Development of pH Sensitive Alginate/Gum Tragacanth Based Hydrogels for Oral Insulin Delivery

Functionalization of almond gum through covalent and non-covalent interactions for biomedical applications

The versatile properties of carbohydrate polymers make them a relevant, promising precursor to design innovative materials for use in biomedical applications. Recent research mainly focuses on the development of the polysaccharide based functional materials. Hydrogel derived materials are a source of great motivation for the development of drug delivery (DD) carriers with inherent therapeutic potential. Herein, almond gum-based hydrogels were synthesized for the delivery of the anticancer drug methotrexate after impregnation to improve the DD profile. Hydrogels were characterized by FESEM, EDS, AFM, 13C NMR, FTIR, TGA, DSC, XRD, mechanical strength & biomedical assay. The optimized network hydrogel exhibited a mesh size of 19.764 mm and a cross-linking density of 5.002 × 10-5 mol/cm3 of the hydrogels. Morphological features revealed irregular, uneven internal morphology of hydrogels in FE-SEM. The inclusion of sulphated and amide polymers in hydrogels was found in elemental composition (C = 60.72 %, O = 29.79 %, N = 6.63 % and S = 2.86 %) of hydrogels inferred from EDS. Spectroscopic characterization by FT-IR and 13C NMR confirmed the inclusion of PVP and PVSA through grafting reaction. The crosslinked product formed was found thermally stable and amorphous in nature through TGA and XRD analysis. The sustained release was found through supramolecular interactions and release complied a non-Fickian mechanism for drug diffusion (n = 0.73) and the release profile was best described by the Hixson-Crowell kinetic model in colonic pH. The hydrogels were mucoadhesive in nature and required 144 ± 10.54 mN force for the separation of hydrogels from the mucosal surface during the adhesion test. Hydrogel illustrated antioxidant activity (32.68 ± 0.83 μg GAE) during their radical scavenging test by FC reagent assay. Drug encapsulated hydrogels demonstrated antimicrobial efficacy against microbes. The results of physico-chemical and biomedical properties of hydrogels suggested their suitability for biomedical uses.

Core-shell aerogel design for enhanced oral insulin delivery

Current protein-based therapies often rely on intravenous and subcutaneous injections leading to patient discomfort due to the need for frequent administration. Oral administration route presents a more patient-friendly alternative, but overcoming the challenge of low drug bioavailability remains paramount. This limitation is primarily attributed to protein degradation in the harsh gastric environment, enzymatic breakdown, and poor intestinal permeability. With their unique properties, such as high porosity and surface area, and easy scalability, aerogels offer a promising platform for oral delivery of therapeutic proteins. This study focused on the development and characterization of both conventional and core-shell aerogels derived from natural polysaccharides for the oral delivery of insulin, utilizing Humulin R® U-100 as the insulin source for the first time. Aerogels were produced via supercritical carbon dioxide (sc-CO2) drying of alginate gel beads. Scanning Electron Microscopy (SEM) images confirmed that the core-shell aerogels had higher uniformity in size and a more well-defined porous structure in comparison to conventional aerogels. Structural differences of two alginate sources were evaluated by Fourier Transform Infrared (FTIR) spectroscopy. A notable difference in encapsulation efficiencies was observed between conventional (12 %) and core-shell (53 %) aerogels, highlighting the superior carrier characteristics of the latter ones. In vitro insulin release profiles from the core-shell aerogels demonstrated their potential suitability for delivering regular/short-acting insulin therapeutics since only 30 % of insulin was released in Simulated Gastric Fluid (SGF) after 120 min, whereas 60 % of insulin was released in Simulated Intestinal Fluid (SIF) within the first hour followed by a sustained release stage.

Exploring the potential of a pH-sensitive hydrogel sponge: interpenetrating network of tragacanth and pectin for controlled delivery of levosulpiride

