Polymeric hydrogels for oral insulin delivery

Propionate-functionalized chitosan hydrogel nanoparticles for effective oral delivery of insulin

Oral delivery of macromolecular drugs is often hampered by the harsh gastrointestinal environment, which makes the drugs have poor bioavailability. Insulin, the most used drug for diabetes, also faces the same challenge for oral administration. Hence, we decorated microbial metabolite propionate on chitosan (CS) to fabricate insulin-loaded propionate-modified CS hydrogel nanoparticles (IN-CS/PA HNPs). The prepared IN-CS/PA HNPs exhibited high encapsulation efficiency (> 95 %) and loading capacity (∼10 %) for insulin. The system provided better protection for insulin in gastrointestinal environment compared to unmodified IN-CS HNPs. Moreover, the active functional group of propionate can be recognized and transported by mono-carboxylate transporter protein 1 (MCT1) targeting. Thus, in both Caco-2 cells and the ligated intestinal loops of rats, IN-CS/PA HNPs significantly improved permeability and uptake of insulin on intestinal epithelium, which was attributed to MCT1-mediated endocytosis. In type 1 diabetic (T1D) rats, oral delivery of IN-CS/PA HNPs with 60 IU/kg insulin led to more stable and long-lasting hypoglycemic effect than a 5IU/kg dose of subcutaneously injected insulin. It also generated 2.29-fold and 11.88-fold higher relative oral bioavailability compared with empty IN-CS HNPs and free insulin, respectively. This study demonstrated that propanoic acid-functionalized chitosan hydrogel nanoparticles could improve the oral absorption of insulin by overcoming multiple barriers in gastrointestinal tract, providing a promising active targeting strategy for the oral delivery of macromolecules drugs.

A Wearable Integrated Microneedle Electrode Patch for Exercise Management in Diabetes

Exercise is one of the preferred management strategies for diabetic patients, but the exercise mode including type, intensity, and duration time is quite different for each patient because of individual differences. Inadequate exercise has no effect on the blood glucose control, while overexercise may cause serious side effects, such as hypoglycemia and loss of blood glucose control. In this work, we report a closed-loop feedback mode for exercise management in diabetes. A minimally invasive, biocompatible microneedle electrode patch was fabricated and used for continuously monitoring the glucose in the interstitial fluid. Further, in conjunction with using a wireless electrochemical device, the glucose signals can be analyzed to output the potency of exercise and give advice on exercise management. A custom exercise given by this closed-loop feedback mode can reduce the used dose of insulin and avoid side effect during and after exercise. We believe that this work can provide a novel comprehensive guidance for diabetic patients.

Preparation, Characterization and In vitro Evaluation of Insulin-PHBV Nanoparticles/Alginate Hydrogel Composite System for Prolonged Delivery of Insulin

PURPOSE

In the present study, biodegradable poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanoparticles (NPs) containing insulin were loaded in sodium alginate/jeffamine (ALG/jeff) hydrogel for prolonged delivery of insulin. The main aim of this work was to fabricate an efficient insulin delivery system to improve patient adherence by decreasing the repetition of injections.

METHODS

Swelling and morphological properties and crosslinking efficiency of ALG/jeff hydrogel were assessed. The composite hydrogel was prepared by adding PHBV NPs to ALG/jeff hydrogel concurrently with crosslinking process. The morphology and loading capacity of composite hydrogel were analyzed.

RESULTS

Circular dichroism measurement demonstrated that insulin remains stable following fabrication process. The release profile exhibited 54.6 % insulin release from composite hydrogel within 31 days with minor initial burst release equated to nanoparticles and hydrogels. MTT cell viability analysis was performed by applying L-929 cell line and no cytotoxic effect was observed.

CONCLUSIONS

Favorable results clearly introduced fabricated composite hydrogel as an excellent candidate for drug delivery systems and also paves the route for prolonged delivery systems of other proteins.

Recent advances in the development of poly(ester amide)s-based carriers for drug delivery

Biodegradable and biocompatible biomaterials have several important applications in drug delivery. The biomaterial family known as poly(ester amide)s (PEAs) has garnered considerable interest because it exhibits the benefits of both polyester and polyamide, as well as production from readily available raw ingredients and sophisticated synthesis techniques. Specifically, α-amino acid-based PEAs (AA-PEAs) are promising carriers because of their structural flexibility, biocompatibility, and biodegradability. Herein, we summarize the latest applications of PEAs in drug delivery systems, including antitumor, gene therapy, and protein drugs, and discuss the prospects of drug delivery based on PEAs, which provides a reference for designing safe and efficient drug delivery carriers.

Commercial hydrogel product for drug delivery based on route of administration

Hydrogels are hydrophilic, three-dimensional, cross-linked polymers that absorb significant amounts of biological fluids or water. Hydrogels possess several favorable properties, including flexibility, stimulus-responsiveness, versatility, and structural composition. They can be categorized according to their sources, synthesis route, response to stimulus, and application. Controlling the cross-link density matrix and the hydrogels' attraction to water while they're swelling makes it easy to change their porous structure, which makes them ideal for drug delivery. Hydrogel in drug delivery can be achieved by various routes involving injectable, oral, buccal, vaginal, ocular, and transdermal administration routes. The hydrogel market is expected to grow from its 2019 valuation of USD 22.1 billion to USD 31.4 billion by 2027. Commercial hydrogels are helpful for various drug delivery applications, such as transdermal patches with controlled release characteristics, stimuli-responsive hydrogels for oral administration, and localized delivery via parenteral means. Here, we are mainly focused on the commercial hydrogel products used for drug delivery based on the described route of administration.

