Lectin-mediated drug delivery: the second generation of bioadhesives

Barriers and Strategies for Oral Peptide and Protein Therapeutics Delivery: Update on Clinical Advances

Peptide and protein (PP) therapeutics are highly specific and potent biomolecules that treat chronic and complex diseases. However, their oral delivery is significantly hindered by enzymatic degradation, instability, and poor permeability through the gastrointestinal (GI) epithelium, resulting in low bioavailability. Various strategies have emerged as transformative solutions to address existing challenges, offering enhanced protection, stabilization, and absorption of PPs. These strategies primarily focus on two major challenges: protecting the PP against harsh conditions and enhancing permeation across the intestinal membrane. Innovative approaches such as pH modulation and incorporation of enzyme inhibitors are usually used to mitigate proteolytic degradation of PP during transit across the GI tract. In a similar vein, absorption enhancers and prodrug strategies facilitate epithelial transport, while targeted delivery systems focus on specific areas of the GI tract to enhance absorption. Likewise, mucus-penetrating and mucoadhesive strategies have enhanced retention and interaction with epithelial cells, effectively overcoming barriers like the mucus layer and tight epithelial junctions. Furthermore, structural modifications such as lipidation, peptide cyclization, and polyethylene glycosylation are promising alternatives to render stability, prolong circulation time, and membrane permeability. In particular, functional biomaterials, active targeting, and lymphatic transport strategies have provided new platforms for oral PP delivery. Advancing in materials science, nanotechnology, and the disruption of medical devices holds new frontiers to overcome barriers. Despite substantial advancements, the limited success in clinical translation underscores the urgency of innovative strategies. This review presents oral PPs as a promising platform, highlighting the key barriers and strategies to transform their therapeutic landscapes.

Bioavailability Enhancement and Formulation Technologies of Oral Mucosal Dosage Forms: A Review

The oral mucosa is a versatile surface for drug administration, supporting both local and systemic therapies. Many active substances are effectively absorbed in the oral cavity, offering an alternative to enteral administration by bypassing the harsh gastrointestinal environment and hepatic first-pass metabolism. This has made oral mucosal drug delivery a growing area of research. Enhancing the bioavailability of active ingredients is a key focus in pharmaceutical technology, especially given the challenges of developing new drugs. Numerous strategies to improve bioavailability are compatible with oral mucosal delivery, with the unique anatomy of the oral cavity enabling specialized applications. A variety of dosage forms tailored for oral mucosal delivery meet therapeutic needs while addressing biopharmaceutical and patient compliance challenges. Proper formulation can achieve controlled release, improved bioavailability, and patient convenience. This review highlights the potential of oral mucosal drug delivery, focusing on bioavailability enhancement methods and the types and production technologies of dosage forms optimized for use in the oral cavity.

Mucoadhesion across scales: Towards the design of protein-based adhesives

Mucoadhesion is a special case of bioadhesion in which a material adheres to soft mucosal tissues. This review elucidates our current understanding of mucoadhesion across length, time, and energy scales by focusing on relevant structural features of mucus. We highlight the importance of both covalent and non-covalent interactions that can be tailored to maximize mucoadhesive interactions, particularly concerning proteinaceous mucoadhesives, which have been explored only to a limited extent so far in the literature. In particular, we highlight the importance of thiol groups, hydrophobic moieties, and charged species inherent to proteins as key levers to fine tune mucoadhesive performance. Some aspects of protein surface modification by grafting specific functional groups or coupling with polysaccharides to influence mucoadhesive performance are examined. Insights from this review offer a physicochemical roadmap to inform the development of biocompatible, protein-based mucoadhesive systems that can fulfil dual roles for both adhesion and delivery of actives, enabling the fabrication of advanced biomedical, nutritional and allied soft material technologies.

Strategies for intravesical drug delivery: From bladder physiological barriers and potential transport mechanisms

Intravesical drug delivery (IDD), as a noninvasive, local pathway of administration, has great clinical significance for bladder diseases, especially bladder cancer. Despite the many advantages of IDD such as enhanced focal drug exposure and avoidance of systemic adverse drug reactions, the effectiveness of drug delivery is greatly challenged by the physiological barriers of the bladder. In this review, the routes and barriers encountered in IDD are first discussed, and attention is paid to the potential internal/mucosal retention and absorption-transport mechanisms of drugs. On this basis, the avoidance, overcoming and utilization of the "three barriers" is further emphasized, and current design and fabrication strategies for intravesical drug delivery systems (IDDSs) are described mainly from the perspectives of constructing drug reservoirs, enhancing permeability and targeting, with the hope of providing systematic understanding and inspirations for the research of novel IDDSs and their treatment of bladder diseases.

Transformative Impact of Nanocarrier‐Mediated Drug Delivery: Overcoming Biological Barriers and Expanding Therapeutic Horizons

Advancing therapeutic progress is centered on developing drug delivery systems (DDS) that control therapeutic molecule release, ensuring precise targeting and optimal concentrations. Targeted DDS enhances treatment efficacy and minimizes off‐target effects, but struggles with drug degradation. Over the last three decades, nanopharmaceuticals have evolved from laboratory concepts into clinical products, highlighting the profound impact of nanotechnology in medicine. Despite advancements, the effective delivery of therapeutics remains challenging because of biological barriers. Nanocarriers offer a solution with a small size, high surface‐to‐volume ratios, and customizable properties. These systems address physiological and biological challenges, such as shear stress, protein adsorption, and quick clearance. They allow targeted delivery to specific tissues, improve treatment outcomes, and reduce adverse effects. Nanocarriers exhibit controlled release, decreased degradation, and enhanced efficacy. Their size facilitates cell membrane penetration and intracellular delivery. Surface modifications increase affinity for specific cell types, allowing precise treatment delivery. This study also elucidates the potential integration of artificial intelligence with nanoscience to innovate future nanocarrier systems.

