Enhanced Immune Responses to Mucosa by Functionalized Chitosan-Based Composite Nanoparticles as a Vaccine Adjuvant for Intranasal Delivery

The review of nasal drug delivery system: The strategies to enhance the efficiency of intranasal drug delivery by improving drug absorption

Nasal drug administration constitutes an efficient and non-invasive modality of drug delivery, and its distinctive physiological structure offers potentialities for treating a variety of diseases. To elevate the drug absorption and delivery efficiency, it is of paramount importance to delineate the transport routes and their enhancement mechanisms. Nevertheless, drug absorption pathways vary depending on the disease target, these variations present opportunities for targeted delivery and challenges for achieving precision. Hence, this review outlines the anatomical structure of the nasal cavity, and subsequently elaborates on the drug transport pathways within the nasal cavity and their influencing factors. Based on the distinct sites of drug action, diseases suitable for nasal drug administration are categorized into three types: systemic diseases, local nasal diseases, and central nervous system diseases. Grounded on multiple transport routes and their influencing factors, this review proposes strategies like optimizing formulation viscosity, using penetration enhancers, adding mucosal adhesives and improving delivery device, offering insights into future advancements in nasal drug delivery systems.

Multi-adjuvant emulsion system stabilized via mannosylated chitosan nanoparticles for subunit vaccine delivery

Adjuvants, which are vaccine ingredients substances that amplify antigen-specific immune responses, enhance the ability of antigen-presenting cells (APCs) to process and present antigens and hold great market potential. However, the development of adjuvants faces various challenges, including limited functionality, poor stability, and weak effects on cellular immunity, considerably restricting their application. Herein, we prepared a Pickering emulsion using mannose-modified chitosan nanoparticles (CNPs) and squalene for subunit vaccine delivery. In this delivery system, mannose-modified chitosan can target APCs and promote endocytosis. Chitosan and squalene synergistically function as dual adjuvants, enhancing immune responses. This delivery system can substantially improve cellular immunity, which is inadequate in case of commercial subunit vaccines. Furthermore, the emulsion exhibits good stability and antigen reservoir effect after injection to ensure continuous antigen release. This study presents an innovatively designed polysaccharide emulsion vaccine, demonstrating the strong immune response of the associated multi-adjuvant system and providing a valuable practical reference for the fabrication of vaccine adjuvant formulations.

Enhanced mucosal immune response through nanoparticle delivery system based on chitosan-catechol and a recombinant antigen targeted towards M cells

In mucosal vaccination, the targeted delivery of antigens through M (microfold) cells is essential for initiating a robust antigen-specific immune response. In the present study, we devised a nano-delivery platform to target M cells. This platform involved coating mesoporous silica nanoparticles (MSN) with a mucoadhesive chitosan-catechol (Chic) layer, incorporating a recombinant antigen to form nanoparticles that enhance the immune response. The collagenase equivalent domain (COE) of porcine epidemic diarrhea virus (PEDV) terminated with the M cell-targeting sequence RGD (COER), was initially expressed by Escherichia coli (E. coli) and subsequently conjugated to the surface of MSN-Chic, forming the MSN-Chic-COER nanoparticles. MSN-Chic-COER with strong mucoadhesive properties and a propensity for M cell targeting, demonstrated enhanced uptake by dendritic cells (DCs) and trafficking to lymph nodes, compared to COE/COER after intranasal administration. MSN-Chic-COER recruited more dendritic cells to the antigen-located site via stimulating chemokine CCL20 secretion was evidenced by cell co-culture model. Additionally, it enhanced antigen permeability by disrupting the distribution of the ZO-1 protein in epithelial cells. Notably, MSN-Chic-COER elicited a higher level of cellular immunity, humoral immunity, and PEDV neutralizing antibody production. These findings underscore the potential of MSN-Chic-COER as a promising intranasal vaccine delivery system.

