PEG modified liposomes containing CRX-601 adjuvant in combination with methylglycol chitosan enhance the murine sublingual immune response to influenza vaccination

Innovative translational platforms for rapid developing clinical vaccines against COVID-19 and other infectious disease

A vaccine is a biological preparation that contains the antigen capable of stimulating the immune system to form the defense against pathogens. Vaccine development often confronts big challenges, including time/energy-consuming, low efficacy, lag to pathogen emergence and mutation, and even safety concern. However, these seem now mostly conquerable through constructing the advanced translational platforms that can make innovative vaccines, sometimes, potentiated with a distinct multifunctional VADS (vaccine adjuvant delivery system), as evidenced by the development of various vaccines against the covid-19 pandemic at warp speed. Particularly, several covid-19 vaccines, such as the viral-vectored vaccines, mRNA vaccines and DNA vaccines, regarded as the innovative ones that are rapidly made via the high technology-based translational platforms. These products have manifested powerful efficacy while showing no unacceptable safety profile in clinics, allowing them to be approved for massive vaccination at also warp speed. Now, the proprietary translational platforms integrated with the state-of-the-art biotechnologies, and even the artificial intelligence (AI), represent an efficient mode for rapid making innovative clinical vaccines against infections, thus increasingly attracting interests of vaccine research and development. Herein, the advanced translational platforms for making innovative vaccines, together with their design principles and immunostimulatory efficacies, are comprehensively elaborated.

Specific surface modification of liposomes for gut targeting of food bioactive agents

Liposomes have become a research hotspot in recent years as food delivery systems with attractive properties, including the bilayer structure assembled like the cell membrane, reducing the side-effect and improving environmental stability of cargos, controlling release, extending duration of functional ingredients, and high biodegradable and biocompatible abilities in the body. However, the conventional liposomes lack stability during storage and are weak in targeted absorption in the gastrointestinal track. At present, surface modification has been approved to be an effective platform to shield these barricades and help liposomes deliver the agents safely and effectively to the ideal site. In this review, the gastrointestinal stability of conventional liposomes, cargo release models from liposomes, and the biological fate of the core materials after release were emphasized. Then, the strategies in both physical and chemical perspectives to improve the stability and utilization of liposomes in the gastrointestinal tract, and the emerging approaches for improving gut targeting by specifically modified liposomes and the intestinal receptors relative to liposomes/cargos absorption were highlighted. Last but not the least, the safety, challenges, and opportunities for the improvement of liposomal bioavailability were also discussed to inspire new applications of liposomes as oral carriers.

Liposome-based vaccines for minimally or noninvasive administration: an update on current advancements

INTRODUCTION

Vaccination requires innovation to provide effective protection. Traditional vaccines have several drawbacks, which can be overcome with advanced technologies and different administration routes. Over the past 10  years, a significant amount of research has focussed on the delivery of antigens into liposomes due to their dual role as antigen-carrying systems and vaccine adjuvants able to increase the immunogenicity of the carried antigen.

AREAS COVERED

This review encompasses the progress made over the last 10  years with liposome-based vaccines designed for minimally or noninvasive administration, filling the gaps in previous reviews and providing insights on composition, administration routes, results achieved, and Technology Readiness Level of the most recent formulations.

EXPERT OPINION

Liposome-based vaccines administered through minimally or noninvasive routes are expected to improve efficacy and complacency of vaccination programs. However, the translation from lab-scale production to large-scale production and collaborations with hospitals, research centers, and companies are needed to allow new products to enter the market and improve the vaccination programs in the future.

Mucoadhesive Vaccine Delivery Systems for the Oral Mucosa

Vaccine technology has evolved continuously since its beginning, and mucosal vaccination, including intranasal, sublingual, and oral administrations, has recently gained great scientific interest. The oral mucosa represents a promising minimally invasive route for antigen delivery, mainly at sublingual and buccal mucosal sites, and it is easily accessible, immunologically rich, and able to promote an effective systemic and local immune response. The aim of this review is to provide an updated overview on the technologies for oral mucosal vaccination, with emphasis on mucoadhesive biomaterial-based delivery systems. Polymeric-based nanoparticles, multilayer films and wafers, liposomes, microneedles, and thermoresponsive gels are the most investigated strategies to deliver antigens locally, showing mucoadhesive properties, controlled release of the antigen, and the ability to enhance immunological responses. These formulations have achieved adequate properties in terms of vaccine stability, are minimally invasive, and are easy to produce and manage. To date, oral mucosa vaccine delivery systems represent a promising and open field of research. Future directions should focus on the role of these systems to induce sustained innate and adaptive immune responses, by integrating the recent advances achieved in mucoadhesion with those related to vaccine technology. Being painless, easy to administer, highly stable, safe, and effective, the antigen delivery systems via the oral mucosa may represent a useful and promising strategy for fast mass vaccination, especially during pandemic outbreaks.

Advances in formulation and manufacturing strategies for the delivery of therapeutic proteins and peptides in orally disintegrating dosage forms

Therapeutic proteins and peptides (TPPs) are increasingly favoured above small drug molecules due to their high specificity to the site of action and reduced adverse effects resulting in increased use of these agents for medical treatments and therapies. Consequently, there is a need to formulate TPPs in dosage forms that are accessible and suitable for a wide range of patient groups as the use of TPPs becomes increasingly prevalent in healthcare settings worldwide. Orally disintegrating dosage forms (ODDF) are formulations that can ensure easy-to-administer medication to a wider patient population including paediatrics, geriatrics and people in low-resource countries. There are many challenges involved in developing suitable pharmaceutical strategies to protect TPPs during formulation and manufacturing, as well as storage, and maintenance of a cold-chain during transportation. This review will discuss advances being made in the research and development of pharmaceutical and manufacturing strategies used to incorporate various TPPs into ODDF systems.