Revisited and innovative perspectives of oral ulcer: from biological specificity to local treatment

Mouth ulcers, a highly prevalent ailment affecting the oral mucosa, leading to pain and discomfort, significantly impacting the patient's daily life. The development of innovative approaches for oral ulcer treatment is of great importance. Moreover, a deeper and more comprehensive understanding of mouth ulcers will facilitate the development of innovative therapeutic strategies. The oral environment possesses distinct traits as it serves as the gateway to the digestive and respiratory systems. The permeability of various epithelial layers can influence drug absorption. Moreover, oral mucosal injuries exhibit distinct healing patterns compared to cutaneous lesions, influenced by various inherent and extrinsic factors. Furthermore, the moist and dynamic oral environment, influenced by saliva and daily physiological functions like chewing and speaking, presents additional challenges in local therapy. Also, suitable mucosal adhesion materials are crucial to alleviate pain and promote healing process. To this end, the review comprehensively examines the anatomical and structural aspects of the oral cavity, elucidates the healing mechanisms of oral ulcers, explores the factors contributing to scar-free healing in the oral mucosa, and investigates the application of mucosal adhesive materials as drug delivery systems. This endeavor seeks to offer novel insights and perspectives for the treatment of oral ulcers.

Current Advancements on Oral Protein and Peptide Drug Delivery Approaches to Bioavailability: Extensive Review on Patents

Protein and peptide-based drugs have greater therapeutic efficacy and potential application and lower toxicity compared to chemical entities in long-term use within optimum concentration as they are easily biodegradable due to biological origin. While oral administration is preferable, most of these substances are currently administered intravenously or subcutaneously. This is primarily due to the breakdown and poor absorption in the GI tract. Hence, ongoing research is focused on investigating absorption enhancers, enzyme inhibitors, carrier systems, and stability enhancers as potential strategies to facilitate the oral administration of proteins and peptides. Investigations have been directed towards advancing novel technologies to address gastrointestinal (GI) barriers associated with protein and peptide medications. The current review intensifies formulation and stability approaches for oral protein & peptide drug delivery systems with all significant parameters intended for patient safety. Notably, certain innovative technologies have been patented and are currently undergoing clinical trials or have already been introduced into the market. All the approaches stated for the administration of protein and peptide drugs are critically discussed, having their current status, future directions, and recent patents published in the last decades.

Mucoadhesive drug delivery systems: a promising noninvasive approach to bioavailability enhancement. Part II: formulation considerations

INTRODUCTION

Mucoadhesive drug delivery systems (MDDS) are specifically designed to interact and bind to the mucosal layer of the epithelium for localized, prolonged, and/or targeted drug delivery. Over the past 4 decades, several dosage forms have been developed for localized as well as systemic drug delivery at different anatomical sites.

AREAS COVERED

The objective of this review is to provide a detailed understanding of the different aspects of MDDS. Part II describes the origin and evolution of MDDS, followed by a discussion of the properties of mucoadhesive polymers. Finally, a synopsis of the different commercial aspects of MDDS, recent advances in the development of MDDS for biologics and COVID-19 as well as future perspectives are provided.

EXPERT OPINION

A review of the past reports and recent advances reveal MDDS as highly versatile, biocompatible, and noninvasive drug delivery systems. The rise in the number of approved biologics, the introduction of newer highly efficient thiomers, as well as the recent advances in the field of nanotechnology have led to several excellent applications of MDDS, which are predicted to grow significantly in the future.

Mucoadhesive drug delivery systems: a promising non-invasive approach to bioavailability enhancement. Part I: biophysical considerations

INTRODUCTION

Mucoadhesive drug delivery systems (MDDS) are specifically designed to interact and bind to the mucosal layer for localized, prolonged, and/or targeted drug delivery. Over the past 4 decades, different sites have been explored for mucoadhesion including the nasal, oral, and vaginal cavities, the gastrointestinal tract and ocular tissues.

AREAS COVERED

The present review aims to provide a comprehensive understanding of different aspects of MDDS development. Part I focuses on the anatomical and biological aspects of mucoadhesion, which include a detailed elucidation of the structure and anatomy of the mucosa, the properties of mucin, the different theories of mucoadhesion and evaluation techniques.

EXPERT OPINION

The mucosal layer presents a unique opportunity for effective localization as well as systemic drug delivery via MDDS. Formulation of MDDS requires a thorough understanding of the anatomy of mucus tissue, the rate of mucus secretion and turnover, and the physicochemical properties of mucus. Further, the moisture content and the hydration of polymers are crucial for interaction with mucus. A confluence of different theories used to explain the mechanism of mucoadhesion is useful for understanding the mucoadhesion of different MDDS and their evaluation is subject to factors, such as the site of administration, type of dosage form, and duration of action. [Figure: see text].

