Advanced materials for drug delivery across mucosal barriers

Co-axial electrosprayed RAD001-loaded polycaprolactone/polyvinyl alcohol core-shell particles for treating pediatric brain tumours

Core-shell particles composed of polycaprolactone/polyvinyl alcohol (PCL/PVA) with pH sensitive properties were successfully fabricated by co-axial electrospraying in which PVA and PCL formed the shell and core layers respectively. The core-shell structure was confirmed by FTIR, DSC and SEM analysis. No chemical interaction between PVA and PCL core-shell were observed in the FTIR analysis. The RAD001 loaded core-shell particles showed a sustained and pH dependent drug release and was assayed via our previously developed HPLC method. After indirect treatment of the PF-A cells with the core-shell particles for 24 h and 5 days a decrease in cell viability was observed. Additionally, a comparison was made with our previously developed nanoparticles containing 2 %PVA-14 %SOL®-0.6 % RAD001, for the cell viability study on ependymoma. Our findings show that optimised core-shell particles exerted a significant effect for the 24 h and 5 day treatment however further studies are required to ensure toxicity of the control core-shell particles with no drug is reduced. In comparison, the 2 %PVA-14 %SOL®-0.6 %RAD001 uniaxial electrosprayed nanoparticles also exerted a toxicity effect decreasing cell viability with no toxicity observed for the control nanoparticles as well. Such pH-sensitive core-shell particles, which can degrade effectively in either acidic or neutral condition, have great potential for application in the biomedical field.

Injectable Hydrogel Mucosal Vaccine Elicits Protective Immunity against Respiratory Viruses

Intranasal vaccines, eliciting mucosal immune responses, can prevent early invasion, replication, and transmission of pathogens in the respiratory tract. However, the effective delivery of antigens through the nasal barrier and boosting of a robust systematic and mucosal immune remain challenges in intranasal vaccine development. Here, we describe an intranasally administered self-healing hydrogel vaccine with a reversible strain-dependent sol-gel transition by precisely modulating the self-assembly processes between the natural drug rhein and aluminum ions. The highly bioadhesive hydrogel vaccine enhances antigen stability and prolongs residence time in the nasal cavity and lungs by confining the antigen to the surface of the nasal mucosa, acting as a "mucosal mask". The hydrogel also stimulates superior immunoenhancing properties, including antigen internalization, cross-presentation, and dendritic cell maturation. Furthermore, the formulation recruits immunocytes to the nasal mucosa and nasal-associated lymphoid tissue (NALT) while enhancing antigen-specific humoral, cellular, and mucosal immune responses. Our findings present a promising strategy for preparing intranasal vaccines for infectious diseases or cancer.

Zeta potential changing self-nanoemulsifying drug delivery systems: A newfangled approach for enhancing oral bioavailability of poorly soluble drugs

The mucus is a defensive barrier for different drug-loaded systems. To overcome this obstacle, the crucial factor is the surface charge. Due to mucus negative charge behavior; it was revealed that negatively charged formulations can move across mucus, whereas positively charged nanoformulations could not diffuse via mucus due to interactions. However, cellular intake of negatively charged nanoformulations to the epithelium by endocytosis is less prominent as compared to positively charged carriers. Self-emulsifying drug delivery systems (SEDDS) improve the drug permeability of drugs, especially which have poor oral drug solubility. Moreover, SEDDS have the ability to reduce the degradation of drugs in the GI tract. Currently, drug carrier systems that can shift zeta potential from negative to positive were developed. The benefits of inducing zeta potential changing approach are that negatively charged nanoformulations permeate quickly across the mucus and surface charges reversed to positive at epithelium surface to increase cellular uptake. Among various systems of drug delivery, zeta potential changing SEDDS seem to signify a promising approach as they can promptly diffuse over mucus due to their smaller size and shape distortion ability. Due to such findings, mucus permeation and drug diffusion may improve by the mixture of the zeta potential changing approach and SEDDS.

Transmucosal Delivery of Peptides and Proteins Through Nanofibers: Current Status and Emerging Developments

Advancements in recombinant DNA technology have made proteins and peptides available for diagnostic and therapeutic applications, but their effectiveness when taken orally leads to poor patient compliance, requiring clinical administration. Among the alternative routes, transmucosal delivery has the advantage of being noninvasive and bypassing hepato-gastrointestinal clearance. Various mucosal routes-buccal, nasal, pulmonary, rectal, and vaginal-have been explored for delivering these macromolecules. Nanofibers, due to their unique properties like high surface-area-to-volume ratio, mechanical strength, and improved encapsulation efficiency, serve as promising carriers for proteins and peptides. These nanofibers can be tailored for quick dissolution, controlled release, enhanced encapsulation, targeted delivery, and improved bioavailability, offering superior pharmaceutical and pharmacokinetic performance compared to conventional methods. This leads to reduced dosages, fewer side effects, and enhanced patient compliance. Hence, nanofibers hold tremendous potential for protein/peptide delivery, especially through mucosal routes. This review focuses on the therapeutic application of proteins and peptides, challenges faced in their conventional delivery, techniques for fabricating different types of nanofibers and, various nanofiber-based dosage forms, and factors influencing nanofiber generation. Insights pertaining to the precise selection of materials used for fabricating nanofibers and regulatory aspects have been covered. Case studies wherein the use of specific protein/peptide-loaded nanofibers and delivered via oral/vaginal/nasal mucosa for diagnostic/therapeutic use and related preclinical and clinical studies conducted have been included in this review.

Synthesis of a Rivastigmine and Insulin Combinational Mucoadhesive Nanoparticle for Intranasal Delivery

Efficient drug delivery remains a critical challenge for treating neurodegenerative diseases, such as Alzheimer's disease (AD). Using innovative nanomaterials, delivering current medications like acetylcholinesterase inhibitors to the brain through the intranasal route is a promising strategy for managing AD. Here, we developed a unique combinational drug delivery system based on N,N,N-trimethyl chitosan nanoparticles (NPs). These NPs encapsulate rivastigmine, the most potent acetylcholinesterase inhibitor, along with insulin, a complementary therapeutic agent. The spherical NPs exhibited a zeta potential of 17.6 mV, a size of 187.00 nm, and a polydispersity index (PDI) of 0.29. Our findings demonstrate significantly improved drug transport efficiency through sheep nasal mucosa using the NPs compared to drug solutions. The NPs exhibited transport efficiencies of 73.3% for rivastigmine and 96.9% for insulin, surpassing the efficiencies of the drug solutions, which showed transport efficiencies of 52% for rivastigmine and 21% for insulin ex vivo. These results highlight the potential of a new drug delivery system as a promising approach for enhancing nasal transport efficiency. These combinational mucoadhesive NPs offer a novel strategy for the simultaneous cerebral delivery of rivastigmine and insulin, which could prove helpful in developing effective treatments of AD and other neurodegenerative conditions.

