Nanoparticles coated with high molecular weight PEG penetrate mucus and provide uniform vaginal and colorectal distribution in vivo

Nanocarrier drug delivery system: promising platform for targeted depression therapy

Depression is a chronic mental disorder characterized by persistent low mood and loss of interest. Treatments for depression are varied but may not be sufficient cure. Drug-based treatment regimens have drawbacks such as slow onset of action, low bioavailability, and drug side effects. Nanocarrier Drug Delivery Systems (NDDS) has received increasing attention for brain drug delivery since it assists the drug through the blood-brain barrier and improves bioavailability, which may be beneficial for treating depression. Due to the particle size and physicochemical properties of nanocarriers, it presents a promise to improve the stability and solubility of antidepressants, thereby enhancing the drug concentration. Moreover, ligand-modified nanocarriers can be taken as a target direct medicines release system and reduce drug side effects. The purpose of the present review is to provide an up-to-date understanding of the Nanocarrier drug delivery system and relevant antidepressants in different routes of ingestion, to lay a foundation for the treatment of patients with depression.

Reinforcement of the intestinal mucosal barrier via mucus-penetrating PEGylated bacteria

The breakdown of the gut's mucosal barrier that prevents the infiltration of microorganisms, inflammatory cytokines and toxins into bodily tissues can lead to inflammatory bowel disease and to metabolic and autoimmune diseases. Here we show that the intestinal mucosal barrier can be reinforced via the oral administration of commensal bacteria coated with poly(ethylene glycol) (PEG) to facilitate their penetration into mucus. In mice with intestinal homoeostatic imbalance, mucus-penetrating PEGylated bacteria preferentially localized in mucus at the lower gastrointestinal tract, inhibited the invasion of pathogenic bacteria, maintained homoeostasis of the gut microbiota, stimulated the secretion of mucus and the expression of tight junctions, and prevented the mice from developing colitis and diabetes. Orally delivered PEGylated bacteria may help prevent and treat gastrointestinal disorders.

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

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Personalized Cancer Nanomedicine: Overcoming Biological Barriers for Intracellular Delivery of Biopharmaceuticals

The success of personalized medicine in oncology relies on using highly effective and precise therapeutic modalities such as small interfering RNA (siRNA) and monoclonal antibodies (mAbs). Unfortunately, the clinical exploitation of these biological drugs has encountered obstacles in overcoming intricate biological barriers. Drug delivery technologies represent a plausible strategy to overcome such barriers, ultimately facilitating the access to intracellular domains. Here, an overview of the current landscape on how nanotechnology has dealt with protein corona phenomena as a first and determinant biological barrier is presented. This continues with the analysis of strategies facilitating access to the tumor, along with conceivable methods for enhanced tumor penetration. As a final step, the cellular barriers that nanocarriers must confront in order for their biological cargo to reach their target are deeply analyzed. This review concludes with a critical analysis and future perspectives of the translational advances in personalized oncological nanomedicine.

Nanotechnology for enhanced nose-to-brain drug delivery in treating neurological diseases

Despite the increasing global incidence of brain disorders, achieving sufficient delivery towards the central nervous system (CNS) remains a formidable challenge in terms of translating into improved clinical outcomes. The brain is highly safeguarded by physiological barriers, primarily the blood-brain barrier (BBB), which routinely excludes most therapeutics from entering the brain following systemic administration. Among various strategies investigated to circumvent this challenge, intranasal administration, a noninvasive method that bypasses the BBB to allow direct access of drugs to the CNS, has been showing promising results. Nanotechnology-based drug delivery systems, in particular, have demonstrated remarkable capacities in overcoming the challenges posed by nose-to-brain drug delivery and facilitating targeted drug accumulation within the brain while minimizing side effects of systemic distribution. This review comprehensively summarizes the barriers of nose-to-brain drug delivery, aiming to enhance our understanding of potential physiological obstacles and improve the efficacy of nasal delivery in future trials. We then highlight cutting-edge nanotechnology-based studies that enhance nose-to-brain drug delivery in three key aspects, demonstrating substantial potential for improved treatment of brain diseases. Furthermore, the attention towards clinical studies will ease the regulatory approval process for nasal administration of nanomedicines targeting brain disease.

Inhalable Bottlebrush Polymer Bioconjugates as Vectors for Efficient Pulmonary Delivery of Oligonucleotides

Antisense oligonucleotides hold therapeutic promise for various lung disorders, but their efficacy is limited by suboptimal delivery. To address this challenge, we explored the use of inhaled bottlebrush polymer-DNA conjugates, named pacDNA, as a delivery strategy. Inhaled pacDNA exhibits superior mucus penetration, achieving a uniform and sustained lung distribution in mice. Targeting the 5' splice site of an aberrant enhanced green fluorescence protein (EGFP) pre-mRNA in EGFP-654 mice, inhaled pacDNA more efficiently corrects splicing than a B-peptide conjugate and restores EGFP expression in the lung. Additionally, in an orthotopic NCI-H358 non-small-cell lung tumor mouse model, inhaled pacDNA targeting wild-type KRAS mRNA effectively suppresses KRAS expression and inhibits lung tumor growth, requiring a substantially lower dosage compared to intravenously injected pacDNA. These findings demonstrate the potential of bottlebrush polymer-DNA conjugates as a promising agent for enhanced oligonucleotide therapy in the lung and advancing the treatment landscape for lung disorders.

Delivery and short-term maternal and fetal safety of vaginally administered PEG-PLGA nanoparticles

At the onset of pregnancy, people with preexisting conditions face additional challenges in carrying their pregnancy to term, as the safety of the developing fetus and pregnant person is a significant factor of concern. Nanoparticle (NP)-based therapies have displayed success against various conditions and diseases in non-pregnant patients, but the use of NPs in maternal-fetal health applications needs to be better established. Local vaginal delivery of NPs is a promising administration route with the potential to yield high cargo retention in the vagina and improved therapeutic efficacy compared to systemic administration that results in rapid NP clearance by the hepatic first-pass effect. In this study, we investigated the biodistribution and short-term toxicity of poly(ethylene glycol)-poly(lactic-co-glycolic acid) (PEG-PLGA) NPs in pregnant mice following vaginal delivery. The NPs were either loaded with DiD fluorophores for tracking cargo distribution (termed DiD-PEG-PLGA NPs) or included Cy5-tagged PLGA in the formulation for tracking polymer distribution (termed Cy5-PEG-PLGA NPs). DiD-PEG-PLGA NPs were administered at gestational day (E)14.5 or 17.5, and cargo biodistribution was analyzed 24 h later by fluorescence imaging of whole excised tissues and histological sections. No gestational differences in DiD distribution were observed, so Cy5-PEG-PLGA NPs were administered at only E17.5 to evaluate polymer distribution in the reproductive organs of pregnant mice. Cy5-PEG-PLGA NPs distributed to the vagina, placentas, and embryos, whereas DiD cargo was only observed in the vagina. NPs did not impact maternal, fetal, or placental weight, suggesting they display no short-term effects on maternal or fetal growth. The results from this study encourage future investigation into the use of vaginally delivered NP therapies for conditions affecting the vagina during pregnancy.

