Surface-modified P(HEMA-co-MAA) nanogel carriers for oral vaccine delivery: design, characterization, and in vitro targeting evaluation

Paracellular Delivery of Protein Drugs with Smart EnteroPatho Nanoparticles

A general platform for the safe and effective oral delivery of biologics would revolutionize the administration of protein-based drugs, improving access for patients and lowering the financial burden on the health-care industry. Because of their dimensions and physiochemical properties, nanomaterials stand as promising vehicles for navigating the complex and challenging environment in the gastrointestinal (GI) tract. Recent developments have led to materials that protect protein drugs from degradation and enable controlled release in the small intestine, the site of absorption for most proteins. Yet, once present in the small intestine, the protein must transit through the secreted mucus and epithelial cells of the intestinal mucosa into systemic circulation, a process that remains a bottleneck for nanomaterial-based delivery. One attractive pathway through the intestinal mucosa is the paracellular route, which avoids cell trafficking and other degradative processes in the interior of cells. Direct flux between cells is regulated by epithelial tight junctions (TJs) that seal the paracellular space and prevent protein flux. Here, we describe a smart nanoparticle system that directly and transiently disrupts TJs for improved protein delivery, an unrealized goal to-date. We take inspiration from enteropathogenic bacteria that adhere to intestinal epithelia and secrete inhibitors that block TJ interactions in the local environment. To mimic these natural mechanisms, we engineer nanoparticles (EnteroPatho NPs) that attach to the epithelial glycocalyx and release TJ modulators in response to the intestinal pH. We show that EnteroPatho NPs lead to TJ disruption and paracellular protein delivery, giving rise to a general platform for oral delivery.

Dual stimuli-responsive delivery system for self-regulated colon-targeted delivery of poorly water-soluble drugs

Inflammatory bowel disease (IBD) are chronic inflammatory conditions which cause significant patient morbidity. Local drug delivery to the colon can improve treatment efficacy and reduce side effects associated with IBD treatment. Smart drug delivery systems are designed to regulate the release of therapeutic agents at the desired site of action. pH-responsive drug carriers have been previously utilised for improved oral drug delivery beyond stomach harsh conditions. Additionally, the colon possesses a diverse microbiome secreting bioactive molecules e.g., enzymes, that can be exploited for targeted drug delivery. We herein synthesised and characterised a 2-hydroxyethyl methacrylate and methacrylic acid copolymer, crosslinked with an azobenzyl crosslinker, that displayed pH- and enzyme-responsive properties. The swelling and drug release from hydrogel were analysed in pH 1.2, 6.5 and 7.4 buffers, and in the presence of rat caecal matter using metronidazole and mesalamine as model BCS Class I and IV drugs, respectively. Swelling studies displayed pH-responsive swelling behaviour, where swelling was maximum at pH 7.4 and minimum at pH 1.2 (69 % versus 32 %). Consequently, drug release was limited in gastric and small intestinal conditions but increased significantly when exposed to colonic conditions containing caecal matter. This system displays promising capacity for achieving colon-targeted drug delivery with enhanced dissolution of poorly water-soluble drugs for local treatment of IBD and other colon-targeted therapies.

Polymer-Based Hydrogels Applied in Drug Delivery: An Overview

Polymer-based hydrogels are hydrophilic polymer networks with crosslinks widely applied for drug delivery applications because of their ability to hold large amounts of water and biological fluids and control drug release based on their unique physicochemical properties and biocompatibility. Current trends in the development of hydrogel drug delivery systems involve the release of drugs in response to specific triggers such as pH, temperature, or enzymes for targeted drug delivery and to reduce the potential for systemic toxicity. In addition, developing injectable hydrogel formulations that are easily used and sustain drug release during this extended time is a growing interest. Another emerging trend in hydrogel drug delivery is the synthesis of nano hydrogels and other functional substances for improving targeted drug loading and release efficacy. Following these development trends, advanced hydrogels possessing mechanically improved properties, controlled release rates, and biocompatibility is developing as a focus of the field. More complex drug delivery systems such as multi-drug delivery and combination therapies will be developed based on these advancements. In addition, polymer-based hydrogels are gaining increasing attention in personalized medicine because of their ability to be tailored to a specific patient, for example, drug release rates, drug combinations, target-specific drug delivery, improvement of disease treatment effectiveness, and healthcare cost reduction. Overall, hydrogel application is advancing rapidly, towards more efficient and effective drug delivery systems in the future.