Review: Current trends, challenges, and success stories in adjuvant research

Vaccine adjuvant research is being fueled and driven by progress in the field of innate immunity that has significantly advanced in the past two decades with the discovery of countless innate immune receptors and innate immune pathways. Receptors for pathogen-associated molecules (PAMPs) or host-derived, danger-associated molecules (DAMPs), as well as molecules in the signaling pathways used by such receptors, are a rich source of potential targets for agonists that enable the tuning of innate immune responses in an unprecedented manner. Targeted modulation of immune responses is achieved not only through the choice of immunostimulator - or select combinations of adjuvants - but also through formulation and systematic modifications of the chemical structure of immunostimulatory molecules. The use of medium and high-throughput screening methods for finding immunostimulators has further accelerated the identification of promising novel adjuvants. However, despite the progress that has been made in finding new adjuvants through systematic screening campaigns, the process is far from perfect. A major bottleneck that significantly slows the process of turning confirmed or putative innate immune receptor agonists into vaccine adjuvants continues to be the lack of defined in vitro correlates of in vivo adjuvanticity. This brief review discusses recent developments, exciting trends, and notable successes in the adjuvant research field, albeit acknowledging challenges and areas for improvement.

Recent advances on chitosan as an adjuvant for vaccine delivery

Chitosan (CS) is a natural polymer derived from chitin that has wide applications in drugs, vaccines, and antigen delivery. The distinctive mucoadhesive, biocompatibility, biodegradable, and less toxic properties of chitosan compared to the currently used vaccine adjuvants made it a promising candidate for use as an adjuvant/carrier in vaccine delivery. In addition, chitosan exhibits intrinsic immunomodulating properties making it a suitable adjuvant in preparing vaccines delivery systems. Nanoparticles (NPs) of chitosan and its derivatives loaded with antigen have been shown to induce cellular and humoral responses. Versatility in the physicochemical properties of chitosan can provide an excellent opportunity to engineer antigen-specific adjuvant/delivery systems. This review discusses the recent advances of chitosan and its derivatives as adjuvants in vaccine deliveryand the published literature in the last fifteen years. The impact of physicochemical properties of chitosan on vaccine formulation has been described in detail. Applications of chitosan and its derivatives, their physicochemical properties, and mechanisms in enhancing immune responses have been discussed. Finally, challenges and future aspects of chitosan use has been pointed out.

Strategies for fighting pandemic virus infections: Integration of virology and drug delivery

Respiratory viruses have sometimes resulted in worldwide pandemics, with the influenza virus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) being major participants. Long-term efforts have made it possible to control the influenza virus, but seasonal influenza continues to take many lives each year, and a pandemic influenza virus sometimes emerges. Although vaccines for coronavirus disease 2019 (COVID-19) have been developed, we are not yet able to coexist with the SARS-CoV-2. To overcome such viruses, it is necessary to obtain knowledge about international surveillance systems, virology, ecology and to determine that immune responses are effective. The information must then be transferred to drugs. Delivery systems would be expected to contribute to the rational development of drugs. In this review, virologist and drug delivery system (DDS) researchers discuss drug delivery strategies, especially the use of lipid-based nanocarriers, for fighting to respiratory virus infections.

Advances in the therapeutic delivery and applications of functionalized Pluronics: A critical review

Pluronic (PEO-PPO-PEO) block copolymers can form nano-sized micelles with a structure composed of a hydrophobic PPO core and hydrophilic PEO shell layer. Pluronics are U.S. Food and Drug Administration approved polymers, which are widely used for solubilization of drugs and their delivery, gene/therapeutic delivery, diagnostics, and tissue engineering applications due to their non-ionic properties, non-toxicity, micelle forming ability, excellent biocompatibility and biodegradability. Although Pluronics have been employed as drug carrier systems for several decades, numerous issues such as rapid dissolution, shorter residence time in biological media, fast clearance and weak mechanical strength have hindered their efficacy. Pluronics have been functionalized with pH-sensitive, biological-responsive moieties, antibodies, aptamers, folic acid, drugs, different nanoparticles, and photo/thermo-responsive hydrogels. These functionalization strategies enable Pluronics to act as stimuli responsive and targeted drug delivery vehicles. Moreover, Pluronics have emerged in nano-emulsion formulations and have been utilized to improve the properties of cubosomes, dendrimers and nano-sheets, including their biocompatibility and aqueous solubility. Functionalization of Pluronics results in the significant improvement of target specificity, loading capacity, biocompatibility of nanoparticles and stimuli responsive hydrogels for the promising delivery of a range of drugs. Therefore, this review presents an overview of all advancements (from the last 15 years) in functionalized Pluronics, providing a valuable tool for industry and academia in order to optimize their use in drug or therapeutic delivery, in addition to several other biomedical applications.

Brief on Recent Application of Liposomal Vaccines for Lower Respiratory Tract Viral Infections: From Influenza to COVID-19 Vaccines

Vaccination is the most effective means of preventing infectious diseases and saving lives. Modern biotechnology largely enabled vaccine development. In the meantime, recent advances in pharmaceutical technology have resulted in the emergence of nanoparticles that are extensively investigated as promising miniaturized drug delivery systems. Scientists are particularly interested in liposomes as an important carrier for vaccine development. Wide acceptability of liposomes lies in their flexibility and versatility. Due to their unique vesicular structure with alternating aqueous and lipid compartments, liposomes can enclose both hydrophilic and lipophilic compounds, including antigens. Liposome composition can be tailored to obtain the desired immune response and adjuvant characteristics. During the current pandemic of COVID-19, many liposome-based vaccines have been developed with great success. This review covers a liposome-based vaccine designed particularly to combat viral infection of the lower respiratory tract (LRT), i.e., infection of the lung, specifically in the lower airways. Viruses such as influenza, respiratory syncytial virus (RSV), severe acute respiratory syndrome (SARS-CoV-1 and SARS-CoV-2) are common causes of LRT infections, hence this review mainly focuses on this category of viruses.