Combination nanochemotherapy of brain tumor using polymeric nanoparticles loaded with doxorubicin and paclitaxel: An in vitro and in vivo study

This study aims to overcome physiological barriers and increase the therapeutic index for the treatment of glioblastoma (GBM) tumors by using Paclitaxel (PTX) loaded Poly(lactic co-glycolic acid) nanoparticles (PTX-PLGA-NPs) and Doxorubicin (DOX) loaded Poly (lactic co-glycolic acid) nanoparticles (DOX-PLGA-NPs). The hydrodynamic diameter of nanoparticles (NPs) was characterized by dynamic light scattering (DLS) which was 94 ± 4 nm and 133 ± 6 nm for DOX-PLGA-NPs, and PTX-PLGA-NPs, respectively. The zeta potential for DOX-PLGA-NPs and PTX-PLGA-NPs were -15.2 ± 0.18 mV and -17.3 ± 0.34 mV, respectively. The cytotoxicity of PTX-PLGA-NPs and DOX-PLGA-NPs was augmented compared to DOX and PTX on C6 GBM cells. The Lactate dehydrogenase (LDH) tests for various formulations were carried out. The results indicated that the amount of released LDH was 262 ± 7.84 U.L-1 at the concentration of 2 mg/mL in the combination therapy, which was much higher than other groups (DOX-PLGA-NPs (210 ± 6.92 U.L-1), PTX-PLGA-NPs (201 ± 8.65 U.L-1), DOX (110 ± 9.81 U.L-1), PTX (95 ± 5.02 U.L-1) and PTX + DOX (67 ± 4.89 U.L-1)). MRI results of the combination therapy of PTX-PLGA-NPs and DOX-PLGA-NPs indicated that GBM tumor size decreased considerably compared to the other formulations. Also, combination therapy of PTX-PLGA-NPs and DOX-PLGA-NPs demonstrated a longer median survival of more than 80 days compared to PTX (38 days), DOX (37 days) and PTX + DOX (48 days), PTX-NPs (58 days) and DOX-NPs (62 days). The results of locomotion, body weight, rearing and grooming assays indicated that combination therapy of PTX-PLGA-NPs and DOX-PLGA-NPs had the most positive effect on the movements of rats compared to the other formulations.

Nanomaterial surface modification toolkit: Principles, components, recipes, and applications

Surface-functionalized nanostructures are at the forefront of biotechnology, providing new opportunities for biosensors, drug delivery, therapy, and bioimaging applications. The modification of nanostructures significantly impacts the performance and success of various applications by enabling selective and precise targeting. This review elucidates widely practiced surface modification strategies, including click chemistry, cross-coupling, silanization, aldehyde linkers, active ester chemistry, maleimide chemistry, epoxy linkers, and other protein and DNA-based methodologies. We also delve into the application-focused landscape of the nano-bio interface, emphasizing four key domains: therapeutics, biosensing, environmental monitoring, and point-of-care technologies, by highlighting prominent studies. The insights presented herein pave the way for further innovations at the intersection of nanotechnology and biotechnology, providing a useful handbook for beginners and professionals. The review draws on various sources, including the latest research articles (2018-2023), to provide a comprehensive overview of the field.

Surface functionalization affects the retention and bio-distribution of orally administered mesoporous silica nanoparticles in a colitis mouse model

Besides the many advantages of oral drug administration, challenges like premature drug degradation and limited bioavailability in the gastro-intestinal tract (GIT) remain. A prolonged residence time in the GIT is beneficial for enhancing the therapeutic outcome when treating diseases associated with an increased intestinal clearance rate, like inflammatory bowel disease (IBD). In this study, we synthesized rod-shaped mesoporous silica nanoparticles (MSNs) functionalized with polyethylene glycol (PEG) or hyaluronic acid (HA) and investigated their bio-distribution upon oral administration in vivo. The negatively charged, non-toxic particles showed different accumulation behavior over time in healthy mice and in mice with dextran sulfate sodium (DSS)-induced intestinal inflammation. PEGylated particles were shown to accumulate in the lower intestinal tract of healthy animals, whereas inflammation promoted retention of HA-functionalized particles in this area. Overall systemic absorption was low. However, some particles were detected in organs of mice with DSS-induced colitis, especially in the case of MSN-PEG. The in vivo findings were connected to surface chemistry-related differences in particle adhesion on Caco-2/Raji and mucus-producing Caco-2/Raji/HT29 cell co-culture epithelial models in vitro. While the particle adhesion behavior in vivo was mirrored in the in vitro results, this was not the case for the resorption results, suggesting that the in vitro model does not fully reflect the erosion of the inflamed epithelial tissue. Overall, our study demonstrates the possibility to modulate accumulation and retention of MSNs in the GIT of mice with and without inflammation through surface functionalization, which has important implications for the formulation of nanoparticle-based delivery systems for oral delivery applications.

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

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

Mechanisms of Nanoparticle Transport across Intestinal Tissue: An Oral Delivery Perspective

Oral drug administration has been a popular choice due to patient compliance and limited clinical resources. Orally delivered drugs must circumvent the harsh gastrointestinal (GI) environment to effectively enter the systemic circulation. The GI tract has a number of structural and physiological barriers that limit drug bioavailability including mucus, the tightly regulated epithelial layer, immune cells, and associated vasculature. Nanoparticles have been used to enhance oral bioavailability of drugs, as they can act as a shield to the harsh GI environment and prevent early degradation while also increasing uptake and transport of drugs across the intestinal epithelium. Evidence suggests that different nanoparticle formulations may be transported via different intracellular mechanisms to cross the intestinal epithelium. Despite the existence of a significant body of work on intestinal transport of nanoparticles, many key questions remain: What causes the poor bioavailability of the oral drugs? What factors contribute to the ability of a nanoparticle to cross different intestinal barriers? Do nanoparticle properties such as size and charge influence the type of endocytic pathways taken? In this Review, we summarize the different components of intestinal barriers and the types of nanoparticles developed for oral delivery. In particular, we focus on the various intracellular pathways used in nanoparticle internalization and nanoparticle or cargo translocation across the epithelium. Understanding the gut barrier, nanoparticle characteristics, and transport pathways may lead to the development of more therapeutically useful nanoparticles as drug carriers.

Barriers for orally inhaled therapeutic antibodies

INTRODUCTION

Respiratory diseases represent a worldwide health issue. The recent Sars-CoV-2 pandemic, the burden of lung cancer, and inflammatory respiratory diseases urged the development of innovative therapeutic solutions. In this context, therapeutic antibodies (Abs) offer a tremendous opportunity to benefit patients with respiratory diseases. Delivering Ab through the airways has been demonstrated to be relevant to improve their therapeutic index. However, few inhaled Abs are on the market.

