Innovative Methods and Applications in Mucoadhesion Research

Encapsulation of short-chain bioactive peptides (BAPs) for gastrointestinal delivery: a review

The majority of known peptides with high bioactivity (BAPs) such as antihypertensive, antidiabetic, antioxidant, hypocholesterolemic, anti-inflammatory and antimicrobial actions, are short-chain sequences of less than ten amino acids. These short-chain BAPs of varying natural and synthetic origin must be bioaccessible to be capable of being adsorbed systemically upon oral administration to show their full range of bioactivity. However, in general, in vitro and in vivo studies have shown that gastrointestinal digestion reduces BAPs bioactivity unless they are protected from degradation by encapsulation. This review gives a critical analysis of short-chain BAP encapsulation and performance with regard to the oral delivery route. In particular, it focuses on short-chain BAPs with antihypertensive and antidiabetic activity and encapsulation methods via nanoparticles and microparticles. Also addressed are the different wall materials used to form these particles and their associated payloads and release kinetics, along with the current challenges and a perspective of the future applications of these systems.

Nanomedicines for intranasal delivery: understanding the nano-bio interactions at the nasal mucus-mucosal barrier

INTRODUCTION

Intranasal administration is an effective drug delivery routes in modern pharmaceutics. However, unlike other in vivo biological barriers, the nasal mucosal barrier is characterized by high turnover and selective permeability, hindering the diffusion of both particulate drug delivery systems and drug molecules. The in vivo fate of administrated nanomedicines is often significantly affected by nano-biointeractions.

AREAS COVERED

The biological barriers that nanomedicines encounter when administered intranasally are introduced, with a discussion on the factors influencing the interaction between nanomedicines and the mucus layer/mucosal barriers. General design strategies for nanomedicines administered via the nasal route are further proposed. Furthermore, the most common methods to investigate the characteristics and the interactions of nanomedicines when in presence of the mucus layer/mucosal barrier are briefly summarized.

EXPERT OPINION

Detailed investigation of nanomedicine-mucus/mucosal interactions and exploration of their mechanisms provide solutions for designing better intranasal nanomedicines. Designing and applying nanomedicines with mucus interaction properties or non-mucosal interactions should be customized according to the therapeutic need, considering the target of the drug, i.e. brain, lung or nose. Then how to improve the precise targeting efficiency of nanomedicines becomes a difficult task for further research.

Chitosan as a promising materials for the construction of nanocarriers for diabetic retinopathy: an updated review

Diabetic retinopathy (DR) is a condition that causes swelling of the blood vessels of the retina and leaks blood and fluids. It is the most severe form of diabetic eye disease. It causes vision loss in its advanced stage. Diabetic retinopathy is responsible for causing 26% of blindness. Very insufficient therapies are accessible for the treatment of DR. As compared to the conventional therapies, there should be enhanced research on the controlled release, shorter duration, and cost-effective therapy of diabetic retinopathy. The expansion of advanced nanocarriers-based drug delivery systems has been now employed to exploit as well as regulate the transport of many therapeutic agents to target sites via the increase in penetration or the extension of the duration of contact employing production by enclosing as well as distributing tiny molecules in nanostructured formulation. Various polymers have been utilized for the manufacturing of these nanostructured formulations. Chitosan possesses incredible biological and chemical properties, that have led to its extensive use in pharmaceutical and biomedical applications. Chitosan has been used in many studies because of its enhanced mucoadhesiveness and non-toxicity. Multiple studies have used chitosan as the best candidate for manufacturing nanocarriers and treating diabetic retinopathy. Numerous nanocarriers have been formulated by using chitosan such as nanostructured lipid carriers, solid lipid nanoparticles, liposomes, and dendrimers for treating diabetic retinopathy. This current review elaborates on the recent advancements of chitosan as a promising approach for the manufacturing of nanocarriers that can be used for treating diabetic retinopathy.

Biophysical analysis on molecular interactions between chitosan-coated sinapic acid loaded liposomes and mucin

BACKGROUND

The mucus biomembrane is a primary barrier in delivering drugs to the brain via intranasal delivery. The negatively charged nanoformulations suffer from poor mucoadhesive ability and less retention time in the nasal cavity, which limits further therapeutic efficacy. The positively charged chitosan coating on liposomes may overcome the above issues. Hence, understanding the molecular interactions between the chitosan-coated liposomes and mucin is essential for developing an effective drug delivery system.

METHODS

The molecular interactions of mucin with sinapic acid-loaded liposomes (SA-LPs) and mucin with chitosan-coated sinapic acid-loaded liposomes (SA-CH-LPs) were assessed using different biophysical instrumental analyses by interpreting the UV-Vis spectra and observing the particle size, polydispersity index, surface charge, and rheological behavior.

RESULTS

The mucin interaction with SA-CH-LPs showed increased viscosity as compared to SA-LPs with mucin. Moreover, the mucin interaction with SA-CH-LPs showed stronger mucoadhesive properties as compared to SA-LPs with mucin. The electrostatic interaction between positively charged SA-CH-LPs and negatively charged mucin was responsible for the enhanced mucoadhesive property.

CONCLUSION

The positively charged SA-CH-LPs highly interact with mucin as compared to negatively charged SA-LPs. The mucoadhesive property of SA-CH-LPs could improve the retention of SA in the nasal cavity as compared to SA-LPs. These findings emphasize the importance of chitosan in modulating the mucoadhesive behavior of liposomes.

GENERAL SIGNIFICANCE

Overall, this study helps to understand the molecular interactions and mucoadhesive nature of the chitosan-coated liposomes with mucin, which is essential for biological activity in the physiological environment.

Transfer-based nuclear magnetic resonance uncovers unique mechanisms for protein-polymer and protein-nanoparticle binding behavior

Nanoparticle-based drug delivery systems have shown increasing popularity as a means to improve patient outcomes by improving the effectiveness of active pharmaceutical ingredients (APIs). Similarly, nanoparticles have shown success in targeting alternative routes of API administration, such as applying mucoadhesion or mucopenetration to mucosal drug delivery to enhance uptake. While there are many promising examples of mucoadhesive nanomedicines in literature, there are also many examples of contradictory mucoadhesive binding behavior, most prominently in cases using the same nanoparticle materials. We have uncovered mechanistic insights in polymer-protein binding systems using nOe transfer-based NMR and sought to leverage them to explore nanoparticle-protein interactions. We tested several polymer-coated nanoparticles and micellar polymer nanoparticles and evaluated their binding with mucin proteins. We uncovered that the composition and interaction intimacy of polymer moieties that promote mucin binding change when the polymers are incorporated onto nanoparticle surfaces compared to polymer in solution. This change from solution state to nanoparticle coating can enable switching of behavior of these materials from inert to binding, as we observed in polyvinyl pyrrolidone. We also found the nanoparticle core was influential in determining the binding fate of polymer materials, whereas the nanoparticle size did not possess a clear correlation in the ranges we tested (60-270 nm). These experiments demonstrate that identical polymers may switch their binding behavior to mucin as a function of conformational changes that are induced by incorporating the polymers onto the surface of nanoparticles. These NMR-derived insights could be further leveraged to optimize nanoparticle formulations and guide polymer-mediated mucoadhesion.