Nanochitin and Nanochitosan in Pharmaceutical Applications: Innovations, Applications, and Future Perspective

Nanochitin is a nanoscale form of chitin-a polysaccharide found in the exoskeletons of crustaceans, insects, and some fungal cell walls-that is newly garnering significant attention in the pharmaceutical space. Its good properties, such as biocompatibility, biodegradability, and an easily adjustable surface, render it attractive for various medical and pharmaceutical applications. Nanochitin, from drug delivery systems and wound-care formulations to vaccine adjuvants and antimicrobial strategies, has demonstrated its strong potential in meeting diverse therapeutic needs. This review covers the background of nanochitin, including methods for its extraction and refining and its principal physicochemical and biological properties. It further discusses various hydrolysis and enzymatic approaches for the structural and functional characterization of nanochitin and highlights some pharmaceutical applications where this biopolymer has been studied. The review also addresses toxicity issues, regulatory matters, and challenges in large-scale industrial production. Finally, it underscores novel avenues of investigation and future opportunities, emphasizing the urgent requirement for standardized production methods, rigorous safety assessment, and interdisciplinary partnerships to maximize nanochitin's potential in pharmaceutical research, demonstrating the importance of chitin in drug delivery.

Design, preparation, and characterization of bovine papillomavirus chitosan-based nanoparticles as a prototype for a bovine papillomatosis vaccine

The bovine papillomavirus (BPV) is known to cause lesions in the epithelial tissue of cattle, which causes bovine papillomatoses. This disease is characterized by wart lesions in different body parts, causing losses in the animal value. Despite the economic impact, there are no effective vaccines available at this moment. The present study aims to develop a nanoformulated autogenous vaccine using the inactivated virus present in warts to control the diseases associated with BPV. To this end, papillomavirus was collected from infected bovines on a farm in Goiás, Brazil. The warts containing the viruses were macerated to obtain the inactivated viruses to be formulated within chitosan nanoparticles. The chitosan nanoparticles containing the inactivated viruses presented 330.7 nm in size, a polydispersity index of 0.41, and a positive Zeta potential of 38.2 mV. The association efficiency was 58.3%. The nanoparticles containing the inactivated virus were stable for up to 30 days and presented no hemolysis toxicity. This could be an interesting approach to develop a vaccine to protect bovines from BPV infection.

A respiratory mucosal vaccine based on chitosan/aluminum adjuvant induces both mucosal and systemic immune responses

The respiratory mucosa serves as a critical barrier against the invasion of pathogens. Effective mucosal vaccines are essential for enhancing local immunity. However, there is an urgent need to develop new mucosal adjuvants. Chitosan is preferred as a mucosal adjuvant due to its mucosal adhesion and immunostimulatory properties. In this work, a novel mucosal adjuvant was synthesized by combining nano-aluminum hydroxide and chitosan (Al-CS), formulating a particle size approximately 1.5 μm. In vitro assays revealed that Al-CS notably promotes antigen uptake by enhancing activation and maturation of dendritic cells and macrophages. Furthermore, in vivo experiments indicated that Al-CS could extend antigen release duration, facilitate immune cell migration to the lungs, stimulates antigen-presenting cell maturation, enhances antigen presentation and significantly improves both humoral and cellular immunity as well as B/T cell memory differentiation. The immunological potential of Al-CS exceeds that of either aluminum or chitosan alone, making it a promising and safe adjuvant for the advancement of mucosal vaccine carrier systems.

N-2-Hydroxypropyl Trimethyl Ammonium Chloride Chitosan-Aluminum Nano-Adjuvant Elicit Strong Immune Responses in Porcine Epidemic Diarrhea Inactivated Vaccine

Background

Porcine epidemic diarrhea virus (PEDV) inactivated vaccine lacks an effective vaccine adjuvant as an immune activator. The aim of this study was to develop N-2-HACC-Al nano-adjuvant as a high immune-enhancing adjuvant and to make the vaccine suitable for intramuscular and oral administration.