Investigating the Impact of Network Functionalization on Protein Adsorption to Polymer Nanogels

This study explores the impact of network functionalization and chemical composition on the pH-responsive behavior of polymer nanogels and their adsorption of proteins. Using a thermodynamic theory informed by a molecular model, this work evaluates the interactions of three proteins with varying isoelectric points (insulin, myoglobin, and cytochrome c) and pH-responsive nanogels based on methacrylic acid or allylamine motifs. Three different functionalization strategies are considered, with pH-responsive segments distributed randomly, at the center, or on the surface of the polymer network. Our results show that the spatial distribution of functional units affects both the nanogels' mechanical response to pH changes and the level and localization of adsorbed proteins. The dependence of protein adsorption on the salt concentration is also investigated, with the conclusion that it is best to encapsulate proteins at low salt concentrations and aim for release at high salt concentrations. These results provide valuable information for the design of pH-responsive nanogels as vehicles for protein encapsulation, transport, and administration.

Hydrogel-based Drug Delivery System in Diabetes Management

BACKGROUND

It is estimated that there are over 200 million people living with diabetes mellitus (DM) all over the world. It is a metabolic condition caused by decreased insulin action or secretion. Diabetes Mellitus is also known as Type 2 Diabetes Mellitus. Type 1 diabetes mellitus and type 2 diabetes mellitus are the two most common types of DM. Treatment for type 1 diabetes often consists of insulin replacement therapy, while treatment for type 2 diabetes typically consists of oral hypoglycemics.

OBJECTIVES

Conventional dosing schedules for the vast majority of these medications come with a number of drawbacks, the most common of which are frequent dosing, a short half-life, and low bioavailability. Thus, innovative and regulated oral hypoglycemic medication delivery methods have been developed to reduce the limitations of standard dose forms.

METHODS

The studies and reviews published under the title were looked up in several databases (including PubMed, Elsevier, and Google Scholar).

RESULTS

Hydrogels made from biopolymers are three-dimensional polymeric networks that can be physically or chemically crosslinked. These networks are based on natural polymers and have an inherent hydrophilic quality because of the functional groups they contain. They have a very high affinity for biological fluids in addition to a high water content, softness, flexibility, permeability, and biocompatibility. The fact that these features are similar to those of a wide variety of soft living tissues paves the way for several potentials in the field of biomedicine. In this sense, hydrogels offer excellent platforms for the transport of medications and the controlled release of those drugs. Additionally, biopolymer-based hydrogels can be put as coatings on medical implants in order to improve the biocompatibility of the implants and to prevent medical diseases.

CONCLUSION

The current review focuses on the most recent advancements made in the field of using biopolymeric hydrogels that are physically and chemically crosslinked, in addition to hydrogel coatings, for the purpose of providing sustained drug release of oral hypoglycemics and avoiding problems that are associated with the traditional dosage forms of oral hypoglycemics.

Polymeric hydrogels-based materials for wastewater treatment

Low-cost and reliable wastewater treatment is a relevant issue worldwide to reduce the concentration of environmental pollutants. Industrial effluents containing dyes, heavy metals, and other inorganic and organic compounds can pollute water resources; therefore, novel technologies are required to mitigate and control their release into the environment. Adsorption is one of the simplest methods for treating contaminated water in which a wide spectrum of adsorbents can be used to remove emerging compounds. Hydrogels are interesting materials with high adsorption capacities that can be synthesized via green routes. These adsorbents are promising for large-scale industrial wastewater treatment applications; however, gaps still exist in achieving sustainable commercial implementation. This review focuses on the discussion and analysis of preparation, characterization, and adsorption properties of hydrogels for water purification. The advantages of these polymeric materials for water treatment were analyzed, including their performance in the removal of different organic and inorganic contaminants. Recent advances in the functionalization of hydrogels and the synthesis of novel composites have also been described. The adsorption capacities of hydrogel-based adsorbents are higher than 500 mg/g for different organic and inorganic pollutants, and can reach values of up to >2000 mg/g for organic compounds, significantly outperforming other materials reported for water cleaning. The main interactions involved in the adsorption of water pollutants using hydrogel-based adsorbents were described and explained to allow the interpretation of their removal mechanisms. The current challenges in the implementation of hydrogels for water purification in real-life operations are also highlighted. This review provides an updated picture of hydrogels as interesting materials to address water depollution worldwide.

Insulin-loaded liposomes packaged in alginate hydrogels promote the oral bioavailability of insulin

Compared to subcutaneous injections, oral administration of insulin would be a preferred route of drug administration for diabetic patients. For oral delivery, both liposomes and alginate hydrogels face many challenges, including early burst release of the encapsulated drug and poor intestinal drug absorption. Also, adhesion to the intestinal mucosa remains weak, which all result in a low bioavailability of the payload. This study reports on an alginate hydrogel loaded with liposomes for oral insulin administration. Liposomes (Lip) loaded with arginine-insulin complexes (AINS) were incorporated into a hydrogel prepared from cysteine modified alginate (Cys-Alg) to form liposome-in-alginate hydrogels (AINS-Lip-Gel). An ex vivo study proves that intestinal permeation of AINS and AINS-Lip is approximately 2.0 and 6.0-fold, respectively, higher than that of free insulin. The hydrogel retarded early release of insulin (∼30%) from the liposomes and enhanced the intestinal mucosal retention. In vivo experiments revealed that the AINS-Lip-Gel released insulin in a controlled manner and possessed strong hypoglycemic effects. We conclude that liposome-in-alginate hydrogels loaded with AINS represent an attractive strategy for the oral delivery of insulin.

Polysaccharide-based hydrogels for drug delivery and wound management: a review

INTRODUCTION

Polysaccharide-based hydrogels (PBHs) offer several advantages over their synthetic counterparts. Their natural origin contributes to their nontoxicity, high biocompatibility, and in vivo biodegradability. Their properties can be tuned finely to obtain hydrogels with desired mechanical, structural, and chemical properties.