Recent Advances in the Biomedical Applications of Functionalized Nanogels

Nanomaterials have been extensively used in several applications in the past few decades related to biomedicine and healthcare. Among them, nanogels (NGs) have emerged as an important nanoplatform with the properties of both hydrogels and nanoparticles for the controlled/sustained delivery of chemo drugs, nucleic acids, or other bioactive molecules for therapeutic or diagnostic purposes. In the recent past, significant research efforts have been invested in synthesizing NGs through various synthetic methodologies such as free radical polymerization, reversible addition-fragmentation chain-transfer method (RAFT) and atom transfer radical polymerization (ATRP), as well as emulsion techniques. With further polymeric functionalizations using activated esters, thiol-ene/yne processes, imines/oximes formation, cycloadditions, nucleophilic addition reactions of isocyanates, ring-opening, and multicomponent reactions were used to obtain functionalized NGs for targeted delivery of drug and other compounds. NGs are particularly intriguing for use in the areas of diagnosis, analytics, and biomedicine due to their nanodimensionality, material characteristics, physiological stability, tunable multi-functionality, and biocompatibility. Numerous NGs with a wide range of functionalities and various external/internal stimuli-responsive modalities have been possible with novel synthetic reliable methodologies. Such continuous development of innovative, intelligent materials with novel characteristics is crucial for nanomedicine for next-generation biomedical applications. This paper reviews the synthesis and various functionalization strategies of NGs with a focus on the recent advances in different biomedical applications of these surface modified/functionalized single-/dual-/multi-responsive NGs, with various active targeting moieties, in the fields of cancer theranostics, immunotherapy, antimicrobial/antiviral, antigen presentation for the vaccine, sensing, wound healing, thrombolysis, tissue engineering, and regenerative medicine.

Bioengineered nanogels for cancer immunotherapy

Recent years have witnessed increasingly rapid advances in nanocarrier-based biomedicine aimed at improving treatment paradigms for cancer. Nanogels serve as multipurpose and constructed vectors formed via intramolecular cross-linking to generate drug delivery systems, which is attributed predominantly to their satisfactory biocompatibility, bio-responsiveness, high stability, and low toxicity. Recently, immunotherapy has experienced unprecedented growth and has become the preferred strategy for cancer treatment, and mainly involves the mobilisation of the immune system and an enhanced anti-tumour immunity of the tumour microenvironment. Despite the inspiring success, immunotherapeutic strategies are limited due to the low response rates and immune-related adverse events. Like other nanomedicines, nanogels are comparably limited by lower focal enrichment rates upon introduction into the organism via injection. Because nanogels are three-dimensional cross-linked aqueous materials that exhibit similar properties to natural tissues and are structurally stable, they can comfortably cope with shear forces and serum proteins in the bloodstream, and the longer circulation life increases the chance of nanogel accumulation in the tumour, conferring deep tumour penetration. The large specific surface area can reduce or eliminate off-target effects by introducing stimuli-responsive functional groups, allowing multiple physical and chemical modifications for specific purposes to improve targeting to specific immune cell subpopulations or immune organs, increasing the bioavailability of the drug, and conferring a low immune-related adverse events on nanogel therapies. The slow release upon reaching the tumour site facilitates long-term awakening of the host's immune system, ultimately achieving enhanced therapeutic effects. As an effective candidate for cancer immunotherapy, nanogel-based immunotherapy has been widely used. In this review, we mainly summarize the recent advances of nanogel-based immunotherapy to deliver immunomodulatory small molecule drugs, antibodies, genes and cytokines, to target antigen presenting cells, form cancer vaccines, and enable chimeric antigen receptor (CAR)-T cell therapy. Future challenges as well as expected and feasible prospects for clinical treatment are also highlighted.

Engineered Nanoparticles inside a Microparticle Oral System for Enhanced Mucosal and Systemic Immunity