Methods

N-2-HACC-Al nano-adjuvant was prepared by ion crosslinking method using the N-2-hydroxypropyl trimethyl ammonium chloride chitosan (N-2-HACC). The N-2-HACC-Al nano-adjuvant was characterised, and its safety was determined by analysing the cytotoxicity and hemolysis. PED inactivated vaccine (N-2-HACC-Al/PEDV) was prepared by electrostatic adsorption method, and mice were inoculated by intramural injection and orally to evaluate the immune enhancement effect and application potential of the N-2-HACC-Al/PEDV.

Results

The hemolysis rate was 3.89 ± 0.12% and the activity of PK15 cells was 77.40 ± 1.74%, indicating that the N-2-HACC-Al/PEDV had good biosafety. The levels of PEDV antibodies induced by the N-2-HACC-Al/PEDV were higher than those of commercially available vaccines, both by intramural injection and oral administration. Except for the serum IgG1 levels in the N-2-HACC-Al/PEDV injection group, which were similar to those in the commercial PEDV group, the serum IgG1, IgG2a, IgG2c and sIgA levels in the injection, and the oral groups were significantly higher than those in the commercial group. These results indicated and that N-2-HACC-Al nano-adjuvant significantly enhanced cellular immunity and N-2-HACC-Al nano-adjuvant could deliver PEDV antigen across the mucosal layer of the intestine and induced a strong mucosal immune response.

Conclusion

N-2-HACC-Al nano-adjuvant is safe and can efficiently induce humoral, cellular and mucosal immunity efficiently, which provides a new idea for the development of oral mucosal vaccine adjuvant.

A pH-responsive microneedle patch for the transdermal delivery of biomineralized insulin nanoparticles to diabetes treatment

Diabetes mellitus is a chronic metabolic disease, and insulin injection administration remains the most commonly used treatment approach in clinical practice. However, this method faces the risks of insufficient specificity and high toxic side effects on normal tissues. Therefore, developing more effective drug administration methods is crucial for improving the safety and bioavailability of insulin. In this study, a swellable composite microneedle delivery system loaded with biomineralized insulin nanoparticles was constructed for effective diabetes treatment via percutaneous administration. The microneedle arrays were prepared by using N-2-hydroxypropyl trimethyl ammonium chloride chitosan (N-2-HACC) and hyaluronic acid (HA) with the assistance of β-Glycerophosphate Tetrahydrate (β-GP). Glucose oxidase (GOx) and calcium phosphate-biomineralized insulin nanoparticles (BINPs) were co-encapsulated in the microneedle arrays. After insertion into the skin, the interstitial fluid and high glucose concentration facilitated the sustained transdermal delivery of BINPs from the tips of the microneedle patches and the glucose-responsive release of insulin. The constructed composite microneedle patches demonstrated desirable therapeutic effects for diabetes with high biosafety, biodegradation and long-lasting effects. This study proposes a new strategy for developing intelligent drug delivery systems based on polymeric microneedle patches, and it is expected to be used in the broader biomedical field with potential applications.

Advancements in Nanoparticle-Based Adjuvants for Enhanced Tuberculosis Vaccination: A Review

Tuberculosis (TB) remains a leading cause of morbidity and mortality worldwide, necessitating the development of more effective vaccines. Nanoparticle-based adjuvants represent a promising approach to enhancing tuberculosis vaccine efficacy. This review focuses on the advantages of nanoparticulate-loaded vaccines, emphasizing their ability to improve antigen delivery, safety, and immunogenicity. We discuss the various types of nanoparticles and their unique physicochemical properties that contribute to improved antigen delivery and sustained immune activation. Additionally, we highlight the advantages of nanoparticle-based adjuvants in inducing strong cellular and humoral immunity, enhancing vaccine stability, and reducing adverse effects. Finally, we address current challenges and future perspectives in the application of these novel adjuvants, emphasizing their potential to transform TB vaccine strategies and ultimately contribute to better global health outcomes.

