Nanosphere based oral insulin delivery

Bioinspired orthogonal-shaped protein-biometal nanocrystals enable oral protein absorption

With the growing number of marketed biological drugs, the development of technological strategies for their oral systemic absorption, becomes increasingly important. The harsh gastrointestinal environment and low permeability of the intestinal epithelium, represent a huge challenge for their systemic delivery. Herein, bioinspired in the physiological insulin-Zn interaction, the design of orthogonal-shaped protein-biometal hybrid nanocrystals, further enveloped by a bilayer of functional biomaterials, is reported. The nanocrystals exhibited a size of 80 nm, a neutral surface charge and a high insulin loading. In vitro studies showed the capacity of the nanocomplexes to control the release of the associated insulin, while preserving its stability. In vivo evaluation showed sustained blood glucose reductions in both healthy and diabetic rats (up to 40 % and 80 %, respectively), while chronic immunotoxicity studies in mice indicated no toxicity effect. Preliminary efficacy studies in healthy awake pigs following oral capsule administration showed over 20 % absolute bioavailability.

An Engineered Nanosugar Enables Rapid and Sustained Glucose-Responsive Insulin Delivery in Diabetic Mice

Glucose-responsive insulin-delivery platforms that are sensitive to dynamic glucose concentration fluctuations and provide both rapid and prolonged insulin release have great potential to control hyperglycemia and avoid hypoglycemia diabetes. Here, biodegradable and charge-switchable phytoglycogen nanoparticles capable of glucose-stimulated insulin release are engineered. The nanoparticles are "nanosugars" bearing glucose-sensitive phenylboronic acid groups and amine moieties that allow effective complexation with insulin (≈95% loading capacity) to form nanocomplexes. A single subcutaneous injection of nanocomplexes shows a rapid and efficient response to a glucose challenge in two distinct diabetic mouse models, resulting in optimal blood glucose levels (below 200 mg dL^-1 ) for up to 13 h. The morphology of the nanocomplexes is found to be key to controlling rapid and extended glucose-regulated insulin delivery in vivo. These studies reveal that the injected nanocomplexes enabled efficient insulin release in the mouse, with optimal bioavailability, pharmacokinetics, and safety profiles. These results highlight a promising strategy for the development of a glucose-responsive insulin delivery system based on a natural and biodegradable nanosugar.

Exploration of and insights into advanced topical nanocarrier systems for the treatment of psoriasis

Psoriasis is a chronic inflammatory skin disease with an underlying autoimmune pathogenesis that has brought great distress to patients. Current treatment options include topical therapy, systemic therapy, and phototherapy. By disrupting the stratum corneum, nanocarriers have unique advantages in allowing drug carriers to be tailored to achieve targeted drug delivery, improve efficacy, and minimize adverse effects. Furthermore, despite their limited success in market translatability, nanocarriers have been extensively studied for psoriasis, owing to their excellent preclinical results. As topical formulations are the first line of treatment, utilize the safest route, and facilitate a targeted approach, this study, we specifically describes the management of psoriasis using topical agents in conjunction with novel drug delivery systems. The characteristics, advantages, weaknesses, and mechanisms of individual nanocarriers, when applied as topical anti-psoriatic agents, were reviewed to distinguish each nanocarrier.

Improved oral delivery of insulin by PLGA nanoparticles coated with 5β-cholanic acid conjugated glycol chitosan

Oral insulin has been regarded as the best alternative to insulin injection in therapy of diabetes because of its convenience and painlessness. However, several obstacles in the gastrointestinal tract, such as gastric acid and enzyme, greatly reduce the bioavailability of oral insulin. Herein, we report design and preparation of poly (d, l-lactic-co-glycolic acid) nanoparticles (PLGA NPs) coated with 5β-cholanic acid modified glycol chitosan (GC-CA) (GC-CA@PLGA NPs) to improve the oral delivery of insulin. The GC-CA@PLGA NPs with the size of (302.73 ± 5.13 nm) and zeta potential of (25.03 ± 0.31 mV) were synthesized using the double-emulsion method. The insulin-loading capacity and encapsulation efficiency were determined to be 5.77 ± 0.58% and 51.99 ± 5.27%, respectively. Compared with GC-modified PLGA NPs (GC@PLGA NPs) and bare PLGA NPs, the GC-CA@PLGA NPs showed excellent stability and uptake by Caco-2 cells after simulated gastric acid digestion. Further experiment suggests good biocompatibility of GC-CA@PLGA NPs, including hemolysis and cytotoxicity. Inin vivoexperiment, the insulin loaded in the GC-CA@PLGA NPs exhibited a long-term and stable release profile for lowering blood glucose and presented 30.43% bioavailability in oral administration. In brief, we have developed an efficient and safe drug delivery system, GC-CA@PLGA NPs, for significantly improved oral administration of insulin, which may find potential application in the treatment of diabetes.