Antigen delivery through an oral route requires overcoming multiple challenges, including gastrointestinal enzymes, mucus, and epithelial tight junctions. Although each barrier has a crucial role in determining the final efficiency of the oral vaccination, transcytosis of antigens through follicle-associated epithelium (FAE) represents a major challenge. Most of the research is focused on delivering an antigen to the M-cell for FAE transcytosis because M-cells can easily transport the antigen from the luminal site. However, the fact is that the M-cell population is less than 1% of the total gastrointestinal cells, and most of the oral vaccines have failed to show any effect in clinical trials. To challenge the current dogma of M-cell targeting, in this study, we designed a novel tandem peptide with a FAE-targeting peptide at the front position and a cell-penetrating peptide at the back position. The tandem peptide was attached to a smart delivery system, which overcomes the enzymatic barrier and the mucosal barrier. The result showed that the engineered system could target the FAE (enterocytes and M-cells) and successfully penetrate the enterocytes to reach the dendritic cells located at the subepithelium dome. There was successful maturation and activation of dendritic cells in vitro confirmed by a significant increase in maturation markers such as CD40, CD86, presentation marker MHC I, and proinflammatory cytokines (TNF-α, IL-6, and IL-10). The in vivo results showed a high production of CD4+ T-lymphocytes (helper T-cell) and a significantly higher production of CD8+ T-lymphocytes (killer T-cell). Finally, the production of mucosal immunity (IgA) in the trachea, intestine, and fecal extracts and systemic immunity (IgG, IgG1, and IgG2a) was successfully confirmed. To the best of our knowledge, this is the first study that designed a novel tandem peptide to target the FAE, which includes M-cells and enterocytes rather than M-cell targeting and showed that a significant induction of both the mucosal and systemic immune response was achieved compared to M-cell targeting.

Formulation Development and Evaluation of Pravastatin-Loaded Nanogel for Hyperlipidemia Management

Hyperlipidemia is a crucial risk factor for the initiation and progression of atherosclerosis, ultimately leading to cardiovascular disease. The nanogel-based nanoplatform has emerged as an extremely promising drug delivery technology. Pravastatin Sodium (PS) is a cholesterol-lowering drug used to treat hyperlipidemia. This study aimed to fabricate Pravastatin-loaded nanogel for evaluation of its effect in hyperlipidemia treatment. Pravastatin-loaded chitosan nanoparticles (PS-CS-NPs) were prepared by the ionic gelation method; then, these prepared NPs were converted to nanogel by adding a specified amount of 5% poloxamer solution. Various parameters, including drug entrapment efficacy, in vitro drug release, and hemolytic activity of the developed and optimized formulation, were evaluated. The in vitro drug release of the nanogel formulation revealed the sustained release (59.63% in 24 h) of the drug. The drug excipients compatibility studies revealed no interaction between the drug and the screened excipients. Higher drug entrapment efficacy was observed. The hemolytic activity showed lesser toxicity in nanoformulation than the pure drug solution. These findings support the prospective use of orally administered pravastatin-loaded nanogel as an effective and safe nano delivery system in hyperlipidemia treatment.

Receptor-targeted nanoparticles modulate cannabinoid anticancer activity through delayed cell internalization

Δ9-tetrahydrocannabinol (Δ9-THC) is known for its antitumor activity and palliative effects. However, its unfavorable physicochemical and biopharmaceutical properties, including low bioavailability, psychotropic side effects and resistance mechanisms associated to dosing make mandatory the development of successful drug delivery systems. In this work, transferring (Tf) surface-modified Δ9-THC-loaded poly(lactide-co-glycolic) nanoparticles (Tf-THC-PLGA NPs) were proposed and evaluated as novel THC-based anticancer therapy. Furthermore, in order to assess the interaction of both the nanocarrier and the loaded drug with cancer cells, a double-fluorescent strategy was applied, including the chemical conjugation of a dye to the nanoparticle polymer along with the encapsulation of either a lipophilic or a hydrophilic dye. Tf-THC PLGA NPs exerted a cell viability decreased down to 17% vs. 88% of plain nanoparticles, while their internalization was significantly slower than plain nanoparticles. Uptake studies in the presence of inhibitors indicated that the nanoparticles were internalized through cholesterol-associated and clathrin-mediated mechanisms. Overall, Tf-modification of PLGA NPs showed to be a highly promising approach for Δ9-THC-based antitumor therapies, potentially maximizing the amount of drug released in a sustained manner at the surface of cells bearing cannabinoid receptors.

Messenger RNA-based vaccines: Past, present, and future directions in the context of the COVID-19 pandemic

mRNA vaccines have received major attention in the fight against COVID-19. Formulations from companies such as Moderna and BioNTech/Pfizer have allowed us to slowly ease the social distancing measures, mask requirements, and lockdowns that have been prevalent since early 2020. This past year's focused work on mRNA vaccines has catapulted this technology to the forefront of public awareness and additional research pursuits, thus leading to new potential for bionanotechnology principles to help drive further innovation using mRNA. In addition to alleviating the burden of COVID-19, mRNA vaccines could potentially provide long-term solutions all over the world for diseases ranging from influenza to AIDS. Herein, we provide a brief commentary based on the history and development of mRNA vaccines in the context of the COVID-19 pandemic. Furthermore, we address current research using the technology and future directions of mRNA vaccine research.