The development of drug delivery systems that allow precise control over drug release pattern has fetched significant attention in the pharmaceutical field. This research work investigates the potential of a pH-sensitive interpenetrating network (IPN) composed of tragacanth and pectin as a carrier for the controlled release of levosulpiride. To enhance the solubility of poorly soluble drug levosulpiride, inclusion complexes were formed with beta cyclodextrin (βCD). The IPN was prepared by cross-linking tragacanth with pectin by adopting a green chemistry approach. The resulting cross-linked polymeric network was subjected to repetitive freeze-drying cycles for preparation of spongy mass. The physicochemical properties of the resultant product were thoroughly characterized using a range of analytical techniques, including Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermal analyses (DSC/TGA), and X-ray diffraction (XRD). The physical parameters like sol-gel fraction (%), drug loading (%), swelling behavior, electrolyte responsiveness, and in vitro drug release profile of the developed sponge were systematically evaluated under varying pH conditions. Results of FTIR demonstrated the formation of cross-linked network, ruling out drug-excipient interaction. SEM analysis unveiled porous and rough geometry. Thermal analyses proved the hydrogel network thermally stable whereas, PXRD demonstrated the overall amorphous nature of the hydrogel sponge. The outcomes of physical parameters demonstrated an incremental trend in gel fraction from 63 to 85% on raising the molar concentration of cross-linker from TP1 to TP3. However, increasing tragacanth content escalation in gel fraction from 75 to 79% was noticed. While gel fraction was augmented from 79 to 83% with increasing pectin contents. The maximum drug loading formulation TP3 was computed to be 89%. Hydrogel sponges also demonstrated electrolyte responsiveness. The release profile indicated a pH-responsive behavior, with sustained release up to 10 h observed in a buffer solution of pH 6.8 and 7.4. In an acidic medium, a minor amount of drug was released during 10 h dissolution. Drug release kinetics was observed to be in zero order. The findings of this study highlight the promising potential of the tragacanth/pectin hydrogel sponge as a pH-sensitive dais for the controlled delivery of levosulpiride, emphasizing its potential application in personalized drug therapy and the treatment of gastrointestinal disorders.

Advances in Nanotechnology for Enhancing the Solubility and Bioavailability of Poorly Soluble Drugs

This manuscript offers a comprehensive overview of nanotechnology's impact on the solubility and bioavailability of poorly soluble drugs, with a focus on BCS Class II and IV drugs. We explore various nanoscale drug delivery systems (NDDSs), including lipid-based, polymer-based, nanoemulsions, nanogels, and inorganic carriers. These systems offer improved drug efficacy, targeting, and reduced side effects. Emphasizing the crucial role of nanoparticle size and surface modifications, the review discusses the advancements in NDDSs for enhanced therapeutic outcomes. Challenges such as production cost and safety are acknowledged, yet the potential of NDDSs in transforming drug delivery methods is highlighted. This contribution underscores the importance of nanotechnology in pharmaceutical engineering, suggesting it as a significant advancement for medical applications and patient care.

Oral Insulin Delivery: A Review on Recent Advancements and Novel Strategies

BACKGROUND

Due to the lifestyle of people in the community in recent years, the prevalence of diabetes mellitus has increased, so New drugs and related treatments are also being developed.

INTRODUCTION

One of the essential treatments for diabetes today is injectable insulin forms, which have their problems and limitations, such as invasive and less admission of patients and high cost of production. According to the mentioned issues, Theoretically, Oral insulin forms can solve many problems of injectable forms.

METHODS

Many efforts have been made to design and introduce Oral delivery systems of insulin, such as lipid-based, synthetic polymer-based, and polysaccharide-based nano/microparticle formulations. The present study reviewed these novel formulations and strategies in the past five years and checked their properties and results.

RESULTS

According to peer-reviewed research, insulin-transporting particles may preserve insulin in the acidic and enzymatic medium and decrease peptide degradation; in fact, they could deliver appropriate insulin levels to the intestinal environment and then to blood. Some of the studied systems increase the permeability of insulin to the absorption membrane in cellular models. In most investigations, in vivo results revealed a lower ability of formulations to reduce BGL than subcutaneous form, despite promising results in in vitro and stability testing.

CONCLUSION

Although taking insulin orally currently seems unfeasible, future systems may be able to overcome mentioned obstacles, making oral insulin delivery feasible and producing acceptable bioavailability and treatment effects in comparison to injection forms.

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.

Yeast extracts from different manufacturers and supplementation of amino acids and micro elements reveal a remarkable impact on alginate production by A. vinelandii ATCC9046

BACKGROUND

In research and production, reproducibility is a key factor, to meet high quality and safety standards and maintain productivity. For microbial fermentations, complex substrates and media components are often used. The complex media components can vary in composition, depending on the lot and manufacturing process. These variations can have an immense impact on the results of biological cultivations. The aim of this work was to investigate and characterize the influence of the complex media component yeast extract on cultivations of Azotobacter vinelandii under microaerobic conditions. Under these conditions, the organism produces the biopolymer alginate. The focus of the investigation was on the respiration activity, cell growth and alginate production.