Future Nanotechnology-Based Strategies for Improved Management of Helicobacter pylori Infection

Helicobacter pylori (H. pylori) is a recalcitrant pathogen, which can cause gastric disorders. During the past decades, polypharmacy-based regimens, such as triple and quadruple therapies have been widely used against H. pylori. However, polyantibiotic therapies can disturb the host gastric/gut microbiota and lead to antibiotic resistance. Thus, simpler but more effective approaches should be developed. Here, some recent advances in nanostructured drug delivery systems to treat H. pylori infection are summarized. Also, for the first time, a drug release paradigm is proposed to prevent H. pylori antibiotic resistance along with an IVIVC model in order to connect the drug release profile with a reduction in bacterial colony counts. Then, local delivery systems including mucoadhesive, mucopenetrating, and cytoadhesive nanobiomaterials are discussed in the battle against H. pylori infection. Afterward, engineered delivery platforms including polymer-coated nanoemulsions and polymer-coated nanoliposomes are poposed. These bioinspired platforms can contain an antimicrobial agent enclosed within smart multifunctional nanoformulations. These bioplatforms can prevent the development of antibiotic resistance, as well as specifically killing H. pylori with no or only slight negative effects on the host gastrointestinal microbiota. Finally, the essential checkpoints that should be passed to confirm the potential effectiveness of anti-H. pylori nanosystems are discussed.

Curcumin nanocrystals-in-nanofibres as a promising platform for the management of periodontal disease

It is estimated that nearly a half of the world's population over 30 years old suffer from some kind of periodontal disease (PD). Although preventable, PD can pose a significant health burden to patients, causing from pain and discomfort to disfigurement and death. The management of PD often requires surgical procedures accompanied of systemic antibiotic and anti-inflammatory treatments. Curcumin (CUR), a potent anti-inflammatory and antimicrobial active, has shown great promise in the management of PD; however, its effects are often limited by its low bioavailability. In this work, we report the development of electrospun nanofibres (NFs) loaded with CUR nanocrystals (NCs) for the management of PD. NCs of 100 nm were obtained by media milling and loaded into dissolving polyvinyl alcohol NFs using electrospinning. The resultant NCs-in-NFs dissolved in water spontaneously, releasing NCs with a particle size of ∼120 nm. The physiochemical characterisation of the systems indicated the absence of chemical interactions between drug and polymer, and nanofibres with an amorphous nature. In vitro release profiles demonstrated that the NCs had a significantly higher dissolution rate (∼100 % at day 40) than the control group (approximately 6 % at day 40), which consisted of NFs containing a physical mixture of the drug and stabiliser. Finally, mucosal deposition studies demonstrated a 10-fold higher capacity of the novel NCs-in-NFs system to deposit CUR ex vivo using excised neonatal porcine mucosal tissue, when compared to the control group.

Organometallic Phyllosilicate-Gold Nanocomplex: An Effective Oral Delivery System of Methotrexate for Enhanced in vivo Efficacy Against Colorectal Cancer

Purpose

Oral administration, although convenient and preferred for treating colorectal cancer (CRC), faces challenges due to limited CRC-related intestinal positioning and a dense mucus barrier. In the present study, a gold-nanoparticle decorated-organometallic phyllosilicate nanocomposite (AC-Au), with a pH-dependent surface coating, was employed for more effective oral delivery of anticancer drugs to treat CRC.

Methods

The organometallic AC-Au was synthesized using the in-situ sol-gel method. Subsequently, methotrexate (MTX) was loaded into AC-Au, and the complex (AC-Au/MTX) was surface-coated with poly (methacrylic acid-co-methyl methacrylate) (1:2), a pH-dependent polymer (E/AC-Au /MTX). The in vitro characteristics of nanoparticles were examined using various analytical methods. In vivo efficacy studies were also conducted using an HCT-116 orthotopic colorectal cancer model.

Results

AC-Au emerged as a spherical nanoparticle with a mean size of 26.5 ± 0.43 nm, displaying a positive charge over the pH range of 2-10. Both the uncoated and coated drug-loaded nanocomplexes (AC-Au/MTX and E/AC-Au/MTX) were fabricated with high entrapment efficiency (> 80%). Various analyses, including ultraviolet-visible spectroscopy, X-ray powder diffraction, transmission electron microscopy, and energy dispersive X-ray spectroscopy, confirmed the formation of the nanocomplexes. While AC-Au/MTX achieved rapid and extensive drug release at the pH range of 1.2-7.4, E/AC-Au/MTX exhibited pH-dependent drug release, with approximately 23% at pH 1.2 and 74% at pH 7.4. Relative to free MTX, the AC-Au-based nanocomplex significantly enhanced the cytotoxicity of MTX in HCT-116 cells. Furthermore, orally administered E/AC-Au/MTX significantly improved the anti-tumor activity of MTX in an HCT-116 orthotopic colorectal cancer model, resulting in approximately 60% suppression of tumor mass compared with the positive control.

Conclusion

The organometallic AC-Au nanocomplex coated with a pH-dependent polymer has the potential to be an effective colonic drug delivery system of MTX, enhancing in vivo efficacy against colorectal cancer.

Recent Advancements in the Development of Nanocarriers for Mucosal Drug Delivery Systems to Control Oral Absorption

Oral administration of active pharmaceutical ingredients is desirable because it is easy, safe, painless, and can be performed by patients, resulting in good medication adherence. The mucus layer in the gastrointestinal (GI) tract generally acts as a barrier to protect the epithelial membrane from foreign substances; however, in the absorption process after oral administration, it can also disturb effective drug absorption by trapping it in the biological sieve structured by mucin, a major component of mucus, and eliminating it by mucus turnover. Recently, functional nanocarriers (NCs) have attracted much attention due to their immense potential and effectiveness in the field of oral drug delivery. Among them, NCs with mucopenetrating and mucoadhesive properties are promising dosage options for controlling drug absorption from the GI tracts. Mucopenetrating and mucoadhesive NCs can rapidly deliver encapsulated drugs to the absorption site and/or prolong the residence time of NCs close to the absorption membrane, providing better medications than conventional approaches. The surface characteristics of NCs are important factors that determine their functionality, owing to the formation of various kinds of interactions between the particle surface and mucosal components. Thus, a deeper understanding of surface modifications on the biopharmaceutical characteristics of NCs is necessary to develop the appropriate mucosal drug delivery systems (mDDS) for the treatment of target diseases. This review summarizes the basic information and functions of the mucosal layer, highlights the recent progress in designing functional NCs for mDDS, and discusses their performance in the GI tract.

The Potential of Films as Transmucosal Drug Delivery Systems

Pharmaceutical films are polymeric formulations used as a delivery platform for administration of small and macromolecular drugs for local or systemic action. They can be produced by using synthetic, semi-synthetic, or natural polymers through solvent casting, electrospinning, hot-melt extrusion, and 3D printing methods, and depending on the components and the manufacturing methods used, the films allow the modulation of drug release. Moreover, they have advantages that have drawn interest in the development and evaluation of film application on the buccal, nasal, vaginal, and ocular mucosa. This review aims to provide an overview of and critically discuss the use of films as transmucosal drug delivery systems. For this, aspects such as the composition of these formulations, the theories of mucoadhesion, and the methods of production were deeply considered, and an analysis of the main transmucosal pathways for which there are examples of developed films was conducted. All of this allowed us to point out the most relevant characteristics and opportunities that deserve to be taken into account in the use of films as transmucosal drug delivery systems.

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.