AREAS COVERED

Such versatile characteristics have potentiated the use of PBHs for the delivery of drugs, vaccines, protein and peptide therapeutics, genes, cells, probiotics, bacteriophages, and other therapeutic agents. Recent advances in hydrogel-based formulations such as nanogels, microgels, microneedles, hydrogel beads, nanocarrier-loaded hydrogels, and complexation hydrogels have enabled the precise delivery of a wide range of therapeutics. This review aims to give a holistic overview of hydrogels in the delivery of a variety of therapeutics through different routes.

EXPERT OPINION

PBHs have been used to enable the oral delivery of vaccines and other biologicals, thereby allowing self-administration of life-saving vaccines during public health emergencies. There is a lack of commercialized wound dressings for the treatment of chronic wounds. PBH-based wound dressings, especially those based on chitosan and loaded with actives and growth factors, have the potential to help in the long-term treatment of such wounds. Recent developments in the 3D printing of hydrogels can enable the quick and large-scale production of drug-loaded hydrogels.

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.

Oral insulin delivery: a patent review

Insulin, on oral administration, is very troublesome because of its limited bioavailability. The evolution of oral insulin delivery formulations is greatly desired for non-invasive therapy by overcoming its low bioavailability, GIT enzymatic deactivation, poor lipophilicity and low stability. Different approaches have been proposed to boost oral insulin bioavailability in insulin-delivery systems and emerging effective therapies by using nanoparticle formulation, nanocapsid, modified chitosan particles, polydopamine microcapsules and nanoliposomes. The present review includes patents and patent applications that were published between 2017 and January 2022.

Ionically cross-linked alginate-chitosan core-shell hydrogel beads for oral delivery of insulin

Here, core-shell hydrogel beads for oral insulin delivery at intestine was reported, which was a target site for insulin absorption. The core-shell hydrogel beads were prepared using naturally derived alginate and chitosan polysaccharides by simple dropping technique. In order to effectively control leakage of insulin from core-shell hydrogel beads, insulin was embedded into the layered double hydroxides (LDHs). LDH/insulin-loaded complexes were firstly coated with chitosan, and then coated with alginate to generate core-shell hydrogel beads. The biocompatibility and angiogenic response of core-shell hydrogel beads were evaluated by direct contact of the beads with chick embryo chorioallantoic membrane, which indicates safety of the core-shell beads. The beads successfully retained the insulin within the core-shell structure at pH 1.2, indicating that insulin had a good protective effect in harsh acidic environments. Interestingly, insulin release starts at the simulated intestinal fluid (pH 6.8) and continue to release for 24 h in a sustained manner.

Casein micelles embedded composite organohydrogel as potential wound dressing

Excellent mechanical and tissue adhesive properties, long-lasting environmental suitability and reliable biocompatibility are essential factors for the hydrogels to be applied as wound dressing in the clinical fields. Based on the self-assembly micelle structures, a new type of casein micelles (CEs)/polyvinyl alcohol (PVA) GW (glycerol-water) organohydrogel was designed and synthesized by a simple one-pot method. Through a unique "load sharing" effect, the CEs which own suitable adhesion abilities and drug loading capacities simultaneously were embedded into the PVA networks by rich hydrogen bonds, so that to obtain the composite organ hydrogel with not only excellent adhesive abilities, but also enhanced mechanical properties. Benefited from the unique GW binary solvent system, the organohydrogel showed long-lasting moisture lock-in capacity and extreme temperature tolerance (in the range of --20 °C ~ 60 °C). Particularly, after loading the model antibacterial drugs (allicin) within the CEs, the as-developed CEs/PVA GW gel exhibited a prominent long-lasting (>100 h) antibacterial properties (>90%). Furthermore, the organohydrogel was confirmed with prominent biocompatibility to support fibroblast cell proliferation and migration. This work proposed a new strategy to build CEs-based gel system, which have a great potential application in terms of prevent bacterial infection, accelerate tissue proliferation and wound healing.

Engineering Emulsion Gels as Functional Colloids Emphasizing Food Applications: A Review

Gels are functional materials with well-defined structures (three-dimensional networks) assembled from the dispersed colloids, and capable of containing a large amount of water, oil, or air (by replacing the liquid within the gel pores), known as a hydrogel, oleogel, and aerogel, respectively. An emulsion gel is a gelled matrix filled with emulsion dispersion in which at least one phase, either continuous phase or dispersed phase forms spatial networks leading to the formation of a semisolid texture. Recently, the interest in the application of gels as functional colloids has attracted great attention in the food industry due to their tunable morphology and microstructure, promising physicochemical, mechanical, and functional properties, and superior stability, as well as controlled release, features for the encapsulated bioactive compounds. This article covers recent research progress on functional colloids (emulsion gels), including their fabrication, classification (protein-, polysaccharide-, and mixed emulsion gels), and properties specifically those related to the gel-body interactions (texture perception, digestion, and absorption), and industrial applications. The emerging applications, including encapsulation and controlled release, texture design and modification, fat replacement, and probiotics delivery are summarized. A summary of future perspectives to promote emulsion gels' use as functional colloids and delivery systems for scouting potential new applications in the food industry is also proposed. Emulsion gels are promising colloids being used to tailor breakdown behavior and sensory perception of food, as well as for the processing, transportation, and targeted release of food additives, functional ingredients, and bioactive substances with flexibility in designing structural and functional parameters.