New Biopharmaceutical Characteristics of In Situ Systems Based on Poloxamer 407

Thermosensitive systems based on poloxamer 407 are widely used in targeted drug delivery; however, the stability of the phase transition temperature remains insufficiently studied. This article presents the results of a study on the effect of adding polyethylene glycols (PEG) with different molecular weights and some classical gel-forming polymers on the gelation temperature of thermoreversible compositions based on poloxamer 407 in a long-term experiment. The study showed a positive effect of PEG addition with average molecular weights at concentrations of 1.5-2.0%, as well as gelling agents at a concentration below the critical gelation concentration. The proposed rheological test for studying the samples' adhesion can give an indirect forecast of the composition adhesive rate. Based on the conducted studies, three experimental binary systems based on poloxamer 407 were selected, with the addition of HPMC 0.5%, sodium alginate 0.5%, and PEG 1500 1.5%. These systems are the most promising for the further development of in situ targeted drug delivery systems.

Arginine-Rich Peptidomimetic Ampicillin/Gentamicin Conjugate To Tackle Nosocomial Biofilms: A Promising Strategy To Repurpose First-Line Antibiotics

Combined therapy with penicillins and aminoglycosides has been proved beneficial to address many persistent bacterial infections with possible synergistic effects. However, the different pharmacokinetic profiles of these two antibiotic classes may not guarantee a concerted spatio-temporal delivery at the site of action, decreasing the efficacy of this combination and promoting resistance. Herein, we propose a multifunctional antibiotic-polymer conjugate, designed to colocalize ampicillin and gentamicin to tackle persistent biofilm infections. The two antibacterial molecules were grafted along with the amino acid l-arginine to a biocompatible polymer backbone with peptidomimetic hydrophilic structure, obtaining the antimicrobial poly(argilylaspartamide-co-aspartic) acid-ampicillin, gentamicin (PAA-AG) conjugate. The PAA-AG conjugate displayed excellent biocompatibility on human cell lines if compared with free drugs, potentially enlarging their therapeutic window and safety, and suitable mucoadhesive characteristics which may help local treatments of mucosal infections. Studies on planktonic cultures of clinical and reference strains of S. aureus, P. aeruginosa, and E. coli revealed that PAA-AG holds a broad-spectrum antibacterial efficacy, revealing high potency in inhibiting the growth of the tested strains. More interestingly, PAA-AG exhibited excellent antibiofilm activity on both Gram+ and Gram- communities, showing inhibition of their formation at subMIC concentrations as well as inducing the regression of mature biofilms. Given the high biocompatibility and broad antibiofilm efficacy, combined with the opportunity for synchronous co-delivery, the PAA-AG conjugate could be a valuable tool to increase the success of ampicillin/gentamicin-based antibiotic multitherapy.

Lipid-core nanoparticles: Classification, preparation methods, routes of administration and recent advances in cancer treatment

Nanotechnological drug delivery platforms represent a new paradigm for cancer therapeutics as they improve the pharmacokinetic profile and distribution of chemotherapeutic agents over conventional formulations. Among nanoparticles, lipid-based nanoplatforms possessing a lipid core, that is, lipid-core nanoparticles (LCNPs), have gained increasing interest due to lipid properties such as high solubilizing potential, versatility, biocompatibility, and biodegradability. However, due to the wide spectrum of morphologies and types of LCNPs, there is a lack of consensus regarding their terminology and classification. According to the current state-of-the-art in this critical review, LCNPs are defined and classified based on the state of their lipidic components in liquid lipid nanoparticles (LLNs). These include lipid nanoemulsions (LNEs) and lipid nanocapsules (LNCs), solid lipid nanoparticles (SLNs) and nanostructured lipid nanocarriers (NLCs). In addition, we present a comprehensive and comparative description of the methods employed for their preparation, routes of administration and the fundamental role of physicochemical properties of LCNPs for efficient antitumoral drug-delivery application. Market available LCNPs, clinical trials and preclinical in vivo studies of promising LCNPs as potential treatments for different cancer pathologies are summarized.

Mucus adhesion vs. mucus penetration? Screening nanomaterials for nasal inhalation by MD simulation

Nanocarrier-aided drug delivery techniques have improved the absorption and permeability of drugs in nose-to-brain delivery. However, the molecular properties of nanocarriers during the delivery process are of great interest; in particular, the characteristics when penetrating barriers in vivo are crucial for the screening and optimization of materials for nasal inhalation. In this study, we have focused on two types of delivery systems: mucoadhesive nanoparticles (MAPs) and mucopenetrating nanoparticles (MPPs); both have been widely used for mucosal delivery, although a method for selecting the more effective type of drug carriers for mucosal delivery has not been established. Molecular dynamics (MD) simulations were used to reveal the all-atom dynamic characteristics of the interaction between different delivery systems and the nasal mucus protein MUC5AC. Among the systems tested, hydroxypropyltrimethyl ammonium chloride chitosan (HTCC) had the strongest interaction with mucin, suggesting it had better mucoadhesive performance, and that it interacted with MUC5AC more strongly than unmodified chitosan. In contrast, the mucus-penetrating material polyethylene glycol-poly lactic acid-co-glycolic acid (PEG-PLGA), had almost no interaction with MUC5AC. The results of the MD simulations were verified by in vitro experiments on nanoparticles (NPs) and mucin binding. The drug delivery performance of the four types of NPs, analyzed by in vitro and ex vivo mucosal penetration, were all generally consistent with the properties of the material predicted from the MD simulation. These clues to the molecular mechanism of MAPs and MPPs may provide useful insight into the screening and optimization of nanomaterials suitable for nasal inhalation.