Nanotechnologies for the delivery of biologicals: Historical perspective and current landscape

Biological macromolecule-based therapeutics irrupted in the pharmaceutical scene generating a great hope due to their outstanding specificity and potency. However, given their susceptibility to degradation and limited capacity to overcome biological barriers new delivery technologies had to be developed for them to reach their targets. This review aims at analyzing the historical seminal advances that shaped the development of the protein/peptide delivery field, along with the emerging technologies on the lead of the current landscape. Particularly, focus is made on technologies with a potential for transmucosal systemic delivery of protein/peptide drugs, followed by approaches for the delivery of antigens as new vaccination strategies, and formulations of biological drugs in oncology, with special emphasis on mAbs. Finally, a discussion of the key challenges the field is facing, along with an overview of prospective advances are provided.

NANO-BIOTECHNOLOGY AND ITS INNOVATIVE PERSPECTIVE IN DIABETES MANAGEMENT

Diabetes occurs due to the imbalance of glucose in the body known as glucose homeostasis, thus leading to metabolic changes in the body. The two stages hypoglycemia or hyperglycemia classify diabetes into various categories. Various bio-nanotechnological approaches are coupled up with nano particulates, polymers, liposome, various gold plated and solid lipid particulates, regulating transcellular transport, non specific cellular uptake, and paracellular transport, leading to oral, trans-dermal , pulmonary, buccal , nasal , specific gene oriented administration to avoid the patient's non compliance with the parental routes of administration. Phytochemicals are emerging strategies for the future prospects of diabetes management.

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.

Oral delivery of therapeutic proteins bioencapsulated in plant cells: preclinical and clinical advances

Oral delivery of protein drugs (PDs) made in plant cells could revolutionize current approaches of their production and delivery. Expression of PDs reduces their production cost by elimination of prohibitively expensive fermentation, purification, cold transportation/storage, and sterile injections and increases their shelf life for several years. Ability of plant cell wall to protect PDs from digestive acids/enzymes, commensal bacteria to release PDs in gut lumen after lysis of plant cell wall and role of GALT in inducing tolerance facilitate prevention or treatment allergic, autoimmune diseases or anti-drug antibody responses. Delivery of functional proteins facilitate treatment of inherited or metabolic disorders. Recent advances in making PDs free of antibiotic resistance genes in edible plant cells, long-term storage at ambient temperature maintaining their efficacy, production in cGMP facilities, IND enabling studies for clinical advancement and FDA approval of orally delivered PDs augur well for advancing this novel drug delivery platform technology.

Treatment Strategies Against Psoriasis: Principle, Perspectives and Practices

BACKGROUND

Psoriasis is a genetically predisposed autoimmune disease mediated by cytokines released by the activated immune cells. It manifests inflammatory, scaly red or white silvery flaky skin which may be a fluid-filled lesion with soreness and itchiness. The prevalence rate of psoriasis is increasing day by day. Despite having such a high prevalence rate, the treatment of psoriasis is still limited. Hence, there is a need to rethink the various treatment strategies available in the allopathic as well as in the alternative systems of medicine.

METHODS

Various bibliographic databases of previously published peer-reviewed research papers were explored and systematic data culminated in terms of various treatment strategies used for the management of psoriasis. The prime focus is given towards modern as well as alternative systems of medicine such as phototherapy, a combination of phototherapy with pharmacotherapy such as Ayurveda, Yoga and naturopathy, Unani, Siddha, and Homeopathy to treat psoriasis.

RESULTS

A comprehensive review of 161 papers, including both research and review articles, was carried out to make the article readily understandable. The pathogenesis including inflammatory mediators and type of psoriasis is discussed before the treatment strategies to understand the pathophysiology of the disease. The uniqueness, procedure, advantages, and limitations of conventional, advanced, and traditional systems of medicine to treat psoriasis are discussed in detail. Emphasis has also been given towards marine sources such as fish oil, marine sponges, and algae.