AREAS COVERED

This review describes the different barriers that may alter the fate of inhaled therapeutic Abs in the lungs at steady state. It addresses both physical and biological barriers and discusses the importance of taking into consideration the pathological changes occurring during respiratory disease, which may reinforce these barriers.

EXPERT OPINION

The pulmonary route remains rare for delivering therapeutic Abs, with few approved inhaled molecules, despite promising evidence. Efforts must focus on the intertwined barriers associated with lung diseases to develop appropriate Ab-formulation-device combo, ensuring optimal Ab deposition in the respiratory tract. Finally, randomized controlled clinical trials should be carried out to establish inhaled Ab therapy as prominent against respiratory diseases.

Airway mucus in pulmonary diseases: Muco-adhesive and muco-penetrating particles to overcome the airway mucus barriers

Airway mucus is a complex viscoelastic gel that provides a defensive physical barrier and shields the airway epithelium by trapping inhaled foreign pathogens and facilitating their removal via mucociliary clearance (MCC). In patients with respiratory diseases, such as chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF), non-CF bronchiectasis, and asthma, an increase in crosslinking and physical entanglement of mucin polymers as well as mucus dehydration often alters and typically reduces mucus mesh network pore size, which reduces neutrophil migration, decreases pathogen capture, sustains bacterial infection, and accelerates lung function decline. Conventional aerosol particles containing hydrophobic drugs are rapidly captured and removed by MCC. Therefore, it is critical to design aerosol delivery systems with the appropriate size and surface chemistry that can improve drug retention and absorption with the goal of increased efficacy. Biodegradable muco-adhesive particles (MAPs) and muco-penetrating particles (MPPs) have been engineered to achieve effective pulmonary delivery and extend drug residence time in the lungs. MAPs can be used to target mucus as they get trapped in airway mucus by steric obstruction and/or adhesion. MPPs avoid muco-adhesion and are designed to have a particle size smaller than the mucus network, enhancing lung retention of particles as well as transport to the respiratory epithelial layer and drug absorption. In this review, we aim to provide insight into the composition of airway mucus, rheological characteristics of airway mucus in healthy and diseased subjects, the most recent techniques to study the flow dynamics and particle diffusion in airway mucus (in particular, multiple particle tracking, MPT), and the advancements in engineering MPPs that have contributed to improved airway mucus penetration, lung distribution, and retention.

Surface design of nanocarriers: Key to more efficient oral drug delivery systems

As nanocarriers (NCs) can improve the solubility of drugs, prevent their degradation by gastrointestinal (GI) enzymes and promote their transport across the mucus gel layer and absorption membrane, the oral bioavailability of these drugs can be substantially enhanced. All these properties of NCs including self-emulsifying drug delivery systems (SEDDS), solid lipid nanoparticles (SLNs), nanostructured lipid carriers (NLCs), liposomes, polymeric nanoparticles, inorganic nanoparticles and polymeric micelles depend mainly on their surface chemistry. In particular, interaction with food, digestive enzymes, bile salts and electrolytes, diffusion behaviour across the mucus gel layer and fate on the absorption membrane are determined by their surface. Bioinert surfaces limiting interactions with gastrointestinal fluid and content as well as with mucus, adhesive surfaces providing an intimate contact with the GI mucosa and absorption enhancing surfaces can be designed. Furthermore, charge converting surfaces shifting their zeta potential from negative to positive directly at the absorption membrane and surfaces providing a targeted drug release are advantageous. In addition to these passive surfaces, even active surfaces cleaving mucus glycoproteins on their way through the mucus gel layer can be created. Within this review, we provide an overview on these different surfaces and discuss their impact on the performance of NCs in the GI tract.

Expanding opportunities to engineer mucosal vaccination with biomaterials

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

Mucus Penetration of Surface-Engineered Nanoparticles in Various pH Microenvironments

The penetration behavior of nanoparticles in mucous depends on physicochemical properties of the nanoparticles and the mucus microenvironment, due to particle-mucin interactions and the presence of the mucin mesh space filtration effect. To date, it is still unclear how the surface properties of nanoparticles influence their mucus penetration behaviors in various physiological and pathophysiological conditions. In this study, we have prepared a comprehensive library of amine-, carboxyl-, and PEG-modified silica nanoparticles (SNPs) with controlled surface ligand densities. Using multiple particle tracking, we have studied the mechanism responsible for the mucus penetration behaviors of these SNPs. It was found that PEG- and amine-modified SNPs exhibited pH-independent immobilization under iso-density conditions, while carboxyl-modified SNPs exhibited enhanced movement only in weakly alkaline mucus. Biophysical characterizations demonstrated that amine- and carboxyl-modified SNPs were trapped in mucus due to electrostatic interactions and hydrogen bonding with mucin. In contrast, high-density PEGylated surface formed a brush conformation that shields particle-mucin interactions. We have further investigated the surface property-dependent mucus penetration behavior using a murine airway distribution model. This study provides insights for designing efficient transmucosal nanocarriers for prevention and treatment of pulmonary diseases.

Tailoring surface properties of liposomes for dexamethasone intraocular administration

Diseases of the posterior eye segment are often characterized by intraocular inflammation, which causes, in the long term, severe impairment of eye functions and, ultimately, vision loss. Aimed at enhancing the delivery of anti-inflammatory drugs to the posterior eye segment upon intravitreal administration, we developed liposomes with an engineered surface to control their diffusivity in the vitreous and retina association. Hydrogenated soybean phosphatidylcholine (HSPC)/cholesterol liposomes were coated with (agmatinyl)₆-maltotriosyl-acetamido-N-(octadec-9-en-1-yl)hexanamide (Agm₆-M-Oleate), a synthetic non-peptidic cell penetration enhancer (CPE), and/or 5% of mPEG_2kDa-DSPE. The zeta potential of liposomes increased, and the mobility in bovine vitreous and colloidal stability decreased with the Agm₆-M-Oleate coating concentration. Oppositely, mPEG_2kDa-DSPE decreased the zeta potential of liposomes and restored both the diffusivity and the stability in vitreous. Liposomes with 5 mol% Agm₆-M-Oleate coating were well tolerated by ARPE-19 retina cells either with or without mPEG_2kDa-DSPE, while 10 mol% Agm₆-M-Oleate showed cytotoxicity. Agm₆-M-Oleate promoted the association of liposomes to ARPE-19 cells with respect to plain liposomes, while mPEG_2kDa-DSPE slightly reduced the cell interaction. Dexamethasone hemisuccinate (DH) was remotely loaded into liposomes with a loading capacity of ∼10 wt/wt%. Interestingly, mPEG_2kDa-DSPE coating reduced the rate of DH release and enhanced the disposition of Agm₆-M-Oleate coated liposomes in the ARPE-19 cell cytosol resulting in a more efficient anti-inflammatory effect. Finally, mPEG_2kDa-DSPE enhanced the association of DH-loaded Agm₆-M-Oleate coated liposomes to explanted rat retina, which reflected in higher viability of inner and outer nuclear layer cells.