Mucus-Inspired Dynamic Hydrogels: Synthesis and Future Perspectives

Mucus hydrogels at biointerfaces are crucial for protecting against foreign pathogens and for the biological functions of the underlying cells. Since mucus can bind to and host both viruses and bacteria, establishing a synthetic model system that can emulate the properties and functions of native mucus and can be synthesized at large scale would revolutionize the mucus-related research that is essential for understanding the pathways of many infectious diseases. The synthesis of such biofunctional hydrogels in the laboratory is highly challenging, owing to their complex chemical compositions and the specific chemical interactions that occur throughout the gel network. In this perspective, we discuss the basic chemical structures and diverse physicochemical interactions responsible for the unique properties and functions of mucus hydrogels. We scrutinize the different approaches for preparing mucus-inspired hydrogels, with specific examples. We also discuss recent research and what it reveals about the challenges that must be addressed and the opportunities to be considered to achieve desirable de novo synthetic mucus hydrogels.

A robust mucin-containing poly(vinyl alcohol) hydrogel model for the in vitro characterization of mucoadhesion of solid dosage forms

Mucoadhesion testing at macroscopic scale needs a robust, convenient in vitro method as ex vivo methods suffer from poor reproducibility and ethical problems. Here we synthesized mucin-free poly(vinyl alcohol) (PVA) and mucin-containing PVA hydrogel substrates (Muc/PVA) to measure adhesion of polymer tablets. Freezing-thawing method was used for gelation to avoid chemical cross-linking and to preserve the functionality of mucin. The adhesion of first generation mucoadhesive polymers, poly(acrylic acid) (PAA) and hydroxypropylmethylcellulose (HPMC) was tested with outstanding reproducibility on individual batches of hydrogels and qualitative agreement with ex vivo literature data. Negatively charged PAA was less adhesive on Muc/PVA surface than on mucin-free PVA whereas HPMC as a neutral polymer displayed similar adhesion strength on both surfaces. Chitosan as a positively charged polymer showed enhanced adhesion on Muc/PVA substrate compared to mucin-free PVA. These results are corroborated by turbidimetric titration which indicated attractive electrostatic interactions between chitosan and mucin in contrast to the lack of attractive interactions for PAA and HPMC. These results prove the role of electronic theory in macroscopic mucoadhesion.

Untangling Mucosal Drug Delivery: Engineering, Designing, and Testing Nanoparticles to Overcome the Mucus Barrier

Mucus is a complex viscoelastic gel and acts as a barrier covering much of the soft tissue in the human body. High vascularization and accessibility have motivated drug delivery to various mucosal surfaces; however, these benefits are hindered by the mucus layer. To overcome the mucus barrier, many nanomedicines have been developed, with the goal of improving the efficacy and bioavailability of drug payloads. Two major nanoparticle-based strategies have emerged to facilitate mucosal drug delivery, namely, mucoadhesion and mucopenetration. Generally, mucoadhesive nanoparticles promote interactions with mucus for immobilization and sustained drug release, whereas mucopenetrating nanoparticles diffuse through the mucus and enhance drug uptake. The choice of strategy depends on many factors pertaining to the structural and compositional characteristics of the target mucus and mucosa. While there have been promising results in preclinical studies, mucus-nanoparticle interactions remain poorly understood, thus limiting effective clinical translation. This article reviews nanomedicines designed with mucoadhesive or mucopenetrating properties for mucosal delivery, explores the influence of site-dependent physiological variation among mucosal surfaces on efficacy, transport, and bioavailability, and discusses the techniques and models used to investigate mucus-nanoparticle interactions. The effects of non-homeostatic perturbations on protein corona formation, mucus composition, and nanoparticle performance are discussed in the context of mucosal delivery. The complexity of the mucosal barrier necessitates consideration of the interplay between nanoparticle design, tissue-specific differences in mucus structure and composition, and homeostatic or disease-related changes to the mucus barrier to develop effective nanomedicines for mucosal delivery.

Tocotrienols-rich naringenin nanoemulgel for the management of diabetic wound: Fabrication, characterization and comparative in vitro evaluations

The present research had been attempted to formulate and characterize tocotrienols-rich naringenin nanoemulgel for topical application in chronic wound conditions associated with diabetes. In due course, different phases of the nanoemulsion were chosen based on the solubility study, where combination of Capryol 90 and tocotrienols, Solutol HS15, and Transcutol P were selected as oil, surfactant, and cosurfactant, respectively. The nanoemulsions were formulated using the spontaneous emulsification method. Subsequently, Carbopols were incorporated to develop corresponding nanoemulgels of the optimized nanoemulsions. Thermodynamically stable optimized nanoemulgels were evaluated for their globule size, polydispersity index (PDI), surface charge, viscosity, mucoadhesive property, spreadability, in vitro release and release mechanism. Further, increasing polymer concentration in the nanoemulgels was reflected with the increased mucoadhesive property with corresponding decrease in the release rate of the drug. The optimized nanoemulgel (NG1) consisted of uniform dispersion (PDI, 0.452 ​± ​0.03) of the nanometric globules (145.58 ​± ​12.5) of the dispersed phase, and negative surface charge (−21.1 ​± ​3.32 ​mV) with viscosity 297,600 ​cP and good spreadability. In vitro release of naringenin in phosphate buffer saline revealed a sustained release profile up to a maximum of 74.62 ​± ​4.54% from the formulated nanoemulgel (NG1) within the time-frame of 24 ​h. Alternatively, the release from the nanoemulsion was much higher (89.17 ​± ​2.87%), which might be due to lack of polymer coating on the dispersed oil droplets. Moreover, the in vitro release kinetics from the nanoemulgel followed the first-order release and Higuchi model with non-Fickian diffusion. Therefore, encouraging results in this research is evident in bringing a promising future in wound management, particularly associated with diabetes complications.

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Thermodynamically stable naringenin-loaded tocotrienol-rich nanoemulgels were fabricated using spontaneous method.

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Developed nanoemulgel possesses nanometric globule size with good spreadability.

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Controlled in vitro release was obtained over a period of 24 ​h.

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First-order release and Higuchi model with non-Fickian diffusion was established in the in vitro release kinetic profile.

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This nanoemulgel could be a promising tool in the management of chronic wound condition.