RESULTS

Yeast extracts from 6 different manufacturers and 2 different lots from one manufacturer were evaluated. Significant differences on respiratory activity, growth and production were observed. Concentration variations of three different yeast extracts showed that the performance of poorly performing yeast extracts can be improved by simply increasing their concentration. On the other hand, the results with well-performing yeast extracts seem to reach a saturation, when their concentration is increased. Cultivations with poorly performing yeast extract were supplemented with grouped amino acids, single amino acids and micro elements. Beneficial results were obtained with the supplementation of copper sulphate, cysteine or a combination of both. Furthermore, a correlation between the accumulated oxygen transfer and the final viscosity (as a key performance indicator), was established.

CONCLUSION

The choice of yeast extract is crucial for A. vinelandii cultivations, to maintain reproducibility and comparability between cultivations. The proper use of specific yeast extracts allows the cultivation results to be specifically optimised. In addition, supplements can be applied to modify and improve the properties of the alginate. The results only scratch the surface of the underlying mechanisms, as they are not providing explanations on a molecular level. However, the findings show the potential of optimising media containing yeast extract for alginate production with A. vinelandii, as well as the potential of targeted supplementation of the media.

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.

Effect of Different Syrup Types on Turkish Delights (Lokum): A TD-NMR Relaxometry Study

Turkish delights were formulated by using sucrose (control) and different types of corn syrups (having varying glucose/fructose ratios) and allulose syrup. 30% allulose syrup and 30% sucrose-containing Turkish delights were found to exhibit an amorphous structure. Time-domain NMR relaxometry experiments were also conducted on delights by measuring T ₂ relaxation times, and two distinct proton populations were observed in all formulations. The use of different syrup types at different substitution levels led to significant changes in the relaxation times (T _2a and T _2b) of the samples, indicating that the relaxation spectrum might be used as a fingerprint for Turkish delights containing different types and amounts of syrup types. Second moment (M ₂) values which were measured from the signal acquired using a magic sandwich echo pulse sequence were also found to be an effective and promising indicator to detect the crystallinity of Turkish delights.

Mucoadhesive carriers for oral drug delivery

Among the various dosage forms, oral medicine has extensive benefits including ease of administration and patients' compliance, over injectable, suppositories, ocular and nasal. Despite of extensive demand and emerging advantages, over 50% of therapeutic molecules are not available in oral form due to their physicochemical properties. More importantly, most of the biologics, proteins, peptide, and large molecular drugs are mostly available in injectable form. Conventional oral drug delivery system has limitation such as degradation and lack of stability within stomach due to presence of highly acidic gastric fluid, hinders their therapeutic efficacy and demand more frequent and higher dosing. Hence, formulation for controlled, sustained, and targeted drug delivery, need to be designed with feasibility to target the specific region of gastrointestinal (GI) tract such as stomach, small intestine, intestine lymphatic, and colon is challenging. Among various oral delivery approaches, mucoadhesive vehicles are promising and has potential for improving oral drug retention and controlled absorption to treat local diseases within the GI tract, as well systemic diseases. This review provides the overview about the challenges and opportunities to design mucoadhesive formulation for oral delivery of therapeutics in a way to target the specific region of the GI tract. Finally, we have concluded with future perspective and potential of mucoadhesive formulations for oral local and systemic delivery.

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.

Facile synthesis of biogenic silica nanomaterial loaded transparent tragacanth gum hydrogels with improved physicochemical properties and inherent anti-bacterial activity

In this report, biogenic, crystalline (∼60.5 ± 2%) bowknot structured silica nanoparticles (BSNPs) of length ∼ 274 ± 7 nm and width ∼ 36 ± 2 nm were isolated from invasive species viz. Lantana camara. These were then chemically modified using nitrogen containing moieties viz. APTES and CTAB. These modified BSNPs were then used as electrostatic cross-linking agents for the formation of tragacanth gum (TG) hydrogels. The cytocompatible CTAB@BSNP-TG hydrogels documented ∼10-12 fold enhancement in anti-bacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa when compared with TG hydrogels. Disruption of the bacterial membrane by ROS generation and protein leakage were responsible for anti-bacterial activity. A cell migration assay suggested that CTAB@BSNP-TG augmented the cell proliferation of NIH-3T3 cells compared to other TG hydrogels. The present study will pave the path for the development of organic-inorganic hybrid nanocomposite-based hydrogels for anti-bacterial and cell migration applications.