Montmorillonite stabilized chitosan-co-mucin hydrogel for tissue engineering applications

The role of polymers has played a crucial role in developing templates that can promote regeneration as tissue-engineered matrices. The present study aims to develop functional matrices involving the protein mucin. The mucin used in this study is characterised using MALDI-TOF TOF and CD spectroscopy prior to conjugation. Thereupon, a hybrid scaffold comprising of a polysaccharide, chitosan, chemically conjugated to a protein, mucin, and encapsulated with montmorillonite is developed. Grafting of hydroxyethyl methacrylate (HEMA) is done to overcome the issue of mechanical weakness that mucin hydrogels usually undergo. It was observed that the presence of montmorillonite led to the stability of the hydrogels. The conjugations with varied ratios of the polysaccharide and protein were characterized using spectroscopic techniques. The prepared gels showed appreciable material properties in terms of water uptake and porosity. Hydrogels with different ratios of the polysaccharide and protein were evaluated for their biocompatibility. The biological evaluation of the hydrogels was performed with MC3T3E1 and C2C12 cell lines indicating their potential for wider tissue engineering applications.

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

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

Nanogels Capable of Triggered Release

This chapter provides an overview of soft and environmentally sensitive polymeric nanosystems, which are widely known as nanogels. These particles keep great promise to the area of drug delivery due to their high biocompatibility with body fluids and tissues, as well as due to their ability to encapsulate and release the loaded drugs in a controlled manner. For a long period of time, the controlled drug delivery systems were designed to provide long-termed or sustained release. However, some medical treatments such as cancer chemotherapy, protein and gene delivery do not require the prolonged release of the drug in the site of action. In contrast, the rapid increase of the drug concentration is needed for gaining the desired biological effect. Being very sensitive to surrounding media and different stimuli, nanogels can undergo physico-chemical transitions or chemical changes in their structure. Such changes can result in more rapid release of the drugs, which is usually referred to as triggered drug release. Herein we give the basic information on nanogel unique features, methods of sensitive nanogels preparation, as well as on main mechanisms of triggered release. Additionally, the triggered release of low-molecular drugs and biomacromolecules are discussed.

Natural and synthetic carbohydrate-based vaccine adjuvants and their mechanisms of action

Modern subunit vaccines based on homogeneous antigens offer more precise targeting and improved safety compared with traditional whole-pathogen vaccines. However, they are also less immunogenic and require an adjuvant to increase the immunogenicity of the antigen and potentiate the immune response. Unfortunately, few adjuvants have sufficient potency and low enough toxicity for clinical use, highlighting the urgent need for new, potent and safe adjuvants. Notably, a number of natural and synthetic carbohydrate structures have been used as adjuvants in clinical trials, and two have recently been approved in human vaccines. However, naturally derived carbohydrate adjuvants are heterogeneous, difficult to obtain and, in some cases, unstable. In addition, their molecular mechanisms of action are generally not fully understood, partly owing to the lack of tools to elucidate their immune-potentiating effects, thus hampering the rational development of optimized adjuvants. To address these challenges, modification of the natural product structure using synthetic chemistry emerges as an attractive approach to develop well-defined, improved carbohydrate-containing adjuvants and chemical probes for mechanistic investigation. This Review describes selected examples of natural and synthetic carbohydrate-based adjuvants and their application in synthetic self-adjuvanting vaccines, while also discussing current understanding of their molecular mechanisms of action.

Advances in Oral Subunit Vaccine Design

Many pathogens invade the host at the intestinal surface. To protect against these enteropathogens, the induction of intestinal secretory IgA (SIgA) responses is paramount. While systemic vaccination provides strong systemic immune responses, oral vaccination is the most efficient way to trigger protective SIgA responses. However, the development of oral vaccines, especially oral subunit vaccines, is challenging due to mechanisms inherent to the gut. Oral vaccines need to survive the harsh environment in the gastrointestinal tract, characterized by low pH and intestinal proteases and need to reach the gut-associated lymphoid tissues, which are protected by chemical and physical barriers that prevent efficient uptake. Furthermore, they need to surmount default tolerogenic responses present in the gut, resulting in suppression of immunity or tolerance. Several strategies have been developed to tackle these hurdles, such as delivery systems that protect vaccine antigens from degradation, strong mucosal adjuvants that induce robust immune responses and targeting approaches that aim to selectively deliver vaccine antigens towards specific immune cell populations. In this review, we discuss recent advances in oral vaccine design to enable the induction of robust gut immunity and highlight that the development of next generation oral subunit vaccines will require approaches that combines these solutions.