Mucoadhesion: mucin-polymer molecular interactions

Mucoadhesion, adhesion of a material to a mucous membrane or a mucus-covered surface, has been employed in drug delivery to prolong contact with adsorption sites and consequently a likely improvement of drug absorption. Mucoadhesion in the oral cavity also provides additional effects on tactile mouthfeel and extended flavor delivery, which impact consumer perception. The mechanisms behind mucoadhesion have not been well understood and there are contradictory literature results on the ranking of mucoadhesive properties of different polymers based on what in-vitro methods that are used. We herein examine the molecular interactions of different polymers with mucin from bovine submaxillary glands at pH 6.6 by using ¹H NMR (Nuclear Magnetic Resonance) that provides atomically resolved information on conformational mobility of the mucin. Studying different types of polymers with different chemical structures and degrees of polymerization (DP), we can via the NMR linewidths and the signal intensities distinguish if the polymers interact with specific segments of the mucin or if they have a universal effect on the mobility of all the molecular segments of the mucin. The specific interaction sites on the mucin for positively charged polymer poly(ethyleneimine) are shown to be different from those for negatively and neutrally charged polymers. In addition, the interactions are also driven by the DP, the concentration of the polymers, and the dehydration. Deepened understanding of molecular effects of the different polymers on the mucin can therefore have strong impact on the development of mucoadhesive products in pharmaceutical and food applications. Finally, we raise awareness of the interpretation of rheological data in terms of mucoadhesion.

Investigating the Molecular Mechanism of Protein-Polymer Binding with Direct Saturation Compensated Nuclear Magnetic Resonance

Herein, we describe a new technique, direct saturation compensated transfer (DISCO) NMR, to characterize protein-macromolecule interactions. DISCO enables the direct observation of intermolecular interactions and is used to investigate mucoadhesion, a type of polymer-protein interaction that is widely implemented in drug delivery but remains poorly understood. In a model system of bovine submaxillary mucin and poly(acrylic acid), DISCO identifies selective backbone interactions that facilitate mucoadhesion through chain interpenetration. DISCO demonstrated distinct patterns of molecular selectivity between mucoadhesive polymers when applied to hydroxypropyl cellulose and carboxymethyl cellulose and that functionalizing adhesive polymers with strongly interacting moieties may be detrimental to the overall adhesive interaction. Additionally, DISCO was used to estimate polymer-protein dissociation constants using individual proton signals as reporters. Overall, DISCO can be used as a label-free screening tool to generate polymer-specific binding fingerprints to map and quantify interactions between macromolecules.

Posterior Segment Ophthalmic Drug Delivery: Role of Muco-Adhesion with a Special Focus on Chitosan

Posterior segment eye diseases (PSEDs) including age macular degeneration (AMD) and diabetic retinopathy (DR) are amongst the major causes of irreversible blindness worldwide. Due to the numerous barriers encountered, highly invasive intravitreal (IVT) injections represent the primary route to deliver drugs to the posterior eye tissues. Thus, the potential of a more patient friendly topical route has been widely investigated. Mucoadhesive formulations can decrease precorneal clearance while prolonging precorneal residence. Thus, they are expected to enhance the chances of adherence to corneal and conjunctival surfaces and as such, enable increased delivery to the posterior eye segment. Among the mucoadhesive polymers available, chitosan is the most widely explored due to its outstanding mucoadhesive characteristics. In this review, the major PSEDs, their treatments, barriers to topical delivery, and routes of topical drug absorption to the posterior eye are presented. To enable the successful design of mucoadhesive ophthalmic drug delivery systems (DDSs), an overview of mucoadhesion, its theory, characterization, and considerations for ocular mucoadhesion is given. Furthermore, chitosan-based DDs that have been explored to promote topical drug delivery to the posterior eye segment are reviewed. Finally, challenges of successful preclinical to clinical translation of these DDSs for posterior eye drug delivery are discussed.

Development and optimization of tibezonium iodide and lignocaine hydrochloride containing novel mucoadhesive buccal tablets: A pharmacokinetic investigation among healthy humans

OBJECTIVE

It is clinically important to deliver sustained-release mucoadhesive dosage of local anesthetic and antimicrobial agent for pain control. The current study aimed to develop and evaluate chitosan (CHI) based buccal mucoadhesive delivery for local release of tibezonium iodide (TBN) and lignocaine hydrochloride (LGN).

METHODS

Direct compression technique was employed, aided by other mucoadhesive polymers like hydroxypropylmethylcellulose (HPMC) and sodium alginate (SA) and evaluated for physicochemical and in vivo character.

RESULTS

Fourier transform infrared spectral analysis (FTIR), powdered X-ray diffraction (XRPD), and differential scanning calorimetry (DSC) absence of physical interaction between ingredients. The physical parameters complied with USP specifications for all formulations. Optimum swellability (551.9%) was offered from formulation TL15, containing 30% SA. Highest ex vivo mucoadhesive strength (24.79 g) and time (18.39 h) was found with TL8. Formulation TL8 also exhibited maximum in vivo residence time (11.37 h). Almost complete drug release at 6 h was possessed by formulation TL5 (HPMC and CHI, 20% each) for TBN (99.98%) and LGN (99.06%). The optimized formulation TL5 exhibited dosage stability up to 6 months at 75% relative humidity and retained drug contents. TL5 was well tolerated by the volunteers with no inflammation, pain or irritation found. Almost 73% of volunteers reported an increase in salivary secretion. The first-order salivary C_max of TBN and LGN were found as 16.02 and 7.80 µg/mL within 4 h, respectively.

CONCLUSION

Therefore, the sustained release mucoadhesive dosage form of TBN and LGN can be an effective and alternative option to conventional delivery.

Recent advances in electrospun nanofiber vaginal formulations for women's sexual and reproductive health

Electrospinning is an innovative technique that allows production of nanofibers and microfibers by applying a high voltage to polymer solutions of melts. The properties of these fibers - which include high surface area, high drug loading capacity, and ability to be manufactured from mucoadhesive polymers - may be particularly useful in a myriad of drug delivery and tissue engineering applications. The last decade has witnessed a surge of interest in the application of electrospinning technology for the fabrication of vaginal drug delivery systems for the treatment and prevention of diseases associated with women's sexual and reproductive health, including sexually transmitted infections (e.g. infection with human immunodeficiency virus and herpes simplex virus) vaginitis, preterm birth, contraception, multipurpose prevention technology strategies, cervicovaginal cancer, and general maintenance of vaginal health. Due to their excellent mechanical properties, electrospun scaffolds are also being investigated as next-generation materials in the surgical treatment of pelvic organ prolapse. In this article, we review the latest advances in the field.