CONCLUSION

Although there are many modern and alternative treatment strategies available to treat psoriasis, none of them have been proven to provide complete relief to patients. Moreover, they are associated with certain side effects. In order to overcome them, novel drug delivery systems have been utilized and found effective; however, their stability and safety become the major impediments towards their successful positioning. Traditional and alternative treatment strategies have found to be safe and effective but their use is localized to certain areas. In a nutshell, to achieve successful treatment of psoriasis, there is a need to focus on the development of stable and non-toxic novel drug delivery systems or the promotion of traditional systems to treat psoriasis.

Hydrogels For Peptide Hormones Delivery: Therapeutic And Tissue Engineering Applications

Peptides are the most abundant biological compounds in the cells that act as enzymes, hormones, structural element, and antibodies. Mostly, peptides have problems to move across the cells because of their size and poor cellular penetration. Therefore, a carrier that could transfer peptides into cells is ideal and would be effective for disease treatment. Until now, plenty of polymers, e.g., polysaccharides, polypeptides, and lipids were used in drug delivery. Hydrogels made from polysaccharides showed significant development in targeted delivery of peptide hormones because of their natural characteristics such as networks, pore sizes, sustainability, and response to external stimuli. The main aim of the present review was therefore, to gather the important usages of the hydrogels as a carrier in peptide hormone delivery and their application in tissue engineering and regenerative medicine.

Drug Delivery Strategies for the Treatment of Metabolic Diseases

Metabolic diseases occur when normal metabolic processes are disrupted in the human body, which can be congenital or acquired. The incidence of metabolic diseases worldwide has reached epidemic proportions. So far, various methods including systemic drug therapy and surgery are exploited to prevent and treat metabolic diseases. However, current pharmacotherapeutic options for treatment of these metabolic disorders remain limited and ineffective, especially reducing patient compliance to treatment. Therefore, it is desirable to exploit effective drug delivery approaches to effectively treat metabolic diseases and reduce side effects. This brief review summarizes novel delivery strategies including local, targeted, and oral drug delivery strategies, as well as intelligent stimulus-responsive drug delivery strategy, for the treatment of metabolic disorders including diabetes, obesity, and atherosclerosis.

Biodegradable polyanhydride-based nanomedicines for blood to brain drug delivery

An urgent need to deliver therapeutics across the blood-brain barrier (BBB) underlies a paucity of effective therapies currently available for treatment of degenerative, infectious, traumatic, chemical, and metabolic disorders of the nervous system. With an eye toward achieving this goal, an in vitro BBB model was employed to simulate biodegradable polyanhydride nanoparticle-based drug delivery to the brain. Using a combination of confocal microscopy, flow cytometry, and high performance liquid chromatography, we examined the potential of polyanhydride nanoparticles containing the anti-oxidant, mito-apocynin, to be internalized and then transferred from monocytes to human brain microvascular endothelial cells. The efficacy of this nanoparticle-based delivery platform was demonstrated by neuronal protection against oxidative stress. Taken together, this polyanhydride nanoparticle-based delivery system holds promise for enhancing neuroprotection by facilitating drug transport across the BBB. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2881-2890, 2018.

Single Step Double-walled Nanoencapsulation (SSDN)

A quick fabrication method for making double-walled (DW) polymeric nanospheres is presented. The process uses sequential precipitation of two polymers. By choosing an appropriate solvent and non-solvent polymer pair, and engineering two sequential phase inversions which induces first precipitation of the core polymer followed by precipitation of the shell polymer, DW nanospheres can be created instantaneously. A series of DW formulations were prepared with various core and shell polymers, then characterized using laser diffraction particle sizing, scanning electron microscopy, atomic force microscopy, Fourier transform infrared spectroscopy, and differential scanning calorimetry (DSC). Atomic force microscopy (AFM) imaging confirmed existence of a single core polymer coated with a second polymer. Insulin (3.3% loading) was used as a model drug to assess its release profile from core (PLGA) and shell (PBMAD) polymers and resulted with a tri-phase release profile in vitro for two months. Current approaches for producing DW nanoparticles (NPs) are limited by the complexity and time involved. Additional issues include aggregation and entrapment of multiple spheres and the undesired formation of heterogeneous coatings. Therefore, the technique presented here is advantageous because it can produce NPs with distinct, core-shell morphologies through a rapid, spontaneous, self-assembly process. This method not only produces DW NPs, but can also be used to encapsulate therapeutic drug. Furthermore, modification of this process to other core and shell polymers is feasible using the general guidelines provided in this paper.