Oral Delivery of Biologics for Precision Medicine

The emerging field of precision medicine is rapidly growing, fostered by the advances in genome mapping and molecular diagnosis. In general, the translation of these advances into precision treatments relies on the use of biological macromolecules, whose structure offers a high specificity and potency. Unfortunately, due to their complex structure and limited ability to overcome biological barriers, these macromolecules need to be administered via injection. The scientific community has devoted significant effort to making the oral administration of macromolecules plausible thanks to the implementation of drug delivery technologies. Here, an overview of the current situation and future prospects in the field of oral delivery of biologics is provided. Technologies in clinical trials, as well as recent and disruptive delivery systems proposed in the literature for local and systemic delivery of biologics including peptides, antibodies, and nucleic acids, are described. Strategies for the specific targeting of gastrointestinal regions-stomach, small bowel, and colon-cell populations, and internalization pathways, are analyzed. Finally, challenges associated with the clinical translation, future prospects, and identified opportunities for advancement in this field are also discussed.

An overview of nanogel-based vaccines

Introduction: The development of more efficacious vaccines, especially subunit vaccines administered via non-invasive routes, is a priority in vaccinology. Nanogels are materials that can meet the requirements to serve as efficient vaccine delivery vehicles (in terms of thermo-sensitivity, biocompatibility, and pH-responsiveness; among others); thus there is a growing interest in exploring the potential of nanogels for vaccine development. Areas covered: Herein, a critical analysis of nanogel synthesis methodologies is presented and nanogel-based vaccines under development are summarized and placed in perspective. Promising vaccine candidates based on nanogels have been reported for cancer, obesity, and infectious diseases (mainly respiratory diseases). Some of the candidates were administered by mucosal routes which are highly attractive in terms of simple administration and induction of protective responses at both mucosal and systemic levels. Expert opinion: The most advanced models of nanogel-based vaccines comprise candidates against cancer, based on cholesteryl pullulan nanogels evaluated in clinical trials with promising findings; as well as some vaccines against respiratory pathogens tested in mice thus far. Nonetheless, the challenge for this field is advancing in clinical trials and proving the protective potential in test animals for many other candidates. Implementing green synthesis approaches for nanogels is also required.

Engineered microscale hydrogels for drug delivery, cell therapy, and sequencing

Engineered microscale hydrogels have emerged as promising therapeutic approaches for the treatment of various diseases. These microgels find wide application in the biomedical field because of the ease of injectability, controlled release of therapeutics, flexible means of synthesis, associated tunability, and can be engineered as stimuli-responsive. While bulk hydrogels of several length-scale dimensions have been used for over two decades in drug delivery applications, their use as microscale carriers of drug and cell-based therapies is relatively new. Herein, we critically summarize the fundamentals of hydrogels based on their equilibrium and dynamics of their molecular structure, as well as solute diffusion as it relates to drug delivery. In addition, examples of common microgel synthesis techniques are provided. The ability to tune microscale hydrogels to obtain controlled release of therapeutics is discussed, along with microgel considerations for cell encapsulation as it relates to the development of cell-based therapies. We conclude with an outlook on the use of microgels for cell sequencing, and the convergence of the use of microscale hydrogels for drug delivery, cell therapy, and cell sequencing based systems.

Versatile functionalization of surface-tailorable polymer nanohydrogels for drug delivery systems

Surface-tailorable nanohydrogels with catechol groups as a universal anchor were developed for versatile functionalization in drug delivery applications.

Oral Vaccine Delivery for Intestinal Immunity-Biological Basis, Barriers, Delivery System, and M Cell Targeting

Most currently available commercial vaccines are delivered by systemic injection. However, needle-free oral vaccine delivery is currently of great interest for several reasons, including the ability to elicit mucosal immune responses, ease of administration, and the relatively improved safety. This review summarizes the biological basis, various physiological and immunological barriers, current delivery systems with delivery criteria, and suggestions for strategies to enhance the delivery of oral vaccines. In oral vaccine delivery, basic requirements are the protection of antigens from the GI environment, targeting of M cells and activation of the innate immune response. Approaches to address these requirements aim to provide new vaccines and delivery systems that mimic the pathogen's properties, which are capable of eliciting a protective mucosal immune response and a systemic immune response and that make an impact on current oral vaccine development.