Amphotericin B nanohydrogel ocular formulation using alkyl glyceryl hyaluronic acid: Formulation, characterization, and in vitro evaluation

The present study focused on the development of an amphotericin B (AmB) nanoformulation for ophthalmic applications. Accordingly, AmB nanohydrogels (AHA/AmB) using alkyl glyceryl hyaluronic acid (Hyalorepair®, AHA), a hydrophobized hyaluronic acid, were prepared by employing the dialysis method, followed by assessments of physical properties, drug efficacy, and toxicity. In the AHA/AmB formulation, AmB existed in a self-aggregated and amorphous state in the hydrophobic environment of the AHA moiety. AHA/AmB was shown in vitro to interact with mucin, which is known to be expressed in the corneal epithelium and was expected to improve its corneal retention. Compared with the conventional AmB formulation, amphotericin B sodium deoxycholate, AHA/AmB had the same in vitro antifungal activity but significantly lower in vitro toxicity. These findings indicate that nanohydrogels prepared with AHA possess high fungal selectivity and serve as a promising system for ophthalmic AmB delivery.

Nanocrystals for Improving Oral Bioavailability of Drugs: Intestinal Transport Mechanisms and Influencing Factors

With the limitation of solubility and dissolution rate of insoluble drugs, following oral administration, they would rifely prove poor and volatile bioavailability, which may fail to realize its therapeutic value. The drug nanocrystals are perceived as effective tactic for oral administration of insoluble drugs attributes to possess many prominent properties such as elevating dissolution rate and saturation solubility, high drug loading capacity, and improving oral bioavailability. Based on these advantages, the application of nanocrystals in oral drug delivery has acquired significant achievement, and so far more than 20 products of drug nanocrystals have been confirmed in the market. However, the oral absorption of drug nanocrystals is still facing huge challenges due to the limitation of many factors. Intrinsic properties of the drugs and complex physiological environment of the intestinal tract are the two most important factors affecting the oral bioavailability of drugs. In addition, the research on the multi-aspect mechanisms of nanocrystals promoting gastrointestinal absorption and bioavailability has been gradually deepened. In this review, we summarized recent advances of the nanocrystals delivered orally, and provided an overview to the research progress for crossing the intestinal tract transport mechanisms of the nanocrystals by some new research techniques. Meanwhile, the factors relevant to the transport of drug nanocrystals were also elaborated in detail. Graphical Abstract.

Characteristic Evaluation of Gel Formulation Containing Niosomes of Melatonin or Its Derivative and Mucoadhesive Properties Using ATR-FTIR Spectroscopy

Chitosan or polyvinyl pyrrolidone (PVP) were used in combination with hydroxypropyl methylcellulose (HPMC) and poloxamer 407 (P407) as gelling agents for oral drug delivery. The performance interaction with mucin of chitosan-composed gel (F1) and PVP-composed gel (F2) was compared using attenuated total reflectance-Fourier-transform infrared (ATR-FTIR) spectroscopy at controlled temperatures of 25 and 37 °C for 1 and 5 min. F1 containing niosome-entrapped melatonin or its derivatives was investigated for mucoadhesive interaction on mucosa by ATR-FTIR spectroscopy under the same conditions. The results showed that F1-treated mucin gave a significantly lower amide I/amide II ratio than untreated mucin and F2-treated mucin did within 1 min, suggesting improved rapid affinity between mucin and chitosan. The spectra of mucosa treated with F1 incorporating niosomes of melatonin or its derivatives showed peak shifts at C=O (amide I), N-H (amide II), and carbohydrate regions and an associated decrease in the amide I/amide II ratio and increase in the carbohydrate/amide II ratio. These results indicated electrostatic interaction and hydrogen bonding between chitosan and mucin on the mucosa. In conclusion, the molecular interaction between gels and mucin/mucosa detected at amide I and amide II of proteins and the carbohydrate region could lead to an improved mucoadhesive property of the gel on the mucosa.

The progress on sulfhydryl modified polymers with regard to synthesis, characterization and mucoadhesion

The concepts of mucoadhesion and mucoadhesive polymers were introduced in the 20th century, leading to several advantages. These included enhanced drug absorption and extended residence at specific site of action. Polymeric excipients underwent chemical modification with sulfhydryl groups on the polymeric backbone so as to improve mucoadhesive features as well as potential. This modification resulted in compounds mimicking the nature of secreted mucus glycoproteins. Thus, these thiol group-bearing excipients presented the ability to attach covalently to the mucosa by the disulfide bonding. Nevertheless, the first generation of these thiol-modified polymers, named thiomers, presented disadvantages such as low stability in aqueous media and/or the high susceptibility towards oxidation along with the drawback of low sufficient reactive functional moieties on the polymeric backbone at lower pH. Therefore, in the 21st century, a second generation of preactivated or S-protected polymers with protected thiol moieties were developed, as well as a third generation of thiomers, solving some of the previously described problems. This review article aimed to highlight the progess on a potent sulfhydryl modification during the last decades and the posterior characterization and in vitro/ex vivo/in vivo mucoadhesiveness.

Thiolated PVP-Amphotericin B Complexes: An Innovative Approach toward Highly Mucoadhesive Gels for Mucosal Leishmaniasis Treatment

The aim of this study was to synthesize polymeric excipients that can form mucoadhesive hydrogels containing amphotericin B (AmB) for the treatment of mucosal leishmaniasis. 2-(2-Acryloylaminoethyldisulfanyl)-nicotinic acid (ACENA) was copolymerized with N-vinyl pyrrolidone to obtain thiolated polyvinylpyrrolidone (PVP) that was then complexed with AmB to improve its solubility. The resulting structure of thiolated PVP was evaluated by ¹H nuclear magnetic resonance to confirm S-protected thiol groups, and the average molecular mass was determined by size exclusion chromatography. Moreover, variants of thiolated PVP-AmB were studied for the thiol content, amount of complexed AmB, cytotoxicity, mucoadhesive properties, and antileishmaniasis activity. The highest achieved degree of thiolation was 772 ± 24.64 μmol/g, and the amount of complexed AmB was 27.05 ± 0.31 μmol per g of polymer. Thiolated PVP and thiolated PVP-AmB variants (0.5% m/v) showed no cytotoxicity, whereas the equivalent concentration of free AmB reduced Caco-2 cell viability to 70% within 24 h. Thiol-functionalized PVP and PVP-AmB complexes displayed 7.66- and 7.20-fold higher adhesion to the mucosal surface in comparison to unmodified PVP and PVP-AmB, respectively. In addition, variants of thiolated PVP-AmB complexes displayed 100% antileishmaniasis activity in comparison to the 80% killing efficiency of Fungizone, which has been applied in the equivalent AmB concentration of 0.2 μg/mL. Thiol-functionalized PVP proved to be a promising novel excipient for the delivery of AmB providing enhanced solubility and improved mucoadhesive properties which are beneficial for the treatment of mucosal leishmaniasis.