Microfluidics for producing poly (lactic-co-glycolic acid)-based pharmaceutical nanoparticles

Microfluidic chips allow the rapid production of a library of nanoparticles (NPs) with distinct properties by changing the precursors and the flow rates, significantly decreasing the time for screening optimal formulation as carriers for drug delivery compared to conventional methods. The batch-to-batch reproducibility which is essential for clinical translation is achieved by precisely controlling the precursors and the flow rate, regardless of operators. Poly (lactic-co-glycolic acid) (PLGA) is the most widely used Food and Drug Administration (FDA)-approved biodegradable polymers. Researchers often combine PLGA with lipids or amphiphilic molecules to assemble into a core/shell structure to exploit the potential of PLGA-based NPs as powerful carriers for cancer-related drug delivery. In this review, we discuss the advantages associated with microfluidic chips for producing PLGA-based functional nanocomplexes for drug delivery. These laboratory-based methods can readily scale up to provide sufficient amount of PLGA-based NPs in microfluidic chips for clinical studies and industrial-scale production.

pH-Responsive Microencapsulation Systems for the Oral Delivery of Polyanhydride Nanoparticles

Multicompartmental polymer carriers, referred to as Polyanhydride-Releasing Oral MicroParticle Technology (PROMPT), were formed by a pH-triggered antisolvent precipitation technique. Polyanhydride nanoparticles were encapsulated into anionic pH-responsive microparticle gels, allowing for nanoparticle encapsulation in acidic conditions and subsequent release in neutral pH conditions. The effects of varying the nanoparticle composition and feed ratio on the encapsulation efficiency were evaluated. Nanoparticle encapsulation was confirmed by confocal microscopy and infrared spectroscopy. pH-triggered protein delivery from PROMPT was explored using ovalbumin (ova) as a model drug. PROMPT microgels released ova in a pH-controlled manner. Increasing the feed ratio of nanoparticles into the microgels increased the total amount of ova delivered, as well as decreased the observed burst release. The cytocompatibility of the polymer materials were assessed using cells representative of the GI tract. Overall, these results suggest that pH-dependent microencapsulation is a viable platform to achieve targeted intestinal delivery of polyanhydride nanoparticles and their payload(s).

Can natural polymers assist in delivering insulin orally?

Diabetes mellitus is one of the most grave and lethal non communicable diseases. Insulin is normally used to medicate diabetes. Due to bioavailability issues, the most regular route of administration is through injection, which may pose compliance problems to treatment. The oral administration thus appears as a suitable alternative, but with several important problems. Low stability of insulin in the gastrointestinal tract and low intestinal permeation are some of the issues. Encapsulation of insulin into polymer-based particles emerges as a plausible strategy. Different encapsulation approaches and polymers have been used in this regard. Polymers with different characteristics from natural or synthetic origin have been assessed to attain this goal, with natural polymers being preferable. Natural polymers studied so far include chitosan, alginate, carrageenan, starch, pectin, casein, tragacanth, dextran, carrageenan, gelatine and cyclodextrin. While some promising knowledge and results have been gained, a polymeric-based particle system to deliver insulin orally has not been introduced onto the market yet. In this review, effectiveness of different natural polymer materials developed so far along with fabrication techniques are evaluated.

Surfactin variants for intra-intestinal delivery of insulin

Surfactin is a Bacillus-produced natural lipopeptide, which can overcome the epithelial cell barriers for orally delivering insulin, but its ability to promote uptake of insulin by the intestine need to be further improved for a higher oral bioavailability. Here, we designed and synthesized several surfactin variants to improve its ability for oral delivery of insulin. Firstly, we replaced Glu with Gln in surfactin for decreasing its negative charges, but found this replacement weakened its ability to orally delivery insulin. We further chemically synthesized surfactin variant by replacing its fatty acid chain (C15) with a shortened one (C14), and found this replacement did not influence its ability to orally deliver insulin. Lastly, we replaced its amino acids (Leu) with more hydrophobic ones (Ile), and found the replacement could significantly improve its ability to deliver insulin, with a maximal blood glucose decrease to 27.33% of the initial level and an insulin bioavailability of 18.25%. We also replaced its amino acids of Leu with Val, and Val with Ile, and found this replacement could also significantly improve its ability to deliver insulin with a maximal blood glucose decrease to 18.36% of the initial level and a high insulin bioavailability of 26.32% in diabetic mice. Further analysis by CD, we found the surfactin variants with more hydrophobic amino acid residuals significantly induced insulin from rigid (α-helix) to flexible structure (β-sheet and random coil), that is favorable for insulin to permeate across the intestine epithelial membrane. Collectively, surfactin variants with more hydrophobicity are very potential for delivery of insulin in the everyday control of blood glucose.