Polysaccharides as vaccine adjuvants

Adjuvant is a substance added to vaccine to improve the immunogenicity of antigens, and it can induce stronger immune responses and reduce the dosage and production cost of vaccine in populations responding poorly to vaccination. Adjuvants in development or in use mainly include aluminum salts, oil emulsions, saponins, immune-stimulating complexes, liposomes, microparticles, nonionic block copolymers, polysaccharides, cytokines and bacterial derivatives. Polysaccharide adjuvants have attracted much attention in the preparation of nano vaccines and nano drugs because natural polysaccharides have the characteristics of intrinsic immunomodulating, biocompatibility, biodegradability, low toxicity and safety. Moreover, it has been proved that a variety of natural polysaccharides possess better immune promoting effects, and they can enhance the effects of humoral, cellular and mucosal immunities. In the present study, we systematically reviewed the recent studies on polysaccharides with vaccine adjuvant activities, including chitosan-based nanoparticles (NPs), glucan, mannose, inulin polysaccharide and Chinese medicinal herb polysaccharide. The application and future perspectives of polysaccharides as adjuvants were also discussed. These findings lay a foundation for the further development of polysaccharide adjuvants. Collectively, more and more polysaccharide adjuvants will be developed and widely used in clinical practice with more in-depth investigations of polysaccharide adjuvants.

Advance in oral delivery systems for therapeutic protein

Oral delivery is the most common method of drug administration with high safety and good compliance for patients. However, delivering therapeutic proteins to the target site via oral route involves tremendous challenge due to unfavourable conditions like biochemical barrier, mucus barrier and epithelial barriers. According to the functional differences of various protein drug delivery systems, the recent advances in pH responsive polymer-based drug delivery system, mucoadhesive polymer-based drug delivery system, absorption enhancers-based drug delivery system and composite polymer-based delivery system all were briefly summarised in this review, which not only clarified the clinic potential of these novel drug delivery systems, but also described the way for increasing oral bioavailability of therapeutic protein.

Tunable poly(methacrylic acid-co-acrylamide) nanoparticles through inverse emulsion polymerization

Environmentally responsive biomaterials have played key roles in the design of biosensors and drug delivery vehicles. Their physical response to external stimuli, such as temperature or pH, can transduce a signal or trigger the release of a drug. In this work, we designed a robust, highly tunable, pH-responsive nanoscale hydrogel system. We present the design and characterization of poly(methacrylic acid-co-acrylamide) hydrogel nanoparticles, crosslinked with methylenebisacrylamide, through inverse emulsion polymerization. The effects of polymerization parameters (i.e., identities and concentrations of monomer and surfactant) and polymer composition (i.e., weight fraction of ionic and crosslinking monomers) on the nanoparticles' bulk and environmentally responsive properties were determined. We generated uniform, spherical nanoparticles which, through modulation of crosslinking, exhibit a volume swelling of 1.77-4.07, relative to the collapsed state in an acidic environment. We believe our system has potential as a base platform for the targeted, injectable delivery of hydrophilic therapeutics. With equal importance, however, we hope that our systematic analysis of the individual impacts of polymerization and purification conditions on nanoparticle composition, morphology, and performance can be used to expedite the development of alternate hydrophilic nanomaterials for a range of biomedical applications. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1677-1686, 2018.

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

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

Responsive crosslinked polymer nanogels for imaging and therapeutics delivery

Nanogels are water-soluble crosslinked polymer networks with tremendous potential in targeted imaging and controlled drug and gene delivery.

pH-Responsive carriers for oral drug delivery: challenges and opportunities of current platforms

Oral administration is a desirable alternative of parenteral administration due to the convenience and increased compliance to patients, especially for chronic diseases that require frequent administration. The oral drug delivery is a dynamic research field despite the numerous challenges limiting their effective delivery, such as enzyme degradation, hydrolysis and low permeability of intestinal epithelium in the gastrointestinal (GI) tract. pH-Responsive carriers offer excellent potential as oral therapeutic systems due to enhancing the stability of drug delivery in stomach and achieving controlled release in intestines. This review provides a wide perspective on current status of pH-responsive oral drug delivery systems prepared mainly with organic polymers or inorganic materials, including the strategies used to overcome GI barriers, the challenges in their development and future prospects, with focus on technology trends to improve the bioavailability of orally delivered drugs, the mechanisms of drug release from pH-responsive oral formulations, and their application for drug delivery, such as protein and peptide therapeutics, vaccination, inflammatory bowel disease (IBD) and bacterial infections.