Overcoming barriers by local drug delivery with liposomes

Localized or topical administration of drugs may be considered as a potential approach for overcoming the problems caused by the various biological barriers encountered in drug delivery. The combination of using localized administration routes and delivering drugs in nanoparticulate formulations, such as liposomes, may have additional advantages. Such advantages include prolonged retention of high drug loads at the site of action and controlled release of the drug, ensuring prolonged therapeutic effect; decreased potential for side-effects and toxicity (due to the high topical concentrations of drugs); and increased protection of drugs from possible harsh environments at the site of action. The use of targeted liposomal formulations may further potentiate any acquired therapeutic advantages. In this review we present the most advanced cases of localized delivery of liposomal formulations of drugs, which have been investigated pre-clinically and clinically in the last ten years, together with the reported therapeutic advantages, in each case.

Recent advances in nano/microparticle-based oral vaccines

Background

Vaccines are often recognized as one of the most cost-effective public health interventions in controlling infectious diseases. Most pathogens infiltrate the body from mucosal sites, primarily from the oral and pulmonary region and reach the systemic circulation where disease manifestation starts. Traditional needle-based vaccines are usually not capable of inducing immunity at the mucosal sites where pathogen infiltrates start, but induces systemic immunity. In contrast to needle-based vaccines, mucosally administered vaccines induce immunity at both the mucosal sites and systemically. The oral route of immunization is the most convenient way to administer the vaccines. However, due to the complicated and hostile gastrointestinal structure and environment, vaccines need to overcome major hurdles while retaining their stability and immunogenicity.

Area covered

This review will briefly discuss different barriers to oral vaccine development. It gives a brief overview of different types of nano/microparticle-based oral vaccines and discusses how physicochemical characteristics of the particles influence overall immunity after oral immunization.

Expert opinion

Formulation strategies using novel lipid and polymer-based nano/microparticle platforms retain stability and antigenicity of vaccines against the harsh gastrointestinal condition. The physicochemical properties of particles can be uniquely tailored to prolong the release of antigens, and attached ligands (M-cells and APC-ligands) can precisely target uptake by immune cells. These represent viable strategies for efficient delivery of oral vaccines.

Is the oral microbiome a source to enhance mucosal immunity against infectious diseases?

Mucosal tissues act as a barrier throughout the oral, nasopharyngeal, lung, and intestinal systems, offering first-line protection against potential pathogens. Conventionally, vaccines are applied parenterally to induce serotype-dependent humoral response but fail to drive adequate mucosal immune protection for viral infections such as influenza, HIV, and coronaviruses. Oral mucosa, however, provides a vast immune repertoire against specific microbial pathogens and yet is shaped by an ever-present microbiome community that has co-evolved with the host over thousands of years. Adjuvants targeting mucosal T-cells abundant in oral tissues can promote soluble-IgA (sIgA)-specific protection to confer increased vaccine efficacy. Th17 cells, for example, are at the center of cell-mediated immunity and evidence demonstrates that protection against heterologous pathogen serotypes is achieved with components from the oral microbiome. At the point of entry where pathogens are first encountered, typically the oral or nasal cavity, the mucosal surfaces are layered with bacterial cohabitants that continually shape the host immune profile. Constituents of the oral microbiome including their lipids, outer membrane vesicles, and specific proteins, have been found to modulate the Th17 response in the oral mucosa, playing important roles in vaccine and adjuvant designs. Currently, there are no approved adjuvants for the induction of Th17 protection, and it is critical that this research is included in the preparedness for the current and future pandemics. Here, we discuss the potential of oral commensals, and molecules derived thereof, to induce Th17 activity and provide safer and more predictable options in adjuvant engineering to prevent emerging infectious diseases.

A vaccine combination of lipid nanoparticles and a cholera toxin adjuvant derivative greatly improves lung protection against influenza virus infection

This is a proof-of-principle study demonstrating that the combination of a cholera toxin derived adjuvant, CTA1-DD, and lipid nanoparticles (LNP) can significantly improve the immunogenicity and protective capacity of an intranasal vaccine. We explored the self-adjuvanted universal influenza vaccine candidate, CTA1-3M2e-DD (FPM2e), linked to LNPs. We found that the combined vector greatly enhanced survival against a highly virulent PR8 strain of influenza virus as compared to when mice were immunized with FPM2e alone. The combined vaccine vector enhanced early endosomal processing and peptide presentation in dendritic cells and upregulated co-stimulation. The augmenting effect was CTA1-enzyme dependent. Whereas systemic anti-M2e antibody and CD4⁺ T-cell responses were comparable to those of the soluble protein, the local respiratory tract IgA and the specific Th1 and Th17 responses were strongly enhanced. Surprisingly, the lung tissue did not exhibit gross pathology upon recovery from infection and M2e-specific lung resident CD4⁺ T cells were threefold higher than in FPM2e-immunized mice. This study conveys optimism as to the protective ability of a combination vaccine based on LNPs and various forms of the CTA1-DD adjuvant platform, in general, and, more specifically, an important way forward to develop a universal vaccine against influenza.

Engineered Nanoparticle Applications for Recombinant Influenza Vaccines

Influenza viruses cause seasonal epidemics and represent a pandemic risk. With current vaccine methods struggling to protect populations against emerging strains, there is a demand for a next-generation flu vaccine capable of providing broad protection. Recombinant biotechnology, combined with nanomedicine techniques, could address this demand by increasing immunogenicity and directing immune responses toward conserved antigenic targets on the virus. Various nanoparticle candidates have been tested for use in vaccines, including virus-like particles, protein and carbohydrate nanoconstructs, antigen-carrying lipid particles, and synthetic and inorganic particles modified for antigen presentation. These methods have yielded some promising results, including protection in animal models against antigenically distinct influenza strains, production of antibodies with broad reactivity, and activation of potent T cell responses. Based on the evidence of current research, it is feasible that the next generation of influenza vaccines will combine recombinant antigens with nanoparticle carriers.