SNAC for Enhanced Oral Bioavailability: An Updated Review

The delivery of proteins and peptides via an oral route poses numerous challenges to improve the oral bioavailability and patient compliance. To overcome these challenges, as well as to improve the permeation of proteins and peptides via intestinal mucosa, several chemicals have been studied such as surfactants, fatty acids, bile salts, pH modifiers, and chelating agents, amongst these medium chain fatty acid like C10 (sodium caprate) and Sodium N-[8-(2-hydroxybenzoyl) amino] caprylate (SNAC) and its derivatives that have been well studied from a clinical perspective. This current review enumerates the challenges involved in protein and peptide delivery via the oral route, i.e., non-invasive routes of protein and peptide administration. This review also covers the chemistry behind SNAC and toxicity as well as mechanisms to enhance the oral delivery of clinically proven molecules like simaglutide and other small molecules under clinical development, as well as other permeation enhancers for efficient delivery of proteins and peptides.

Oromucosal delivery of macromolecules: Challenges and recent developments to improve bioavailability

Owing to their biological diversity, high potency, good tolerability, low immunogenicity, site-specific activity, and great efficacy, macromolecular drugs (i.e., proteins and peptides, antibodies, hormones, nucleic acids, vaccines, etc.) are extensively used as diagnostics, prophylactics, and therapeutics in various diseases. To overcome drawbacks associated with parenteral (invasive) delivery of macromolecules as well as to preserve their therapeutic integrity, oromucosal route (sublingual and buccal) has been proven efficient alternate port of delivery. This review aims to summarize challenges associated with oromucosal route and overtime developments in conventional delivery systems with special emphasis on most recent delivery strategies. Over the past few decades, significant efforts have been made for improving the oromucosal absorption of macromolecules by employing chemical penetration enhancers (CPE), enzyme inhibitors, chemical modification of drug structure (i.e., lipidation, PEGylation, etc.), and mucoadhesive materials in the form of buccal tablets, films (or patches), sprays, fast disintegrating tablets, and microneedles. Adaptation of adjunct strategies (e.g., iontophoresis in conjunction with CPE) has shown significant improvement in oromucosal absorption of macromolecules; however, these approaches were also associated with many drawbacks. To overcome these shortcomings and to further improve therapeutic outcomes, specialized delivery devices called "hybrid nanosystems" have been designed in recent times. This newer intervention showed promising potential for promoting oromucosal absorption and absolute bioavailability of macromolecules along with improved thermostability (cold chain free storage), enabling self-administration, site-specific activity, improving therapeutic efficacy and patient compliance. We anticipate that tailoring of hybrid nanosystems to clinical trials as well as establishing their short- and long-term safety profile would substantiate their therapeutic value as pharmaceutical devices for oromucosal delivery of macromolecules.

Budesonide-Loaded Hyaluronic Acid Nanoparticles for Targeted Delivery to the Inflamed Intestinal Mucosa in a Rodent Model of Colitis

The aim of the present study was to investigate the therapeutic potential of budesonide- (BDS-) loaded hyaluronic acid nanoparticles (HANPs) for treatment of inflammatory bowel disease (IBD) using an acute model of colitis in rats. The therapeutic efficacy of BDS-loaded HANPs in comparison with an aqueous suspension of the drug with the same dose (30 μg/kg) was investigated 48 h following induction of colitis by intrarectal administration of acetic acid 4% in rats. Microscopic and histopathologic examinations were conducted in inflamed colonic tissue. Tissue concentration of tumor necrosis factor (TNF)-α was assessed by ELISA assay kit, while the activity of myeloperoxidase (MPO) was measured spectrophotometrically. Results from in vivo evaluations demonstrated that administrations of BDS-HANPs ameliorated the general endoscopic appearance, quite close to the healthy animals with no signs of inflammation and reduced the cellular infiltration, as well as the TNF-α level, and the MPO activity. It was found that delivery by BDS-loaded HANPSs alleviated the induced colitis significantly better than the same dose of the free drug. These data further suggest the potential of HANPs as a targeted drug delivery system to the inflamed colon mucosa.

Recent advances in functionally modified polymers for mucoadhesive drug delivery

Novel methods for the delivery of drugs other than the conventional method of oral administration have been a thrust area of research for a few decades. Mucoadhesive delivery of drugs opened up a new domain where rapid and patient-friendly delivery of drugs can be achieved. Delivery of drugs through the mucosal sites such as buccal, nasal, ocular, sublingual, rectal and vaginal facilitates bypassing the first-pass metabolism and the drug reaches the systemic circulation directly. This helps to increase the bioavailability of the drug. The study of the chemical characteristics of polymers with mucoadhesive properties and how the molecules or the pharmaceuticals are transported across the mucosa is very much needed for the advancement of research in this field. And at the same time, it is very pertinent to know about the anatomy and the physiology of the mucosal tissue and its variation in different regions of the body. In this review, we try to present a comprehensive understanding of relevant topics of mucoadhesion giving more emphasis on the mechanism of transport of drugs across mucosa, and different possible functional modifications of polymers to enhance the property of mucoadhesion.