Recent Advances in Polysaccharide-Based Physical Hydrogels and Their Potential Applications for Biomedical and Wastewater Treatment

Polysaccharides have been widely employed to fabricate hydrogels owing to their intrinsic properties including biocompatibility, biodegradability, sustainability, and easy modification. However, a considerable amount of polysaccharide-based hydrogels are prepared by chemical crosslinking method using organic solvents or toxic crosslinkers. The presence of reaction by-products and residual toxic substances in the obtained materials cause a potential secondary pollution risk and thus severely limited their practical applications. In contrast, polysaccharide-based physical hydrogels are preferred over chemically derived hydrogels and can be used to address existing drawbacks of chemical hydrogels. The polysaccharide chains of such hydrogel are typically crosslinked by dynamic non-covalent bonds, and the co-existence of multiple physical interactions stabilize the hydrogel network. This review focuses on providing a detailed outlook for the design strategies and formation mechanisms of polysaccharide-based physical hydrogels as well as their specific applications in tissue engineering, drug delivery, wound healing, and wastewater treatment. The main preparation principles, future challenges, and potential improvements are also outlined. The authors hope that this review could provide valuable information for the rational fabrication of polysaccharide-based physical hydrogel. The specific research works listed in the review will provide a systematic and solid research basis for the reliable development of polysaccharide-based physical hydrogel. This article is protected by copyright. All rights reserved.

Hard, Soft, and Hard-and-Soft Drug Delivery Carriers Based on CaCO3 and Alginate Biomaterials: Synthesis, Properties, Pharmaceutical Applications

Because free therapeutic drug molecules often have adverse effects on normal tissues, deliver scanty drug concentrations and exhibit a potentially low efficacy at pathological sites, various drug carriers have been developed for preclinical and clinical trials. Their physicochemical and toxicological properties are the subject of extensive research. Inorganic calcium carbonate particles are promising candidates as drug delivery carriers owning to their hardness, porous internal structure, high surface area, distinctive pH-sensitivity, low degradability, etc, while soft organic alginate hydrogels are also widely used because of their special advantages such as a high hydration, bio-adhesiveness, and non-antigenicity. Here, we review these two distinct substances as well as hybrid structures encompassing both types of carriers. Methods of their synthesis, fundamental properties and mechanisms of formation, and their respective applications are described. Furthermore, we summarize and compare similarities versus differences taking into account unique advantages and disadvantages of these drug delivery carriers. Moreover, rational combination of both carrier types due to their performance complementarity (yin-&yang properties: in general, yin is referred to for definiteness as hard, and yang is broadly taken as soft) is proposed to be used in the so-called hybrid carriers endowing them with even more advanced properties envisioned to be attractive for designing new drug delivery systems.

Marine Polysaccharides in Tailor- Made Drug Delivery

Abstract:

Marine sources have attracted much interest as an emerging source of biomaterials in drug delivery applications. Amongst all other marine biopolymers, polysaccharides have been the mostly investigated class of biomaterials. The low cytotoxic behavior, in combination with the newly explored health benefits of marine polysaccharides has made it one of the prime research areas in the pharmaceutical and biomedical fields. In this review, we focused on all available marine polysaccharides, including their classification based on biological sources. The applications of several marine polysaccharides in recent years for tissue-specific novel drug delivery including gastrointestinal, brain tissue, transdermal, ocular, liver, and lung have also been discussed here. The abundant availability in nature, cost-effective extraction, and purification process along with a favorable biodegradable profile will encourage researchers to continue investigating marine polysaccharides for exploring newer applications in targeting specific delivery of therapeutics.