Hydrophobic ion pairing-based self-emulsifying drug delivery systems: a new strategy for improving the therapeutic efficacy of water-soluble drugs

INTRODUCTION

Self-emulsifying drug delivery systems (SEDDS) are formulations consisting of oil phase, emulsifiers, and co-emulsifiers, which can be spontaneously emulsified in the body to form O/W microemulsion. Traditionally, SEDDS are used commercially for the improvement of oral absorption and in vivo performances for poorly water-soluble drugs. However, SEDDS formulations were rarely reported for the delivery of water-soluble drugs. Recent studies have found that SEDDS have the potential for water-soluble macromolecular drugs by the application of the hydrophobic ion pairing (HIP) technology.

AREAS COVERED

This review summarized the characteristics of HIP complexes in SEDDS and introduced their advantages and discussed the future prospects of HIP-based SEDDS in drug delivery.

EXPERT OPINION

Hydrophobic ion pairing (HIP) is a technology that combines lipophilic structures on polar counterions to increase the lipophilicity through electrostatic interaction. Recent studies showed that HIP-based SEDDS offer an effective way to increase the mucosal permeability and improve the chemical stability for antibiotics, proteases, DNA-based drugs, and other water-soluble macromolecular drugs. It is believed that HIP-based SEDDS offer a potential and attractive method capable of delivering hydrophilic macromolecules with ionizable groups for oral administration.

Generating an In Vitro Gut Model with Physiologically Relevant Biophysical Mucus Properties

Introduction

Gastrointestinal (GI) in vitro models have received lasting attention as an effective tool to model drug and nutrient absorption, study GI diseases, and design new drug delivery vehicles. A complete model of the GI epithelium should at a minimum include the two key functional components of the GI tract: mucus and the underlying epithelium. Mucus plays a key role in protecting and lubricating the GI tract, poses a barrier to orally administered therapies and pathogens, and serves as the microenvironment for the GI microbiome. These functions are reliant on the biophysical material properties of the mucus produced, including viscosity and pore size.

Methods

In this study, we generated in vitro models containing Caco-2 enterocyte-like cells and HT29-MTX goblet-like cells and determined the effects of coculture and mucus layer on epithelial permeability and biophysical properties of mucus using multiple particle tracking (MPT).

Results

We found that mucus height increased as the amount of HT29-MTX goblet-like cells increased. Additionally, we found that increasing the amount of HT29-MTX goblet-like cells within culture corresponded to an increase in mucus pore size and mucus microviscosity, measured using MPT. When compared to ex vivo mucus samples from mice and pigs, we found that a 90:10 ratio of Caco-2:HT29-MTX coculture displayed similar mucus pore size to porcine jejunum and that the mucus produced from 90:10 and 80:20 ratios of cells shared mechanical properties to porcine jejunum and ileum mucus.

Conclusions

GI coculture models are valuable tools in simulating the mucus barrier and can be utilized for a variety of applications including the study of GI diseases, food absorption, or therapeutic development.

Vaginal Nanoformulations for the Management of Preterm Birth

Preterm birth (PTB) is a leading cause of infant morbidity and mortality in the world. In 2020, 1 in 10 infants were born prematurely in the United States. The World Health Organization estimates that a total of 15 million infants are born prematurely every year. Current therapeutic interventions for PTB have had limited replicable success. Recent advancements in the field of nanomedicine have made it possible to utilize the vaginal administration route to effectively and locally deliver drugs to the female reproductive tract. Additionally, studies using murine models have provided important insights about the cervix as a gatekeeper for pregnancy and parturition. With these recent developments, the field of reproductive biology is on the cusp of a paradigm shift in the context of treating PTB. The present review focuses on the complexities associated with treating the condition and novel therapeutics that have produced promising results in preclinical studies.

Current knowledge on the tissue distribution of mRNA nanocarriers for therapeutic protein expression

Exogenously delivered mRNA-based drugs are emerging as a new class of therapeutics with the potential to treat several diseases. Over the last decade, advancements in the design of non-viral delivery tools have enabled mRNA to be evaluated for several therapeutic purposes including protein replacement therapies, gene editing, and vaccines. However, in vivo delivery of mRNA to targeted organs and cells remains a critical challenge. Evaluation of the biodistribution of mRNA vehicles is of utmost importance for the development of effective pharmaceutical candidates. In this review, we discuss the recent advances in the design of nanoparticles loaded with mRNA and extrapolate the key factors influencing their biodistribution following administration. Finally, we highlight the latest developments in the preclinical and clinical translation of mRNA therapeutics for protein supplementation therapy.

Mucus interaction to improve gastrointestinal retention and pharmacokinetics of orally administered nano-drug delivery systems

Oral delivery of therapeutics is the preferred route of administration due to ease of administration which is associated with greater patient medication adherence. One major barrier to oral delivery and intestinal absorption is rapid clearance of the drug and the drug delivery system from the gastrointestinal (GI) tract. To address this issue, researchers have investigated using GI mucus to help maximize the pharmacokinetics of the therapeutic; while mucus can act as a barrier to effective oral delivery, it can also be used as an anchoring mechanism to improve intestinal residence. Nano-drug delivery systems that use materials which can interact with the mucus layers in the GI tract can enable longer residence time, improving the efficacy of oral drug delivery. This review examines the properties and function of mucus in the GI tract, as well as diseases that alter mucus. Three broad classes of mucus-interacting systems are discussed: mucoadhesive, mucus-penetrating, and mucolytic drug delivery systems. For each class of system, the basis for mucus interaction is presented, and examples of materials that inform the development of these systems are discussed and reviewed. Finally, a list of FDA-approved mucoadhesive, mucus-penetrating, and mucolytic drug delivery systems is reviewed. In summary, this review highlights the progress made in developing mucus-interacting systems, both at a research-scale and commercial-scale level, and describes the theoretical basis for each type of system.

Mucopenetration study of solid lipid nanoparticles containing magneto sensitive iron oxide

In most chronic respiratory diseases, excessive viscous airway secretions oppose a formidable permeation barrier to drug delivery systems (DDSs), with a limit to their therapeutic efficacy for the targeting epithelium. Since mucopenetration of DDSs with slippery technology (i.e. PEGylation) has encountered a reduction in the presence of sticky and complex airway secretions, our aim was to evaluate the relevance of magnetic PEGylated Solid Lipid Nanoparticles (mSLNs) for pulling them through chronic obstructive pulmonary disease (COPD) airway secretions. Thus, COPD sputum from outpatient clinic, respiratory secretions aspirated from high (HI) and low (LO) airways of COPD patients in acute respiratory insufficiency, and porcine gastric mucus (PGM) were investigated for their permeability to mSLN particles under a magnetic field. Rheological tests and mSLN adhesion to airway epithelial cells (AECs) were also investigated. The results of mucopenetration show that mSLNs are permeable both in PGM sputum and in COPD, while HI and LO secretions are always impervious. Parallel rheological results show a different elastic property, which can be associated with different mucus mesostructures. Finally, adhesion tests confirm the role of the magnetic field in improving the interaction of SLNs with epithelial cells. Overall, our results reveal that mesostructure is of paramount importance in determining the mucopenetration of magnetic SLNs.