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

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

Preliminary Assessment of Polysaccharide-Based Emulgels Containing Delta-Aminolevulinic Acid for Oral Lichen planus Treatment

Photodynamic therapy using delta-aminolevulinic acid is considered a promising option in the treatment of oral lichen planus. In the present work, three emulgel compositions prepared from natural polysaccharide gums, tragacanth, xanthan and gellan, were preliminarily tested for oromucosal delivery of delta-aminolevulinic acid. Apart from cytotoxicity studies in two gingival cell lines, the precise goal was to investigate whether the presence of the drug altered the rheological and mucoadhesive behavior of applied gelling agents and to examine how dilution with saliva fluid influenced the retention of the designed emulgels by oromucosal tissue. Ex vivo mucoadhesive studies revealed that a combination of xanthan and gellan gum enhanced carrier retention by buccal tissue even upon dilution with the saliva. In turn, the incorporation of delta-aminolevulinic acid favored interactions with mucosal tissue, particularly formulations comprised of tragacanth. The designed preparations had no significant impact on the cell viability after a 24 h incubation in the tested concentration range. Cytotoxicity studies demonstrated that tragacanth-based and gellan/xanthan-based emulgels might exert a protective effect on the metabolic activity of human gingival fibroblasts and keratinocytes. Overall, the presented data show the potential of designed emulgels as oromucosal platforms for delta-aminolevulinic acid delivery.

Polysaccharide-Based Nanogels to Overcome Mucus, Skin, Cornea, and Blood-Brain Barriers: A Review

Nanocarriers have been extensively developed in the biomedical field to enhance the treatment of various diseases. However, to effectively deliver therapeutic agents to desired target tissues and enhance their pharmacological activity, these nanocarriers must overcome biological barriers, such as mucus gel, skin, cornea, and blood-brain barriers. Polysaccharides possess qualities such as excellent biocompatibility, biodegradability, unique biological properties, and good accessibility, making them ideal materials for constructing drug delivery carriers. Nanogels, as a novel drug delivery platform, consist of three-dimensional polymer networks at the nanoscale, offering a promising strategy for encapsulating different pharmaceutical agents, prolonging retention time, and enhancing penetration. These attractive properties offer great potential for the utilization of polysaccharide-based nanogels as drug delivery systems to overcome biological barriers. Hence, this review discusses the properties of various barriers and the associated constraints, followed by summarizing the most recent development of polysaccharide-based nanogels in drug delivery to overcome biological barriers. It is expected to provide inspiration and motivation for better design and development of polysaccharide-based drug delivery systems to enhance bioavailability and efficacy while minimizing side effects.

Gliadin nanoparticles for oral administration of bioactives: Ex vivo and in vivo investigations

This study aims to provide a thorough characterization of Brij O2-stabilized gliadin nanoparticles to be used for the potential oral administration of various compounds. Different techniques were used in order to evaluate their physico-chemical features and then in vivo studies in rats were performed for the investigation of their biodistribution and gastrointestinal transit profiles. The results showed that the gliadin nanoparticles accumulated in the mucus layer of the bowel mucosa and evidenced their ability to move along the digestive systems of the animals. The incubation of the nanosystems with Caenorhabditis elegans, used as an additional in vivo model, confirmed the intake of the particles and evidenced their presence along the entire gastrointestinal tract of these nematodes. The gliadin nanoparticles influenced neither the egg-laying activity of the worms nor their metabolism of lipids up to 10 μg/mL of nanoformulation. The systems decreased the content of the age-related lipofuscin pigment in the nematodes in a dose-dependent manner, demonstrating a certain antioxidant activity. Lastly, dihydroethidium staining showed the absence of oxidative stress upon incubation of the worms together with the formulations, confirming their safe profile. This data paves the way for the future application of the proposed nanosystems regarding the oral delivery of various bioactives.

Zwitterionic Inhaler with Synergistic Therapeutics for Reprogramming of M2 Macrophage to Pro-Inflammatory Phenotype

Myriad lung diseases are life threatening and macrophages play a key role in both physiological and pathological processes. Macrophages have each pro-/anti-inflammatory phenotype, and each lung disease can be aggravated by over-polarized macrophage. Therefore, development of a method capable of mediating the macrophage phenotype is one of the solutions for lung disease treatment. For mediating the phenotype of macrophages, the pulmonary delivery system (PDS) is widely used due to its advantages, such as high efficiency and accessibility of the lungs. However, it has a low drug delivery efficiency ironically because of the perfect lung defense system consisting of the mucus layer and airway macrophages. In this study, zwitterion-functionalized poly(lactide-co-glycolide) (PLGA) inhalable microparticles (ZwPG) are synthesized to increase the efficiency of the PDS. The thin layer of zwitterions formed on PLGA surface has high nebulizing stability and show high anti-mucus adhesion and evasion of macrophages. As a reprogramming agent for macrophages, ZwPG containing dexamethasone (Dex) and pirfenidone (Pir) are treated to over-polarized M2 macrophages. As a result, a synergistic effect of Dex/Pir induces reprogramming of M2 macrophage to pro-inflammatory phenotypes.

Comparison of virus-capsid mimicking biologic-shell based versus polymeric-shell nanoparticles for enhanced oral insulin delivery

Virus-capsid mimicking mucus-permeable nanoparticles are promising oral insulin carriers which surmount intestinal mucus barrier. However, the impact of different virus-capsid mimicking structure remains unexplored. In this study, utilizing biotin grafted chitosan as the main skeleton, virus-mimicking nanoparticles endowed with biologic-shell (streptavidin coverage) and polymeric-shell (hyaluronic acid/alginate coating) were designed with insulin as a model drug by self-assembly processes. It was demonstrated that biologic-shell mimicking nanoparticles exhibited a higher intestinal trans-mucus (>80%, 10 min) and transmucosal penetration efficiency (1.6-2.2-fold improvement) than polymeric-shell counterparts. Uptake mechanism studies revealed caveolae-mediated endocytosis was responsible for the absorption of biologic-shell mimicking nanoparticles whereas polymeric-shell mimicking nanoparticles were characterized by clathrin-mediated pathway with anticipated lysosomal insulin digestion. Further, in vivo hypoglycemic study indicated that the improved effect of regulating blood sugar levels was virus-capsid structure dependent out of which biologic-shell mimicking nanoparticles presented the best performance (5.1%). Although the findings of this study are encouraging, much more work is required to meet the standards of clinical translation. Taken together, we highlight the external structural dependence of virus-capsid mimicking nanoparticles on the muco-penetrating and uptake mechanism of enterocytes that in turn affecting their in vivo absorption, which should be pondered when engineering virus-mimicking nanoparticles for oral insulin delivery.

Native gastrointestinal mucus: Critical features and techniques for studying interactions with drugs, drug carriers, and bacteria

Gastrointestinal mucus plays essential roles in modulating interactions between intestinal lumen contents, including orally delivered drug carriers and the gut microbiome, and underlying epithelial and immune tissues and cells. This review is focused on the properties of and methods for studying native gastrointestinal mucus and its interactions with intestinal lumen contents, including drug delivery systems, drugs, and bacteria. The properties of gastrointestinal mucus important to consider in its analysis are first presented, followed by a discussion of different experimental setups used to study gastrointestinal mucus. Applications of native intestinal mucus are then described, including experimental methods used to study mucus as a barrier to drug delivery and interactions with intestinal lumen contents that impact barrier properties. Given the significance of the microbiota in health and disease, its impact on drug delivery and drug metabolism, and the use of probiotics and microbe-based delivery systems, analysis of interactions of bacteria with native intestinal mucus is then reviewed. Specifically, bacteria adhesion to, motility within, and degradation of mucus is discussed. Literature noted is focused largely on applications of native intestinal mucus models as opposed to isolated mucins or reconstituted mucin gels.