Acidified sucralfate encapsulated chitosan derivative nanoparticles as oral vaccine adjuvant delivery enhancing mucosal and systemic immunity

Oral vaccines are generally perceived to be safe, easy to administer, and have the potential to induce both systemic and mucosal immune responses. However, given the challenges posed by the harsh gastrointestinal environment and mucus barriers, the development of oral vaccines necessitates the employment of a safe and efficient delivery system. In recent years, nanoparticle-based delivery has proven to be an ideal delivery vector for the manufacture of oral vaccines. Hence, considering the above, the sucralfate acidified (SA) encapsulated N-2-Hydroxypropyl trimethyl ammonium chloride chitosan (N-2-HACC)/N,O-carboxymethyl chitosan (CMCS) nanoparticles (SA@N-2-HACC/CMCS NPs) were prepared, and the BSA was used as a model antigen to investigate the immune responses. The SA@N-2-HACC/CMCS NPs had a particle size of 227 ± 7.0 nm and a zeta potential of 8.43 ± 2.62 mV. The NPs displayed slow and sustained release and high stability in simulated gastric juice and intestinal fluid. RAW 264.7 macrophage-like cell line demonstrated enhanced uptake of the SA@N-2-HACC/CMCS/BSA Nps. The vaccine via oral administration markedly enhanced the residence time of BSA in the intestine for more than 12 h and elicited the production of IgG and sIgA. The SA@N-2-HACC/CMCS NPs developed here for oral administration is an excellent technique for delivering antigens and provides a path of mucosal vaccine research.

Pathogen-Mimicking Nanoparticles Based on Rigid Nanomaterials as an Efficient Subunit Vaccine Delivery System for Intranasal Immunization

Despite the safety profile of subunit vaccines, the inferior immunogenicity hinders their application in the nasal cavity. This study introduces a novel antigen delivery and adjuvant system utilizing mucoadhesive chitosan-catechol (Chic) on silica spiky nanoparticles (Ssp) to enhance immunity through multiple mechanisms. The Chic functionalizes the Ssp surface and incorporates with SARS-CoV-2 spike protein receptor-binding domain (RBD) and toll-like receptor (TLR)9 agonist unmethylated cytosine-guanine (CpG) motif, forming uniform virus-like nanoparticles (Ssp-Chic-RBD-CpG) via electrostatic and covalent interactions. Ssp-Chic-RBD-CpG, mimicking the morphology and function of inactive virions, effectively prolongs the retention time of RBD in the nasal mucosa by 3.92-fold compared to RBD alone, enhances the maturation of dendritic cells (DCs), and facilitates the antigen trafficking to the draining lymph nodes, which subsequently induces a stronger mucosal immunity. Mechanistically, the enhanced chemokine chemokine (C-C motif) ligand 20 (CCL20)-driven DCs recruitment and maturation by Ssp-Chic-RBD-CpG are evidenced by a cell co-culture model. In addition, the overexpression of TLR4/9 and activation of MYD88/NF-κB signaling pathway in activation of DCs are observed. Proof of principle is obtained for RBD, but similar delivery mechanisms can be applied in other protein-based subunit vaccines as well when intranasal administration is needed.

Applications of Chitosan in Prevention and Treatment Strategies of Infectious Diseases

Chitosan is the most commonly investigated functional cationic biopolymer in a wide range of medical applications due to its promising properties such as biocompatibility, biodegradability, and bioadhesivity, as well as its numerous bioactive properties. Within the last three decades, chitosan and its derivatives have been investigated as biomaterials for drug and vaccine delivery systems, besides for their bioactive properties. Due to the functional groups in its structure, it is possible to tailor the delivery systems with desired properties. There has been a great interest in the application of chitosan-based systems also for the prevention and treatment of infectious diseases, specifically due to their antimicrobial, antiviral, and immunostimulatory effects. In this review, recent applications of chitosan in the prevention and treatment of infectious diseases are reviewed, and possibilities and limitations with regards to technical and regulatory aspects are discussed. Finally, the future perspectives on utilization of chitosan as a biomaterial are discussed.