Biocoating-A Critical Step Governing the Oral Delivery of Polymeric Nanoparticles

Decades of research into the topic of oral nanoparticle (NP) delivery has still not provided a clear consensus regarding which properties produce an effective oral drug delivery system. The surface properties-charge and bioadhesiveness-as well as in vitro and in vivo correlation seem to generate the greatest number of disagreements within the field. Herein, a mechanism underlying the in vivo behavior of NPs is proposed, which bridges the gaps between these disagreements. The mechanism relies on the idea of biocoating-the coating of NPs with mucus-which alters their surface properties, and ultimately their systemic uptake. Utilizing this mechanism, several coated NPs are tested in vitro, ex vivo, and in vivo, and biocoating is found to affect NPs size, zeta-potential, mucosal diffusion coefficient, the extent of aggregation, and in vivo/in vitro/ex vivo correlation. Based on these results, low molecular weight polylactic acid exhibits a 21-fold increase in mucosal diffusion coefficient after precoating as compared to uncoated particles, as well as 20% less aggregation, and about 30% uptake to the blood in vivo. These discoveries suggest that biocoating reduces negative NP charge which results in an enhanced mucosal diffusion rate, increased gastrointestinal retention time, and high systemic uptake.

Surface Modification of Lipid-Based Nanoparticles

There is a growing interest in the development of lipid-based nanocarriers for multiple purposes, including the recent increase of these nanocarriers as vaccine components during the COVID-19 pandemic. The number of studies that involve the surface modification of nanocarriers to improve their performance (increase the delivery of a therapeutic to its target site with less off-site accumulation) is enormous. The present review aims to provide an overview of various methods associated with lipid nanoparticle grafting, including techniques used to separate grafted nanoparticles from unbound ligands or to characterize grafted nanoparticles. We also provide a critical perspective on the usefulness and true impact of these modifications on overcoming different biological barriers, with our prediction on what to expect in the near future in this field.

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

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

Impact of PEGylation on an antibody-loaded nanoparticle-based drug delivery system for the treatment of inflammatory bowel disease

Nanoparticle-based oral drug delivery systems have the potential to target inflamed regions in the gastrointestinal tract by specifically accumulating at disrupted colonic epithelium. But, delivery of intact protein drugs at the targeted site is a major challenge due to the harsh gastrointestinal environment and the protective mucus layer. Biocompatible nanoparticles engineered to target the inflamed colonic tissue and efficiently penetrate the mucosal layer can provide a promising approach for orally delivering monoclonal antibodies to treat inflammatory bowel disease. The study aims to develop mucus-penetrating nanoparticles composed of poly(lactic-co-glycolic acid, PLGA) polymers with two different polyethylene glycol (PEG) chain lengths (2 kDa and 5kDa) to encapsulate monoclonal antibody against tumor necrosis factor-α (TNF-α). The impact of different PEG chain lengths on the efficacy of the nanosystems was evaluated in vitro, ex vivo, and in vivo. Both PLGA-PEG2k and PLGA-PEG5k nanoparticles successfully encapsulated the antibody and significantly reduced TNF-α secretion from activated macrophages and intestinal epithelial cells. However, only antibody-loaded PLGA-PEG2k nanoparticles were able to alleviate the experimental acute colitis in mice demonstrated by improved colon weight/length ratio, histological score, and reduced tissue-associated myeloperoxidase activity and expression of proinflammatory cytokine TNF-α levels compared with the control group. The results suggest that despite having no significant differences in the in vitro cell-based assays, PEG chain length has a significant impact on the in vivo performance of the mucus penetrating nanoparticles. Overall, PLGA-PEG2k nanoparticles were presented as a promising oral delivery system for targeted antibody delivery to treat inflammatory bowel disease. STATEMENT OF SIGNIFICANCE: There is an unmet therapeutic need for oral drug delivery systems for safe and effective antibody therapy of inflammatory bowel disease. Therefore, we have developed PEGylated PLGA-based nanoparticulate drug delivery systems for oral targeted delivery of anti-TNF-α antibody as a potential alternative treatment strategy. The PEG chain length did not affect encapsulation efficiency or interaction with mucin in vitro but resulted in differences in in vitro release profile and in vivo efficacy study. We demonstrated the superiority of anti-TNF-α mAb-PLGA-PEG2k over mAb-PLGA-PEG5k nanoparticles to effectively exhibit anti-inflammatory responses in an acute murine colitis model. These nanoparticle-based formulations may be adjusted to encapsulate other drugs that could be applied to a number of disorders at different mucosal surfaces.

Oral delivery of therapeutic peptides and proteins: Technology landscape of lipid-based nanocarriers

The oral administration of therapeutic peptides and proteins is favoured from a patient and commercial point of view. In order to reach the systemic circulation after oral administration, these drugs have to overcome numerous barriers including the enzymatic, sulfhydryl, mucus and epithelial barrier. The development of oral formulations for therapeutic peptides and proteins is therefore necessary. Among the most promising formulation approaches are lipid-based nanocarriers such as oil-in-water nanoemulsions, self-emulsifying drug delivery systems (SEDDS), solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC), liposomes and micelles. As the lipophilic character of therapeutic peptides and proteins can be tremendously increased such as by the formation of hydrophobic ion pairs (HIP) with hydrophobic counter ions, they can be incorporated in the lipophilic phase of these carriers. Since gastrointestinal (GI) peptidases as well as sulfhydryl compounds such as glutathione and dietary proteins are too hydrophilic to enter the lipophilic phase of these carriers, the incorporated therapeutic peptide or protein is protected towards enzymatic degradation as well as unintended thiol/disulfide exchange reactions. Stability of lipid-based nanocarriers towards lipases can be provided by the use to excipients that are not or just poorly degraded by these enzymes. Nanocarriers with a size <200 nm and a mucoinert surface such as PEG or zwitterionic surfaces exhibit high mucus permeating properties. Having reached the underlying absorption membrane, lipid-based nanocarriers enable paracellular and lymphatic drug uptake, induce endocytosis and transcytosis or simply fuse with the cell membrane releasing their payload into the systemic circulation. Numerous in vivo studies provide evidence for the potential of these delivery systems. Within this review we provide an overview about the different barriers for oral peptide and protein delivery, highlight the progress made on lipid-based nanocarriers in order to overcome them and discuss strengths and weaknesses of these delivery systems in comparison to other technologies.