Rational application of nanoadjuvant for mucosal vaccine delivery system

The surface of the mucosa is the biggest path through which pathogens enter the human body. We need an understanding of mucosal immune systems to use vaccines that generate protective mucosal and systemic immunity to regulate the outbreak of various infectious diseases. The better impact of the mucosal vaccine over traditional injectable vaccines are that not only do they induce efficient immune reactions to the mucosa but they are also comfortable in physical aspect & psychological aspect. The material of the vaccine includes pathogens antigens and adjuvants, which enable vaccination to be effective. Vaccines are classified into different criteria, including the used vaccine material and method of administration. Vaccines have traditionally been injected through a needle. However, as most of the pathogens first infect the mucosal surfaces, and growing interest is expressed in establishing protective immunity from the mucosa, which is accomplished through mucosal paths through vaccinosis. To improve the existing vaccines further, innovative strategies derived from interdisciplinary scientific research will need to develop new vaccine production, storage, and delivery systems. A distinctive & vast research and development platform has been set up for the growth of the next generation of mucosal vaccinations. The latest science and technological advancement in the areas of molecular biology, bio and chemical engineering, genome and system biology has provided accumulated understanding of the inborn and acquired multi-dimensional immune system. This review summarizes recent developments in the use of mucosal vaccines and their associated nanoadjuvants for the control of infectious diseases.

Enabling sublingual peptide immunization with molecular self-assemblies

Short peptides are poorly immunogenic when delivered sublingually - under the tongue. Nanomaterial delivery of peptides could be utilized to improve immunogenicity towards designed sublingual vaccines, but nanomaterials have not been widely successful in sublingual vaccines owing to the challenges of transport through the sublingual mucosa. Here, we report that the sublingual immunogenicity of peptides is negligible, even in the presence of sublingual adjuvants or when PEGylated, but can be dramatically enhanced by assembly into supramolecular polymer-peptide nanofibers bearing low-molecular weight PEG, optimally between 2000 and 3000 Da. Neither PEGylation nor a sublingual adjuvant were capable of rendering peptides immunogenic without assembly into nanofibers. We found that PEG decreased nanofiber interactions with mucin and promoted longer residence time at the sublingual immunization site. Parallel investigations with shortened nanofibers indicated that the size of the assemblies had a surprisingly negligible influence over sublingual immunogenicity. In mice, optimized formulations were capable of raising strong and highly durable systemic antibody responses, antibodies in the upper respiratory and reproductive tracts, and systemic antigen-specific T-cell responses. These nanofiber-based sublingual vaccines were effective with both protein and nucleotide adjuvants and raised responses against both a model peptide epitope and a peptide epitope from M. tuberculosis. Further, PASylation (modification of nanofibers with peptide sequences rich in Pro, Ala, and Ser) could be substituted for PEGylation to also achieve sublingual immunogenicity. These findings indicated that surface properties supersede nanomaterial size in modulating sublingual nanomaterial immunogenicity, having important implications for the design of synthetic sublingual vaccines.

Prevention of influenza virus infection and transmission by intranasal administration of a porous maltodextrin nanoparticle-formulated vaccine

Influenza vaccines administered intramuscularly exhibit poor mucosal immune responses in the respiratory tract which is the prime site of the infection. Intranasal vaccination is a potential route for vaccine delivery which has been demonstrated effective in inducing protective immune responses in both systemic and mucosal compartments. For this purpose, nanoparticles have been used as antigen delivery systems to improve antigen capture by immune cells. In this paper we demonstrate efficient delivery of viral antigens to airway epithelial cells, macrophages and dendritic cells, using polysaccharide nanoparticles (NPL), leading to a strong protection against influenza virus infection. A formulation combining split Udorn virus antigens with NPL and the mucosal protein adjuvant CTA1-DD was administered intranasally and resulted in an enhanced specific humoral immune response. Furthermore, NPL carrying split Udorn, with or without CTA1-DD, inhibited virus transmission from infected to uninfected naive mice. These results demonstrate that an intranasal delivery system combining NPL, mucosal adjuvant CTA1-DD and split virus antigens confers robust protection against influenza infection and inhibits virus transmission.

Development of an Orodispersible Film Containing Stabilized Influenza Vaccine

Most influenza vaccines are administered via injection, which is considered as user-unfriendly. Vaccination via oral cavity using an orodispersible film (ODF) might be a promising alternative. To maintain the antigenicity of the vaccine during preparation and subsequent storage of these ODFs, sugars such as trehalose and pullulan can be employed as stabilizing excipients for the antigens. In this study, first, β-galactosidase was used as a model antigen. Solutions containing β-galactosidase and sugar (trehalose or trehalose/pullulan blends) were pipetted onto plain ODFs and then either air- or vacuum-dried. Subsequently, sugar ratios yielding the highest β-galactosidase stability were used to prepare ODFs containing H5N1 whole inactivated influenza virus vaccine (WIV). The stability of the H5N1 hemagglutinin was assessed by measuring its hemagglutination activity. Overall, various compositions of trehalose and pullulan successfully stabilized β-galactosidase and WIV in ODFs. WIV incorporated in ODFs showed excellent stability even at challenging storage conditions (60 °C/0% relative humidity or 30 °C/56% relative humidity) for 4 weeks. Except for sugars, the polymeric component of ODFs, i.e., hypromellose, possibly improved stability of WIV as well. In conclusion, ODFs may be suitable for delivering of WIV to the oral cavity and can possibly serve as an alternative for injections.