Skin Patchable Sensor Surveillance for Continuous Glucose Monitoring

Diabetes mellitus is a physiological and metabolic disorder affecting millions of people worldwide, associated with global morbidity, mortality, and financial expenses. Long-term complications can be avoided by frequent, continuous self-monitoring of blood glucose. Therefore, this review summarizes the current state-of-art glycemic control regimes involving measurement approaches and basic concepts. Following an introduction to the significance of continuous glucose sensing, we have tracked the evolution of glucose monitoring devices from minimally invasive to non-invasive methods to present an overview of the spectrum of continuous glucose monitoring (CGM) technologies. The conveniences, accuracy, and cost-effectiveness of the real-time CGM systems (rt-CGMs) are the factors considered for discussion. Transdermal biosensing and drug delivery routes have recently emerged as an innovative approach to substitute hypodermal needles. This work reviews skin-patchable glucose monitoring sensors for the first time, providing specifics of all the major findings in the past 6 years. Skin patch sensors and their progressive form, i.e., microneedle (MN) array sensory and delivery systems, are elaborated, covering self-powered, enzymatic, and non-enzymatic devices. The critical aspects reviewed are material design and assembly techniques focusing on flexibility, sensitivity, selectivity, biocompatibility, and user-end comfort. The review highlights the advantages of patchable MNs' multi-sensor technology designed to maintain precise blood glucose levels and administer diabetes drugs or insulin through a "sense and act" feedback loop. Subsequently, the limitations and potential challenges encountered from the MN array as rt-CGMs are listed. Furthermore, the current statuses of working prototype glucose-responsive "closed-loop" insulin delivery systems are discussed. Finally, the expected future developments and outlooks in clinical applications are discussed.

Advanced Hydrogels for the Controlled Delivery of Insulin

Insulin is a peptide hormone that is key to regulating physiological glucose levels. Its molecular size and susceptibility to conformational change under physiological pH make it challenging to orally administer insulin in diabetes. The most effective route for insulin delivery remains daily injection. Unfortunately, this results in poor patient compliance and increasing the risk of micro- and macro-vascular complications and thus rising morbidity and mortality rates in diabetics. The use of 3D hydrogels has been used with much interest for various biomedical applications. Hydrogels can mimic the extracellular matrix (ECM) and retain large quantities of water with tunable properties, which renders them suitable for administering a wide range of sensitive therapeutics. Several studies have demonstrated the fixation of insulin within the structural mesh of hydrogels as a bio-scaffold for the controlled delivery of insulin. This review provides a concise incursion into recent developments for the safe and effective controlled delivery of insulin using advanced hydrogel platforms with a special focus on sustained release injectable formulations. Various hydrogel platforms in terms of their methods of synthesis, properties, and unique features such as stimuli responsiveness for the treatment of Type 1 diabetes mellitus are critically appraised. Key criteria for classifying hydrogels are also outlined together with future trends in the field.

Synthesis of nanomedicine hydrogel microcapsules by droplet microfluidic process and their pH and temperature dependent release

Chitosan and alginate hydrogels are attractive because they are highly biocompatible and suitable for developing nanomedicine microcapsules. Here we fabricated a polydimethylsiloxane-based droplet microfluidic reactor to synthesize nanomedicine hydrogel microcapsules using Au@CoFeB-Rg3 as a nanomedicine model and a mixture of sodium alginate and PEG-g-chitosan crosslinked by genipin as a hydrogel model. The release kinetics of nanomedicines from the hydrogel were evaluated by simulating the pH and temperature of the digestive tract during drug transport and those of the target pathological cell microenvironment. Their pH and temperature-dependent release kinetics were studied by measuring the mass loss of small pieces of thin films formed by the nanomedicine-encapsulating hydrogels in buffers of pH 1.2, 7.4, and 5.5, which replicate the pH of the stomach, gut and blood, and cancer microenvironment, respectively, at 20 °C and 37 °C, corresponding to the storage temperature of hydrogels before use and normal body temperature. Interestingly, nanomedicine-encapsulating hydrogels can undergo rapid decomposition at pH 5.5 and are relatively stable at pH 7.4 at 37 °C, which are desirable qualities for drug delivery, controlled release, and residue elimination after achieving target effects. These results indicate that the designed nanomedicine hydrogel microcapsule system is suitable for oral administration.

Chitosan-Based Biocompatible Copolymers for Thermoresponsive Drug Delivery Systems: On the Development of a Standardization System

Chitosan is a natural polysaccharide that is considered to be biocompatible, biodegradable and non-toxic. The polymer has been used in drug delivery applications for its positive charge, which allows for adhesion with and recognition of biological tissues via non-covalent interactions. In recent times, chitosan has been used for the preparation of graft copolymers with thermoresponsive polymers such as poly-N-vinylcaprolactam (PNVCL) and poly-N-isopropylamide (PNIPAM), allowing the combination of the biodegradability of the natural polymer with the ability to respond to changes in temperature. Due to the growing interest in the utilization of thermoresponsive polymers in the biological context, it is necessary to increase the knowledge of the key principles of thermoresponsivity in order to obtain comparable results between different studies or applications. In the present review, we provide an overview of the basic principles of thermoresponsivity, as well as a description of the main polysaccharides and thermoresponsive materials, with a special focus on chitosan and poly-N-Vinyl caprolactam (PNVCL) and their biomedical applications.

Dissolving Polymer Microneedles for Transdermal Delivery of Insulin

It’s of great significance to develop insulin-loaded dissolving microneedles (MNs) which are fabricated with various methods and materials for transdermal delivery of insulin to effectively and efficiently treat diabetes. In this work, we present a kind of FITC-insulin tip-loaded dissolving MNs fabricated with the mixture of polyvinyl alcohol (PVA) and sucrose using homemade PDMS MNs mold under vacuum conditions. The uniform appearance of MN arrays contributes to controlling the drug dosage well as required. Sufficient mechanical strength for penetrating tough stratum corneum can be obtained by vacuum frozen-drying for at least 6 h after peeling MNs off the mold. About 90% of the FITC-insulin is localized in the conical MN tips and can be released into the skin within 2 min after insertion. The in vivo insulin absorption study and hypoglycemic effect in diabetic mice demonstrate that the proposed insulin-loaded MNs can efficiently deliver the insulin to the systemic circulation and exhibit a similar effect to hypodermic injection on hypoglycemic administration. Together these results suggested that the efficient MN fabrication process proposed in this work shows great potential for mass production and practical application of drug-loaded dissolving MNs in the future.