Polymeric particle-based therapies for acute inflammatory diseases

Acute inflammation is essential for initiating and coordinating the body's response to injuries and infections. However, in acute inflammatory diseases, inflammation is not resolved but propagates further, which can ultimately lead to tissue damage such as in sepsis, acute respiratory distress syndrome and deep vein thrombosis. Currently, clinical protocols are limited to systemic steroidal treatments, fluids and antibiotics that focus on eradicating inflammation rather than modulating it. Strategies based on stem cell therapeutics and selective blocking of inflammatory molecules, despite showing great promise, still lack the scalability and specificity required to treat acute inflammation. By contrast, polymeric particle systems benefit from uniform manufacturing at large scales while preserving biocompatibility and versatility, thus providing an ideal platform for immune modulation. Here, we outline design aspects of polymeric particles including material, size, shape, deformability and surface modifications, providing a strategy for optimizing the targeting of acute inflammation.

OUP accepted manuscript

BACKGROUND

To provide the optimal milieu for implantation and fetal development, the female reproductive system must orchestrate uterine dynamics with the appropriate hormones produced by the ovaries. Mature oocytes may be fertilized in the fallopian tubes, and the resulting zygote is transported toward the uterus, where it can implant and continue developing. The cervix acts as a physical barrier to protect the fetus throughout pregnancy, and the vagina acts as a birth canal (involving uterine and cervix mechanisms) and facilitates copulation. Fertility can be compromised by pathologies that affect any of these organs or processes, and therefore, being able to accurately model them or restore their function is of paramount importance in applied and translational research. However, innate differences in human and animal model reproductive tracts, and the static nature of 2D cell/tissue culture techniques, necessitate continued research and development of dynamic and more complex in vitro platforms, ex vivo approaches and in vivo therapies to study and support reproductive biology. To meet this need, bioengineering is propelling the research on female reproduction into a new dimension through a wide range of potential applications and preclinical models, and the burgeoning number and variety of studies makes for a rapidly changing state of the field.

OBJECTIVE AND RATIONALE

This review aims to summarize the mounting evidence on bioengineering strategies, platforms and therapies currently available and under development in the context of female reproductive medicine, in order to further understand female reproductive biology and provide new options for fertility restoration. Specifically, techniques used in, or for, the uterus (endometrium and myometrium), ovary, fallopian tubes, cervix and vagina will be discussed.

SEARCH METHODS

A systematic search of full-text articles available in PubMed and Embase databases was conducted to identify relevant studies published between January 2000 and September 2021. The search terms included: bioengineering, reproduction, artificial, biomaterial, microfluidic, bioprinting, organoid, hydrogel, scaffold, uterus, endometrium, ovary, fallopian tubes, oviduct, cervix, vagina, endometriosis, adenomyosis, uterine fibroids, chlamydia, Asherman’s syndrome, intrauterine adhesions, uterine polyps, polycystic ovary syndrome and primary ovarian insufficiency. Additional studies were identified by manually searching the references of the selected articles and of complementary reviews. Eligibility criteria included original, rigorous and accessible peer-reviewed work, published in English, on female reproductive bioengineering techniques in preclinical (in vitro/in vivo/ex vivo) and/or clinical testing phases.

OUTCOMES

Out of the 10 390 records identified, 312 studies were included for systematic review. Owing to inconsistencies in the study measurements and designs, the findings were assessed qualitatively rather than by meta-analysis. Hydrogels and scaffolds were commonly applied in various bioengineering-related studies of the female reproductive tract. Emerging technologies, such as organoids and bioprinting, offered personalized diagnoses and alternative treatment options, respectively. Promising microfluidic systems combining various bioengineering approaches have also shown translational value.

WIDER IMPLICATIONS

The complexity of the molecular, endocrine and tissue-level interactions regulating female reproduction present challenges for bioengineering approaches to replace female reproductive organs. However, interdisciplinary work is providing valuable insight into the physicochemical properties necessary for reproductive biological processes to occur. Defining the landscape of reproductive bioengineering technologies currently available and under development for women can provide alternative models for toxicology/drug testing, ex vivo fertility options, clinical therapies and a basis for future organ regeneration studies.

A scale-up strategy for the synthesis of chitosan derivatives used in micellar nanomedicines

Nanomedicines have been increasingly investigated and used by pharmaceutical industry due to their potential in solving various public health problems. However, standardizing and approving nanomedicines remains a significant challenge, as the translation from the laboratory to the market is still limited. These constraints are due to a lack of reproducibility and standardization of procedures, small batch sizes due to inability to scale-up, or the associated production costs as a result of the production methods chosen. In this work, two chitosan derivatives, methoxypolyethylene glycol-chitosan (mPEG-CS) and methoxypolyethylene glycol-chitosan-oleic acid (mPEG-CS-OA), produced at the lab scale were implemented in a pharmaceutical industry to achieve the scale-up production using cross flow filtration (CFF). The two copolymers were shown to be capable of retaining their physicochemical properties when produced in larger batch sizes, with reduced production time and increased yield. Also, both chitosan derivatives presented no in vitro cytotoxicity independent of the method of production. Furthermore, after scale-up, polymeric micelles produced from mPEG-CS-OA were tested for storage stability, demonstrating that micelles remained stable at - 20 °C for at least 6 months. This study demonstrated the feasibility of producing polymers and polymeric micelles closer to the bedside due to their suitability for GMP production.

Enhanced Mucosal Transport of Polysaccharide-Calcium Phosphate Nanocomposites for Oral Vaccination

Oral vaccine has attracted much interest, as it can stimulate both mucosal and systemic immunity with noninvasive and good patient compliance. However, the oral vaccine efficiency is strongly constrained by the low absorption of antigens in the small intestine due to the mucosal barriers. Physicochemical characteristics of nanoparticles (NPs) have strong effects on antigen mucosal penetration, helping to improve immune response. However, surface functions of NPs on mucosal transportation have not been clearly understood. In this work, we elaborately investigated how the surface characteristics of mucoadhesive chitosan and its derivant act on oral antigen absorption and immune response. Core-shell chitosan- and o-carboxymethyl chitosan-coated calcium phosphate (CaP) nanocomposites have been fabricated to investigate the surface property effect on protein antigen delivery using the oral route. The interaction between polymer-coated CaP NPs and the intestinal mucosal layer was studied using mucin absorption, NP diffusion through the mucus layer, NP permeability across the epithelium monolayer, and their cellular uptake by antigen presenting cells in detail. Ex vivo mucosa distribution and in vivo oral immunization of polymer-coated CaP nanocomposites were further examined to demonstrate that the surface property of NPs affects CaP diffusion and penetration through the mucosal layer. As expected, OVA orally delivered by polymer-coated CaP nanocomposites improved the response of mucosal immunity compared to antigen OVA itself in vivo.