Therapeutic nanotechnologies for Alzheimer's disease: a critical analysis of recent trends and findings

Alzheimer's Disease (AD) is an irreversible neurodegenerative disease for which no disease modifying therapies are presently available. Besides the identification of pathological targets, AD presents numerous clinical and pharmacological challenges such as efficient active delivery to the central nervous system, cell targeting, and long-term dosing. Nanoparticles have been explored to overcome some of these challenges as drug delivery vehicles or drugs themselves. However, early promises have failed to materialize as no nanotechnology-based product has been able to reach the market and very few have moved past preclinical stages. In this review, we perform a critical analysis of the past decade's research on nanomedicine-based therapies for AD at the preclinical and clinical stages. The main obstacles to nanotechnology products and the most promising approaches were also identified, including renewed promise with gene editing, gene modulation, and vaccines.

New Perspective on Natural Plant Protein-Based Nanocarriers for Bioactive Ingredients Delivery

The health effects of bioactive substances in the human body are affected by several factors, including food processing conditions, storage conditions, light and heat, among others. These factors greatly limit the stability and bioavailability of bioactive substances. These problems can be solved by a novel protein-based nanocarrier technology, which has the excellent potential to enhance solubility, bioavailability, and the controlled release of bioactive substances. In addition, plant protein has the advantages of economy, environmental protection, and high nutrition compared to animal protein. In this review, the preparation, characterization, and application of plant protein-based nanocarriers are summarized. The research deficiency and future prospects of plant protein nanocarriers are emphasized.

Superior Adhesion of a Multifunctional Protein-Based Micropatch to Intestinal Tissue by Harnessing the Hydrophobic Effect

Drug delivery systems comprising drug carriers capable of adhering to intestinal tissue have considerable potential to realize more sophisticated systemic drug delivery and topical drug treatments in the intestinal tract. The development of innovative strategies for improving the adhesion efficiency of carriers is of high importance for the advancement of this field. Herein, a novel approach to achieving high adhesion efficiency of drug carriers is presented, where the accessibility of the carrier to the intestinal surface and its subsequent adhesion to the intestinal tissue are promoted by utilizing the thermodynamic tendency of the hydrophobic carrier and its dispersion solvent, triacetin, to be excluded from the aqueous environment. Drug carriers are fabricated using proteins, imparting multiple functions, including drug release and the removal of reactive oxygen species (ROS). Results of ex vivo studies indicate that this multifunctional protein-based carrier, "protein micropatch," adheres to various mouse intestinal tissues, including the small intestine, colon, and inflamed colon, with high efficiency. Furthermore, protein micropatches, administered to mice via oral or rectal routes, successfully adhere to the intestinal tract. This approach and the highly functionalized carrier described in the study have the potential to significantly contribute to the development of bioadhesive carrier-based drug delivery systems.

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.

Drug Delivery Platforms Containing Thermoresponsive Polymers and Mucoadhesive Cellulose Derivatives: A Review of Patents

Nowadays, the development of mucoadhesive systems for drug delivery has gained keen interest, with enormous potential in applications through different routes. Mucoadhesion characterizes an attractive interaction between the pharmaceutical dosage form and the mucosal surface. Many polymers have shown the ability to interact with mucus, increasing the residence time of local and/or systemic administered preparations, such as tablets, patches, semi-solids, and micro and nanoparticles. Cellulose is the most abundant polymer on the earth. It is widely used in the pharmaceutical industry as an inert pharmaceutical ingredient, mainly in its covalently modified forms: methylcellulose, ethylcellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose, and carboxymethylcellulose salts. Aiming to overcome the drawbacks of oral, ocular, nasal, vaginal, and rectal routes and thereby maintaining patient compliance, innovative polymer blends have gained the interest of the pharmaceutical industry. Combining mucoadhesive and thermoresponsive polymers allows for simultaneous in situ gelation and mucoadhesion, thus enhancing the retention of the system at the site of administration and drug availability. Thermoresponsive polymers have the ability to change physicochemical properties triggered by temperature, which is particularly interesting considering the physiological temperature. The present review provides an analysis of the main characteristics and applications of cellulose derivatives as mucoadhesive polymers and their use in blends together with thermoresponsive polymers, aiming at platforms for drug delivery. Patents were reviewed, categorized, and discussed, focusing on the applications and pharmaceutical dosage forms using this innovative strategy. This review manuscript also provides a detailed introduction to the topic and a perspective on further developments.

Nano-engineering stable contact-based antimicrobials: Chemistry at the interface between nano-gold and bacteria

Contact-based antimicrobials, as antibiotic-free technologies that use non-specific interactions with bacterial cells to exert antimicrobial activity, are a prospective solution in fighting the global issue of bacterial resistance. A very simplified approach to their design considers the direct bonding of cationic guanidine-containing amino acids to the surface of nano-gold carriers. The structure enables antimicrobial activity due to a high density of cationic surface charges. This opens a set of novel questions that are important for their effective engineering, particularly regarding (i) chemistry and events that take place at the interface between NPs and cells, (ii) the direct influence of a charge (and its change) on interactions with bacterial and mammalian cells, and (iii) the stability of structures (and their antimicrobial activity) in the presence of enzymes, which are addressed in this paper. Because of the ability of amino acid-functionalized nano-gold to retain structural and functional activity, even after exposure to a range of physicochemical stimuli, they provide an excellent nanotechnological platform for designing highly effective contact-based antimicrobials and their applications.