Neuronal protection against oxidative insult by polyanhydride nanoparticle-based mitochondria-targeted antioxidant therapy

A progressive loss of neuronal structure and function is a signature of many neurodegenerative conditions including chronic traumatic encephalopathy, Parkinson's, Huntington's and Alzheimer's diseases. Mitochondrial dysfunction and oxidative and nitrative stress have been implicated as key pathological mechanisms underlying the neurodegenerative processes. However, current therapeutic approaches targeting oxidative damage are ineffective in preventing the progression of neurodegeneration. Mitochondria-targeted antioxidants were recently shown to alleviate oxidative damage. In this work, we investigated the delivery of biodegradable polyanhydride nanoparticles containing the mitochondria-targeted antioxidant apocynin to neuronal cells and the ability of the nano-formulation to protect cells against oxidative stress. The nano-formulated mitochondria-targeted apocynin provided excellent protection against oxidative stress-induced mitochondrial dysfunction and neuronal damage in a dopaminergic neuronal cell line, mouse primary cortical neurons, and a human mesencephalic cell line. Collectively, our results demonstrate that nano-formulated mitochondria-targeted apocynin may offer improved efficacy of mitochondria-targeted antioxidants to treat neurodegenerative disease.

Nanoparticle formulation having ability to control the release of protein for drug delivery application

Controlled release of therapeutic protein is desirable for protein delivery applications. This study discuss about a unique nanomaterial which is capable to provide the protein release in controlled manner. The nanomaterial has been synthesized from folic acid molecules and bovine serum albumin (BSA¹) is loaded in these nanoparticles as a model protein. The size distribution of the synthesized folic acid nanoparticles was observed between 200 and 300nm. The release study using high performance liquid chromatography suggests that more than 90% of BSA can be encapsulated in the nanoparticles having BSA loaded up to 19.29mg (57% of folic acid loaded). Release study also reveals that more than 95% of the total folic acid and BSA were released in phosphate buffer saline solution within 48h. Investigation of folic acid release along with BSA release reveals that the particles are formed through folic acid-protein complex. Salt concentration in the release medium and crosslinked cations in the nanoparticles are found to be the key parameters to control the release rate. Thus, folic acid nanoparticles are efficient carrier for protein encapsulation and release in the controlled manner with minimum drug loss.

A review on the strategies for oral delivery of proteins and peptides and their clinical perspectives

In the modern world, a number of therapeutic proteins such as vaccines, antigens, and hormones are being developed utilizing different sophisticated biotechnological techniques like recombinant DNA technology and protein purification. However, the major glitches in the optimal utilization of therapeutic proteins and peptides by the oral route are their extensive hepatic first-pass metabolism, degradation in the gastrointestinal tract (presence of enzymes and pH-dependent factors), large molecular size and poor permeation. These problems can be overcome by adopting techniques such as chemical transformation of protein structures, enzyme inhibitors, mucoadhesive polymers and permeation enhancers. Being invasive, parenteral route is inconvenient for the administration of protein and peptides, several research endeavors have been undertaken to formulate a better delivery system for proteins and peptides with major emphasis on non-invasive routes such as oral, transdermal, vaginal, rectal, pulmonary and intrauterine. This review article emphasizes on the recent advancements made in the delivery of protein and peptides by a non-invasive (peroral) route into the body.

Preparation and in vivo evaluation of insulin-loaded biodegradable nanoparticles prepared from diblock copolymers of PLGA and PEG

The aim of this study was to design a controlled release vehicle for insulin to preserve its stability and biological activity during fabrication and release. A modified, double emulsion, solvent evaporation, technique using homogenisation force optimised entrapment efficiency of insulin into biodegradable nanoparticles (NP) prepared from poly (DL-lactic-co-glycolic acid) (PLGA) and its PEGylated diblock copolymers. Formulation parameters (type of polymer and its concentration, stabiliser concentration and volume of internal aqueous phase) and physicochemical characteristics (size, zeta potential, encapsulation efficiency, in vitro release profiles and in vitro stability) were investigated. In vivo insulin sensitivity was tested by diet-induced type II diabetic mice. Bioactivity of insulin was studied using Swiss TO mice with streptozotocin-induced type I diabetic profile. Insulin-loaded NP were spherical and negatively charged with an average diameter of 200-400 nm. Insulin encapsulation efficiency increased significantly with increasing ratio of co-polymeric PEG. The internal aqueous phase volume had a significant impact on encapsulation efficiency, initial burst release and NP size. Optimised insulin NP formulated from 10% PEG-PLGA retained insulin integrity in vitro, insulin sensitivity in vivo and induced a sustained hypoglycaemic effect from 3h to 6 days in type I diabetic mice.