Nanomedicines for the topical treatment of vulvovaginal infections: Addressing the challenges of antimicrobial resistance

Recent years have, surprisingly, witnessed an increase in incidence of sexually transmitted infections (STIs). At the same time, antimicrobial therapy came under the threat of ever rising antimicrobial resistance (AMR), resulting in STIs with extremely limited therapy options. In this review, we addressed the challenges of treating vaginal infections in an era of AMR. We focused on published work regarding nanomedicine destined for localized treatment of vaginal infections. Localized therapy offers numerous advantages such as assuring high drug concentration at the infection site, limiting systemic drug exposure that can lead to faster development of AMR reduction in the systemic side effects and potentially safe therapy in pregnancy. We provided a state-of-the-art overview of nanoformulations proposed to topically treat STIs, emphasizing the challenges and advantages of each type of nanocarriers, as well as issues of potential toxicity.

Therapeutic antibodies - natural and pathological barriers and strategies to overcome them

Antibody-based therapeutics have become a major class of therapeutics with over 120 recombinant antibodies approved or under review in the EU or US. This therapeutic class has experienced a remarkable expansion with an expected acceleration in 2021-2022 due to the extraordinary global response to SARS-CoV2 pandemic and the public disclosure of over a hundred anti-SARS-CoV2 antibodies. Mainly delivered intravenously, alternative delivery routes have emerged to improve antibody therapeutic index and patient comfort. A major hurdle for antibody delivery and efficacy as well as the development of alternative administration routes, is to understand the different natural and pathological barriers that antibodies face as soon as they enter the body up to the moment they bind to their target antigen. In this review, we discuss the well-known and more under-investigated extracellular and cellular barriers faced by antibodies. We also discuss some of the strategies developed in the recent years to overcome these barriers and increase antibody delivery to its site of action. A better understanding of the biological barriers that antibodies have to face will allow the optimization of antibody delivery near its target. This opens the way to the development of improved therapy with less systemic side effects and increased patients' adherence to the treatment.

Silane Modification of Mesoporous Materials for the Optimization of Antiviral Drug Adsorption and Release Capabilities in Vaginal Media

Three different functionalities have been incorporated into mesoporous materials by means of a coupling reaction with the siloxanes 3-glycidoxypropyl-trimethoxysilane (GLYMO), 3-methacryloxypropyl-trimethoxysilane (MEMO), and 3-mercaptopropyl-trimethoxysilane (MPTMS). The disposition of the different functional groups, as well as the interaction mechanism, with the mesoporous substrate has been identified. The amount of the antiviral drug acyclovir (ACV) adsorbed depends not only on the available surface area but also on the chemical or physicochemical interactions between functionalities. The drug adsorption isotherm of the materials functionalized with GLYMO and MPTMS follow mechanisms dependent on the different surface coverage and the possibilities to establish physicochemical interactions between the drug molecule and the functionalities. On the contrary, when functionalizing with MEMO, the dominant adsorption mechanism is characteristic of chemically bonded adsorbates. The ACV release kinetics is best fitted to the Weibull model in all the functionalized materials. When the MTPMS is used as a functionalizing agent, the drug diffusion occurs at low kinetics and homogeneously along the mesoporous channels.

Women-specific routes of administration for drugs: A critical overview

The woman's body presents a number of unique anatomical features that can constitute valuable routes for the administration of drugs, either for local or systemic action. These are associated with genitalia (vaginal, endocervical, intrauterine, intrafallopian and intraovarian routes), changes occurring during pregnancy (extra-amniotic, intra-amniotic and intraplacental routes) and the female breast (breast intraductal route). While the vaginal administration of drug products is common, other routes have limited clinical application and are fairly unknown even for scientists involved in drug delivery science. Understanding the possibilities and limitations of women-specific routes is of key importance for the development of new preventative, diagnostic and therapeutic strategies that will ultimately contribute to the advancement of women's health. This article provides an overview on women-specific routes for the administration of drugs, focusing on aspects such as biological features pertaining to drug delivery, relevance in current clinical practice, available drug dosage forms/delivery systems and administration techniques, as well as recent trends in the field.

Processing Chitosan for Preparing Chitosan-Functionalized Nanoparticles by Polyelectrolyte Adsorption

Chitosan-coated nanoparticles are a promising class of drug delivery vehicles that have been studied as tools for improving the gastrointestinal delivery of therapeutics. Here we present an analysis of chitosan-coated nanoparticles with an emphasis on characterizing the chitosan polymer properties. Cationic nanoparticles are produced by adsorbing a layer of chitosan HCl on an anionic (-40 mV ζ-potential) polyacrylic acid (PAA) coated primary nanoparticle. Commercially available chitosan (90% deacetylated) must be processed into a nearly completely deacetylated HCl salt form (99% deacetylation); otherwise, primary nanoparticle aggregation occurs. Deacetylated chitosan HCl produces stable, cationic (+35 mV ζ-potential) nanoparticles within 10% of the original anionic particle hydrodynamic diameter at a 1:2 molar ratio of chitosan glucosamine HCl monomers to PAA acrylic acid monomers.

Recent Advances in Polymer-Based Vaginal Drug Delivery Systems

The vagina has been considered a potential drug administration route for centuries. Most of the currently marketed and investigated vaginal formulations are composed with the use of natural or synthetic polymers having different functions in the product. The vaginal route is usually investigated as an administration site for topically acting active ingredients; however, the anatomical and physiological features of the vagina make it suitable also for drug systemic absorption. In this review, the most important natural and synthetic polymers used in vaginal products are summarized and described, with special attention paid to the properties important in terms of vaginal application. Moreover, the current knowledge on the commonly applied and innovative dosage forms designed for vaginal administration was presented. The aim of this work was to highlight the most recent research directions and indicate challenges related to vaginal drug administrations. As revealed in the literature overview, intravaginal products still gain enormous scientific attention, and novel polymers and formulations are still explored. However, there are research areas that require more extensive studies in order to provide the safety of novel vaginal products.

Avoiding a Sticky Situation: Bypassing the Mucus Barrier for Improved Local Drug Delivery

The efficacy of drugs administered by traditional routes is limited by numerous biological barriers that preclude reaching the intended site of action. Further, full body systemic exposure leads to dose-limiting, off-target side effects. Topical formulations may provide more efficacious drug and nucleic acid delivery for diseases and conditions affecting mucosal tissues, but the mucus protecting our epithelial surfaces is a formidable barrier. Here, we describe recent advances in mucus-penetrating approaches for drug and nucleic acid delivery to the ocular surface, the female reproductive tract, the gastrointestinal tract, and the airways.

A mussel-inspired film for adhesion to wet buccal tissue and efficient buccal drug delivery

Administration of drugs via the buccal route has attracted much attention in recent years. However, developing systems with satisfactory adhesion under wet conditions and adequate drug bioavailability still remains a challenge. Here, we propose a mussel-inspired mucoadhesive film. Ex vivo models show that this film can achieve strong adhesion to wet buccal tissues (up to 38.72 ± 10.94 kPa). We also demonstrate that the adhesion mechanism of this film relies on both physical association and covalent bonding between the film and mucus. Additionally, the film with incorporated polydopamine nanoparticles shows superior advantages for transport across the mucosal barrier, with improved drug bioavailability (~3.5-fold greater than observed with oral delivery) and therapeutic efficacy in oral mucositis models (~6.0-fold improvement in wound closure at day 5 compared with that observed with no treatment). We anticipate that this platform might aid the development of tissue adhesives and inspire the design of nanoparticle-based buccal delivery systems.