Enhance the oral insulin delivery route using a modified chitosan-based formulation fabricated by microwave

Chitosan (Cs) was subjected to ball milling and subsequently functionalized with Dinitro salicylic acid (Cs-DNS) to enhance the efficacy of oral insulin delivery. The hydrodynamic spherical particle sizes exhibited 33.29 ± 5.08 nm for modified Cs-DNS NPs. Irrespective of insulin entrapment, zeta potential measurements revealed positively charged Cs-DNS NPs (+ 35 ± 3.5 mV). The entrapment performance (EP%) was evaluated in vitro, and insulin release patterns at various pH levels. The EP% for Cs-DNS NPs was 99.3 ± 1.6. Cs- DNS NPs retained a considerable amount of insulin (92 %) in an acidic medium, and significant quantities were released at increasing pH values over time. In vivo investigations, the diabetic rats which taken insulin-incorporated NPs had lower serum glucose levels (SGL) after 3 h to (39.4 ± 0.6 %) for Cs- DNS NPs. For insulin-incorporated Cs- DNS NPs, the bioavailability (BA%) and pharmacological availability (PA%) were 17.5 ± 0.31 % and 8.6 ± 0.8 %, respectively. The assertion above highlights the significance and effectiveness of modified chitosan in promoting insulin delivery, decreasing SGL levels, and guaranteeing safety.

pH-Mediated Mucus Penetration of Zwitterionic Polydopamine-Modified Silica Nanoparticles

Zwitterionic polymers have emerged as promising trans-mucus nanocarriers due to their superior antifouling properties. However, for pH-sensitive zwitterionic polymers, the effect of the pH microenvironment on their trans-mucus fate remains unclear. In this work, we prepared a library of zwitterionic polydopamine-modified silica nanoparticles (SiNPs-PDA) with an isoelectric point of 5.6. Multiple-particle tracking showed that diffusion of SiNPs-PDA in mucus with a pH value of 5.6 was 3 times faster than that in mucus with pH value 3.0 or 7.0. Biophysical analysis found that the trans-mucus behavior of SiNPs-PDA was mediated by hydrophobic and electrostatic interactions and hydrogen bonding between mucin and the particles. Furthermore, the particle distribution in the stomach, intestine, and lung demonstrated the pH-mediated mucus penetration behavior of the SiNPs-PDA. This study reveals the pH-mediated mucus penetration behavior of zwitterionic nanomaterials, which provides rational design strategies for zwitterionic polymers as nanocarriers in various mucus microenvironments.

Current Role and Potential of Polymeric Biomaterials in Clinical Obesity Treatment

The rise of obesity and associated fatal diseases has taken a massive toll worldwide. Despite the existing pharmaceuticals and bariatric surgeries, these approaches manifest limited efficacy or accompany various side effects. Therefore, researchers seek to facilitate the prolonged and specific delivery of therapeutics. Or else, to mimic the essential part of "gastric bypass" by physically blocking excessive absorption via less invasive methods. To achieve these goals, polymeric biomaterials have gained tremendous interest recently. They are known for synthesizing hydrogels, microneedle patches, mucoadhesive coatings, polymer conjugates, and so forth. In this Review, we provide insights into the current studies of polymeric biomaterials in the prevention and treatment of obesity, inspiring future improvements in this regime of study.

Progress and prospects of polysaccharide-based nanocarriers for oral delivery of proteins/peptides

The oral route has long been recognized as the most preferred route for drug delivery as it offers high patient compliance and requires minimal expertise. Unlike small molecule drugs, the harsh environment of the gastrointestinal tract and low permeability across the intestinal epithelium make oral delivery extremely ineffective for macromolecules. Accordingly, delivery systems that are rationally constructed with suitable materials to overcome barriers to oral delivery are exceptionally promising. Among the most ideal materials are polysaccharides. Depending on the interaction between polysaccharides and proteins, the thermodynamic loading and release of proteins in the aqueous phase can be realized. Specific polysaccharides (dextran, chitosan, alginate, cellulose, etc.) endow systems with functional properties, including muco-adhesiveness, pH-responsiveness, and prevention of enzymatic degradation. Furthermore, multiple groups in polysaccharides can be modified, which gives them a variety of properties and enables them to suit specific needs. This review provides an overview of different types of polysaccharide-based nanocarriers based on different kinds of interaction forces and the influencing factors in the construction of polysaccharide-based nanocarriers. Strategies of polysaccharide-based nanocarriers to improve the bioavailability of orally administered proteins/peptides were described. Additionally, current restrictions and future trends of polysaccharide-based nanocarriers for oral delivery of proteins/peptides were also covered.

FOF1-ATPase Motor-Embedded Chromatophore as Drug Delivery System: Extraction, Cargo Loading Ability and Mucus Penetration Ability

Mucosal drug delivery permits direct and prompt drug absorption, which is capable of reducing undesirable decomposition that occurs before absorption. However, mucus clearance of those mucosal drug delivery systems strongly retards their actual application. Herein, we propose chromatophore nanoparticles embedded with FOF1-ATPase motors to promote mucus penetration. The FOF1-ATPase motor-embedded chromatophores were firstly extracted from Thermus thermophilus by using a gradient centrifugation method. Then, the model drug (curcumin) was loaded onto the chromatophores. The drug loading efficiency and entrapment efficiency were optimized by using different loading approaches. The activity, motility, stability and mucus permeation of the drug-loaded chromatophore nanoparticles were thoroughly investigated. Both the in vitro and in vivo studies revealed that the FOF1-ATPase motor-embedded chromatophore successfully enhanced mucus penetration glioma therapy. This study indicates that the FOF1-ATPase motor-embedded chromatophore is a promising alternative as a mucosal drug delivery system.

Intranasal in situ gelling liquid crystal for delivery of resveratrol ameliorates memory and neuroinflammation in Alzheimer's disease

Alzheimer's disease (AD) is an illness that affects people aged 65 or older and affects around 6.5 million in the United States. Resveratrol is a chemical obtained from natural products and it exhibits biological activity based on inhibiting the formation, depolymerization of the amyloid, and decreasing neuroinflammation. Due to the insolubility of this compound; its incorporation in surfactant-based systems was proposed to design an intranasal formulation. A range of systems has been produced by mixing oleic acid, CETETH-20 and water. Polarised light microscopy (PLM), small angle x-ray scattering (SAXS) and transmission electron microscopy (TEM) confirm the initial liquid formulation (F) presented as microemulsion (ME). After dilution, the gelled systems were characterized as hexagonal mesophase and they showed feasibility proprieties. Pharmacological assays performed after intranasal administration showed the ability to improve learning and memory in animals, as well as remission of neuroinflammation via inhibition of interleukin.