Oral delivery of proteins and peptides: Challenges, status quo and future perspectives

Proteins and peptides (PPs) have gradually become more attractive therapeutic molecules than small molecular drugs due to their high selectivity and efficacy, but fewer side effects. Owing to the poor stability and limited permeability through gastrointestinal (GI) tract and epithelia, the therapeutic PPs are usually administered by parenteral route. Given the big demand for oral administration in clinical use, a variety of researches focused on developing new technologies to overcome GI barriers of PPs, such as enteric coating, enzyme inhibitors, permeation enhancers, nanoparticles, as well as intestinal microdevices. Some new technologies have been developed under clinical trials and even on the market. This review summarizes the history, the physiological barriers and the overcoming approaches, current clinical and preclinical technologies, and future prospects of oral delivery of PPs.

Systematic development of lectin conjugated microspheres for nose-to-brain delivery of rivastigmine for the treatment of Alzheimer's disease

The current study focuses on development of nasal mucoadhesive microspheres for nose-to-brain delivery of rivastigmine for Alzheimer treatment. A systematic development was employed for optimization of the formulation and process parameters influential on the quality attributes of the microspheres. The risk assessment study revealed major influence of the polymer concentration (ethylcellulose: chitosan), the concentration of surfactant solution (polyvinyl alcohol), and stirring speed as the critical factors for optimization of the microspheres. These factors were systematically optimized using Box-Behnken design and microspheres were evaluated for the particle size, entrapment efficiency, and in vitro drug release as the response variables. The optimized microspheres containing 4.4% wt/vol polymers, 1% wt/vol surfactant, and stirring speed at 1500 rpm showed particle size of 19.9 µm, entrapment efficiency of 77.8%, and drug release parameters as T_80% of 7.3 h. The surface modification of microspheres was performed with lectin by carbodiimide activation reaction and confirmed by difference in surface charge before and after chemical functionalization by zeta potential measurement which was found to be - 25.7 mV and 20.5 mV, respectively. Ex vivo study for bioadhesion strength evaluation on goat nasal mucosa indicated a significant difference (p < 0.001) between the plain (29%) and lectin functionalized microspheres (64%). In vivo behavioral and biochemical studies in the rats treated with lectin functionalized microspheres showed markedly better memory-retention vis-à-vis test and pure drug solution treated rats (p < 0.001). In a nutshell, the present studies showed successful development of nasal microspheres for enhanced brain delivery of rivastigmine for Alzheimer's treatment.

Intranasal Delivery of Targeted Nanoparticles Loaded With miR-132 to Brain for the Treatment of Neurodegenerative Diseases

Effective treatments for neurodegenerative diseases need to be developed. MiR132 is abundantly expressed in the brain, and it modulates neuron morphology and plays a key role in maintaining neuron survival. Regulating miR132 can effectively improve the symptoms of Alzheimer’s disease. It can also reduce cell death after cerebral hemorrhage, improve the microenvironment of hematoma lesions and provide a certain protective effect from brain damage after cerebral ischemia. MiR132 has great potential in the treatment of cerebral ischemia and Alzheimer’s disease. To prevent the decline of miR132 of miR132 levels in the blood, we used mouse and rat models of Alzheimer’s disease with ischemic brain injury, and then delivered Wheat germ agglutinin (WGA)-NPs-miR132 intranasally to treat neurological damage after cerebral ischemia. Synaptic protein expression levels in Alzheimer’s mouse models increased significantly after administration. We propose that, nasal delivery of WGA-NPs-miR132 is an interesting novel therapeutic approach for the treatment of neurodegenerative diseases.

Long-acting mucoadhesive thermogels for improving topical treatments of dry eye disease

Dry eye disease (DED) is the most common ocular disorder that causes persistent discomfort and blurry vision in patients. Despite pharmacotherapy strategies, the current topical administration of eye drops remains a great challenge owing to their low bioavailability and short residence time. Herein, we demonstrate an effective topical treatment of DED via rational design of a long-acting and mucoadhesive drug delivery system. Specifically, the drug carrier is a chemically ternary material system consisting of gelatin that serves as an enzyme-mediated degradable matrix, poly(N-isopropylacrylamide) as a thermo-responsive regulator, and lectin Helix pomatia agglutinin as a mucus-binding component. The long-acting drug release performance is exploited via initiator effects during the synthesis of the thermo-responsive polymer, while the mucoadhesive feature is inherited from the mucus-binding material. In a rabbit model of DED, a pharmacotherapy based on one-time topical administration of epigallocatechin gallate-loaded carrier onto the cul-de-sac could effectively repair the defective corneal epithelium via mitigating cellular inflammation, oxidative stress, and cell apoptosis for a sustained period over 14 days. These findings on the initiator and synergy effects in the development of the advanced ophthalmic formulation show great promise for efficient management of complex ocular diseases by a simple topical administration route.

