogel beads: evaluation of structural, physical, and functional properties

Sodium alginate (SA) hydrogel beads have been extensively studied as delivery systems for bioactive compounds. Key challenges include overcoming the highly porous and poor emulsifying properties of SA hydrogels. Herein, soy protein isolate (SPI) was modified by covalent and noncovalent conjugation with epigallocatechin-3-gallate (EGCG), followed by complexation with SA to change the SA structure and fabricate hydrogel beads with low porosities. Microencapsulation beads were fabricated from SA-, SA/SPI-, and SA/SPI-modified EGCG complexes with a corn oil/quercetin mixture core. After the covalent and noncovalent SPI-modified EGCG complexes were combined with SA, the OH stretching vibration shifted, indicating that hydrogen bonds formed between the protein and SA, and the crystal structure of SA was destroyed. To achieve crosslinking, the beads were injected into a CaCl₂ solution, whereby Ca²⁺ ions replaced the Na⁺ ions in SA. Meanwhile, the addition of covalent and noncovalent SPI-modified EGCG complexes promoted the binding capacity of Ca²⁺ and SA. All hydrogel beads possessed open-cell microstructures with interconnecting pores. The SA/SPI-modified EGCG hydrogel beads exhibited smoother surfaces, thicker shells, and lower porosity than the SA hydrogel beads. Moreover, they exhibited significantly higher antioxidant activities. During digestion, all types of hydrogel bead maintained their structure, and only a small part of the encapsulated oil and quercetin was digested in the upper part of the gastrointestinal tract. In short, the formation mechanism of hydrogel beads was clarified, and hydrogel beads with low porosity and high antioxidation activities were successfully fabricated.

Co-encapsulation of probiotic Lactobacillus acidophilus and Reishi medicinal mushroom (Ganoderma lingzhi) extract in moist calcium alginate beads

Probiotic L. acidophilus La-14 cells were co-encapsulated with Ganoderma lingzhi extract to prolong the viability of the cells under simulated gastrointestinal (SGI) condition and to protect the active ingredients of Reishi mushroom during the storage period. Combinations of distinctive reagents (sodium alginate, chitosan, maltose, Hydroxyethyl-cellulose (HEC), hydroxypropyl methylcellulose (HPMC), and calcium lactate) were tested. Optimal double layer Ca-alginate hydrogel beads were fabricated with significantly improved characteristics. The incorporation of maltose significantly decreases the release rate of mushrooms' phenolics, antioxidants, and β-glucan during the storage time. Significant improvement in probiotic cells viability under SGI condition has been found and confirmed by confocal laser microscopy in maltose containing double layer coated calcium alginate beads variants. The encapsulation of newly formulated prebiotic Reishi extract and probiotic L. acidophilus is creating a new potential food application for such medicinal mushrooms and natural products with unpleasant taste upon oral consumption.

Alginate-based delivery systems for food bioactive ingredients: An overview of recent advances and future trends

Due to its advantagessuch as ionic crosslinking, pH responsiveness, excellent biocompatibility, biodegradability and low price, alginate has become one of the most important natural polysaccharides extensively used in constructing desired delivery systems for food bioactive ingredients. In this review, the fundamental knowledge of alginate as a building block for construction of nutraceutical delivery systems is introduced. Then, various types of alginate-based nutraceutical delivery systems are classified and summarized. Furthermore, the future trends of alginate-based delivery systems are highlighted. Currently, alginate-based delivery systems include hydrogel, emulsion, emulsion-filled alginate hydrogel, nanoparticle, microparticle, core-shell particle, liposome, edible film, and aerogel. Although alginate has been widely used in the fabrication of food bioactive ingredient delivery systems, further efforts and improvements are still needed. For this purpose, the future perspectives of alginate-based delivery systems are discussed. The feasible research trends of alginate-based delivery systems include the development of novel large-scale commercial preparation technology, multifunctional delivery system based on alginate, alginate oligosaccharide-based delivery system and alginate-based oleogel. Overall, the objective of this review is to provide useful guidance for rational design and application of alginate-based nutraceutical delivery systems in the future.

New Sensor to Measure the Microencapsulated Active Compounds Released in an Aqueous Liquid Media Based in Dielectric Properties in Radiofrequency Range

In recent years, the general and scientific interest in nutrition, digestion, and what role they play in our body has increased, and there is still much work to be carried out in the field of developing sensors and techniques that are capable of identifying and quantifying the chemical species involved in these processes. Iron deficiency is the most common and widespread nutritional disorder that mainly affects the health of children and women. Iron from the diet may be available as heme or organic iron, or as non-heme or inorganic iron. The absorption of non-heme iron requires its solubilization and reduction in the ferric state to ferrous that begins in the gastric acid environment, because iron in the ferric state is very poorly absorbable. There are chemical species with reducing capacity (antioxidants) that also have the ability to reduce iron, such as ascorbic acid. This paper aims to develop a sensor for measuring the release of encapsulated active compounds, in different media, based on dielectric properties measurement in the radio frequency range. An impedance sensor able to measure the release of microencapsulated active compounds was developed. The sensor was tested with calcium alginate beads encapsulating iron ions and ascorbic acid as active compounds. The prediction and measurement potential of this sensor was improved by developing a thermodynamic model that allows obtaining kinetic parameters that will allow suitable encapsulation design for subsequent release.