Nanoplatform Based Intranasal Vaccines: Current Progress and Clinical Challenges

Multiple vaccine platforms have been employed to develop the nasal SARS-CoV-2 vaccines in preclinical studies, and the dominating pipelines are viral vectored as protein-based vaccines. Among them, several viral vectored-based vaccines have entered clinical development. Nevertheless, some unsatisfactory results were reported in these clinical studies. In the face of such urgent situations, it is imperative to rapidly develop the next-generation intranasal COVID-19 vaccine utilizing other technologies. Nanobased intranasal vaccines have emerged as an approach against respiratory infectious diseases. Harnessing the power of nanotechnology, these vaccines offer a noninvasive yet potent defense against pathogens, including the threat of COVID-19. The improvements made in vaccine mucosal delivery technologies based on nanoparticles, such as lipid nanoparticles, polymeric nanoparticles, inorganic nanoparticles etc., not only provide stability and controlled release but also enhance mucosal adhesion, effectively overcoming the limitations of conventional vaccines. Hence, in this review, we overview the evaluation of intranasal vaccine and highlight the current barriers. Next, the modern delivery systems based on nanoplatforms are summarized. The challenges in clinical application of nanoplatform based intranasal vaccine are finally discussed.

Nanoemulsions and nanocapsules as carriers for the development of intranasal mRNA vaccines

The global emergency of coronavirus disease 2019 (COVID-19) has spurred extensive worldwide efforts to develop vaccines for protection against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Our contribution to this global endeavor involved the development of a diverse library of nanocarriers, as alternatives to lipid nanoparticles (LNPs), including nanoemulsions (NEs) and nanocapsules (NCs), with the aim of protecting and delivering messenger ribonucleic acid (mRNA) for nasal vaccination purposes. A wide range of prototypes underwent rigorous screening through a series of in vitro and in vivo experiments, encompassing assessments of cellular transfection, cytotoxicity, and intramuscular administration of a model mRNA for protein translation. As a result, two promising candidates were identified for nasal administration. One of them was a NE incorporating a combination of an ionizable lipid (C12-200) and cationic lipid (DOTAP), both intended to condense mRNA, along with DOPE, which is known to facilitate endosomal escape. This NE exhibited a size of 120 nm and a highly positive surface charge (+ 50 mV). Another candidate was an NC formulation comprising the same components and endowed with a dextran sulfate shell. This formulation showed a size of 130 nm and a moderate negative surface charge (-16 mV). Upon intranasal administration of mRNA encoding for ovalbumin (mOVA) associated with optimized versions of the said NE and NCs, a robust antigen-specific CD8 + T cell response was observed. These findings underscore the potential of NEs and polymeric NCs in advancing mRNA vaccine development for combating infectious diseases.

Mucoadhesive chitosan-catechol as an efficient vaccine delivery system for intranasal immunization

The mucosal barrier and scavenging effect of the mucosal layer are two main obstacles in inducing mucosal immunization. To overcome these obstacles, we synthesized a bio-inspired mucoadhesive material, chitosan-catechol (ChiC), for surface modification of inactive porcine epidemic diarrhea virus (PEDV). Studies have revealed that PEDV particles can be facilely and mildly modified by Chi-C forming Chi-C-PEDV nanoparticles (Chic-Ps) through the covalent and electrostatic bond, which effectively prolongs the retention time of PEDV in the nasal mucosa. The cell co-culture model demonstrated that Chic-Ps exhibit enhanced recruitment of dendritic cells via the secretion of stimulating chemokine CCL20 and improving antigen permeability by disruption the distribution of ZO-1 protein in epithelial cells. Additionally, the flow cytometry (FCM) analysis revealed that Chic-Ps facilitate trafficking to lymph nodes and induce stronger cellular and humoral immune responses compared to unmodified PEDV. Notably, Chic-Ps induced a higher level of PEDV neutralizing antibody was induced by Chic-Ps in the nasal washes, as confirmed by a plaque reduction neutralization test. These results demonstrate that Chi-C is a promising nasal delivery system for vaccines. Proof of principle was obtained for inactivated PEDV, but similar delivery mechanisms could be applied in other vaccines when intranasal administration is needed.