Amphiphilic Star Polypept(o)ides as Nanomeric Vectors in Mucosal Drug Delivery

Mucosal delivery across the gastrointestinal (GI) tract, airways, and buccal epithelia is an attractive mode of therapeutic administration, but the challenge is to overcome the mucus and epithelial barriers. Here, we present degradable star polypept(o)ides capable of permeating both barriers as a promising biomaterial platform for mucosal delivery. Star polypept(o)ides were obtained by the initiation of benzyl-l-glutamate N-carboxyanhydride (NCA) from an 8-arm poly(propyleneimine) (PPI) dendrimer, with subsequent chain extension with sarcosine NCA. The hydrophobic poly(benzyl-l-glutamate) (PBLG) block length was maintained at 20 monomers, while the length of the hydrophilic poly(sarcosine) (PSar) block ranged from 20-640 monomers to produce star polypept(o)ides with increasing hydrophilic: hydrophobic ratios. Transmission electron microscopy (TEM) images revealed elongated particles of ∼120 nm length, while dynamic light scattering (DLS) provided evidence of a decrease in the size of polymer aggregates in water with increasing poly(sarcosine) block length, with the smallest size obtained for the star PBLG₂₀-b-PSar₆₄₀. Fluorescein isothiocyanate (FITC)-conjugated PBLG₂₀-b-PSar₆₄₀ permeated artificial mucus and isolated rat mucus, as well as rat intestinal jejunal tissue mounted in Franz diffusion chambers. An apparent permeability coefficient (P_app) of 15.4 ± 3.1 ×10^-6 cm/s for FITC-PBLG₂₀-b-PSar₆₄₀ was calculated from the transepithelial flux obtained with the apical-side addition of 7.5 mg polypept(o)ide to jejunal tissue over 2 h. This P_app could not be accounted for by flux of unconjugated FITC. Resistance to trypsin demonstrated the stability of FITC-labeled polypept(o)ide over 2 h, but enzymatic degradation at the mucus-epithelial interface or during flux could not be ruled out as contributing to the P_app. The absence of any histological damage to the jejunal tissue during the 2 h exposure suggests that the flux was not associated with overt toxicity.

Water-Dependent Blending of Pectin Films: The Mechanics of Conjoined Biopolymers

Biodegradable pectin polymers have been recommended for a variety of biomedical applications, ranging from the delivery of oral drugs to the repair of injured visceral organs. A promising approach to regulate pectin biostability is the blending of pectin films. To investigate the development of conjoined films, we examined the physical properties of high-methoxyl pectin polymer-polymer (homopolymer) interactions at the adhesive interface. Pectin polymers were tested in glass phase (10–13% w/w water content) and gel phase (38–41% w/w water content). The tensile strength of polymer-polymer adhesion was measured after variable development time and compressive force. Regardless of pretest parameters, the adhesive strength of two glass phase films was negligible. In contrast, adhesion testing of two gel phase films resulted in significant tensile adhesion strength (p < 0.01). Adhesion was also observed between glass phase and gel phase films—likely reflecting the diffusion of water from the gel phase to the glass phase films. In studies of the interaction between two gel phase films, the polymer-polymer adhesive strength increased linearly with increasing compressive force (range 10–80 N) (R² = 0.956). In contrast, adhesive strength increased logarithmically with time (range 10–10,000 s) (R² = 0.913); most of the adhesive strength was observed within minutes of contact. Fracture mechanics demonstrated that the adhesion of two gel phase films resulted in a conjoined film with distinctive physical properties including increased extensibility, decreased stiffness and a 30% increase in the work of cohesion relative to native polymers (p < 0.01). Scanning electron microscopy of the conjoined films demonstrated cross-grain adhesion at the interface between the adhesive homopolymers. These structural and functional data suggest that blended pectin films have emergent physical properties resulting from the cross-grain intermingling of interfacial pectin chains.

Quantifying and Engineering Mucus Adhesion of Probiotics

Mucus in the gastrointestinal (GI) tract is the primary point-of-interaction between humans and their gut microbiota. This intimates that mucus not only ensures protection against endogenous and exogenous opportunists but also provisions for the human microbiota to reside and flourish. With the emergence of living therapeutics, engineered microbes can deliver and produce increasingly complex medicine, and controlling the mucoadhesive properties of different microbial chassis can dictate dose-response in a patient. Here we present a redesigned, in vitro, plate-based assay to measure the mucus adhesion of various probiotics. Cell-mucus interactions were isolated by immobilizing mucus to the plate surface. Binding parameters were derived for each probiotic strain by measuring cell adhesion over a wide range of cell concentrations, providing dose-dependent adhesion metrics. Surface proteins and cell components known to influence mucoadhesion were then heterologously expressed or altered in Lactococcus lactis MG1363 and Escherichia coli Nissle 1917 to control mucus-binding capacity, avidity, and cooperativity.

Recent Advancements in Using Polymers for Intestinal Mucoadhesion and Mucopenetration

Oral administration of actives is the most desired form of delivery, but the formulations need to overcome a variety of barriers including the intestinal mucus. This feature article summarizes the developments from the past 2-3 years in this context focusing on polymer-based formulations. The progress in assembling mucopenetrating nanoparticles is outlined considering coatings using noninteracting polymers as well as virus-like particles and charge-shifting particles. Next, polymers and their modification to enhance mucoadhesion are discussed, followed by providing examples of double-encapsulation systems that aim to combine mucopenetration with mucoadhesion in the same formulation. Finally, a short outlook is provided highlighting a few of the most pressing challenges to address.

Permeability of the small intestinal mucus for physiologically relevant studies: Impact of mucus location and ex vivo treatment

The small intestinal mucus is a complex colloidal system that coats the intestinal mucosa. It allows passage on nutrients/pharmaceuticals from the gut lumen towards the epithelium, whilst preventing it from direct contact with luminal microorganisms. Mucus collected from intestinal tissue is often used in studies looking at inter-mucosal transport of food particulates, drug carriers, etc. However, detaching the highly hydrated native mucus from the tissue and storing it frozen prior to use may disrupt its physiological microstructure, and thus selective barrier properties. Multiple-particle tracking experiments showed that microstructural organisation of native, jejunal mucus depends on its spatial location in the intestinal mucosa. The inter-villus mucus was less heterogeneous than the mucus covering villi tips in the pig model used. Collecting mucus from tissue and subjecting it to freezing and thawing did not significantly affect (P > 0.05) its permeability to model, sub-micron sized particles, and the microviscosity profile of the mucus reflected the overall profiles recorded for the native mucus in the tissue. This implies the method of collecting and storing mucus is a reliable ex vivo treatment for the convenient planning and performing of mucus-permeability studies that aim to mimic physiological conditions of the transport of molecules/particles in native mucus.