β-Glucan and Fatty Acid Based Mucoadhesive Carrier for Gastrointestinal Tract Specific Local and Sustained Drug Delivery

The oral route is considered the most convenient route of drug administration for both systemic and local delivery. Besides stability and transportation, another unmet but important issue regarding oral medication is retention duration within the specific region of the gastrointestinal (GI) tract. We hypothesize that an oral vehicle that can adhere and maintain retention within the stomach for a longer duration can be more effective to treat stomach-related diseases. Therefore, in this project, we developed a carrier that is highly specific to the stomach and maintains its retention for a longer duration. We developed a vehicle composed of β-Glucan And Docosahexaenoic Acid (GADA) to observe its affinity and specificity to the stomach. GADA forms a spherical-shaped particle with negative zeta potential values that vary based on the feed ratio of docosahexaenoic acid. Docosahexaenoic acid is an omega-3 fatty acid that has transporters and receptors throughout the GI tract, such as CD36, plasma membrane-associated fatty acid-binding protein (FABP (pm)), and a family of fatty acid transport proteins (FATP1-6). The in vitro studies and characterization data showed that GADA has the capability to carry a payload of hydrophobic molecules and specifically deliver the payload to the GI tract, exert its therapeutic effects, and help to maintain stability for more than 12 h in the gastric and intestinal fluid. The particle size and surface plasmon resonance (SPR) data showed that GADA has a strong binding affinity with mucin in the presence of simulated gastric fluids. We observed a comparatively higher drug release of lidocaine in gastric juice than that in intestinal fluids, demonstrating the influence of the pH values of the media on drug-release kinetics. In vivo and ex vivo imaging of mice demonstrated that GADA maintains its retention within the stomach for at least 4 hr. This stomach-specific oral vehicle holds strong promise to translate various injectable therapeutic drugs to oral form upon further optimizations.

Hot Melt Extrusion as an Effective Process in the Development of Mucoadhesive Tablets Containing Scutellariae baicalensis radix Extract and Chitosan Dedicated to the Treatment of Oral Infections

Hot Melt Extrusion (HME) technology was developed to obtain blends containing lyophilized Scutellariae baicalensis root extract and chitosan in order to improve the rheological properties of the obtained blends, including tableting and compressibility properties. (Hydroxypropyl)methyl cellulose (HPMC) in 3 different ratios was used as amorphous matrix formers. The systems were characterized using X-ray powder diffraction (PXRD), Fourier Transform Infrared Spectroscopy with Attenuated Total Reflectance (FTIR-ATR), and in vitro release, permeability, and microbiological activity studies. Then, the extrudates were used to prepare tablets in order to give them the appropriate pharmaceutical form. HPMC-based systems released baicalin more slowly, resulting in delayed peaks in the acceptor fluid. This behavior can be explained by the fact that HPMC swells significantly, and the dissolved substance must have diffused through the polymer network before being released. The best tabletability properties are provided by the formulation containing the extrudate with lyophilized extract HPMC 50:50 w/w. These tablets offer a valuable baicalin release profile while maintaining good mucoadhesive properties that condition the tablet’s retention in the application site and the effectiveness of therapy.

Expanding opportunities to engineer mucosal vaccination with biomaterials

Mucosal vaccines are receiving increasing interest both for protecting against infectious diseases and for inducing therapeutic immune responses to treat non-infectious diseases. However, the mucosal barriers of the lungs, gastrointestinal tract, genitourinary tract, nasal, and oral tissues each present unique challenges for constructing efficacious vaccines. Vaccination through each of these mucosae requires transport through the mucus and across specialized epithelia to reach tissue-specific immune cells and lymphoid structures, necessitating finely tuned and multifunctional strategies. Serving as inspiration for mucosal vaccine design, pathogens have evolved elaborate, diverse, and multipronged approaches to penetrate and infect mucosae. This review is focused on biomaterials-based strategies, many inspired by pathogens, for designing mucosal vaccine platforms. Passive and active technologies are discussed, along with the microbial processes that they seek to mimic.

Exploring Possible Ways to Enhance the Potential and Use of Natural Products through Nanotechnology in the Battle against Biofilms of Foodborne Bacterial Pathogens

Biofilms enable pathogenic bacteria to survive in unfavorable environments. As biofilm-forming pathogens can cause rapid food spoilage and recurrent infections in humans, especially their presence in the food industry is problematic. Using chemical disinfectants in the food industry to prevent biofilm formation raises serious health concerns. Further, the ability of biofilm-forming bacterial pathogens to tolerate disinfection procedures questions the traditional treatment methods. Thus, there is a dire need for alternative treatment options targeting bacterial pathogens, especially biofilms. As clean-label products without carcinogenic and hazardous potential, natural compounds with growth and biofilm-inhibiting and biofilm-eradicating potentials have gained popularity as natural preservatives in the food industry. However, the use of these natural preservatives in the food industry is restricted by their poor availability, stability during food processing and storage. Also there is a lack of standardization, and unattractive organoleptic qualities. Nanotechnology is one way to get around these limitations and as well as the use of underutilized bioactives. The use of nanotechnology has several advantages including traversing the biofilm matrix, targeted drug delivery, controlled release, and enhanced bioavailability, bioactivity, and stability. The nanoparticles used in fabricating or encapsulating natural products are considered as an appealing antibiofilm strategy since the nanoparticles enhance the activity of the natural products against biofilms of foodborne bacterial pathogens. Hence, this literature review is intended to provide a comprehensive analysis of the current methods in nanotechnology used for natural products delivery (biofabrication, encapsulation, and nanoemulsion) and also discuss the different promising strategies employed in the recent and past to enhance the inhibition and eradication of foodborne bacterial biofilms.

Engineered organic nanoparticles to combat biofilms

Biofilms are colonies of microorganisms that are embedded in autocrine extracellular polymeric substances (EPS), imparting antibiotic resistance and recalcitrant bacterial infection. Nanoparticles (NPs) can enhance the biofilm inhibition and eradication of delivered antibiotics. This is mainly because of enhanced EPS penetration and a high local drug concentration. As we discuss here, novel strategies are being developed to further enhance the antibiofilm capacity of NPs, including size optimization, surface modification, stimuli-triggered release, and combined strategies. Thus, NPs represent an effective and promising approach to combat biofilms.

Chitosan-maleic acid conjugate as potential excipient candidate for oral drug delivery?

Aim: To develop and evaluate chitosan-maleic acid conjugate. Methods: Maleic anhydride was attached to chitosan backbone via amide bond formation resulting in chitosan-maleic acid. After characterization of the product via ¹H nuclear magnetic resonance, attenuated total reflectance-Fourier transform IR spectroscopy and 2,4,6-trinitrobenzenesulfonic acid assay, examination of mucoadhesion assessment was carried out. Results: The conjugate presented 44.91% modification and no toxicity could be observed after 1 day of incubation. Mucoadhesive properties exhibited 40.97-fold, 13.31-fold and 9.07-fold increase in elastic modulus, dynamic viscosity and viscous modulus, respectively. Moreover, detachment time was increased in 44.44-fold. Conclusion: Chitosan-maleic acid demonstrated enhanced in mucoadhesive properties resulting in biocompatibility. Therefore, potent candidates as polymeric excipients for oral drug delivery could be developed over corresponding chitosan.