Effective adsorption of methylene blue dye from water solution using renewable natural hydrogel bionanocomposite based on tragacanth gum: Linear-nonlinear calculations

Today, hydrogels opened new windows to the high-tech due to their amazing features. Thus, we applied hydrogel nanocomposite (HNC) made of tragacanth gum (a kind of polysaccharide) and CaCO₃ nanoparticles to remove methylene blue dye (MBD) from the water solution. We used nonlinear and linear isotherms and kinetics as well as thermodynamics to uncover the adsorption mechanism. The results showed that the hydrogel could remove 80% of MBD. Besides, the linear form of the pseudo-second-order kinetic model fits well with the results, showing chemical interactions. We found that this process follows both Sips and Redlich-Peterson models by applying nonlinear and linear isotherm models. The maximum adsorption capacities from nonlinear and linear Sips were 1401 and 2145 mg/g, respectively. Based on the thermodynamic equations, the adsorption of MBD onto HNC was physiochemical and exothermic. According to the phenomenological calculations, diffusion from the bulk (or film diffusion, D_f = 1.2 × 10^-8 cm²/s) is the primary mechanism.

Shear-thinning and self-healing nanohybrid alginate-graphene oxide hydrogel based on guest-host assembly

The study aims to develop a novel nanohybrid shear-thinning hydrogel with fast gelation, and variable mechanical and biological properties. This nanohybrid hydrogel was developed via self-assembly guest-host interaction between β-cyclodextrin modified alginate (host macromere, Alg-CD) and adamantine modified graphene oxide (guest macromere, Ad-GO) and subsequent ionic crosslinking process. We found that the rheological and mechanical properties of hydrogels were controlled via macromere concentration and the host: guest macromere ratio, due to the modulation of crosslinking density and network structure. Noticeably, 12%(1:2) dual-crosslinked hydrogel (2DC12) significantly improved the strength (1.3-folds) and toughness compared to 10%(1:4) dual-crosslinked hydrogel (4DC10). Furthermore, the hydrogel erosion and cytocompatibility relied on the designed parameters. Remarkably, 2DC12 showed less than 20% weight loss after 20 days of incubation in physiological solution and more than 200% cell survival after five days. In conclusion, the nanohybrid Alg-GO hydrogel could be used as an injectable hydrogel for soft tissue engineering applications.

Gum Tragacanth (GT): A Versatile Biocompatible Material beyond Borders

The use of naturally occurring materials in biomedicine has been increasingly attracting the researchers’ interest and, in this regard, gum tragacanth (GT) is recently showing great promise as a therapeutic substance in tissue engineering and regenerative medicine. As a polysaccharide, GT can be easily extracted from the stems and branches of various species of Astragalus. This anionic polymer is known to be a biodegradable, non-allergenic, non-toxic, and non-carcinogenic material. The stability against microbial, heat and acid degradation has made GT an attractive material not only in industrial settings (e.g., food packaging) but also in biomedical approaches (e.g., drug delivery). Over time, GT has been shown to be a useful reagent in the formation and stabilization of metal nanoparticles in the context of green chemistry. With the advent of tissue engineering, GT has also been utilized for the fabrication of three-dimensional (3D) scaffolds applied for both hard and soft tissue healing strategies. However, more research is needed for defining GT applicability in the future of biomedical engineering. On this object, the present review aims to provide a state-of-the-art overview of GT in biomedicine and tries to open new horizons in the field based on its inherent characteristics.

Natural polymers for vaginal mucoadhesive delivery of vinegar, using design of experiment methods

Background/Aim. Vinegars are of the main international traditional nutraceuticals which have been used as vaginal health protectant due to vagina pH balance maintenance and antimicrobial properties. Since the main used form of vinegar was liquid, it was difficult for vaginal application with low residence time; in this study a vaginal mucoadhesive gel of vinegar was designed. Methods. Xanthan gum (XG) and tragacanth (TG) were utilized as natural gel forming polymers. The effects of Xanthan gum and tragacanth on mucoadhesion strength and drug release of the gel formulations were optimized using a 3 level (32) factorial design. Several physico-chemical properties of the gel formulations including gel viscosity, spreadability, scanning electron microscopy (SEM) images of hydrogel chains, and release kinetic were also investigated. Results. demonstrated that tragacanth possesses a statistically significant effect on release rate control (p-value=0.0027) while both tragacanth and xanthan gum have significant effect (p value= 0.0001 and 0.0017, respectively) on mucoadhesion property. Conclusion. Design of experiment suggested that formulation F7 with 5% xanthan gum and 1% tragacanth (mucoadhesion = 0.4632 N and release rate = 88.8% in 6 hours) can be considered as the optimum formulation with some modifications.