Investigation of Mucoadhesion and Degradation of PCL and PLGA Microcontainers for Oral Drug Delivery

Microfabricated devices have been introduced as a promising approach to overcome some of the challenges related to oral administration of drugs and, thereby, improve their oral bioavailability. In this study, we fabricate biodegradable microcontainers with different polymers, namely poly-ɛ-caprolactone (PCL), poly(lactic-co-glycolic acid) (PLGA) 50:50 and PLGA 75:25 by hot punching. The mucoadhesion of the microcontainers is assessed with an ex vivo retention model on porcine intestinal tissue. Finally, in vitro degradation studies of the biodegradable microcontainers are completed for six weeks in simulated intestinal medium with the addition of pancreatic enzymes. Through SEM inspection, the PLGA 50:50 microcontainers show the first signs of degradation already after two weeks and complete degradation within four weeks, while the other polymers slowly degrade in the medium over several weeks.

Mucin immobilization in calcium alginate: A possible mucus mimetic tool for evaluating mucoadhesion and retention of flavour

To reduce animal testing, there is a need to develop novel in-vitro models for evaluating the retention of bioactive compounds in food and pharmaceutical products. Here, a mucus-mimetic platform was developed through a one-step approach based on encapsulating mucin within alginate gel beads. We found that mucins form micron sized aggregates distributed across the surface of the calcium-alginate bead, as shown by environmental scanning electron microscopy (ESEM). Retention of bioactive compounds on the mucin-functionalised surface was tested using a commercial orange drink formulation. To aid flavour retention, different mucoadhesive polymers with varying charge, including anionic, neutral and strongly cationic, were tested for their ability to interact with mucin and aid retaining flavour compounds within the mucin-alginate bead. The alginate-mucin mucus mimic was validated using an ex-vivo bovine tongue, with the flavour retention results showing qualitative agreement. The developed method proved to be a convenient, efficient tool for providing information on the effectiveness of mucoadhesive polymers without variability, safety and sustainability issues associated with an ex-vivo or in-vivo system. We propose that by encapsulating other relevant oral proteins, alongside mucins, current gaps between in-vitro and the ex-vivo systems may be narrowed.

Novel O/W nanoemulsions for nasal administration: Structural hints in the selection of performing vehicles with enhanced mucopenetration

We propose novel oil-in-water nanoemulsions (O/W NEs) including PEGylated surfactants and chitosan, showing good biocompatibility and optimization for nasal administration of drugs or vaccines. The transmucosal route has been shown to be ideal for a fast and efficient absorption and represents a viable alternative when the oral administration is problematic. The critical structural features in view of optimal encapsulation and transmucosal delivery were assessed by characterizing the NEs with complementary scattering techniques, i.e. dynamic light scattering (DLS), small angle X-ray (SAXS) and neutron scattering (SANS). Combined results allowed for selecting the formulations with the best suited structural properties and in addition establishing their propensity to enter the mucus barrier. To this scope, mucin was used as a model system and the effect of adding chitosan to the NEs, as adjuvant, was investigated. Remarkably, the presence of chitosan had a positive impact on the diffusion of the NE particles through the mucin matrix. We can infer that chitosan-mucin interaction induces density inhomogeneity and an increase in the pore size within the gel matrix that enhances the PEGylated NEs mobility. The coupling of mucoadhesive and mucopenetrating agents is shown to be a promising strategy for innovative transmucosal delivery systems.

Maleimide-functionalised PLGA-PEG nanoparticles as mucoadhesive carriers for intravesical drug delivery

Low permeability of the urinary bladder epithelium, poor retention of the chemotherapeutic agents due to dilution and periodic urine voiding as well as intermittent catheterisations are the major limitations of intravesical drug delivery used in the treatment of bladder cancer. In this work, maleimide-functionalised poly(lactide-co-glycolide)-block-poly(ethylene glycol) (PLGA-PEG-Mal) nanoparticles were developed. Their physicochemical characteristics, including morphology, architecture and molecular parameters have been investigated by means of dynamic light scattering, transmission electron microscopy and small-angle neutron scattering techniques. It was established that the size of nanoparticles was dependent on the solvent used in their preparation and molecular weight of PEG, for example, 105 ± 1 nm and 68 ± 1 nm particles were formed from PLGA_20K-PEG_5K in dimethyl sulfoxide and acetone, respectively. PLGA-PEG-Mal nanoparticles were explored as mucoadhesive formulations for drug delivery to the urinary bladder. The retention of fluorescein-loaded nanoparticles on freshly excised lamb bladder mucosa in vitro was evaluated and assessed using a flow-through fluorescence technique and Wash Out₅₀ (WO₅₀) quantitative method. PLGA-PEG-Mal nanoparticles (NPs) exhibited greater retention on urinary bladder mucosa (WO₅₀ = 15 mL) compared to maleimide-free NPs (WO₅₀ = 5 mL). The assessment of the biocompatibility of PEG-Mal using the slug mucosal irritation test revealed that these materials are non-irritant to mucosal surfaces.

Progress and Current Trends in the Synthesis of Novel Polymers with Enhanced Mucoadhesive Properties

Mucoadhesion is defined as the adherence of a synthetic or natural polymer to a mucosal membrane via physical or chemical interactions. Mucoadhesive materials are widely used to develop dosage forms for transmucosal drug delivery via ocular, nasal, esophageal, oral, vaginal, rectal, and intravesical routes of administration. This review will discuss some of the most prominent and recent synthetic methodologies employed to modify polymeric materials in order to enhance their mucoadhesive properties. This includes chemical conjugation of polymers with molecules bearing thiol-, catechol-, boronate-, acrylate-, methacrylate-, maleimide-, and N-hydroxy(sulfo)succinimide ester- groups.