Novel porous starch/alginate hydrogels for controlled insulin release with dual response to pH and amylase

An important principle in the development of oral insulin is to protect insulin from the harsh conditions of the stomach and release it in a controlled manner in the intestine. In the present study, novel insulin-loaded porous starch-alginate hydrogel systems (In-S-Alg) including In-MS-Alg (prepared with porous maize starch), In-WS-Alg (porous waxy maize starch), and In-RS-Alg (porous rice starch) were successfully developed. As a representative, In-MS-Alg was further coated with gelatinized-retrograded high amylose maize starch (HA) films with different thicknesses to prepare In-MS-HA/Alg hydrogel beads for improving the functionality of controlled release of insulin under the action of α-amylase. The In-S-Alg and In-MS-HA/Alg hydrogel beads were evaluated in terms of structural and morphological properties, encapsulation effect on insulin as well as its release behavior. The results show that insulin was distributed in the pores and cavities of porous starch granules. In In-MS-HA/Alg hydrogel beads, insulin was increasingly blocked inside porous starch with the increased thickness of the HA film. Encapsulation efficiency of insulin in all In-S-Alg and In-MS-HA/Alg hydrogel beads was >80%. Amazingly, both the hydrogel beads successfully achieved the goal of triggered release upon pH changes and α-amylase addition. Most of the insulin (about 90%) was retained in the simulated gastric fluid; while the release rate of insulin in the simulated intestinal fluid increased gradually, and was further accelerated in the presence of α-amylase. Furthermore, for the In-MS-HA/Alg hydrogel beads, the insulin release rate can be gradually reduced by increasing the thickness of the HA film, which provided the possibility to match the rate of increase of the blood glucose level after the intake of food with different glycemic indices. Therefore, the novel hydrogel prepared in this study may be a promising and safe delivery carrier for oral insulin.

Reduction of enzymatic degradation of insulin via encapsulation in a lipidic bicontinuous cubic phase

Oral delivery of the protein drug insulin is not currently possible due to rapid degradation of the secondary structure in low pH conditions in the stomach and under the influence of digestive enzymes in the gastrointestinal tract. Effective oral delivery of insulin and other protein- or peptide-based drugs will, therefore, require encapsulation in a material or nanoparticle. Herein we investigate the ability of the lipid bicontinuous cubic phase formed by two lipids, monoolein (MO) and phytantriol (PT), to protect encapsulated insulin from degradation by the enzyme chymotrypsin, typically found in the small intestine. High encapsulation efficiency (>80%) was achieved in both lipid cubic phases with retention of the underlying cubic nanostructure. Release of insulin from the cubic matrix was shown to be diffusion-controlled; the release rate was dependent on the cubic nanostructure and consistent with measured diffusion coefficients for encapsulated insulin. Encapsulation was shown to significantly retard enzymatic degradation relative to that in water, with the protective effect lasting up to 2 h, exemplifying the potential of these materials to protect the encapsulated protein payload during oral delivery.

Polysaccharide Chemistry in Drug Delivery, Endocrinology, and Vaccines

Polysaccharides, due to their outstanding properties, have attracted the attention of researchers, working in the biomedical field and especially of those working in drug delivery. Modified/functionalized polysaccharides further increase the importance for various applications. Delivery of therapeutics for diverse ailments in different endocrine glands and hormones safely, is a focal point of researchers working in the field. Among the routes followed, the transdermal route is preferred due to non-exposure of active moieties to the harsh gastric environment and first-pass metabolism. This review starts with the overview of polysaccharides used for the delivery of various therapeutic agents. Advantages of polysaccharides used in the transdermal route are addressed in detail. Types of polysaccharides will be elaborated through examples, and in this context, special emphasis will be on the polysaccharides being used for synthesis of the membranes/films. Techniques employed for their modification to design novel carriers for therapeutics delivery will also be discussed. The review will end with a brief discussion on recent developments and future perspectives for delivery of therapeutic agents, and vaccine development.

In vivo oral insulin delivery via covalent organic frameworks

With diabetes being the 7th leading cause of death worldwide, overcoming issues limiting the oral administration of insulin is of global significance. The development of imine-linked-covalent organic framework (nCOF) nanoparticles for oral insulin delivery to overcome these delivery barriers is herein reported. A gastro-resistant nCOF was prepared from layered nanosheets with insulin loaded between the nanosheet layers. The insulin-loaded nCOF exhibited insulin protection in digestive fluids in vitro as well as glucose-responsive release, and this hyperglycemia-induced release was confirmed in vivo in diabetic rats without noticeable toxic effects. This is strong evidence that nCOF-based oral insulin delivery systems could replace traditional subcutaneous injections easing insulin therapy.

Significant biopolymers and their applications in buccal mediated drug delivery

Considerable research exercises have been directed towards the development of efficient and safe drug delivery systems. Various materials are used in different pharmaceutical formulations for the development of efficient drug delivery systems in the treatment of disease. Biopolymers are a choice of research as an excipient delivery system due to their biodegradability, low toxicity, safe, stable, and renewable nature. Biopolymers are naturally occurring polymers or polymer matrix composites, that are extracted from animals, bacteria, fungi, and plants. Cellulose, starches are carbohydrate-based polymers, and wool, silk, gelatin, and collagen are protein-based biopolymers. Biopolymers are obtained from various sources but biopolymers, that belong to the carbohydrate origin, have been found very promising in drug delivery through various routes. The review mainly focuses on the biopolymers currently in use for buccal-mediated pharmaceutical drug delivery systems because the buccal route is an efficient drug delivery system that allows direct systemic circulation of drugs. It also prevents the hydrolysis of the drug molecule in the gastrointestinal tract and thus increases the bioavailability of the drug. The present review discusses the overview of other drug delivery routes, challenges with conventional drug delivery systems, pharmaceutical applications of some biopolymers used in buccal drug delivery systems, that are published recently, currently in use, or used over the past decade.