Fabrication of chitosan-based emulsion as an adjuvant to enhance nasal mucosal immune responses

Nasal vaccine is a non-invasive vaccine that activates systemic and mucosal immunity in the presence of an adjuvant, thereby enhancing immune function. In this work, chitosan/oligochitosan/tween 80 (CS-COS-T80) co-stabilized emulsion was designed and further used as the nasal adjuvant. CS-COS-T80 emulsion exhibited outstanding stability under pH 6-8 with uniformly dispersed droplets and nano-scale particle size (<0.25 μm), and maintained stable at 4 °C for 150-day storage. Addition of model antigen ovalbumin (OVA) had no effect on the stability of CS-COS-T80 emulsion. In vivo nasal immunity indicated that CS-COS-T80 emulsion prolonged the retention time of OVA in the nasal cavity (from 4 to 8 h to >12 h), as compared to T80-emulsion. CS-COS-T80 emulsion produced a stronger mucosal immune response to OVA, with secretory IgA levels 5-fold and 2-fold higher than those of bare OVA and commercial adjuvant MF59, respectively. Compared to MF59, CS-COS-T80 induced a stronger humoral immune response and a mixed Th1/Th2 immune response of OVA after immunization. Furthermore, in the presence of CS-COS-T80 emulsion, the secretion of IL-4 and IFN-γ and the activation of splenocyte memory T-cell differentiation increased from 173.98 to 210.21 pg/mL and from 75.46 to 104.01 pg/mL, respectively. Therefore, CS-COS-T80 emulsion may serve as a promising adjuvant platform.

Chitosan Nanoparticles for Intranasal Drug Delivery

This manuscript explores the use of nanostructured chitosan for intranasal drug delivery, targeting improved therapeutic outcomes in neurodegenerative diseases, psychiatric care, pain management, vaccination, and diabetes treatment. Chitosan nanoparticles are shown to enhance brain delivery, improve bioavailability, and minimize systemic side effects by facilitating drug transport across the blood-brain barrier. Despite substantial advancements in targeted delivery and vaccine efficacy, challenges remain in scalability, regulatory approval, and transitioning from preclinical studies to clinical applications. The future of chitosan-based nanomedicines hinges on advancing clinical trials, fostering interdisciplinary collaboration, and innovating in nanoparticle design to overcome these hurdles and realize their therapeutic potential.

Polymeric Nanoparticles for Drug Delivery

The recent emergence of nanomedicine has revolutionized the therapeutic landscape and necessitated the creation of more sophisticated drug delivery systems. Polymeric nanoparticles sit at the forefront of numerous promising drug delivery designs, due to their unmatched control over physiochemical properties such as size, shape, architecture, charge, and surface functionality. Furthermore, polymeric nanoparticles have the ability to navigate various biological barriers to precisely target specific sites within the body, encapsulate a diverse range of therapeutic cargo and efficiently release this cargo in response to internal and external stimuli. However, despite these remarkable advantages, the presence of polymeric nanoparticles in wider clinical application is minimal. This review will provide a comprehensive understanding of polymeric nanoparticles as drug delivery vehicles. The biological barriers affecting drug delivery will be outlined first, followed by a comprehensive description of the various nanoparticle designs and preparation methods, beginning with the polymers on which they are based. The review will meticulously explore the current performance of polymeric nanoparticles against a myriad of diseases including cancer, viral and bacterial infections, before finally evaluating the advantages and crucial challenges that will determine their wider clinical potential in the decades to come.