Basic concepts and recent advances in nanogels as carriers for medical applications

Nanogels in biomedical field are promising and innovative materials as dispersions of hydrogel nanoparticles based on crosslinked polymeric networks that have been called as next generation drug delivery systems due to their relatively high drug encapsulation capacity, uniformity, tunable size, ease of preparation, minimal toxicity, stability in the presence of serum, and stimuli responsiveness. Nanogels show a great potential in chemotherapy, diagnosis, organ targeting and delivery of bioactive substances. The main subjects reviewed in this article concentrates on: (i) Nanogel assimilation in the nanomedicine domain; (ii) Features and advantages of nanogels, the main characteristics, such as: swelling capacity, stimuli sensitivity, the great surface area, functionalization, bioconjugation and encapsulation of bioactive substances, which are taken into account in designing the structures according to the application; some data on the advantages and limitations of the preparation techniques; (iii) Recent progress in nanogels as a carrier of genetic material, protein and vaccine. The majority of the scientific literature presents the multivalency potential of bioconjugated nanogels in various conditions. Today's research focuses over the overcoming of the restrictions imposed by cost, some medical requirements and technological issues, for nanogels' commercial scale production and their integration as a new platform in biomedicine.

Current state and challenges in developing oral vaccines

While vaccination remains the most cost effective strategy for disease prevention, communicable diseases persist as the second leading cause of death worldwide. There is a need to design safe, novel vaccine delivery methods to protect against unaddressed and emerging diseases. Development of vaccines administered orally is preferable to traditional injection-based formulations for numerous reasons including improved safety and compliance, and easier manufacturing and administration. Additionally, the oral route enables stimulation of humoral and cellular immune responses at both systemic and mucosal sites to establish broader and long-lasting protection. However, oral delivery is challenging, requiring formulations to overcome the harsh gastrointestinal (GI) environment and avoid tolerance induction to achieve effective protection. Here we address the rationale for oral vaccines, including key biological and physicochemical considerations for next-generation oral vaccine design.

Double conjugated nanogels for selective intracellular drug delivery

One of the most important drawbacks of nanomedicine is related to the unwanted rapid diffusion of drugs loaded within nanocarriers towards the external biological environment, according to the high clearance of body fluids.

“Click” functionalization of dual stimuli-responsive polymer nanocapsules for drug delivery systems

“Clickable” and dual stimuli-responsive nanocapsules were developed for facile surface functionalizationviathiol–yne click chemistry and employed as drug nano-carriers.

The identification of goat peroxiredoxin-5 and the evaluation and enhancement of its stability by nanoparticle formation

An anticancer bioactive peptide (ACBP), goat peroxiredoxin-5 (gPRDX5), was identified from goat-spleen extract after immunizing the goat with gastric cancer-cell lysate. Its amino acid sequence was determined by employing 2D nano-LC-ESI-LTQ-Orbitrap MS/MS combined with Mascot database search in the goat subset of the Uniprot database. The recombinant gPRDX5 protein was acquired by heterogeneous expression in Escherichia coli. Subsequently, the anti-cancer bioactivity of the peptide was measured by several kinds of tumor cells. The results indicated that the gPRDX5 was a good anti-cancer candidate, especially for killing B16 cells. However, the peptide was found to be unstable without modification with pharmaceutical excipients, which would be a hurdle for future medicinal application. In order to overcome this problem and find an effective way to evaluate the gPRDX5, nanoparticle formation, which has been widely used in drug delivery because of its steadiness in application, less side-effects and enhancement of drug accumulation in target issues, was used here to address the issues. In this work, the gPRDX5 was dispersed into nanoparticles before delivered to B16 cells. By the nanotechnological method, the gPRDX5 was stabilized by a fast and accurate procedure, which suggests a promising way for screening the peptide for further possible medicinal applications.

Shape-Dependent Activation of Cytokine Secretion by Polymer Capsules in Human Monocyte-Derived Macrophages

Particles with tailored geometries have received significant attention due to their specific interactions with biological systems. In this work, we examine the effect of polymer capsule shape on cytokine secretion by human monocyte-derived macrophages. Thiolated poly(methacrylic acid) (PMASH) polymer capsules with different shapes (spherical, short rod-shaped, and long rod-shaped) were prepared by layer-by-layer assembly. The effect of PMASH capsule shape on cellular uptake and cytokine secretion by macrophages differentiated from THP-1 monocytes (dTHP-1) was investigated. PMASH capsules with different shapes were internalized to a similar extent in dTHP-1 cells. However, cytokine secretion was influenced by capsule geometry: short rod-shaped PMASH capsules promoted a stronger increase in TNF-α and IL-8 secretion compared with spherical (1.7-fold in TNF-α and 2.1-fold in IL-8) and long rod-shaped (2.8-fold in TNF-α and 2.0-fold in IL-8) PMASH capsules in dTHP-1 cells (capsule-to-cell ratio of 100:1). Our results indicate that the immunological response based on the release of cytokines is influenced by the shape of the polymer capsules, which could be potentially exploited in the rational design of particle carriers for vaccine delivery.