Engineered Microgels-Their Manufacturing and Biomedical Applications

Microgels are hydrogel particles with diameters in the micrometer scale that can be fabricated in different shapes and sizes. Microgels are increasingly used for biomedical applications and for biofabrication due to their interesting features, such as injectability, modularity, porosity and tunability in respect to size, shape and mechanical properties. Fabrication methods of microgels are divided into two categories, following a top-down or bottom-up approach. Each approach has its own advantages and disadvantages and requires certain sets of materials and equipments. In this review, we discuss fabrication methods of both top-down and bottom-up approaches and point to their advantages as well as their limitations, with more focus on the bottom-up approaches. In addition, the use of microgels for a variety of biomedical applications will be discussed, including microgels for the delivery of therapeutic agents and microgels as cell carriers for the fabrication of 3D bioprinted cell-laden constructs. Microgels made from well-defined synthetic materials with a focus on rationally designed ultrashort peptides are also discussed, because they have been demonstrated to serve as an attractive alternative to much less defined naturally derived materials. Here, we will emphasize the potential and properties of ultrashort self-assembling peptides related to microgels.

Alginate Calcium Microbeads Containing Chitosan Nanoparticles for Controlled Insulin Release

Effective delivery system for oral insulin administration is a promising way for diabetes therapy. Herein, we prepared alginate microbeads containing chitosan nanoparticles (CNP) for controlled release of insulin. CNP was developed by reaction between tripolyphosphate (TPP) and chitosan. The ratio of TPP to chitosan was optimized aiming with smaller and more unified distributed CNP. TEM and DLS analysis confirmed that CNP has size around 150 nm with low PDI value and strong surface charge. Encapsulate ability for bovine serum albumin, working as model protein, was 11.45%, and the encapsulate efficiency was 23.70%. To modify the release profile of protein suitable for oral insulin delivery, sodium alginate was applied to coat on the surface of CNP by electrostatic interaction. After that, CaCl₂ was added to reinforce the alginate coating layer. FTIR analysis confirmed the interaction of alginate with chitosan and reaction with calcium ion. After reaction with Ca²⁺ ion, size measurement revealed that CNP was incorporated into alginate microbeads with mean diameter about 3.197 μm. Alginate microbeads presented irregular shape with small particles inside as revealed by optical microscope. Meanwhile, the release test demonstrated that protein release was pH-dependent. Acidic pH value retards protein release and neutral pH value promotes protein release. At last, insulin-loaded alginate microbeads were administrated to hyperglycemia model mice and blood glucose profile was monitored afterward. Insulin-loaded microbeads significantly lowered blood glucose level compared with mice treated with alginate microbeads without insulin. It is noted that insulin-loaded alginate microbeads could lower blood glucose level in much prolonged period of 96 h, indicating that insulin was released in controlled manner.

Performance of chitosan polymer as platform during sensors fabrication and sensing applications

Chitosan is an important polymer produced from deacetylation of several sea and insects crusts. Due to its environmental fate and biological biocompatibility, it can be used in several biological and environmental applications. Sensing of biological compounds in human bodies and also in serum, blood, and different body fluids has found an important application instead of direct determination of the body fluids using complicated tools. Sensing process of biological compounds during bio-analysis of the biological systems, especially human fluids lack of several parameters including: high sensitivity, repeatability, speed of analysis and biocompatibility of the used analytical methods, especially in-vivo analysis. That was due to the time between sample handling and sample determination can change various components and concentrations of the bio-compounds. The need for in-situ analysis was directed the researchers for biosensors to overcome the upgrading problems of bio-analysis. Biosensors were the future of this issue. Chitosan can reserve as great platform for fabrication of different sensors to determine the elements, compounds and body bioactive compounds. The presence of different terminal amino and hydroxyl groups within chitosan framework facilitates the immobilization of different biomarkers to be used as sensing elements for the determined compounds. The use of chitosan as sensors platform was enhanced by using chitosan in its nanoforms.

"Oil-soluble" reversed lipid nanoparticles for oral insulin delivery

BACKGROUND

In this study, we aimed to design a novel oral insulin delivery system, named "oil-soluble" reversed lipid nanoparticles (ORLN), in which a hydrophilic insulin molecule is encapsulated by a phospholipid (PC) shell and dissolved in oil to prevent the enzymatic degradation of insulin. ORLN was characterized by transmission electron microscopy and dynamic light scattering.

RESULTS

In vitro enzymatic stability studies showed higher concentrations of insulin in cells incubated with ORLN-encapsulated insulin than in those incubated with free insulin solution in artificial intestinal fluid (pH 6.5). The protective effect of ORLN was attributed to its special release behavior and the formulation of the PC shell and oil barrier. Furthermore, an in vivo oral efficacy study confirmed that blood glucose levels were markedly decreased after ORLN administration in both healthy and diabetic mice. In vivo pharmacokinetic results showed that the bioavailability of ORLN-conjugated insulin was approximately 28.7% relative to that of the group subcutaneously administered with an aqueous solution of insulin, indicating enhanced oral absorption.

CONCLUSIONS

In summary, the ORLN system developed here shows promise as a nanocarrier for improving the oral absorption of insulin.