Versatile Oral Insulin Delivery Nanosystems: From Materials to Nanostructures

Diabetes is a chronic metabolic disease characterized by lack of insulin in the body leading to failure of blood glucose regulation. Diabetes patients usually need frequent insulin injections to maintain normal blood glucose levels, which is a painful administration manner. Long-term drug injection brings great physical and psychological burden to diabetic patients. In order to improve the adaptability of patients to use insulin and reduce the pain caused by injection, the development of oral insulin formulations is currently a hot and difficult topic in the field of medicine and pharmacy. Thus, oral insulin delivery is a promising and convenient administration method to relieve the patients. However, insulin as a peptide drug is prone to be degraded by digestive enzymes. In addition, insulin has strong hydrophilicity and large molecular weight and extremely low oral bioavailability. To solve these problems in clinical practice, the oral insulin delivery nanosystems were designed and constructed by rational combination of various nanomaterials and nanotechnology. Such oral nanosystems have the advantages of strong adaptability, small size, convenient processing, long-lasting pharmaceutical activity, and drug controlled-release, so it can effectively improve the oral bioavailability and efficacy of insulin. This review summarizes the basic principles and recent progress in oral delivery nanosystems for insulin, including physiological absorption barrier of oral insulin and the development of materials to nanostructures for oral insulin delivery nanosystems.

Recent Progress in Biopolymer-Based Hydrogel Materials for Biomedical Applications

Hydrogels from biopolymers are readily synthesized, can possess various characteristics for different applications, and have been widely used in biomedicine to help with patient treatments and outcomes. Polysaccharides, polypeptides, and nucleic acids can be produced into hydrogels, each for unique purposes depending on their qualities. Examples of polypeptide hydrogels include collagen, gelatin, and elastin, and polysaccharide hydrogels include alginate, cellulose, and glycosaminoglycan. Many different theories have been formulated to research hydrogels, which include Flory-Rehner theory, Rubber Elasticity Theory, and the calculation of porosity and pore size. All these theories take into consideration enthalpy, entropy, and other thermodynamic variables so that the structure and pore sizes of hydrogels can be formulated. Hydrogels can be fabricated in a straightforward process using a homogeneous mixture of different chemicals, depending on the intended purpose of the gel. Different types of hydrogels exist which include pH-sensitive gels, thermogels, electro-sensitive gels, and light-sensitive gels and each has its unique biomedical applications including structural capabilities, regenerative repair, or drug delivery. Major biopolymer-based hydrogels used for cell delivery include encapsulated skeletal muscle cells, osteochondral muscle cells, and stem cells being delivered to desired locations for tissue regeneration. Some examples of hydrogels used for drug and biomolecule delivery include insulin encapsulated hydrogels and hydrogels that encompass cancer drugs for desired controlled release. This review summarizes these newly developed biopolymer-based hydrogel materials that have been mainly made since 2015 and have shown to work and present more avenues for advanced medical applications.

Evaluation of anti-inflammatory response of berberine-loaded gum nanocomplexes in carrageenan-induced acute paw edema in rats

BACKGROUND

Berberine is a natural plant alkaloid and has been reported to possess anti-inflammatory activity. However, berberine's poor bioavailability and low solubility have limited its clinical applicability. Nanoencapsulation of berberine using a suitable carrier can be a promising strategy to improve its efficacy. Therefore, this study aimed to produce berberine-loaded gum nanocomplexes to evaluate their therapeutic effects in a carrageenan-induced rat model.

METHODS

Berberine-loaded gum nanocomplexes were prepared by the ionic complexation between the negative charges of the gums (tragacanth and acacia gum) using a cross-linker for loading cationic berberine and their anti-inflammatory activity was evaluated against carrageenan-induced paw edema in rats. ELISA and qRT-PCR were employed to measure the concentration and mRNA expression level of inflammatory mediators in plasma and paw tissue, respectively.

RESULTS

Berberine nanocomplexes were characterized for particle size (219.5 nm), zeta potential by the dynamic light scattering (DLS), and for entrapment efficiency (93.2%) Infrared spectroscopy affirmed the loading of berberine in gum nanocomplexes. Transmission electron microscopy of formulation showed the spherical shape of nanocomplexes and small particle size (100-150 nm). Pretreatment of rats with berberine nanocomplexes significantly reduced the paw edema in inflamed rat paws, decreased the production of nitrite and TNF-α in plasma and repressed the mRNA expression levels of TNF-α and IL-1β in paw tissue in comparison to berberine per se treated rats.

CONCLUSION

The obtained berberine-loaded gum nanocomplexes produced a better anti-inflammatory effect as compared to berberine alone and hence can be used as an efficient candidate in the treatment of inflammation. The schematic representation of the preparation of the preparation of berberine-loaded tragacanth/acacia gum nanocomplexes and the evaluation in vivo for anti-inflammatory effects.