Basics to advances in nanotherapy of colorectal cancer

Colorectal cancer (CRC) is the third most common cancer existing across the globe. It begins with the formation of polyps leading to the development of metastasis, especially in advanced stage patients, who necessitate intensive chemotherapy that usually results in a poor response and high morbidity owing to multidrug resistance and severe untoward effects to the non-cancerous cells. Advancements in the targeted drug delivery permit the targeting of tumor cells without affecting the non-tumor cells. Various nanocarriers such as liposomes, polymeric nanoparticles, carbon nanotubes, micelles, and nanogels, etc. are being developed and explored for effective delivery of cytotoxic drugs to the target site thereby enhancing the drug distribution and bioavailability, simultaneously subduing the side effects. Moreover, immunotherapy for CRC is being explored for last few decades. Few clinical trials have even potentially benefited patients suffering from CRC, still immunotherapy persists merely an experimental alternative. Assessment of the ongoing and completed trials is to be warranted for effective treatment of CRC. Scientists are paying efforts to develop novel carrier systems that may enhance the targeting potential of low therapeutic index chemo- and immune-therapeutics. Several preclinical studies have revealed the superior efficacy of nanotherapy in CRC as compared to conventional approaches. Clinical trials are being recruited to ascertain the safety and efficacy of CRC therapies. The present review discourses in a nutshell the molecular interventions including the genetics, signaling pathways involved in CRC, and advances in various strategies explored for the treatment of CRC with a special emphasis on nanocarriers based drug targeting.

Fluorescence "Turn-on" Lectin Sensors Fabricated by Ligand-Assisted Labeling Probes for Detecting Protein-Glycoprotein Interactions

Elucidation of protein-protein interactions (PPIs) is often very challenging and yields complex and unclear results. Lectin-glycoprotein interactions are especially difficult to study due to the noncovalent nature of the interactions and inherently low binding affinities of proteins to glycan ligands on glycoproteins. Here, we report a "ligand-directed labeling probe (LLP)"-based approach to fabricate protein probes for elucidating protein-glycoprotein interactions. LLP was designed with dual photoactivatable groups for the introduction of an alkyne handle proximal to the carbohydrate-binding pocket of lectins, Ricinus communis agglutinin 120 (RCA₁₂₀) and recombinant human Siglec-2-Fc. In proof-of-principle studies, alkynylated lectins were conjugated with a photoreactive diazirine cross-linker and an environment-sensitive fluorophore, respectively, by the bioorthogonal click reaction. The modified RCA₁₂₀ or Siglec-2-Fc was used for detecting the interaction with the target glycoprotein in the solution or endogenously expressed glycoproteins on live HeLa cells. We anticipate that the fabrication of these protein probes will accelerate the discovery of novel PPIs.

Advancing the stimuli response of polymer-based drug delivery systems for ocular disease treatment

Recent exploitations of stimuli-responsive polymers as ophthalmic drug delivery systems for the treatment of eye diseases are summarized and discussed.

Aqueous two phase based selective extraction of mannose/glucose specific lectin from Indian cultivar of Pisum sativum seed

Pisum sativum lectin (Psl) being a high-value protein has marked its application in the biomedical and therapeutic field. Aqueous two phase extraction (ATPE) was implemented as a selective partitioning technique for the partial purification of Psl from its seeds. PEG/citrate based biodegradable aqueous two phase system (ATPS) was screened and the factors such as the type and concentration of citrate salts, molar mass and concentration of polyethylene glycol (PEG), tie line length (TLL) and additive (NaCl) concentration, pH, crude load and volume ratio were studied for the selective partition of Psl. The Psl was successfully extracted to the top phase in the ATPS formed with 18% PEG 6000/16% sodium citrate at 41.01% TLL, 2% NaCl and pH of 7.5. A volume ratio of 0.76 and a crude load of 20% showed maximum activity yield of 122.12% with the purification factor of 16.26. The subunits of Psl namely α and β were identified with a molecular weight of 6 and 18 kDa respectively during the purity analysis using SDS PAGE and HPLC.

Nanostructured cubosomes in an in situ nasal gel system: an alternative approach for the controlled delivery of donepezil HCl to brain

The purpose of this research was to develop cubosomal mucoadhesive in situ nasal gel to enhance the donepezil HCl delivery to the brain. Glycerol mono-oleate (GMO) and surfactant poloxamer 407 were used to prepare cubosomes. The developed formulations were characterized for particle size (PS), poly dispersity index (PDI), zeta potential (ZP), entrapment efficiency (EE), transmission electron microscopy (TEM), in vitro drug release and in vivo bio-distribution study in blood and brain tissue. Central composite design was used for the optimization purpose and the selected formulation (containing GMO 2 g and poloxamer 1.5%) was prepared in presence of gellan gum and konjac gum as gelling agent and mucoadhesive agent respectively. The optimal cubosomal dispersion and optimal cubosomal mucoadhesive in situ nasal gel were subjected to in vivo bio-distribution studies in rat model. It showed significantly higher transnasal permeation and better distribution to the brain, when compared to the drug solution. Thus, the formulated cubosomal mucoadhesive in situ gel could be considered as a promising carrier for brain targeting of CNS acting drugs through the transnasal route.