Design and evaluation of pH-responsive hydrogel for oral delivery of amifostine and study on its radioprotective effects

The purpose of this study was to develop a novel pH-sensitive hydrogel which was used to regulate the acute radiation syndrome (ARS). The hydrogel was fabricated by grafting polycaprolactone onto methacrylic acid copolymer (MAC-g-PCL). Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (¹H NMR) confirmed the obtaining of MAC-g-PCL hydrogel. The hydrogel was pH-sensitive, at pH 1.2, it was compact hydrogel, but at pH7.4, it was dissolved solution. Its inner 3D morphology was observed by scanning electron microscope (SEM). Cell experiments indicated that the MAC-g-PCL hyrogel was out of cytotoxicity. The release profile of amifostine showed that small amount drug release in simulated gastric fluid (pH 1.2) and burst release in simulated intestinal fluid (pH 7.4). Thus, the pH-sensitive hydrogels could protect amifostine from enzymatic degradation in acidic stomach and deliver effectively in the intestine. The radioprotective efficacy was determined by peripheral complete blood parameters and 30-day survival study in mice acutely exposed to 4 Gy γ-ray total body irradiation. Results suggested that oral administration MAC-g-PCL/Ami before total body irradiation protected the mice from hematopoietic ARS and enhanced their survival. Furthermore, in vivo bio-distribution studies indicated that the drug could be sustained delivered at intestinal tract and entered the bloodstream. These results demonstrated that oral administration of amifostine hydrogel provided effective radioprotection to reduce the ARS injury.

Nanotechnology: A Promising Approach for Delivery of Neuroprotective Drugs

Central nervous system (CNS) disorders especially neurodegenerative disorders are the major challenge for public health and demand the great attention of researchers to protect people against them. In past few decades, different treatment strategies have been adopted, but their therapeutic efficacy are not enough and have only shown partial mitigation of symptoms. Blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier (BSCFB) guard the CNS from harmful substances and pose as the major challenges in delivering drugs into CNS for treatment of CNS complications such as Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), stroke, epilepsy, brain tumors, multiple sclerosis (MS), and encephalitis, etc. Nanotechnology has come out as an exciting and promising new platform of treating neurological disorders and has shown great potential to overcome problems related to the conventional treatment approaches. Molecules can be nanoengineered to carry out multiple specific functions such as to cross the BBB, target specific cell or signaling pathway, respond to endogenous stimuli, and act as a vehicle for gene delivery, support nerve regeneration and cell survival. In present review, the role of nanocarrier systems such as liposomes, micelles, solid lipid nanoparticles (SLNPs), dendrimers, and nanoemulsions for delivery of various neurotherapeutic agents has been discussed, besides this, their mechanism of action, and nanoformulation of different neuroprotective agents like curcumin, edaravone, nerve growth factors in CNS disorders like Alzheimer’s, Parkinsonism, epilepsy, stroke, and brain tumors has been reviewed.

The effects of synthetic orally administrated insulin nanoparticles in comparison to injectable insulin on the renal function markers of type 1- diabetic rats

OBJECTIVES

Injectable insulin is the most widely used therapy in patients with type 1 diabetes which has several disadvantages. The present study was aimed to evaluate the efficacy of injectable insulin on diabetes mellitus-related complications in comparison to orally encapsulated insulin nanoparticles.

MATERIALS AND METHODS

This study involved 42 Wistar rats separated into 5 groups, including control (C), diabetic control (D), diabetic receiving regular insulin (INS), diabetic receiving encapsulated insulin nanoparticle (INP), and diabetic receiving chitosan for two months. Biochemical parameters in serum and urine were measured using spectrophotometric or ELISA methods. mRNA levels of kidney injury molecule 1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) were evaluated using quantitative PCR.

RESULTS

There were no significant differences between the two forms of insulin in controlling the glycemic condition (P-value>0.05), but oral INP was more effective in correcting diabetic dyslipidemia in comparison to injectable insulin (P-value<0.05). Urine volume and creatinine excretion were significantly modulated by insulin and oral INP in diabetic groups (P-value<0.05), although the effects of INP on the modulation of execration of urea, acid uric, and albumin was more dramatic. Oral INP caused a significant decrease in urine concentration of KIM-1 and NGAL as well as expression of KIM-1 in renal tissue (P-value<0.05).

CONCLUSION

Our results suggested that oral INP is more effective than injectable insulin in modulation of urine and serum diabetic-related parameters.

Fabrication and characterization of a novel semi-interpenetrating network hydrogel based on sodium carboxymethyl cellulose and poly(methacrylic acid) for oral insulin delivery

In this research, pH-sensitive semi-interpenetrating polymer network hydrogels based on sodium carboxymethyl cellulose and poly(methacrylic acid) were synthesized using free radical polymerization and semi-interpenetrating polymer network approach for oral administration of insulin. The chemical structure and thermal stability of the hydrogels were characterized using Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis measurements. The interior morphology was observed by scanning electron microscopy and the inner structure exhibited a porous honeycomb-like shape. The investigations on the swelling properties of hydrogels revealed their ability to response to pH value change. The in vitro release behavior of insulin was pH dependent and the release of insulin was much lower at pH 1.2 compared to pH 6.8. In vitro cytotoxicity assay indicated that the hydrogels were noncytotoxic to HeLa cells. A sustained reduction in blood glucose level was observed after oral administration of insulin-loaded hydrogel to diabetic rats at 75 IU/kg. These results indicated that the hydrogel would be a promising vehicle for oral insulin delivery systems.

Biocompatible Hydrogels Based on Food Gums with Tunable Physicochemical Properties as Scaffolds for Cell Culture

Hydrogels composed of food gums have gained attention for future biomedical applications, such as targeted delivery and tissue engineering. For their translation to clinical utilization, reliable biocompatibility, sufficient mechanical performance, and tunable structure of polysaccharide hydrogels are required aspects. In this work, we report a unique hybrid polysaccharide hydrogel composed of salecan and curdlan, in which the former is a thickening agent and the latter serves as a network matrix. The physicochemical properties, such as mechanical strength, thermal stability, swelling, and morphology, of the developed composite hydrogel can be accurately modulated by varying the polysaccharide content. Importantly, cytotoxicity assays show the non-toxicity of this hybrid hydrogel. Furthermore, this hydrogel system can support cell proliferation, migration, and function. Altogether, our work proposes a new strategy to build a polysaccharide-constructed hydrogel scaffold, which holds much promise for tissue engineering in terms of cell engraftment, survival, proliferation, and function.