Mucoadhesive electrospun nanofibers for drug delivery systems: applications of polymers and the parameters' roles

Electrospun nanofibers have been widely studied for many medical applications. They can be designed with specific features, including mucoadhesive properties. This review summarizes the polymeric scaffolds obtained by the electrospinning process that has been applied for drug release in different mucosal sites such as oral, ocular, gastroenteric, vaginal, and nasal. We analyzed the electrospinning parameters that have to be optimized to create reproducible and efficient mucoadhesive nanofibers, among them are: electrical field, polymer concentration, viscosity, flow rate, needle-collector distance, solution conductivity, solvent, environmental parameters, and electrospinning setup. We also revised the mucoadhesive theories as well as the mucoadhesive properties of the polymers used. This review shows that the most studied mucosal site is the oral cavity, because it is accessible and easy to evaluate, while the rest are uncomfortable for the patient and difficult to assess in vivo. We found problems that need to be solved for mucoadhesive electrospun nanofibers, such as improving adhesion strength and mucosal permanence time, and the design of unidirectional release, multilayer systems for the treatment of several pathologies, to ensure the drug concentration in the tissue or target organ.

An enzymatically controlled mucoadhesive system for enhancing flavour during food oral processing

While a good mucoadhesive biopolymer must adhere to a mucus membrane, it must also have a good unloading ability. Here, we demonstrate that the biopolymer pullulan is partially digested by human salivary α-amylase, thus acting as a controlled release system, in which the enzyme triggers an increased release of flavour. Our oral processing simulations have confirmed an increase in the bioavailability of aroma and salt compounds as a function of oral pullulan degradation, although the release kinetics suggest a rather slow process. One of the greatest challenges in flavour science is to retain and rapidly unload the bioactive aroma and taste compounds in the oral cavity before they are ingested. By developing a cationic pullulan analogue we have, in theory, addressed the "loss through ingestion" issue by facilitating the adhesion of the modified polymer to the oral mucus, to retain more of the flavour in the oral cavity. Dimethylaminoethyl pullulan (DMAE-pullulan) was synthesised for the first time, and shown to bind submaxillary mucin, while still retaining its susceptibility to α-amylase hydrolysis. Although DMAE-pullulan is not currently food grade, we suggest that the synthesis of a sustainable food grade alternative would be a next generation mucoadhesive targeted for the oral cavity.

Crossing biological barriers with nanogels to improve drug delivery performance

The current limitations in the use of nanocarriers to treat constantly evolving diseases call for the design of novel and smarter drug delivery systems (DDS). Nanogels (NGs) are three-dimensional crosslinked polymers with dimensions on the nanoscale and with a great potential for use in the biomedical field. Particular interest focuses on their application as DDS to minimize severe toxic effects and increase the therapeutic index of drugs. They have recently gained attention, since they can include responsive modalities within their structure, which enable them to excerpt a therapeutic function on demand. Their bigger sizes and controlled architecture and functionality, when compared to non-crosslinked polymers, make them particularly interesting to explore novel modalities to cross biological barriers. The present review summarizes the most significant developments of NGs as smart carriers, with focus on smart modalities to cross biological barriers such as cellular membrane, tumor stroma, mucose, skin, and blood brain barrier. We discuss the properties of each barrier and highlight the importance that the NG design has on their capability to overcome them and deliver the cargo at the site of action.

Interaction Between Chitosan and Mucin: Fundamentals and Applications

The term chitosan (CS) refers to a family of aminopolysaccharides derived from chitin. Among other properties, CS is nontoxic, mucoadhesive and can be used for load and transport drugs. Given these and other physicochemical and biological properties, CS is an optimal biopolymer for the development of transmucosal drug delivery systems, as well as for the treatment of pathologies related to mucosal dysfunctions. Mucins are glycoprotein macromolecules that are the major components of mucus overlaying epithelia. CS interacts with mucin and adsorbs on and changes the rheology of mucus. However, CS and mucins denote families of polymers/macromolecules with highly variable chemical structure, properties, and behavior. To date, their interactions at the molecular level have not been completely unraveled. Also, the properties of complexes composed of CS and mucin vary as a function of the sources and preparation of the polymers. As a consequence, the mucoadhesion and drug delivery properties of such complexes vary as well. The breadth of this review is on the molecular interactions between CS and mucin. In particular, in vitro and ex vivo characterization methods to investigate both the interactions at play during the formation of CS-mucin complexes, and the advances on the use of CS for transmucosal drug delivery are addressed.

Solid Lipid Nanoparticles Based on L-Cysteine for Progesterone Intravaginal Delivery

The present work has as its purpose the synthesis and characterization of a novel lipid material to be used in the preparation of solid lipid nanoparticles (SLNs) for the potential sustained release of progesterone in the vagina. For this reason, a material capable of ensuring the permanence of the formulation in the administration site for the time needed to guarantee the transmucosal absorption of the steroid was synthetized in order to reduce the number of administrations and to ensure an effective concentration of drug at the site of action. To this end, an ester, 2,3-dihydroxypropanoate of octadecyl (stearyl glycerine), containing two hydroxyl groups was initially synthesized. In particular, the hydroxyl group less sterically encumbered was functionalized with a thiol group, in a coupling reaction, with the amino acid L-cysteine. The obtained compound was characterized by FT-IR spectrometry and 1H-NMR. The functionalized lipid with L-cysteine was then used for the preparation of solid lipid nanoparticles that were loaded with progesterone. Finally, the release of progesterone from the lipid matrix based on newly synthesized ester, under conditions that simulate the vaginal physiological environment, was evaluated. All the obtained results suggest that the prepared nanoparticles could be used for the administration of progesterone, when its integration is essential, for example, in cases of threats of abortion or to increase fertility.

Preparation and Characterization of an Oral Vaccine Formulation Using Electrosprayed Chitosan Microparticles

Chitosan particles loaded with the antigen ovalbumin (OVA) and the adjuvant Quil-A were produced by electrospray, using mixtures of water/ethanol/acetic acid as a solvent. Three different chitosans designed as HMC⁺70, HMC⁺85, and HMC⁺90 (called as 705010, 855010, and 905010) were tested and its efficacy to be used in oral vaccine delivery applications was investigated. The morphology, size, and zeta potential of the produced particles were investigated, together with the encapsulation efficiency and release of OVA from the three chitosan formulations. Moreover, the mucoadhesion and cytotoxicity of the chitosan microparticles was examined. All the three formulations with OVA and Quil-A were in the micrometer size range and had a positive zeta potential between 46 and 75 mV. Furthermore, all the three formulations displayed encapsulation efficiencies above 80% and the release of OVA over a period of 80 h was observed to be between 38 and 47%. None of the developed formulations exhibited high mucoadhesive properties, either cytotoxicity. The formulation prepared with HMC⁺70, OVA, and Quil-A had the highest stability within 2 h in buffer solution, as measured by dynamic light scattering. The electrosprayed formulation consisting of HMC⁺70 with OVA and Quil-A showed to be the most promising as an oral vaccine system.