Mucus-penetrating dendritic mesoporous silica nanoparticle loading drug nanocrystal clusters to enhance permeation and intestinal absorption

Multiple gastrointestinal barriers (mucus clearance and epithelium barrier) are the main challenges in the oral administration of nanocarriers. To achieve efficient mucus penetration and epithelial absorption, a novel strategy based on mesoporous silica nanoparticles with dendritic superstructure, hydrophilicity, and nearly neutral-charged modification was designed. The mPEG covalently grafted dendritic mesoporous silica nanoparticles (mPEG-DMSNs) had a particle size of about 200 nm and a loading capacity of up to 50% andrographolide (AG) as a nanocrystal cluster in the mesoporous structure. This dual strategy of combining with the surface topography structure and hydrophilic modification maintained a high mucus permeability and showed an increase in cell absorption. The mPEG-DMSN formulation also exhibited effective transepithelial transport and intestinal tract distribution. The pharmacokinetics study demonstrated that compared with other AG formulations, the andrographolide nanocrystals-loaded mPEG-DMSN (AG@mPEG-DMSN) exhibited much higher bioavailability. Also, AG@mPEG-DMSN could significantly improve the in vitro and in vivo anti-inflammatory efficacy of AG. In summary, mPEG-DMSN offers an interesting strategy to overcome the mucus clearance and epithelium barriers of the gastrointestinal tract.

Hydrocaffeic acid-chitosan coating of gastric patch provides long-acting mucoadhesive delivery of model chemotherapeutic agent

The development of a long-acting orally administered dosage form is a challenge. Here, we report development of a multi-layered mucoadhesive gastric patch that could deliver entrapped chemotherapeutic agent for eight days after oral administration. The multi-layered patch was designed to contain core layer, mucoadhesive layer and backing layer. The core layer contained the model chemotherapeutic agent, regorafenib. The mucoadhesive layer made of chitosan-hydrocaffeic acid conjugate showed greatest mucoadhesion strength of 18.1 ± 0.78 kPa in freshly excised rat gastric mucosa. The backing layer made of hydrophobic polycaprolactone-polydimethylsiloxane composite showed the contact angle of 120 ± 4.7° after placement of water drop. The entrapped regorafenib predominantly released from the mucoadhesive-side of the patch into simulated gastric fluid and showed a zero-order release profile. The patches were found to be stable for desired characteristics for up to 3 months in long term storage conditions. The pharmacokinetic studies in rat model revealed constant plasma concentration of regorafenib sustained for 8 days after oral administration of gastric patch. The gastric tissue where the patch adhered for 8 days did not show any significant histological changes compared with the normal gastric tissue. The oral administration of single dose of regorafenib-loaded gastric patch in FaDu cell xenografted tumor bearing athymic nude mice has shown significant (P < 0.05) reduction in the tumor volume over 7 days compared to the control group. Taken together, the multi-layered mucoadhesive gastric patch can be developed as a long-acting oral drug delivery system.

NIR-II-triggered doxorubicin release for orthotopic bladder cancer chemo-photothermal therapy

Intravesical instillation has been widely utilized for bladder cancer treatment in clinic. However, due to the bladder mucosal barrier, its poor penetration efficiency and drug utilization limit the clinical therapeutic effectiveness and result in a high recurrence rate. Therefore, designing an efficient and controllable drug delivery nanoplatform is of great significance for bladder cancer treatment. Non-invasive therapy based on near-infrared-II (NIR-II) photothermal therapy (PTT) conduces to overcome bladder mucosal barrier and enhance drug delivery. Also, the photothermal nanomaterials, Au Hollow Nanorods (AuHNRs), demonstrate strong photothermal properties and drug loading capacity. Herein, a quaternized chitosan N-(2-hydroxyl)propyl-3-trimethyl ammonium chitosan chloride (HTCC)-modified nanocarrier Dox/NH₄HCO₃@AuHNRs-HTCC (DNAH) was designed for controlled drug release and enhanced penetration. The drug loading capacity of DNAH reached 117.20%. Also, the thermal decomposition of NH₄HCO₃ realized NIR-II-triggered gas-driven drug burst release, and the doxorubicin release was 2.79 times higher within 1 h after NIR-II irradiation. Also, the HTCC-modified nanocarriers significantly enhanced the bladder mucosal permeability as well as long-term drug retention, and the penetration efficiency of DNAH increased by 144%. In the orthotopic bladder cancer model, the tumor suppression rate and mouse survival time were significantly improved. DNAH showed potent inhibition of the orthotopic bladder tumor growth owing to the enhanced penetration and drug delivery. This work presents a potential drug delivery nanocarrier, which is promising for optimized bladder mucosal permeability and controlled drug burst release.

Magnetically Driven Muco-Inert Janus Nanovehicles for Enhanced Mucus Penetration and Cellular Uptake

One of the main challenges of transmucosal drug delivery is that of enabling particles and molecules to move across the mucosal barrier of the mucosal epithelial surface. Inspired by nanovehicles and mucus-penetrating nanoparticles, a magnetically driven, mucus-inert Janus-type nanovehicle (Janus-MMSN-pCB) was fabricated by coating the zwitterionic polymer poly(carboxybetaine methacrylate) (pCB) on the mesoporous silica nanorod, which was grown on one side of superparamagnetic Fe3O4 nanoparticle using the sol–gel method. X-ray diffraction, transmission electron microscopy, vibrating sample magnetometry, and Fourier infrared spectroscopy were used to characterize the structure and morphology of the nanovehicles, proving the success of each synthesis step. The in vitro cell viability assessment of these composites using Calu-3 cell lines indicates that the nanovehicles are biocompatible in nature. Furthermore, the multiparticle tracking, Transwell® system, and cell imaging experimental results demonstrate that both the modification of pCB and the application of a magnetic field effectively accelerated the diffusion of the nanovehicles in the mucus and improved the endocytosis through Calu-3. The favorable cell uptake performance of Janus-MMSN-pCB in mucus systems with/without magnetic driving proves its potential role in the diagnosis, treatment, and imaging of mucosal-related diseases.

Three-dimensional bioprinting of mucoadhesive scaffolds for the treatment of oral mucosal lesions; an in vitro study

Background

Chronic oral lesions could be a part of some diseases, including mucocutaneous diseases, immunobullous diseases, gastrointestinal diseases, and graft versus host diseases. Systemic steroids are an effective treatment, but they cause unfavorable and even severe systemic side effects. Discontinuation of systemic corticosteroids or other immunosuppressive drugs leads to relapse, confirming the importance of long-term corticosteroid use. The present study aims to fabricate a mucoadhesive scaffold using three-dimensional (3D) bioprinting for sustained drug delivery in oral mucosal lesions to address the clinical need for alternative treatment, especially for those who do not respond to routine therapy.

Methods

3D bioprinting method was used for the fabrication of the scaffolds. Scaffolds were fabricated in three layers; adhesive/drug-containing, backing, and middle layers. For evaluation of the release profile of the drug, artificial saliva was used as the release medium. Mucoadhesive scaffolds were analyzed using a scanning electron microscope (SEM) and SEM surface reconstruction. The pH of mucoadhesive scaffolds and swelling efficacy were measured using a pH meter and Enslin dipositive, respectively. A microprocessor force gauge was used for the measurement of tensile strength. For the evaluation of the cytotoxicity, oral keratinocyte cells' survival rate was evaluated by the MTT method. Folding endurance tests were performed using a stable microsystem texture analyzer and analytic probe mini tensile grips.

Results

All scaffolds had the same drug release trend; An initial rapid explosive release during the first 12 h, followed by a gradual release. The scaffolds showed sustained drug release and continued until the fourth day. The pH of the surface of the scaffolds was 5.3–6.3, and the rate of swelling after 5 h was 28 ± 3.2%. The tensile strength of the scaffolds containing the drug was 7.8 ± 0.12 MPa. The scaffolds were non-irritant to the mucosa, and the folding endurance of the scaffolds was over three hundred times.