Water dispersible siloxane nanogels: a novel technique to control surface characteristics and drug release kinetics

Amphiphilic, water-dispersible, crosslinked siloxane nanogels were synthesized and applied as optically clear, functional coatings on the surface of lens substrates to demonstrate the feasibility of siloxane-nanogels to generate covalently tethered coatings and modify the surface properties of intraocular lens substrates.

Surfactant-Free Emulsion-Based Preparation of Redox-Responsive Nanogels

A surfactant-free emulsion-based approach is developed for preparation of nanogels. A water-in-oil emulsion is generated feasibly from a mixture of water and a solution of disulfide-containing hyperbranched PEGylated poly(amido amine)s, poly(BAC2-AMPD1)-PEG, in chloroform. The water droplets in the emulsion are stabilized and filled with poly(BAC2-AMPD1)-PEG, and the crosslinked poly(amido amine)s nanogels are formed via the intermolecular disulfide exchange reaction. FITC-dextran is loaded within the nanogels by dissolving the compound in water before emulsification. Transmission electron microscopy and dynamic light scattering are applied to characterize the emulsion and the nanogels. The effects of the homogenization rate and the ratio of water/polymer are investigated. Redox-induced degradation and FITC-dextran release profile of the nanogels are monitored, and the results show efficient loading and redox-responsive release of FITC-dextran. This is a promising approach for the preparation of nanogels for drug delivery, especially for neutral charged carbohydrate-based drugs.

Micro/nanofabricated platforms for oral drug delivery

The oral route of drug administration is most preferred due to its ease of use, low cost, and high patient compliance. However, the oral uptake of many small molecule drugs and biotherapeutics is limited by various physiological barriers, and, as a result, drugs suffer from issues with low solubility, low permeability, and degradation following oral administration. The flexibility of micro- and nanofabrication techniques has been used to create drug delivery platforms designed to address these barriers to oral drug uptake. Specifically, micro/nanofabricated devices have been designed with planar, asymmetric geometries to promote device adhesion and unidirectional drug release toward epithelial tissue, thereby prolonging drug exposure and increasing drug permeation. Furthermore, surface functionalization, nanotopography, responsive drug release, motion-based responses, and permeation enhancers have been incorporated into such platforms to further enhance drug uptake. This review will outline the application of micro/nanotechnology to specifically address the physiological barriers to oral drug delivery and highlight technologies that may be incorporated into these oral drug delivery systems to further enhance drug uptake.

Nanoengineering of vaccines using natural polysaccharides

Currently, there are over 70 licensed vaccines, which prevent the pathogenesis of around 30 viruses and bacteria. Nevertheless, there are still important challenges in this area, which include the development of more active, non-invasive, and thermo-resistant vaccines. Important biotechnological advances have led to safer subunit antigens, such as proteins, peptides, and nucleic acids. However, their limited immunogenicity has demanded potent adjuvants that can strengthen the immune response. Particulate nanocarriers hold a high potential as adjuvants in vaccination. Due to their pathogen-like size and structure, they can enhance immune responses by mimicking the natural infection process. Additionally, they can be tailored for non-invasive mucosal administration (needle-free vaccination), and control the delivery of the associated antigens to a specific location and for prolonged times, opening room for single-dose vaccination. Moreover, they allow co-association of immunostimulatory molecules to improve the overall adjuvant capacity.

The natural and ubiquitous character of polysaccharides, together with their intrinsic immunomodulating properties, their biocompatibility, and biodegradability, justify their interest in the engineering of nanovaccines. In this review, we aim to provide a state-of-the-art overview regarding the application of nanotechnology in vaccine delivery, with a focus on the most recent advances in the development and application of polysaccharide-based antigen nanocarriers.

Surface-Eroding Poly(ortho ester amides) for Highly Efficient Oral Chemotherapy

Two new poly(ortho ester amide) copolymers (POEA-4 and POEA-5) were synthesized via polycondensation of a new ortho ester diamine monomer with active esters of different aliphatic diacids. The kinetics of POEA mass loss and release of 5-FU were both nearly zero-order, suggesting predominantly surface-restricted polymer erosion and drug release. In vitro cytotoxicity tests demonstrated that both copolymers have excellent biocompatibility. In vivo acute toxicity tests suggested that oral administration of POEA-4 and POEA-5 did not cause any adverse effects on mice even at a very high dose (2000 mg/kg). In vivo antitumor efficacy against H22 transplanted tumors of 5-FU-loaded POEA tablets were fully examined. We envision that, with further optimization, POEA-based materials could have great potential as drug carriers for oral chemotherapy.