Macroporous Hydrogel Scaffolds with Tunable Physicochemical Properties for Tissue Engineering Constructed Using Renewable Polysaccharides

Polysaccharides have recently attracted increasing attention in the construction of hydrogel devices for biomedical applications. However, polysaccharide-based hydrogels are not suitable for most preclinical applications because of their limited mechanical properties and poor tunability. In this study, we employed a simple and eco-friendly approach to producing a macroporous polysaccharide hydrogel composed of salecan and κ-carrageenan without the use of toxic chemicals. We evaluated the physicochemical properties of the obtained salecan/κ-carrageenan hydrogel and found that its viscoelasticity, morphology, swelling, and thermal stability could be simply controlled by changing the polysaccharide dose in the pre-gel solution. The co-incubation of the fabricated hydrogel with mouse fibroblast cells demonstrated that the hydrogel can support cell adhesion, migration, and growth. Moreover, the hydrogel exhibited good biocompatibility in vivo. Overall, the findings provide a new strategy for the fabrication and optimization of polysaccharide-based hydrogel scaffolds for application in tissue engineering.

Recent Advances in Encapsulation, Protection, and Oral Delivery of Bioactive Proteins and Peptides using Colloidal Systems

There are many areas in medicine and industry where it would be advantageous to orally deliver bioactive proteins and peptides (BPPs), including ACE inhibitors, antimicrobials, antioxidants, hormones, enzymes, and vaccines. A major challenge in this area is that many BPPs degrade during storage of the product or during passage through the human gut, thereby losing their activity. Moreover, many BPPs have undesirable taste profiles (such as bitterness or astringency), which makes them unpleasant to consume. These challenges can often be overcome by encapsulating them within colloidal particles that protect them from any adverse conditions in their environment, but then release them at the desired site-of-action, which may be inside the gut or body. This article begins with a discussion of BPP characteristics and the hurdles involved in their delivery. It then highlights the characteristics of colloidal particles that can be manipulated to create effective BPP-delivery systems, including particle composition, size, and interfacial properties. The factors impacting the functional performance of colloidal delivery systems are then highlighted, including their loading capacity, encapsulation efficiency, protective properties, retention/release properties, and stability. Different kinds of colloidal delivery systems suitable for encapsulation of BPPs are then reviewed, such as microemulsions, emulsions, solid lipid particles, liposomes, and microgels. Finally, some examples of the use of colloidal delivery systems for delivery of specific BPPs are given, including hormones, enzymes, vaccines, antimicrobials, and ACE inhibitors. An emphasis is on the development of food-grade colloidal delivery systems, which could be used in functional or medical food applications. The knowledge presented should facilitate the design of more effective vehicles for the oral delivery of bioactive proteins and peptides.

Design principles of food gels

Naturally sourced gels from food biopolymers have advanced in recent decades to compare favourably in performance and breadth of application to their synthetic counterparts. Here, we comprehensively review the constitutive nature, gelling mechanisms, design approaches, and structural and mechanical properties of food gels. We then consider how these food gel design principles alter rheological and tribological properties for food quality improvement, nutrient-modification of foods while preserving sensory perception, and targeted delivery of drugs and bioactives within the gastrointestinal tract. We propose that food gels may offer advantages over their synthetic counterparts owing to their source renewability, low cost, biocompatibility and biodegradability. We also identify emerging approaches and trends that may improve and expand the current scope, properties and functionalities of food gels and inspire new applications.

Silica-Coated Nanoparticles with a Core of Zinc, l-Arginine, and a Peptide Designed for Oral Delivery

Nanoparticle constructs for oral peptide delivery at a minimum must protect and present the peptide at the small intestinal epithelium in order to achieve oral bioavailability. In a reproducible, scalable, surfactant-free process, a core was formed with insulin in ratios with two established excipients and stabilizers, zinc chloride and l-arginine. Cross-linking was achieved with silica, which formed an outer shell. The process was reproducible across several batches, and physicochemical characterization of a single batch was confirmed in two independent laboratories. The silica-coated nanoparticles (SiNPs) entrapped insulin with high entrapment efficiency, preserved its structure, and released it at a pH value present in the small intestine. The SiNP delivered insulin to the circulation and reduced plasma glucose in a rat jejunal instillation model. The delivery mechanism required residual l-arginine in the particle to act as a permeation enhancer for SiNP-released insulin in the jejunum. The synthetic process was varied in terms of ratios of zinc chloride and l-arginine in the core to entrap the glucagon-like peptide 1 analogue, exenatide, and bovine serum albumin. SiNP-delivered exenatide was also bioactive in mice to some extent following oral gavage. The process is the basis for a platform for oral peptide and protein delivery.

Hydrogel microparticles for biomedical applications

Hydrogel microparticles (HMPs) are promising for biomedical applications, ranging from the therapeutic delivery of cells and drugs to the production of scaffolds for tissue repair and bioinks for 3D printing. Biologics (cells and drugs) can be encapsulated into HMPs of predefined shapes and sizes using a variety of fabrication techniques (batch emulsion, microfluidics, lithography, electrohydrodynamic (EHD) spraying and mechanical fragmentation). HMPs can be formulated in suspensions to deliver therapeutics, as aggregates of particles (granular hydrogels) to form microporous scaffolds that promote cell infiltration or embedded within a bulk hydrogel to obtain multiscale behaviours. HMP suspensions and granular hydrogels can be injected for minimally invasive delivery of biologics, and they exhibit modular properties when comprised of mixtures of distinct HMP populations. In this Review, we discuss the fabrication techniques that are available for fabricating HMPs, as well as the multiscale behaviours of HMP systems and their functional properties, highlighting their advantages over traditional bulk hydrogels. Furthermore, we discuss applications of HMPs in the fields of cell delivery, drug delivery, scaffold design and biofabrication.