Lentinan-functionalized graphene oxide hydrogel as a sustained antigen delivery system for vaccines

Hydrogel has been proven to have the ability to deliver antigens continuously to achieve slow vaccine delivery, which makes it a promising candidate for an adjuvant delivery platform. Meanwhile, graphene oxide (GO) has garnered significant attention due to its good biosafety, excellent surface area and easy modification. However, GO exists as weak colloidal particles and poses challenges in self-assembling into a hydrogel structure. Here, we propose an innovative strategy involving self-assembling lentinan-functionalized graphene oxide hydrogel ((LNT-GO Gel) by simply mixing lentinan (LNT)-functionalized GO with polyethylene imide (PEI), which can simultaneously encapsulate antigens, achieve long-lasting release of antigens and generate excellent adjuvant activity. The results indicated that the LNT-GO Gel can control the release of OVA at the injection site and confer targeted delivering capacity to lymph nodes. And the date demonstrates that LNT-GO Gel displays favorable safety and biodegradability in vivo. Moreover, LNT-GO Gel can enhance the activation and maturation of dendritic cells (DCs) in lymph node, induce stronger OVA-specific antibody response, and promote spleen T lymphocyte differentiation, which underscores that LNT-GO Gel has ability to generate stronger antigen-specific humoral and cellular immune responses. Collectively, these results demonstrate the adjuvant potential of the lentinan-functionalized graphene oxide hydrogel (LNT-GO Gel) for subunit vaccine.

Next Generation Mucosal Vaccine Strategy for Respiratory Pathogens

Inducing humoral and cytotoxic mucosal immunity at the sites of pathogen entry has the potential to prevent the infection from getting established. This is different from systemic vaccination, which protects against the development of systemic symptoms. The field of mucosal vaccination has seen fewer technological advances compared to nucleic acid and subunit vaccine advances for injectable vaccine platforms. The advent of the next-generation adenoviral vectors has given a boost to mucosal vaccine research. Basic research into the mechanisms regulating innate and adaptive mucosal immunity and the discovery of effective and safe mucosal vaccine adjuvants will continue to improve mucosal vaccine design. The results from clinical trials of inhaled COVID-19 vaccines demonstrate their ability to induce the proliferation of cytotoxic T cells and the production of secreted IgA and IgG antibodies locally, unlike intramuscular vaccinations. However, these mucosal vaccines induce systemic immune responses at par with systemic vaccinations. This review summarizes the function of the respiratory mucosa-associated lymphoid tissue and the advantages that the adenoviral vectors provide as inhaled vaccine platforms.

The combination of vaccines and adjuvants to prevent the occurrence of high incidence of infectious diseases in bovine

As the global population grows, the demand for beef and dairy products is also increasing. The cattle industry is facing tremendous pressures and challenges. The expanding cattle industry has led to an increased risk of disease in cattle. These diseases not only cause economic losses but also pose threats to public health and safety. Hence, ensuring the health of cattle is crucial. Vaccination is one of the most economical and effective methods of preventing bovine infectious diseases. However, there are fewer comprehensive reviews of bovine vaccines available. In addition, the variable nature of bovine infectious diseases will result in weakened or even ineffective immune protection from existing vaccines. This shows that it is crucial to improve overall awareness of bovine vaccines. Adjuvants, which are crucial constituents of vaccines, have a significant role in enhancing vaccine response. This review aims to present the latest advances in bovine vaccines mainly including types of bovine vaccines, current status of development of commonly used vaccines, and vaccine adjuvants. In addition, this review highlights the main challenges and outstanding problems of bovine vaccines and adjuvants in the field of research and applications. This review provides a theoretical and practical basis for the eradication of global bovine infectious diseases.