Nanoparticles for mucosal vaccine delivery

Mucosal surfaces represent important routes of entry into the human body for the majority of pathogens, and they constitute unique sites for targeted vaccine delivery. Nanoparticle-based drug delivery systems are emerging technologies for delivering and improving the efficacy of mucosal vaccines. Recent studies have provided new insights into formulation and delivery aspects of importance for the design of safe and efficacious mucosal subunit vaccines based on nanoparticles. These include novel nanomaterials, their physicochemical properties and formulation approaches, nanoparticle interaction with immune cells in the mucosa, and mucosal immunization and delivery strategies. Here, we present recent progress in the application of nanoparticle-based approaches for mucosal vaccine delivery and discuss future research challenges and opportunities in the field.

Nanomaterials and nanocomposite applications in veterinary medicine

Nowadays, nanotechnology has made huge, significant advancements in biotechnology and biomedicine related to human and animal science, including increasing health safety, production, and the elevation of national income. There are various fields of nanomaterial applications in veterinary medicine such as efficient diagnostic and therapeutic tools, drug delivery, animal nutrition, breeding and reproduction, and valuable additives. Additional benefits include the detection of pathogens, protein, biological molecules, antimicrobial agents, feeding additives, nutrient delivery, and reproductive aids. There are many nanomaterials and nanocomposites that can be used in nanomedicine such as metal nanoparticles, liposomes, carbon nanotubes, and quantum dots. In the near future, nanotechnology research will have the ability to produce novel tools for improving animal health and production. Therefore, this chapter was undertaken to spotlight novel methods created by nanotechnology for application in the improvement of animal health and production. In addition, the toxicity of nanomaterials is fully discussed to avoid the suspected health hazards of toxicity for animal health safety.

Co-encapsulation of synthetic lipidated TLR4 and TLR7/8 agonists in the liposomal bilayer results in a rapid, synergistic enhancement of vaccine-mediated humoral immunity

To increase vaccine immunogenicity, modern vaccines incorporate adjuvants, which serve to enhance immune cross-protection, improve humoral and cell-mediated immunity, and promote antigen dose sparing. Pattern recognition receptors (PRRs), including the Toll-like receptor (TLR) family are promising targets for development of agonist formulations for use as vaccine adjuvants. Combinations of co-delivered TLR4 and TLR7/8 ligands have been demonstrated to have synergistic effects on innate and adaptive immune response. Here, we create liposomes that stably co-encapsulate CRX-601, a synthetic TLR4 agonist, and UM-3004, a lipidated TLR7/8 agonist, within the liposomal bilayer in order to achieve co-delivery, allow tunable physical properties, and induce in vitro and in vivo immune synergy. Co-encapsulation demonstrates a synergistic increase in IL-12p70 cytokine output in vitro from treated human peripheral blood mononuclear cells (hPBMCs). Further, co-encapsulated formulations give significant improvement of early IgG2a antibody titers in BALB/c mice following primary vaccination when compared to single agonist or dual agonists delivered in separate liposomes. This work demonstrates that co-encapsulation of TLR4 and lipidated TLR7/8 agonists within the liposomal bilayer leads to innate and adaptive immune synergy which biases a Th1 immune response. Thus, liposomal co-encapsulation may be a useful and flexible tool for vaccine adjuvant formulation containing multiple TLR agonists.

Liposomes used as a vaccine adjuvant-delivery system: From basics to clinical immunization

Liposomes are widely utilized as a carrier to improve therapeutic efficacy of agents thanks to their merits of high loading capacity, targeting delivery, reliable protection of agents, good biocompatibility, versatile structure modification and adjustable characteristics, such as size, surface charge, membrane flexibility and the agent loading mode. In particular, in recent years, through modification with immunopotentiators and targeting molecules, and in combination with innovative immunization devices, liposomes are rapidly developed as a multifunctional vaccine adjuvant-delivery system (VADS) that has a high capability in inducing desired immunoresponses, as they can target immune cells and even cellular organelles, engender lysosome escape, and promote Ag cross-presentation, thus enormously enhancing vaccination efficacy. Moreover, after decades of development, several products developed on liposome VADS have already been authorized for clinical immunization and are showing great advantages over conventional vaccines. This article describes in depth some critical issues relevant to the development of liposomes as a VADS, including principles underlying immunization, physicochemical properties of liposomes as the immunity-influencing factors, functional material modification to enhance immunostimulatory functions, the state-of-the-art liposome VADSs, as well as the marketed vaccines based on a liposome VADS. Therefore, this article provides a comprehensive reference to the development of novel liposome vaccines.

Theranostics Aspects of Various Nanoparticles in Veterinary Medicine

Nanoscience and nanotechnology shows immense interest in various areas of research and applications, including biotechnology, biomedical sciences, nanomedicine, and veterinary medicine. Studies and application of nanotechnology was explored very extensively in the human medical field and also studies undertaken in rodents extensively, still either studies or applications in veterinary medicine is not up to the level when compared to applications to human beings. The application in veterinary medicine and animal production is still relatively innovative. Recently, in the era of health care technologies, Veterinary Medicine also entered into a new phase and incredible transformations. Nanotechnology has tremendous and potential influence not only the way we live, but also on the way that we practice veterinary medicine and increase the safety of domestic animals, production, and income to the farmers through use of nanomaterials. The current status and advancements of nanotechnology is being used to enhance the animal growth promotion, and production. To achieve these, nanoparticles are used as alternative antimicrobial agents to overcome the usage alarming rate of antibiotics, detection of pathogenic bacteria, and also nanoparticles being used as drug delivery agents as new drug and vaccine candidates with improved characteristics and performance, diagnostic, therapeutic, feed additive, nutrient delivery, biocidal agents, reproductive aids, and finally to increase the quality of food using various kinds of functionalized nanoparticles, such as liposomes, polymeric nanoparticles, dendrimers, micellar nanoparticles, and metal nanoparticles. It seems that nanotechnology is ideal for veterinary applications in terms of cost and the availability of resources. The main focus of this review is describes some of the important current and future principal aspects of involvement of nanotechnology in Veterinary Medicine. However, we are not intended to cover the entire scenario of Veterinary Medicine, despite this review is to provide a glimpse at potential important targets of nanotechnology in the field of Veterinary Medicine. Considering the strong potential of the interaction between the nanotechnology and Veterinary Medicine, the aim of this review is to provide a concise description of the advances of nanotechnology in Veterinary Medicine, in terms of their potential application of various kinds of nanoparticles, secondly we discussed role of nanomaterials in animal health and production, and finally we discussed conclusion and future perspectives of nanotechnology in veterinary medicine.