Preparation and evaluation of PEG-coated zein nanoparticles for oral drug delivery purposes

The aim was to produce PEG-coated nanoparticles (NP-PEG), with mucus-permeating properties, for oral drug delivery purposes by using simple procedures and regulatory-approved compounds in order to facilitate a potential clinical development. For this purpose, zein nanoparticles were prepared by desolvation and, then, coated by incubation with PEG 35,000. The resulting nanocarriers displayed a mean size of about 200 nm and a negative zeta potential. The presence of PEG on the surface of nanoparticles was evidenced by electron microscopy and confirmed by FTIR analysis. Likely, the hydrophobic surface of zein nanoparticles (NP) was significantly reduce by their coating with PEG. This increase of the hydrophilicity of PEG-coated nanoparticles was associated with an important increase of their mobility in pig intestinal mucus. In laboratory animals, NP-PEG (fluorescently labelled with Lumogen® Red 305) displayed a different behavior when compared with bare nanoparticles. After oral administration, NP appeared to be trapped in the mucus mesh, whereas NP-PEG were capable of crossing the protective mucus layer and reach the epithelium. Finally, PEG-coated zein nanoparticles, prepared by a simple and reproducible method without employing reactive reagents, may be adequate carriers for promoting the oral bioavailability of biomacromolecules and other biologically active compounds with low permeability properties.

Recent Advances in Oral Nano-Antibiotics for Bacterial Infection Therapy

Bacterial infections are the main infectious diseases and cause of death worldwide. Antibiotics are used to treat various infections ranging from minor to life-threatening ones. The dominant route to administer antibiotics is through oral delivery and subsequent gastrointestinal tract (GIT) absorption. However, the delivery efficiency is limited by many factors such as low drug solubility and/or permeability, gastrointestinal instability, and low antibacterial activity. Nanotechnology has emerged as a novel and efficient tool for targeting drug delivery, and a number of promising nanotherapeutic strategies have been widely explored to overcome these obstacles. In this review, we explore published studies to provide a comprehensive understanding of the recent progress in the area of orally deliverable nano-antibiotic formulations. The first part of this article discusses the functions and underlying mechanisms by which nanomedicines increase the oral absorption of antibiotics. The second part focuses on the classification of oral nano-antibiotics and summarizes the advantages, disadvantages and applications of nanoformulations including lipid, polymer, nanosuspension, carbon nanotubes and mesoporous silica nanoparticles in oral delivery of antibiotics. Lastly, the challenges and future perspective of oral nano-antibiotics for infection disease therapy are discussed. Overall, nanomedicines designed for oral drug delivery system have demonstrated the potential for the improvement and optimization of currently available antibiotic therapies.

Developing inhaled protein therapeutics for lung diseases

Biologic therapeutics such as protein/polypeptide drugs are conventionally administered systemically via intravenous injection for the treatment of diseases including lung diseases, although this approach leads to low target site accumulation and the potential risk for systemic side effects. In comparison, topical delivery of protein drugs to the lung via inhalation is deemed to be a more effective approach for lung diseases, as proteins would directly reach the target in the lung while exhibiting poor diffusion into the systemic circulation, leading to higher lung drug retention and efficacy while minimising toxicity to other organs. This review examines the important considerations and challenges in designing an inhaled protein therapeutics for local lung delivery: the choice of inhalation device, structural changes affecting drug deposition in diseased lungs, clearance mechanisms affecting an inhaled protein drug’s lung accumulation, protein stability, and immunogenicity. Possible approaches to overcoming these issues will also be discussed.

Synthesis and Biopharmaceutical Characterization of Amphiphilic Squalenyl Derivative Based Versatile Drug Delivery Platform

Limited drug loading capacity (LC), mostly below 5% w/w, is a significant drawback of nanoparticulate drug delivery systems (DDS). Squalenoylation technology, which employs bioconjugation of squalenyl moiety and drug, allows self-assemble of nanoparticles (NPs) in aqueous media with significantly high LC (>30% w/w). The synthesis and particle preparation of squalenoylated prodrugs are, however, not facile for molecules with multiple reactive groups. Taking a different approach, we describe the synthesis of amphiphilic squalenyl derivatives (SqDs) as well as the physicochemical and biopharmaceutical characterizations of their self-assembled NPs as DDSs. The SqDs included in this study are (i) cationic squalenyl diethanolamine (ii) PEGylated SqD (PEG 750 Da), (iii) PEGylated SqD (PEG 3,000 Da), and (iv) anionic squalenyl hydrogen sulfate. All four SqDs self-assemble into NPs in a size range from 100 to 200 nm in an aqueous solution. Furthermore, all NP derivatives demonstrate appropriate biocompatibility and adequate colloidal stability in physiological relevant pH environments. The mucoprotein binding of PEGylated NPs is reduced compared to the charged NPs. Most importantly, this technology allows excellent LC (at maximum of 45% w/w) of a wide range of multifunctional compounds, varying in physicochemical properties and molecular weight. Interestingly, the drug release profile can be tuned by different loading methods. In summary, the SqD-based NPs appear as versatile drug delivery platforms.

Tuning the PEG surface density of the PEG-PGA enveloped Octaarginine-peptide Nanocomplexes

One of the main limitations of protein drugs is their restricted capacity to cross biological barriers. We have previously reported nanostructured complexes of insulin and modified octaarginine (C12-r8), enveloped by a polyethyleneglycol-polyglutamic acid (PEG-PGA) protective shell, and showed their capacity to overcome different barriers associated to the oral modality of administration. The objective of this work was to produce the said nanocomplexes with structurally diverse PEG-PGA shells, i.e. with different chain lengths and PEG substitution degrees, and comparatively analyze their PEG surface density and subsequent impact on their interaction with mucus glycoproteins and Caco-2 cells. The new PEG-PGA enveloped C12-r8-insulin nanocomplexes (ENCPs) exhibited a narrow size distribution (average size of 210-239 nm), a neutral surface charge and a 100% insulin association efficiency (final insulin loading of 16.5-29.6% w/w). Proton nuclear magnetic resonance (¹H NMR) analysis indicated the possibility to modulate the PEG density on the ENCPs from 6.7 to 44.5 PEG chains per 100 nm². This increase in the ENCPs PEG surface density resulted in their reduced interaction with mucins in vitro, while their interaction with Caco-2 cells in vitro remained unaltered. Overall, these data indicate the capacity to tune the surface characteristics of the ENCPS in order to maximize the capacity of these nanocarriers to overcome barriers associated to mucosal surfaces.