Recent Progress on Polysaccharide-Based Hydrogels for Controlled Delivery of Therapeutic Biomolecules

A plethora of applications using polysaccharides have been developed in recent years due to their availability as well as their frequent nontoxicity and biodegradability. These polymers are usually obtained from renewable sources or are byproducts of industrial processes, thus, their use is collaborative in waste management and shows promise for an enhanced sustainable circular economy. Regarding the development of novel delivery systems for biotherapeutics, the potential of polysaccharides is attractive for the previously mentioned properties and also for the possibility of chemical modification of their structures, their ability to form matrixes of diverse architectures and mechanical properties, as well as for their ability to maintain bioactivity following incorporation of the biomolecules into the matrix. Biotherapeutics, such as proteins, growth factors, gene vectors, enzymes, hormones, DNA/RNA, and antibodies are currently in use as major therapeutics in a wide range of pathologies. In the present review, we summarize recent progress in the development of polysaccharide-based hydrogels of diverse nature, alone or in combination with other polymers or drug delivery systems, which have been implemented in the delivery of biotherapeutics in the pharmaceutical and biomedical fields.

pH-sensitive polymer-based carriers as a useful approach for oral delivery of therapeutic protein: A review

There are many proteins and enzymes in the human body, and their dysfunction can lead to disease. The use of proteins as a drug is common in various diseases such as diabetes. Proteins are hydrophilic molecules whose spatial structure is critical to their correct function. There are different ways to the administration of proteins. Protein structures are degraded by gastric acid and enzymes in the gastrointestinal tract and have a slight ability to permeation from the gastrointestinal epithelium due to their large hydrophilic nature. Therefore, their oral use has limitations. Since the oral use of drugs is one of the best and easiest routes for patients, many studies have been done to increase the stability, penetration and ultimately increase the bioavailability of proteins through oral administration. One of the studied strategies for oral delivery of protein is the use of pH-sensitive polymer-based carriers. These carriers use different pH-sensitive polymers such as eudragit®, chitosan, dextran, and alginate. The use of pH-sensitive polymer-based carriers by protecting the protein from stomach acid (low pH) and degrading enzymes, increasing permeability, and maintaining the spatial structure of the protein leads to increased bioavailability. In this review, we focus on the various polymers used to prepare pH-sensitive polymer-based carriers for the oral delivery of proteins.

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.

pH-Responsive Cellulose-Based Microspheres Designed as an Effective Oral Delivery System for Insulin

Functional modified cellulose microsphere (CMs) materials exhibit great application potential in drug various fields. Here, we designed pH-responsive carboxylated cellulose microspheres (CCMs) by the citric/hydrochloric acid hydrolysis method to enhance oral bioavailability of insulin by a green route. The CMs were high purity cellulose that dissolved and regenerated from a green solvent by the green sol-gel method. The prepared microspheres were characterized by spectroscopic techniques, such as field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectrum (FT-IR), X-ray diffraction (XPS), etc. The spherical porous structure and carboxylation of cellulose were confirmed by FESEM and FT-IR, respectively. Insulin was loaded into the CCMs by electrostatic interactions, and the insulin release was controlled through ionization of carboxyl groups and proton balance. In vitro insulin release profiles demonstrated the suppression of insulin release in artificial gastric fluid (AGF), while a significant increase at artificial intestinal fluid (AIF) was observed. The insulin release profile was fitted in Korsmeyer-Peppas kinetic model, and insulin release was governed by the Fickian diffusion mechanism. The stability of the secondary structure of insulin was studied by dichroism circular. Excellent biocompatibility and no cytotoxicity of designed CCMs cast them as a potential oral insulin carrier.

Development of a Novel Oral Delivery Vehicle for Probiotics

BACKGROUND

There is a significant interest in effective oral drug delivery of therapeutic substances. For probiotics, there is a particular need for a delivery platform that protects the bacteria from destruction by the acidic stomach while enabling targeted delivery to the intestine where microbiota naturally reside. The use of probiotics and how they impact the gut microbiota is a growing field and holds promise for the treatment of a variety of gastrointestinal diseases, including irritable bowel disease Crohn's disease and C. diff and other diseases, such as obesity, diabetes, Parkinson's, and Alzheimer's diseases.

OBJECTIVE

The aim of this research was to use our newly developed chemically-modified alginate hydrogel with the characteristic feature of stability in acidic environments but disintegration under neutral-basic pH conditions to design a novel system for effective targeted delivery of ingested probiotics.