An investigation of folic acid-protein association sites and the effect of this association on folic acid self-assembly

The contribution of folic acid (FA)-tryptophan interactions to FA-protein association was investigated in the context of using FA as a drug carrier in protein delivery systems. Bovine serum albumin (BSA) and indolicidin were used as model proteins in the study. The FA-BSA complex was characterized by using the Bradford reagent to identify the impact of FA-BSA association on BSA-dye reagent interactions. UV-visible spectroscopic analysis of the FA-BSA mixture showed that the absorbance maximum of BSA-dye reagent occurred at 595 nm, even after the association of FA with BSA. This confirms that protonated amino acid groups of the protein are not involved in FA-BSA association. Moreover, molecular dynamics (MD) simulation confirmed the presence of an associative interaction between aromatic moieties in FA and tryptophan moieties in the indolicidin molecule, which disrupted FA self-assembly. An X-ray diffraction (XRD) study showed that there was limited disruption of FA self-assembly after the addition of BSA or tryptophan. This suggests that FA and BSA are compatible and associate with each other. Graphical Abstract Mechanism of folic acid and protein association.

Nanoparticle based insulin delivery system: the next generation efficient therapy for Type 1 diabetes

Diabetic cases have increased rapidly in recent years throughout the world. Currently, for type-1 diabetes mellitus (T1DM), multiple daily insulin (MDI) injections is the most popular treatment throughout the world. At this juncture, researchers are trying to develop different insulin delivery systems, especially through oral and pulmonary route using nanocarrier based delivery system. This next generation efficient therapy for T1DM may help to improve the quality of life of diabetic patients who routinely employ insulin by the subcutaneous route. In this paper, we have depicted various next generation nanocarrier based insulin delivery systems such as chitosan-insulin nanoparticles, PLGA-insulin nanoparticles, dextran-insulin nanoparticles, polyalkylcyanoacrylated-insulin nanoparticles and solid lipid-insulin nanoparticles. Modulation of these insulin nanocarriers may lead to successful oral or pulmonary insulin nanoformulations in future clinical settings. Therefore, applications and limitations of these nanoparticles in delivering insulin to the targeted site have been thoroughly discussed.

Probing insulin bioactivity in oral nanoparticles produced by ultrasonication-assisted emulsification/internal gelation

Alginate-dextran sulfate-based particles obtained by emulsification/internal gelation technology can be considered suitable carriers for oral insulin delivery. A rational study focused on the emulsification and particle recovery steps was developed in order to reduce particles to the nanosize range while keeping insulin bioactivity. There was a decrease in size when ultrasonication was used during emulsification, which was more pronounced when a cosurfactant was added. Ultrasonication add-on after particle recovery decreased aggregation and led to a narrower nanoscale particle-size distribution. Insulin encapsulation efficiency was 99.3%±0.5%, attributed to the strong pH-stabilizing electrostatic effect between insulin and nanoparticle matrix polymers. Interactions between these polymers and insulin were predicted using molecular modeling studies through quantum mechanics calculations that allowed for prediction of the interaction model. In vitro release studies indicated well-preserved integrity of nanoparticles in simulated gastric fluid. Circular dichroism spectroscopy proved conformational stability of insulin and Fourier transform infrared spectroscopy technique showed rearrangements of insulin structure during processing. Moreover, in vivo biological activity in diabetic rats revealed no statistical difference when compared to nonencapsulated insulin, demonstrating retention of insulin activity. Our results demonstrate that alginate-dextran sulfate-based nanoparticles efficiently stabilize the loaded protein structure, presenting good physical properties for oral delivery of insulin.

Why most oral insulin formulations do not reach clinical trials

Oral insulin able to induce an efficient antihyperglycemic effect either to replace or complement diabetes mellitus therapy is the major goal of health providers, governments and diabetic patients. Oral therapy is associated not only with the desire to exclude needles from the daily routine of diabetic patient but also with the physiological provision of insulin they would get. Despite numerous efforts over the past few decades to develop insulin delivery systems, there is still no commercially available oral insulin. The reasons why the formulations developed to administer insulin orally fail to reach clinical trials are critically discussed in this review. The principal features of nanoformulations used so far are also addressed as well as the undergoing clinical trials.