Liposome: composition, characterisation, preparation, and recent innovation in clinical applications

In the last decades, pharmaceutical interested researches aimed to develop novel and innovative drug delivery techniques in the medical and pharmaceutical fields. Recently, phospholipid vesicles (Liposomes) are the most known versatile assemblies in the drug delivery systems. The discovery of liposomes arises from self-forming enclosed phospholipid bilayer upon coming in contact with the aqueous solution. Liposomes are uni or multilamellar vesicles consisting of phospholipids produced naturally or synthetically, which are readily non-toxic, biodegradable, and are readily produced on a large scale. Various phospholipids, for instance, soybean, egg yolk, synthetic, and hydrogenated phosphatidylcholine consider the most popular types used in different kinds of formulations. This review summarises liposomes composition, characterisation, methods of preparation, and their applications in different medical fields including cancer therapy, vaccine, ocular delivery, wound healing, and some dermatological applications.

Cleavable PEGylation: a strategy for overcoming the "PEG dilemma" in efficient drug delivery

To prolong the circulation time of drug, PEGylation has been widely used via the enhanced permeability and retention (EPR) effect, thereby providing new hope for better treatment. However, PEGylation also brings the "PEG dilemma", which is difficult for the cellular absorption of drugs and subsequent endosomal escape. As a result, the activity of drugs is inevitably lost after PEG modification. To achieve successful drug delivery for effective treatment, the crucial issue associated with the use of PEG-lipids, that is, “PEG dilemma” must be addressed. In this paper, we introduced the development and application of nanocarriers with cleavable PEGylation, and discussed various strategies for overcoming the PEG dilemma. Compared to the traditional ones, the vehicle systems with different environmental-sensitive PEG-lipids were discussed, which cleavage can be achieved in response to the intracellular as well as the tumor microenvironment. This smart cleavable PEGylation provides us an efficient strategy to overcome “PEG dilemma”, thereby may be a good candidate for the cancer treatment in future.

Lipid-Based Particles: Versatile Delivery Systems for Mucosal Vaccination against Infection

Vaccination is the process of administering immunogenic formulations in order to induce or harness antigen (Ag)-specific antibody and T cell responses in order to protect against infections. Important successes have been obtained in protecting individuals against many deleterious pathological situations after parenteral vaccination. However, one of the major limitations of the current vaccination strategies is the administration route that may not be optimal for the induction of immunity at the site of pathogen entry, i.e., mucosal surfaces. It is now well documented that immune responses along the genital, respiratory, or gastrointestinal tracts have to be elicited locally to ensure efficient trafficking of effector and memory B and T cells to mucosal tissues. Moreover, needle-free mucosal delivery of vaccines is advantageous in terms of safety, compliance, and ease of administration. However, the quest for mucosal vaccines is challenging due to (1) the fact that Ag sampling has to be performed across the epithelium through a relatively limited number of portals of entry; (2) the deleterious acidic and proteolytic environment of the mucosae that affect the stability, integrity, and retention time of the applied Ags; and (3) the tolerogenic environment of mucosae, which requires the addition of adjuvants to elicit efficient effector immune responses. Until now, only few mucosally applicable vaccine formulations have been developed and successfully tested. In animal models and clinical trials, the use of lipidic structures such as liposomes, virosomes, immune stimulating complexes, gas-filled microbubbles and emulsions has proven efficient for the mucosal delivery of associated Ags and the induction of local and systemic immune reponses. Such particles are suitable for mucosal delivery because they protect the associated payload from degradation and deliver concentrated amounts of Ags via specialized sampling cells (microfold cells) within the mucosal epithelium to underlying antigen-presenting cells. The review aims at summarizing recent development in the field of mucosal vaccination using lipid-based particles. The modularity ensured by tailoring the lipidic design and content of particles, and their known safety as already established in humans, make the continuing appraisal of these vaccine candidates a promising development in the field of targeted mucosal vaccination.

Engineering nanomaterials to overcome the mucosal barrier by modulating surface properties

Although nanotechnology has been investigated during recent years to increase the bioavailability and therapeutic effects of mucosal administrated drugs, numerous barriers (e.g., pH environment, enzymes and mucus) still limit the delivery efficiency. And the epithelium would also affect the systemic mucosal drug delivery. Amongst all the barriers, the protective mucus has drawn more and more attention, which strongly hinders the accessibility of nanovehicles to epithelium. Therefore, trials to conquer the mucus barrier have been designed using two controversial strategies: mucoadhesion and mucus-penetration. This review summarizes the influence of mucus layer on nanomaterials and introduces the modification strategies by modulating surface properties (i.e., hydrophilicity/hydrophobicity and surface charge) to overcome mucus barriers. Furthermore, it also reviews advanced modification methods to meet the different surface requirements of nanovehicles to overcome mucus and epithelium barriers in systemic mucosal delivery.