METHODS AND RESULTS

We have used the approach of encapsulation of bacterial cells in the hydrogel of the modified alginate with in vitro studies in both simulated stomach acid and intestinal fluid conditions to demonstrate the potential application of this novel platform in oral delivery of probiotics. Our data provide a proof-of-concept that enables further studies in vivo with this delivery platform.

CONCLUSION

We have demonstrated in the present study that our chemically modified alginate hydrogel is resistant to acidic conditions and protects bacterial cells encapsulated in it, but it is sensitive to neutral-basic pH conditions under which it disintegrates and releases its viable bacteria cell payload. Our data provide a proof-ofconcept that enables further studies in vivo with this delivery platform for the efficacy of therapeutic bacteria in various disease conditions.

Recent advances in the structure, synthesis, and applications of natural polymeric hydrogels

Hydrogels, polymeric network materials, are capable of swelling and holding the bulk of water in their three-dimensional structures upon swelling. In recent years, hydrogels have witnessed increased attention in food and biomedical applications. In this paper, the available literature related to the design concepts, types, functionalities, and applications of hydrogels with special emphasis on food applications was reviewed. Hydrogels from natural polymers are preferred over synthetic hydrogels. They are predominantly used in diverse food applications for example in encapsulation, drug delivery, packaging, and more recently for the fabrication of structured foods. Natural polymeric hydrogels offer immense benefits due to their extraordinary biocompatible nature. Hydrogels based on natural/edible polymers, for example, those from polysaccharides and proteins, can serve as prospective alternatives to synthetic polymer-based hydrogels. The utilization of hydrogels has so far been limited, despite their prospects to address various issues in the food industries. More research is needed to develop biomimetic hydrogels, which can imitate the biological characteristics in addition to the physicochemical properties of natural materials for different food applications.

NMR Relaxometry and magnetic resonance imaging as tools to determine the emulsifying characteristics of quince seed powder in emulsions and hydrogels

Quince seed powder (QSP) is known to exhibit emulsification properties and could be used as a natural emulsifier in colloidal food systems. In this study, emulsion-based alginate hydrogels were formulated using QSP and xanthan gum (XG) as stabilizers. The objective of the study was to show the emulsifying power of QSP in emulsions and their hydrogels using Time Domain (TD) NMR Relaxometry and Magnetic Resonance Imaging (MRI). Rheology and mean particle size measurements for emulsions and scanning electron microscope (SEM) experiments for hydrogels were further conducted as complementary methods. QSP containing emulsions were found to have longer T₂ relaxation times than XG samples (p < 0.05). Addition of either QSP or XG produced a more pseudoplastic flow behavior (p < 0.05) on the emulsions. Relaxation times were also obtained by MR images through T₂ maps. Relaxation decay curves showed the presence of two proton compartments in hydrogels; protons associated with the polymer matrix and protons interacting with the oil phase. The contribution of the first proton pools was the largest in QSP hydrogels confirmed by the lowest standard deviation in the T₂ maps. This behavior was explained by the emulsification ability of QSP. Results showed that NMR Relaxometry and MR images could be used to understand the emulsifying nature of QSP and many other hydrocolloids.

Physicomechanical, rheological and in vitro cytocompatibility properties of the electron beam irradiated blend hydrogels of tyramine conjugated gum tragacanth and poly (vinyl alcohol)

In the present study, preparation of blend hydrogels of tyramine conjugated gum tragacanth and poly (vinyl alcohol) was carried out by electron beam irradiation, and modification of hydrogel properties with poly (vinyl alcohol) was demonstrated. Gel content, swelling behavior, pore size and mechanical and rheological properties of hydrogels prepared at 14, 28 and 56 kilogray (kGy) with different ratios of polymers were investigated. Gel content increased from 67 ± 2% for pure tyramine conjugated gum tragacanth hydrogel to >92% for blend hydrogels. However, the corresponding equilibrium swelling degree decreased from 35.21 ± 1.51 to 9.14 ± 1.66 due to the higher crosslink density of blend hydrogel. The mechanical strength of the hydrogels with interconnected pores increased significantly in the presence of poly (vinyl alcohol) and increasing irradiation dose up to 28 kGy with a twenty-fold enhancement of stress fracture and excellent elastic recovery in cyclic compression analysis. The equilibrium swelling degree of blend hydrogel containing 3% w/v tyramine conjugated gum tragacanth and 2% w/v poly (vinyl alcohol) prepared at 28 kGy was 16.59 ± 0.81. The biocompatibility of hydrogels was tested in the presence of rabbit bone marrow mesenchymal stem cells. The viability of cells exposed to hydrogel extract was >92% after 7 days of culture and indicated hydrogel biocompatibility with potential biomedical applications.