Chitosan: A Potential Biopolymer in Drug Delivery and Biomedical Applications

Chitosan, a biocompatible and biodegradable polysaccharide derived from chitin, has surfaced as a material of promise for drug delivery and biomedical applications. Different chitin and chitosan extraction techniques can produce materials with unique properties, which can be further modified to enhance their bioactivities. Chitosan-based drug delivery systems have been developed for various routes of administration, including oral, ophthalmic, transdermal, nasal, and vaginal, allowing for targeted and sustained release of drugs. Additionally, chitosan has been used in numerous biomedical applications, such as bone regeneration, cartilage tissue regeneration, cardiac tissue regeneration, corneal regeneration, periodontal tissue regeneration, and wound healing. Moreover, chitosan has also been utilized in gene delivery, bioimaging, vaccination, and cosmeceutical applications. Modified chitosan derivatives have been developed to improve their biocompatibility and enhance their properties, resulting in innovative materials with promising potentials in various biomedical applications. This article summarizes the recent findings on chitosan and its application in drug delivery and biomedical science.

Pulmonary Application of Novel Antigen-Loaded Chitosan Nano-Particles Co-Administered with the Mucosal Adjuvant C-Di-AMP Resulted in Enhanced Immune Stimulation and Dose Sparing Capacity

The most successful medical intervention for preventing infectious diseases is still vaccination. This effective strategy has resulted in decreased mortality and extended life expectancy. However, there is still a critical need for novel vaccination strategies and vaccines. Antigen cargo delivery by nanoparticle-based carriers could promote superior protection against constantly emerging viruses and subsequent diseases. This should be sustained by the induction of vigorous cellular and humoral immunity, capable of acting both at the systemic and mucosal levels. Induction of antigen-specific responses at the portal of entry of pathogens is considered an important scientific challenge. Chitosan, which is widely regarded as a biodegradable, biocompatible and non-toxic material for functionalized nanocarriers, as well as having adjuvant activity, enables antigen administration via less-invasive mucosal routes such as sublingual or pulmonic application route. In this proof of principle study, we evaluate the efficacy of chitosan nanocarriers loaded with the model antigen Ovalbumin (OVA) co-administrated with the STING agonist bis-(3',5')-cyclic dimeric adenosine monophosphate (c-di-AMP) given by pulmonary route. Here, BALB/c mice were immunized with four doses of the formulation that stimulates enhanced antigen-specific IgG titers in sera. In addition, this vaccine formulation also promotes a strong Th1/Th17 response characterized by high secretion of IFN-γ, IL-2 and IL-17, as well as induction of CD8⁺ T cells. Furthermore, the novel formulation exhibited strong dose-sparing capacity, enabling a 90% reduction of the antigen concentration. Altogether, our results suggest that chitosan nanocarriers, in combination with the mucosal adjuvant c-di-AMP, are a promising technology platform for the development of innovative mucosal vaccines against respiratory pathogens (e.g., Influenza or RSV) or for therapeutic vaccines.

Natural Polymeric Composites Derived from Animals, Plants, and Microbes for Vaccine Delivery and Adjuvant Applications: A Review

A key element in ensuring successful immunization is the efficient delivery of vaccines. However, poor immunogenicity and adverse inflammatory immunogenic reactions make the establishment of an efficient vaccine delivery method a challenging task. The delivery of vaccines has been performed via a variety of delivery methods, including natural-polymer-based carriers that are relatively biocompatible and have low toxicity. The incorporation of adjuvants or antigens into biomaterial-based immunizations has demonstrated better immune response than formulations that just contain the antigen. This system may enable antigen-mediated immunogenicity and shelter and transport the cargo vaccine or antigen to the appropriate target organ. In this regard, this work reviews the recent applications of natural polymer composites from different sources, such as animals, plants, and microbes, in vaccine delivery systems.