Enhancing immunogenicity of antigens through sustained intradermal delivery using chitosan microneedles with a patch-dissolvable design

Reducing the dosage required for vaccination is highly desirable, particularly in cases of epidemic emergencies. This study evaluated the potential of a chitosan microneedle (MN) system with a patch-dissolvable design for low-dose immunization. This system comprises antigen-loaded chitosan MNs and a hydrophilic polyvinyl alcohol/polyvinyl pyrrolidone supporting array patch, which provides extra strength to achieve complete MN insertion and then quickly dissolves in the skin to reduce patch-induced skin irritation. After insertion, MNs could be directly implanted in the dermal layer as an intradermal (ID) depot to allow a sustained release of the model antigen ovalbumin (OVA) for up to 28 days. We found that rats immunized with MNs containing low-dose OVA (approximately 200 μg) had persistently high antibody levels for 18 weeks, which were significantly higher than those observed after an intramuscular injection of full-dose OVA (approximately 500 μg), demonstrating at least 2.5-fold dose sparing. Moreover, OVA-encapsulated chitosan MNs had superior immunogenicity to OVA plus chitosan solution, indicating that MN-based delivery and prolonged skin exposure can further enhance chitosan's adjuvanticity. Therefore, this patch-dissolvable MN system offers a needle-free, accurate, and reliable ID delivery of antigens and has potential as a sustained ID delivery device to improve vaccine efficacy and facilitate dose sparing with existing vaccines.

STATEMENT OF SIGNIFICANCE

This study developed implantable chitosan microneedles (MNs) with a patch-dissolvable design for the sustained intradermal (ID) delivery of antigens and demonstrated their antigen dose-sparing potential. We found that rats immunized with chitosan MNs containing low-dose OVA had persistently high antibody levels for 18 weeks, which were significantly higher than those observed after an intramuscular injection of full-dose OVA, demonstrating at least 2.5-fold dose sparing. Our results indicate that chitosan MNs can not only serve as an efficient vaccine delivery system but also exert their promising adjuvant activity by forming an ID depot for prolonged antigen exposure and activating dendritic cells for promoting immune responses.

Stability, biocompatibility and antioxidant activity of PEG-modified liposomes containing resveratrol

The present investigation reports the development of PEG-modified liposomes for the delivery of naturally occurring resveratrol. PEG-modified liposomes were prepared by direct sonication of the phospholipid aqueous dispersion, in the presence of two PEG-surfactants. Small, spherical, unilamellar vesicles were produced, as demonstrated by light scattering, cryo-TEM, and SAXS. The aging of the vesicles was assessed by using the Turbiscan^® technology, and their physical stability was evaluated in vitro in simulated body fluids, results showing that the key features of the liposomes were preserved. The biocompatibility of the formulations was demonstrated in an ex vivo model of hemolysis in human erythrocytes. Further, the incorporation of resveratrol in PEG-modified liposomes did not affect its intrinsic antioxidant activity, as DPPH radical was almost completely inhibited, and the vesicles were also able to ensure an optimal protection against oxidative stress in an ex vivo human erythrocytes-based model. Therefore, the proposed PEG-modified liposomes, which were prepared by a simple and reliable method, represent an interesting approach to safely deliver resveratrol, ensuring the preservation of the carrier structural integrity in the biological fluids, and the antioxidant efficacy of the polyphenol to be exploited against oxidative stress associated with cancer.

Current Demands for Food-Approved Liposome Nanoparticles in Food and Safety Sector

Safety of food is a noteworthy issue for consumers and the food industry. A number of complex challenges associated with food engineering and food industries, including quality food production and safety of the food through effective and feasible means can be explained by nanotechnology. However, nanoparticles have unique physicochemical properties compared to normal macroparticles of the same composition and thus could interact with living system in surprising ways to induce toxicity. Further, few toxicological/safety assessments have been performed on nanoparticles, thereby necessitating further research on oral exposure risk prior to their application to food. Liposome nanoparticles are viewed as attractive novel materials by the food and medical industries. For example, nanoencapsulation of bioactive food compounds is an emerging application of nanotechnology. In several food industrial practices, liposome nanoparticles have been utilized to improve flavoring and nutritional properties of food, and they have been examined for their capacity to encapsulate natural metabolites that may help to protect the food from spoilage and degradation. This review focuses on ongoing advancements in the application of liposomes for food and pharma sector.

Porous Inorganic Drug Delivery Systems-a Review

Innovative methods and materials have been developed to overcome limitations associated with current drug delivery systems. Significant developments have led to the use of a variety of materials (as excipients) such as inorganic and metallic structures, marking a transition from conventional polymers. Inorganic materials, especially those possessing significant porosity, are emerging as good candidates for the delivery of a range of drugs (antibiotics, anticancer and anti-inflammatories), providing several advantages in formulation and engineering (encapsulation of drug in amorphous form, controlled delivery and improved targeting). This review focuses on key selected developments in porous drug delivery systems. The review provides a short broad overview of porous polymeric materials for drug delivery before focusing on porous inorganic materials (e.g. Santa Barbara Amorphous (SBA) and Mobil Composition of Matter (MCM)) and their utilisation in drug dosage form development. Methods for their preparation and drug loading thereafter are detailed. Several examples of porous inorganic materials, drugs used and outcomes are discussed providing the reader with an understanding of advances in the field and realistic opportunities.

Oestrone-targeted liposomes for mitoxantrone delivery via oestrogen receptor - synthesis, physicochemical characterization and in-vitro evaluation

OBJECTIVES

Targeted delivery of mitoxantrone (MTO, an anthraquinone drug with high antitumour effect) may be achieved using a novel nanoparticulate delivery system via binding the oestrogen receptor (ER, highly expressed in a variety of human tumours).

METHODS

A novel liposomal nanoparticle (NP) was developed using a conjugate derived from 1, 2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino (polyethylene glycol)-2000] (DSPE-PEG₂₀₀₀ -NH₂ ) and oestrone (ES, is known to bind the ER) to produce an ES-targeted PEGylated liposome (ES-SSL). The resulting targeted NP was loaded with MTO to produce a targeted liposome-MTO formulation (ES-SSL-MTO).