Phase inversion emulsification: Current understanding and applications

This review is addressed to the phase inversion process, which is not only a common, low-energy route to make stable emulsions for a variety of industrial products spanning from food to pharmaceuticals, but can also be an undesired effect in some applications, such as crude oil transportation in pipelines. Two main ways to induce phase inversion are described in the literature, i.e., phase inversion composition (PIC or catastrophic) and phase inversion temperature (PIT or transitional). In the former, starting from one phase (oil or water) with surfactants, the other phase is more or less gradually added until it reverts to the continuous phase. In PIT, phase inversion is driven by a temperature change without varying system composition. Given its industrial relevance and scientific challenge, phase inversion has been the subject of a number of papers in the literature, including extensive reviews. Due to the variety of applications and the complexity of the problem, most of the publications have been focused either on the phase behavior or the interfacial properties or the mixing process of the two phases. Although all these aspects are quite important in studying phase inversion and much progress has been done on this topic, a comprehensive picture is still lacking. In particular, the general mechanisms governing the inversion phenomenon have not been completely elucidated and quantitative predictions of the phase inversion point are limited to specific systems and experimental conditions. Here, we review the different approaches on phase inversion and highlight some related applications, including future and emerging perspectives.

Polymer-based nanoparticles for oral insulin delivery: Revisited approaches

Diabetes mellitus is a high prevalence and one of the most severe and lethal diseases in the world. Insulin is commonly used to treat diabetes in order to give patients a better life condition. However, due to bioavailability problems, the most common route of insulin administration is the subcutaneous route, which may present patients compliance problems to treatment. The oral administration is thus considered the most convenient alternative to deliver insulin, but it faces important challenges. The low stability of insulin in the gastrointestinal tract and low intestinal permeation, are problems to overcome. Therefore, the encapsulation of insulin into polymer-based nanoparticles is presented as a good strategy to improve insulin oral bioavailability. In the last years, different strategies and polymers have been used to encapsulate insulin and deliver it orally. Polymers with distinct properties from natural or synthetic sources have been used to achieve this aim, and among them may be found chitosan, dextran, alginate, poly(γ-glutamic acid), hyaluronic acid, poly(lactic acid), poly(lactide-co-glycolic acid), polycaprolactone (PCL), acrylic polymers and polyallylamine. Promising studies have been developed and positive results were obtained, but there is not a polymeric-based nanoparticle system to deliver insulin orally available in the market yet. There is also a lack of long term toxicity studies about the safety of the developed carriers. Thus, the aims of this review are first to provide a deep understanding on the oral delivery of insulin and the possible routes for its uptake, and then to overview the evolution of this field in the last years of research of insulin-loaded polymer-based nanoparticles in the academic and industrial fields. Toxicity concerns of the discussed nanocarriers are also addressed.

Proteins and peptides: The need to improve them as promising therapeutics for ulcerative colitis

The present review briefly describes the nature, type and pathogenesis of ulcerative colitis, and explores the potential use of peptides and proteins in the treatment of inflammatory bowel disease, especially ulcerative colitis. Intestinal absorption and the barrier mechanism of peptide and protein drugs are also discussed, with special emphasis on various strategies which make these drugs better therapeutics having high specificity, potency and molecular targeting ability. However, the limitation of such therapeutics are oral administration, poor pharmacokinetic profile and decreased bioavailability. The recent findings illustrated in this review will be helpful in designing the peptide/protein drugs as a promising treatment of choice for ulcerative colitis.

Pulmonary biodistribution and cellular uptake of intranasally administered monodisperse particles

PURPOSE

For the rational design of nanovaccines against respiratory pathogens, careful selection of optimal particle size and chemistry is paramount. This work investigates the impact of these properties on the deposition, biodistribution, and cellular interactions of nanoparticles within the lungs.

METHOD

In this work, biodegradable poly(sebacic anhydride) (poly(SA)) nanoparticles of multiple sizes were synthesized with narrow particle size distributions. The lung deposition and retention as well as the internalization by phagocytic cells of these particles were compared to that of non-degradable monodisperse polystyrene nanoparticles of similar sizes.