Mucosal Applications of Poloxamer 407-Based Hydrogels: An Overview

Poloxamer 407, also known by the trademark Pluronic^® F127, is a water-soluble, non-ionic triblock copolymer that is made up of a hydrophobic residue of polyoxypropylene (POP) between the two hydrophilic units of polyoxyethylene (POE). Poloxamer 407-based hydrogels exhibit an interesting reversible thermal characteristic. That is, they are liquid at room temperature, but they assume a gel form when administered at body temperature, which makes them attractive candidates as pharmaceutical drug carriers. These systems have been widely investigated in the development of mucoadhesive formulations because they do not irritate the mucosal membranes. Based on these mucoadhesive properties, a simple administration into a specific compartment should maintain the required drug concentration in situ for a prolonged period of time, decreasing the necessary dosages and side effects. Their main limitations are their modest mechanical strength and, notwithstanding their bioadhesive properties, their tendency to succumb to rapid elimination in physiological media. Various technological approaches have been investigated in the attempt to modulate these properties. This review focuses on the application of poloxamer 407-based hydrogels for mucosal drug delivery with particular attention being paid to the latest published works.

Strategies for the enhanced intracellular delivery of nanomaterials

The intracellular delivery of nanomaterials and drugs has been attracting increasing research interest, mainly because of their important effects and functions in several organelles. Targeting specific organelles can help treat or decrease the symptoms of diabetes, cancer, infectious, and autoimmune diseases. Tuning biological and chemical properties enables the creation of functionalized nanomaterials with enhanced intracellular uptake, ability to escape premature lysosome degradation, and to reach a specific target. Here, we provide an update of recent advances in the intracellular delivery mechanisms that could help drugs reach their target more efficiently.

Development and evaluation of exemestane-loaded lyotropic liquid crystalline gel formulations

Introduction: The use of liquid crystalline (LC) gel formulations for drug delivery has considerably improved the current delivery methods in terms of bioavailability and efficacy. The purpose of this study was to develop and evaluate LC gel formulations to deliver the anti-cancer drug exemestane through transdermal route. Methods: Two LC gel formulations were prepared by phase separation coacervation method using glyceryl monooleate (GMO), Tween 80 and Pluronic® F127 (F127). The formulations were characterized with regard to encapsulation efficiency (EE), vesicle size, Fourier transform infrared (FTIR) spectroscopy, surface morphology (using light and fluorescence microscopy), in vitro release, ex vivo permeation, in vitro effectiveness test on MDA-MB231 cancer cell lines and histopathological analysis. Results: Results exhibited that the EE was 85%-92%, vesicle size was 119.9-466.2 nm while morphology showed spherical vesicles after hydration. An FTIR result also revealed that there was no significant shift in peaks corresponding to Exemestane and excipients. LC formulations release the drug from cellulose acetate and Strat-MTM membrane from 15%-88.95%, whereas ex vivo permeation ranges from 37.09-63%. The in vitro effectiveness study indicated that even at low exemestane concentrations (12.5 and 25 μg/mL) the formulations were able to induce cancer cell death, regardless of the surfactant used. Histopathological analysis thinning of the epidermis as the formulations penetrate into the intercellular regions of squamous cells. Conclusion: The results conjectured that exemestane could be incorporated into LC gels for the transdermal delivery system and further preclinical studies such as pharmacokinetic and pharmacodynamic studies will be carried out with suitable animal models.

Engineering nanomaterials to overcome the mucosal barrier by modulating surface properties

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

Oral insulin delivery: existing barriers and current counter-strategies

Objectives

The chronic and progressive nature of diabetes is usually associated with micro- and macrovascular complications where failure of pancreatic β-cell function and a general condition of hyperglycaemia is created. One possible factor is failure of the patient to comply with and adhere to the prescribed insulin due to the inconvenient administration route. This review summarizes the rationale for oral insulin administration, existing barriers and some counter-strategies trialled.

Key findings

Oral insulin mimics the physiology of endogenous insulin secreted by pancreas. Following the intestinal absorption of oral insulin, it reaches the liver at high concentration via the portal vein. Oral insulin on the other hand has the potential to protect pancreatic β-cells from autoimmune destruction. Structural modification, targeting a particular tissue/receptor, and the use of innovative pharmaceutical formulations such as nanoparticles represent strategies introduced to improve oral insulin bioavailability. They showed promising results in overcoming the hurdles facing oral insulin delivery, although delivery is far from ideal.

Summary

The use of advanced pharmaceutical technologies and further research in particulate carrier system delivery predominantly nanoparticle utilization would offer useful tools in delivering insulin via the oral route which in turn would potentially improve diabetic patient compliance to insulin and the overall management of diabetes.

Phaseolus vulgaris lectins: A systematic review of characteristics and health implications

Legume lectins are carbohydrate-binding proteins of non-immune origin. Significant amounts of lectins have been found in Phaseolus vulgaris beans as far back as in the last century; however, many questions about their potential biological roles still remain obscure. Studies have shown that lectins are anti-nutritional factors that can cause intestinal disorders. Owing to their ability to act as toxic allergens and hemagglutinins, the Phaseolus vulgaris lectins are of grave concern for human health and safety. Nonetheless, their potential beneficial health effects, such as anti-cancer, anti-human immunodeficiency virus (anti-HIV), anti-microbial infection, preventing mucosal atrophy, reducing type 2 diabetes and obesity, promoting nutrients absorption and targeting drugs, are of immense interest. The significance of Phaseolus vulgaris lectins in biological researches and the potential biomedical applications have placed tremendous emphasis on the development of purification strategies to obtain the protein in pure and stable forms. These purification strategies entail considerations such as effects of proteolysis, heating, gamma radiation, and high-hydrostatic-pressure that can have crucial outcomes in either eliminating or improving bioactivities of the lectins. Thus, up-to-date research findings of Phaseolus vulgaris lectins on different aspects such as anti-nutritional and health impacts, purification strategies and novel processing trends, are systematically reviewed.