KEY FINDINGS

The targeted formulation (~140 nm, 1.5 mV) achieved over 95% drug encapsulation efficiency and a favourable stability at 4, 25 and 37 °C up to 48 h. The flow cytometric data indicated that cellular uptake of ES-SSL into human leukaemia HL-60 cells was mediated via binding the oestrogen receptor. In addition, the ES-SSL-MTO significantly reduced the growth of HL-60 cells.

CONCLUSIONS

Our results provide a proof of principle that ES-modified PEGylated liposomes can target the ER, thereby potentially improving the therapeutic benefits in ER-overexpressed tumours.

Mucosal Vaccine Development Based on Liposome Technology

Immune protection against infectious diseases is most effective if located at the portal of entry of the pathogen. Hence, there is an increasing demand for vaccine formulations that can induce strong protective immunity following oral, respiratory, or genital tract administration. At present, only few mucosal vaccines are found on the market, but recent technological advancements and a better understanding of the principles that govern priming of mucosal immune responses have contributed to a more optimistic view on the future of mucosal vaccines. Compared to live attenuated vaccines, subcomponent vaccines, most often protein-based, are considered safer, more stable, and less complicated to manufacture, but they require the addition of nontoxic and clinically safe adjuvants to be effective. In addition, another limiting factor is the large antigen dose that usually is required for mucosal vaccines. Therefore, the combination of mucosal adjuvants with the recent progress in nanoparticle technology provides an attractive solution to these problems. In particular, the liposome technology is ideal for combining protein antigen and adjuvant into an effective mucosal vaccine. Here, we describe and discuss recent progress in nanoparticle formulations using various types of liposomes that convey strong promise for the successful development of the next generation of mucosal vaccines.

Mucosal vaccine delivery: Current state and a pediatric perspective

Most childhood infections occur via the mucosal surfaces, however, parenterally delivered vaccines are unable to induce protective immunity at these surfaces. In contrast, delivery of vaccines via the mucosal routes can allow antigens to interact with the mucosa-associated lymphoid tissue (MALT) to induce both mucosal and systemic immunity. The induced mucosal immunity can neutralize the pathogen on the mucosal surface before it can cause infection. In addition to reinforcing the defense at mucosal surfaces, mucosal vaccination is also expected to be needle-free, which can eliminate pain and the fear of vaccination. Thus, mucosal vaccination is highly appealing, especially for the pediatric population. However, vaccine delivery across mucosal surfaces is challenging because of the different barriers that naturally exist at the various mucosal surfaces to keep the pathogens out. There have been significant developments in delivery systems for mucosal vaccination. In this review we provide an introduction to the MALT, highlight barriers to vaccine delivery at different mucosal surfaces, discuss different approaches that have been investigated for vaccine delivery across mucosal surfaces, and conclude with an assessment of perspectives for mucosal vaccination in the context of the pediatric population.

Advanced Nanobiomaterials: Vaccines, Diagnosis and Treatment of Infectious Diseases

The use of nanoparticles has contributed to many advances due to their important properties such as, size, shape or biocompatibility. The use of nanotechnology in medicine has great potential, especially in medical microbiology. Promising data show the possibility of shaping immune responses and fighting severe infections using synthetic materials. Different studies have suggested that the addition of synthetic nanoparticles in vaccines and immunotherapy will have a great impact on public health. On the other hand, antibiotic resistance is one of the major concerns worldwide; a recent report of the World Health Organization (WHO) states that antibiotic resistance could cause 300 million deaths by 2050. Nanomedicine offers an innovative tool for combating the high rates of resistance that we are fighting nowadays, by the development of both alternative therapeutic and prophylaxis approaches and also novel diagnosis methods. Early detection of infectious diseases is the key to a successful treatment and the new developed applications based on nanotechnology offer an increased sensibility and efficiency of the diagnosis. The aim of this review is to reveal and discuss the main advances made on the science of nanomaterials for the prevention, diagnosis and treatment of infectious diseases. Highlighting innovative approaches utilized to: (i) increasing the efficiency of vaccines; (ii) obtaining shuttle systems that require lower antibiotic concentrations; (iii) developing coating devices that inhibit microbial colonization and biofilm formation.

Supramolecular Nanostructures Based on Cyclodextrin and Poly(ethylene oxide): Syntheses, Structural Characterizations and Applications for Drug Delivery

Cyclodextrins (CDs) have been extensively studied as drug delivery carriers through host⁻guest interactions. CD-based poly(pseudo)rotaxanes, which are composed of one or more CD rings threading on the polymer chain with or without bulky groups (or stoppers), have attracted great interest in the development of supramolecular biomaterials. Poly(ethylene oxide) (PEO) is a water-soluble, biocompatible polymer. Depending on the molecular weight, PEO can be used as a plasticizer or as a toughening agent. Moreover, the hydrogels of PEO are also extensively studied because of their outstanding characteristics in biological drug delivery systems. These biomaterials based on CD and PEO for controlled drug delivery have received increasing attention in recent years. In this review, we summarize the recent progress in supramolecular architectures, focusing on poly(pseudo)rotaxanes, vesicles and supramolecular hydrogels based on CDs and PEO for drug delivery. Particular focus will be devoted to the structures and properties of supramolecular copolymers based on these materials as well as their use for the design and synthesis of supramolecular hydrogels. Moreover, the various applications of drug delivery techniques such as drug absorption, controlled release and drug targeting based CD/PEO supramolecular complexes, are also discussed.

Novel glycyrrhetinic acid conjugated pH-sensitive liposomes for the delivery of doxorubicin and its antitumor activities

A novel pH-sensitive conjugate glycyrrhetinic acid–polyethylene glycol–Schiff bond–cholesterol (GPSC) has been synthesized successfully and used to construct doxorubicin-loaded liposomes with both pH-sensitive features and active targeting ability.