RESULTS

The initial deposition of intranasally administered particles in the lungs was dependent on primary particle size, with maximal deposition occurring for the 360-470 nm particles, regardless of chemistry. Over time, both particle size and chemistry affected the frequency of particle-positive cells and the specific cell types taking up particles. The biodegradable poly(SA) particles associated more closely with phagocytic cells and the dynamics of this association impacted the clearance of these particles from the lung.

CONCLUSIONS

The findings reported herein indicate that both size and chemistry control the fate of intranasally administered particles and that the dynamics of particle association with phagocytic cells in the lungs provide important insights for the rational design of pulmonary vaccine delivery vehicles.

Long-term delivery of protein therapeutics

INTRODUCTION

Proteins are effective biotherapeutics with applications in diverse ailments. Despite being specific and potent, their full clinical potential has not yet been realized. This can be attributed to short half-lives, complex structures, poor in vivo stability, low permeability, frequent parenteral administrations and poor adherence to treatment in chronic diseases. A sustained release system, providing controlled release of proteins, may overcome many of these limitations.

AREAS COVERED

This review focuses on recent development in approaches, especially polymer-based formulations, which can provide therapeutic levels of proteins over extended periods. Advances in particulate, gel-based formulations and novel approaches for extended protein delivery are discussed. Emphasis is placed on dosage form, method of preparation, mechanism of release and stability of biotherapeutics.

EXPERT OPINION

Substantial advancements have been made in the field of extended protein delivery via various polymer-based formulations over last decade despite the unique delivery-related challenges posed by protein biologics. A number of injectable sustained-release formulations have reached market. However, therapeutic application of proteins is still hampered by delivery-related issues. A large number of protein molecules are under clinical trials, and hence, there is an urgent need to develop new methods to deliver these highly potent biologics.

Laronidase-functionalized multiple-wall lipid-core nanocapsules: promising formulation for a more effective treatment of mucopolysaccharidosis type I

PURPOSE

Mucopolysaccharidosis I is a genetic disorder caused by alpha-L-iduronidase deficiency. Its primary treatment is enzyme replacement therapy (ERT), which has limitations such as a high cost and a need for repeated infusions over the patient's lifetime. Considering that nanotechnological approaches may enhance enzyme delivery to organs and can reduce the dosage thereby enhancing ERT efficiency and/or reducing its cost, we synthesized laronidase surface-functionalized lipid-core nanocapsules (L-MLNC).

METHODS

L-MLNCs were synthesized by using a metal complex. Size distributions were evaluated by laser diffraction and dynamic light scattering. The kinetic properties, cytotoxicity, cell uptake mechanisms, clearance profile and biodistribution were evaluated.

RESULTS

Size distributions showed a D[4,3] of 134 nm and a z-average diameter of 71 nm. L-MLNC enhanced the Vmax and Kcat in comparison with laronidase. L-MLNC is not cytotoxic, and nanocapsule uptake by active transport is not only mediated by mannose-6-phosphate receptors. The clearance profile is better for L-MLNC than for laronidase. A biodistribution analysis showed enhanced enzyme activity in different organs within 4 h and 24 h for L-MLNC.

CONCLUSIONS

The use of lipid-core nanocapsules as building blocks to synthesize surface-functionalized nanocapsules represents a new platform for producing decorated soft nanoparticles that are able to modify drug biodistribution.

Facile fabrication of polyanhydride/anesthetic nanoparticles with tunable release kinetics

This work illustrates a two-step strategy for the fabrication of polymer/drug nanoparticles. Utilizing solvent/non-solvent precipitation and gaseous basification, composite nanoparticles with 0-100% drug loadings are fabricated. Drug release kinetics are dictated by nanoparticle composition allowing future tuning for therapeutic applications.

Particle designs for the stabilization and controlled-delivery of protein drugs by biopolymers: a case study on insulin

Natural biopolymers have attracted considerable interest for the development of delivery systems for protein drugs owing to their biocompatibility, non-toxicity, renewability and mild processing conditions. This paper offers an overview of the current status and future perspectives of particle designs using biopolymers for the stabilization and controlled-delivery of a model protein drug--insulin. We first describe the design criteria for polymeric encapsulation and subsequently classify the basic principles of particle fabrication as well as the existing particle designs for oral insulin encapsulation. The performances of these existing particle designs in terms of insulin stability and in vitro release behavior in acidic and alkaline media, as well as their in vivo performance are compared and reviewed. This review forms the basis for future works on the optimization of particle design and material formulation for the development of an improved oral delivery system for protein drugs.