Conclusion

The scaffold fabricated using the 3D bioprinting method could be suitable for treating oral mucosal lesions.

Polysaccharide-based nanocomposites for biomedical applications: a critical review

Polysaccharides (PSA) have taken specific position among biomaterials for advanced applications in medicine. Nevertheless, poor mechanical properties are known as the main drawback of PSA, which highlights the need for PSA modification. Nanocomposites PSA (NPSA) are a class of biomaterials widely used as biomedical platforms, but despite their importance and worldwide use, they have not been reviewed. Herein, we critically reviewed the application of NPSA by categorizing them into generic and advanced application realms. First, the application of NPSA as drug and gene delivery systems, along with their role in the field as an antibacterial platform and hemostasis agent is discussed. Then, applications of NPSA for skin, bone, nerve, and cartilage tissue engineering are highlighted, followed by cell encapsulation and more critically cancer diagnosis and treatment potentials. In particular, three features of investigations are devoted to cancer therapy, i.e., radiotherapy, immunotherapy, and photothermal therapy, are comprehensively reviewed and discussed. Since this field is at an early stage of maturity, some other aspects such as bioimaging and biosensing are reviewed in order to give an idea of potential applications of NPSA for future developments, providing support for clinical applications. It is well-documented that using nanoparticles/nanomaterials above a critical concentration brings about concerns of toxicity; thus, their effect on cellular interactions would become critical. We compared nanoparticles used in the fabrication of NPSA in terms of toxicity mechanism to shed more light on future challenging aspects of NPSA development. Indeed, the neutralization mechanisms underlying the cytotoxicity of nanomaterials, which are expected to be induced by PSA introduction, should be taken into account for future investigations.

Nutraceuticals and Food-Grade Lipid Nanoparticles: From Natural Sources to a Circular Bioeconomy Approach

Nutraceuticals have gained increasing attention over the last years due to their potential value as therapeutic compounds formulated from natural sources. For instance, there is a wide range of literature about the cardioprotective properties of omega-3 lipids and the antioxidant value of some phenolic compounds, which are related to antitumoral activity. However, the value of nutraceuticals can be limited by their instability under gastric pH and intestinal fluids, their low solubility and absorption. That is why encapsulation is a crucial step in nutraceutical design. In fact, pharmaceutical nanotechnology improves nutraceutical stability and bioavailability through the design and production of efficient nanoparticles (NPs). Lipid nanoparticles protect the bioactive compounds from light and external damage, including the gastric and intestinal conditions, providing a retarded delivery in the target area and guaranteeing the expected therapeutic effect of the nutraceutical. This review will focus on the key aspects of the encapsulation of bioactive compounds into lipid nanoparticles, exploring the pharmaceutical production methods available for the synthesis of NPs containing nutraceuticals. Moreover, the most common nutraceuticals will be discussed, considering the bioactive compounds, their natural source and the described biological properties.

Targeting mucus barrier in respiratory diseases by chemically modified advanced delivery systems

Mucus gel constitutes of heavily cross-linked mucin fibers forming a viscoelastic, dense porous network that coats all the exposed epithelia not covered with the skin. The layer provides protection to the underlying gastrointestinal, respiratory, and female reproductive tracts, in addition to the organs such as the surface of eye by trapping the pathogens, irritants, environmental fine particles, and potentially hazardous foreign matter. However, this property of mucus gel poses a substantial challenge for realizing the localized and sustained drug delivery across the mucosal surfaces. The mucus permeating particles that spare the protective properties of mucus gel improve the therapeutic potency of the drugs aimed at the management of diseases, including sexually transmitted infections, lung cancer, irritable bowel disease, degenerative eye diseases and infections, and cystic fibrosis. As such, the mucoadhesive materials conjugated with drug molecules display a prolonged retention time in the mucosal gel that imparts a sustained release of the deliberated drug molecules across the mucosa. The contemporarily developed mucus penetrating materials for drug delivery applications comprise of a finer size, appreciable hydrophilicity, and a neutral surface to escape the entrapment within the cross-inked mucus fibers. Pertaining to the mucus secretion as a first line of defence in respiratory tract in response to the invading physical, chemical, and biological pathogens, the development of mucus penetrating materials hold promise as a stalwart approach for revolutionizing the respiratory drug delivery paradigm. The present review provides an epigrammatic collation of the mucus penetrating/mucoadhesive materials for achieving a controlled/sustained release of the cargo pharmaceutics and drug molecules across the respiratory mucus barrier.

Mucosal vaccine delivery: A focus on the breakthrough of specific barriers

Mucosal vaccines can effectively induce an immune response at the mucosal site and form the first line of defense against microbial invasion. The induced mucosal immunity includes the proliferation of effector T cells and the production of IgG and IgA antibodies, thereby effectively blocking microbial infection and transmission. However, after a long period of development, the transformation of mucosal vaccines into clinical use is still relatively slow. To date, fewer than ten mucosal vaccines have been approved. Only seven mucosal vaccines against coronavirus disease 2019 (COVID-19) are under investigation in clinical trials. A representative vaccine is the adenovirus type-5 vectored COVID-19 vaccine (Ad5-nCoV) developed by Chen and coworkers, which is currently in phase III clinical trials. The reason for the limited progress of mucosal vaccines may be the complicated mucosal barriers. Therefore, this review summarizes the characteristics of mucosal barriers and highlights strategies to overcome these barriers for effective mucosal vaccine delivery.

Preparation and Evaluation of Mucus-Penetrating Inhalable Microparticles of Tiotropium Bromide Containing Sodium Glycocholate

This study aimed to prepare mucus-penetrating inhalable microparticles for dry powder inhalers and to evaluate their applicability in an asthma-induced rat model. Microparticles were prepared from water solutions containing tiotropium bromide, L-leucine, and sodium glycocholate (NaGc) as permeation enhancers using the spray drying method. Four formulations (SDL1, SDL2, SDL3, and SDL4) were used, depending on the various NaGc concentrations. Tiotropium microparticles were characterized by standard methods. Additionally, an asthma-induced rat model was used to confirm the effects of the formulations on lung function. Tiotropium microparticles with NaGc resulted in formulations with a more corrugated morphology and smaller particle size distribution than those without NaGc. SDL 1 had a rough surface with irregular morphology, and SDL 2, 3, and 4 had a corrugated morphology. All SDL formulations had an aerodynamic size of <3 µm. The microparticles with a corrugated morphology aerosolized better than SDL1 microparticles. The apparent permeability coefficient (Papp) values of SDL3 and SDL4 were significantly higher than those for raw tiotropium. In an in vivo study using an asthma-induced rat model, the specific airway resistance (Sraw), airway wall thickness, and mean alveolus size recovered to those of the negative control group in the SDL4 formulation.