Sterculia striata gum as a potential oral delivery system for protein drugs

Natural polysaccharides have been investigated as vehicles for oral insulin administration. Because of their non-toxic, renewable, low cost and readily available properties, gums find multiple applications in the pharmaceutical industry. This work aimed to develop a Sterculia striata gum-based formulation associated with additional biopolymers (dextran sulfate, chitosan, and albumin), a crosslinking agent (calcium chloride) and stabilizing agents (polyethylene glycol and poloxamer 188), to increase the oral bioavailability of proteins. Insulin was used as a model drug and the methods used to prepare the formulation were based on ionotropic pregelation followed by electrolytic complexation of oppositely charged biopolymers under controlled pH conditions. The developed formulation was characterized to validate its efficacy, by the determination of its average particle size (622 nm), the insulin encapsulation efficiency (70%), stability in storage for 30 days, and the in vitro mucoadhesion strength (92.46 mN). Additionally, the developed formulation preserved about 64% of initial insulin dose in a simulated gastric medium. This study proposed, for the first time, a Sterculia striata gum-based insulin delivery system with potential for the oral administration of protein drugs, being considered a valid alternative for efficient delivery of those drugs.

Synthesis of chemically cross-linked hydrogel films based on basil seed (Ocimum basilicum L.) mucilage for wound dressing drug delivery applications

The present study aims toward the preparation of pH-sensitive hydrogel films based on basil seed mucilage (OBM) biopolymer as a novel drug delivery system for wound dressing. Various contents of polyvinyl alcohol (PVA), glutaraldehyde (GA) as cross-linker, and glycerol as a plasticizer were incorporated to have an optimal combination of softness and resilience. OBM hydrogel films characterized by FT-IR, thermogravimetric analysis (TGA), morphological analysis by scanning electron microscope (SEM) and their physical properties were discussed on the reportage of the results of several tests: rheology, mechanical tests (stress at maximum load and Young's modulus), O₂ permeability and water vapor permeability, gel fraction, water retention capacity and swelling degree measurements. The best results for this work were Mu-Gly2, which has the acceptable swelling degree and gel fraction leading to functional water retention capacity, as well as the selected formulations, which were non-toxic and biocompatible according to the result of cytotoxicity test. The optimized formulations of films were used for loading of Tetracycline hydrochloride (TH) as a model drug, and the release studies showed better results at pH = 8.5 and pH = 7.4 rather than acidic pH.

Chemical Modification of Alginate for Controlled Oral Drug Delivery

Here, we report two methods that chemically modify alginate to achieve neutral-basic pH sensitivity of the resultant hydrogel. The first method involves direct amide bond formation between alginate and 4-(2-aminoethyl)benzoic acid. The second method that arose out of the desire to achieve better control of the degradation rate of the alginate hydrogel involves reductive amination of oxidized alginate. The products of both methods result in a hydrogel vehicle for targeted delivery of encapsulated payload under physiological conditions in the gastrointestinal tract. Two-dimensional diffusion-ordered spectroscopy and internal and coaxial external nuclear magnetic resonance standards were used to establish chemical bonding and percent incorporation of the modifying groups into the alginate polymer. The hydrogel made with alginate modified by each method was found to be completely stable under acidic pH conditions while disintegrating within minutes to hours in neutral-basic pH conditions. We found that, while alginate oxidation did not affect the β-d-mannuronate/α-l-guluronate ratio of alginate, the rate of disintegration of the hydrogel made with oxidized alginate was dependent upon the degree of oxidation.

Recent progress in the industrial and biomedical applications of tragacanth gum: A review

Natural polymers have distinct advantages over synthetic polymers because of their abundance, biocompatibility, and biodegradability. Tragacanth gum, an anionic polysaccharide, is a natural polymer which is derived from renewable sources. As a biomaterial, tragacanth gum has been used in industrial settings such as food packaging and water treatment, as well as in the biomedical field as drug carriers and for wound healing purposes. The present review provides an overview on the state-of-the-art in the field of tragacanth gum applications. The structure, properties, cytotoxicity, and degradability as well as the recent advances in industrial and biomedical applications of tragacanth gum are reviewed to offer a backdrop for future research.