Recent advances on biodegradable polymeric carrier-based mucosal immunization: an overview

Mucosal administration of vaccine is most prevalent way to induce desired immunity against various types of antigen and microbial in central and in addition, the peripheral blood in most external mucosal surface. Mucosal delivery of vaccine provides both humoral and cellular responses against mucosal infection. Mucosa, which are exposed to heavy loads of commensal and pathogenic microorganism, are one of the main region where infections are built up, also, thus have frontline status in immunity, making mucosa perfect site for vaccines application. The nasal route is favoured over parenteral route due to ease of administration, protection of antigen from degradation and induces sIgA which is not produced by systemic immunity. Natural and synthetic polymers are utilized to get nanoparticles carrier systems for development of nasal mucosal antibodies. The present review summarized the recent development in the field of vaccine delivery by means of mucoadhesive polymeric carriers. This review also describes the recent patent conceded for mucosal immunization utilizing these polymeric carriers.

ECM Mechano-Sensing Regulates Cytoskeleton Assembly and Receptor-Mediated Endocytosis of Nanoparticles

It is possible to create sophisticated and target-specific devices for nanomedicine thanks to technological advances in the engineering of nanomaterials. When on target, these nanocarriers often have to be internalized by cells in order to accomplish their diagnostic or therapeutic function. Therefore, the control of such uptake mechanism by active targeting strategy has today become the new challenge in nanoparticle designing. It is also well-known that cells are able to sense and respond to the local physical environment and that the substrate stiffness, and not only the nanoparticle design, influences the cellular internalization mechanisms. In this frame, our work reports on the cyclic relationship among substrate stiffness, cell cytoskeleton assembly and internalization mechanism. Nanoparticles uptake has been investigated in terms of the mechanics of cell environment, the resulting cytoskeleton activity and the opportunity of activate molecular specific molecular pathways during the internalization process. To this aim, the surface of 100 nm polystyrene nanoparticles was decorated with a tripeptide (RGD and a scrambled version as a control), which was able to activate an internalization pathway directly correlated to the dynamics of the cell cytoskeleton, in turn, directly correlated to the elastic modulus of the substrates. We found that the substrate stiffness modulates the uptake of nanoparticles by regulating structural parameters of bEnd.3 cells as spreading, volume, focal adhesion, and mechanics. In fact, the nanoparticles were internalized in larger amounts both when decorated with RGD, which activated an internalization pathway directly correlated to the cell cytoskeleton, and when cells resided on stiffer material that, in turn, promoted the formation of a more structured cytoskeleton. This evidence indicates the directive role of the mechanical environment on cellular uptake of nanoparticles, contributing new insights to the rational design and development of novel nanocarrier systems.

Lectins, Interconnecting Proteins with Biotechnological/Pharmacological and Therapeutic Applications

Lectins are proteins extensively used in biomedical applications with property to recognize carbohydrates through carbohydrate-binding sites, which identify glycans attached to cell surfaces, glycoconjugates, or free sugars, detecting abnormal cells and biomarkers related to diseases. These lectin abilities promoted interesting results in experimental treatments of immunological diseases, wounds, and cancer. Lectins obtained from virus, microorganisms, algae, animals, and plants were reported as modulators and tool markers in vivo and in vitro; these molecules also play a role in the induction of mitosis and immune responses, contributing for resolution of infections and inflammations. Lectins revealed healing effect through induction of reepithelialization and cicatrization of wounds. Some lectins have been efficient agents against virus, fungi, bacteria, and helminths at low concentrations. Lectin-mediated bioadhesion has been an interesting characteristic for development of drug delivery systems. Lectin histochemistry and lectin-based biosensors are useful to detect transformed tissues and biomarkers related to disease occurrence; antitumor lectins reported are promising for cancer therapy. Here, we address lectins from distinct sources with some biological effect and biotechnological potential in the diagnosis and therapeutic of diseases, highlighting many advances in this growing field.

Antimicrobial efficacy and safety of mucoadhesive exopolymer produced by Acinetobacter haemolyticus

This study evaluated five extracellular polymers of bacterial origin possessing mucoadhesive properties for their antimicrobial properties and toxicological characteristics. Of the five tested mucoadhesive biopolymers, the extracellular polymer produced by a strain of Acinetobacter haemolyticus exhibited broad antimicrobial efficacy towards Yersinia enterocolitica, Salmonella typhimurium, Listeria monocytogenes, Escherichia coli O157:H7 and Bacillus subtilis. Significant (p<0.05) inhibition of gram negative bacterial pathogens followed by gram positives were observed with the biopolymer at a dose of 40-60μg ml-1 at ambient temperature. The cytotoxicity under in vitro conditions and oral toxicity in murine models was also evaluated. The biopolymer did not elicit either haemolytic activity or toxicity in RAW 264.7 cell lines. Haemotological, histopathological and general examinations indicated no adverse effects in Swiss albino mice fed with the biopolymer (120mg kg-1 body weight-1 day1) over a period of 30 days. These results suggested that the biopolymer was well tolerated without any signs of toxicity and may have several potential biomedical applications where disinfection is desired.