Biological chemotaxis-guided self-thermophoretic nanoplatform augments colorectal cancer therapy through autonomous mucus penetration

Oral drug delivery systems have great potential to treat colorectal cancer (CRC). However, the drug delivery efficiency is restricted by limited CRC-related intestine positioning and dense mucus barrier. Here, we present a biological chemotaxis-guided self-thermophoretic nanoplatform that facilitates precise intestinal positioning and autonomous mucus penetration. The nanoplatform introduces asymmetric platinum-sprayed mesoporous silica to achieve autonomous movement in intestinal mucus. Furthermore, inspired by the intense interaction between pathogenic microbes and CRC, the nanoplatform is camouflaged by Staphylococcus aureus membrane to precisely anchor in CRC-related intestine. Owing to 4.3-fold higher biological chemotactic anchoring of CRC-related intestine and 14.6-fold higher autonomous mucus penetration performance, the nanoplatform vastly improves the oral bioavailability of cisplatin, leading to a tumor inhibition rate of 99.1% on orthotopic CRC-bearing mice. Together, the exquisitely designed nanoplatform to overcome multiple physiological barriers provides a new horizon for the development of oral drug delivery systems.

Orally administrable polyphenol-based nanoparticles achieve anti-inflammation and antitumor treatment of colon diseases

Colorectal cancer is the third most common malignancy that leads to significant mortality around the world. Chronic colonic inflammation could induce a protumor effect by the massive release of pro-inflammatory cytokines, facilitating migration, invasion, and metastasis of malignant cells in colorectal cancer. Therefore, developing a combination regimen of anti-inflammation and antitumor therapies is a promising strategy for the treatment of colorectal cancer. Here, we report that tannic acid-containing nanoparticles, formed by a turbulent-mixing technique, have exhibited uniform size, high stability, and pH-triggered drug release in the gastrointestinal tract, and could overcome intestinal mucosa for drug delivery in the colorectal region. As a drug carrier itself, with potent antioxidant and anti-inflammatory properties, tannic acid-containing nanoparticles showed great therapeutic effect in preventing the development of colitis-associated colorectal cancer (CAC) through oral administration. Furthermore, we used a therapeutic nanocarrier to deliver chemotherapeutic drugs for CAC treatment, generating lower systemic toxicity and superior antitumor performance through concurrent anti-inflammation and antitumor treatment. As a result, we confirmed that the drug carrier itself with therapeutic function could improve the overall therapeutic performance, and provided a safe and effective tannic acid-containing nanoplatform for the prevention and treatment of colon diseases.

Mushroom-brush transitional conformation of mucus-inert PEG coating improves co-delivery of oral liposome for intestinal metaplasia therapy

The blocking of gastric mucosal intestinal metaplasia (IM) has been considered to be the pivotal method to control the occurrence of gastric cancer. However, there is still a lack of effective therapeutic agent. Here, we developed mucus-penetrating liposome system by covering surface with polyethylene glycol (PEG) chains (hydrophilic and electroneutral mucus-inert material) to co-delivery candidate drugs combination. Then studied the impact on the transmucus performance of different conformations, which were constructed by controlling the density of PEG chains on the surface. The results showed that the particle size of 5%PEG-Lip was less than 120 nm, the polydispersity index was less than 0.3, and the surface potential tended to be neutral. The D value (long chain spacing) of 5% PEG-Lip was 3.25 nm, which was close to the R_F value (diameter of spherical PEG long chain group without external force interference) of 3.44 nm, and the L value (extended length) was slightly larger than 3.44 nm. In this case, PEG showed mushroom-brush transitional conformation on the surface of liposomes. This conformation was not only promoted stable delivery, but also shielded the capture of mucus more favorably, leading to a more unrestricted transportation in mucus. The further in vivo experimental results demonstrated the rapid distribution of liposomes, which gradually appeared both in the superficial and deep glandular of mucosa and gland cells at 1 h and absorbed into the cell cytoplasm at 6 h. The 5% PEG-Lip with the mushroom-brush transitional configuration recalled abnormal organ index and improved inflammation and intestinal metaplasia. The modified PEG conformation assay presented here was more suitable for liposomes. This PEG-modified liposome system has potential of mucus-penetrating and provides a strategy for local treatment of gastric mucosal intestinal metaplasia.

Nanocrystals based mucosal delivery system: Research Advances

Nanocrystal technology is a new way to increase the solubility and bioavailability of poorly soluble drugs. As an intermediate preparation technology, nanocrystals are widely used in drug delivery for oral, venous, percutneous and inhalation administration, which exhibits a broad application prospect. By referring to the domestic anforeign literatures, this paper mainly reviews the preparation methods of nanocrystals for poorly soluble natural products and its application in the mucosal delivery for skin, eye, oral cavity and nasal cavity. This can provide the reference for the research and development of nanocrystal technology in natural product preparations.

Airway Delivery of Hydrogel-Encapsulated Niclosamide for the Treatment of Inflammatory Airway Disease

Repurposing of the anthelminthic drug niclosamide was proposed as an effective treatment for inflammatory airway diseases such as asthma, cystic fibrosis, and chronic obstructive pulmonary disease. Niclosamide may also be effective for the treatment of viral respiratory infections, such as SARS-CoV-2, respiratory syncytial virus, and influenza. While systemic application of niclosamide may lead to unwanted side effects, local administration via aerosol may circumvent these problems, particularly when the drug is encapsulated into small polyethylene glycol (PEG) hydrospheres. In the present study, we examined whether PEG-encapsulated niclosamide inhibits the production of mucus and affects the pro-inflammatory mediator CLCA1 in mouse airways in vivo, while effects on mucociliary clearance were assessed in excised mouse tracheas. The potential of encapsulated niclosamide to inhibit TMEM16A whole-cell Cl- currents and intracellular Ca2+ signalling was assessed in airway epithelial cells in vitro. We achieved encapsulation of niclosamide in PEG-microspheres and PEG-nanospheres (Niclo-spheres). When applied to asthmatic mice via intratracheal instillation, Niclo-spheres strongly attenuated overproduction of mucus, inhibited secretion of the major proinflammatory mediator CLCA1, and improved mucociliary clearance in tracheas ex vivo. These effects were comparable for niclosamide encapsulated in PEG-nanospheres and PEG-microspheres. Niclo-spheres inhibited the Ca2+ activated Cl- channel TMEM16A and attenuated mucus production in CFBE and Calu-3 human airway epithelial cells. Both inhibitory effects were explained by a pronounced inhibition of intracellular Ca2+ signals. The data indicate that poorly dissolvable compounds such as niclosamide can be encapsulated in PEG-microspheres/nanospheres and deposited locally on the airway epithelium as encapsulated drugs, which may be advantageous over systemic application.

New IMB16-4 Nanoparticles Improved Oral Bioavailability and Enhanced Anti-Hepatic Fibrosis on Rats

Liver fibrosis is challenging to treat because of the lack of effective agents worldwide. Recently, we have developed a novel compound, N-(3,4,5-trichlorophenyl)-2(3-nitrobenzenesulfonamido) benzamide referred to as IMB16-4. However, its poor aqueous solubility and poor oral bioavailability obstruct the drug discovery programs. To increase the dissolution, improve the oral bioavailability and enhance the antifibrotic activity of IMB16-4, PVPK30 was selected to establish the IMB16-4 nanoparticles. Drug release behavior, oral bioavailability, and anti-hepatic fibrosis effects of IMB16-4 nanoparticles were evaluated. The results showed that IMB16-4 nanoparticles greatly increased the dissolution rate of IMB16-4. The oral bioavailability of IMB16-4 nanoparticles was improved 26-fold compared with that of pure IMB16-4. In bile duct ligation rats, IMB16-4 nanoparticles significantly repressed hepatic fibrogenesis and improved the liver function. These findings indicate that IMB16-4 nanoparticles will provide information to expand a novel anti-hepatic fibrosis agent.