Nanocarriers for ocular drug delivery: current status and translational opportunity

Liposomal topical drug administration surpasses alternative methods in glaucoma therapeutics: a novel paradigm for enhanced treatment

OBJECTIVES

Glaucoma is a leading cause of permanent blindness. Despite therapeutic advancements, glaucoma management remains challenging due to limitations of conventional drug delivery, primarily topical eye drops, resulting in suboptimal outcomes and a global surge in cases. To address these issues, liposomal drug delivery has emerged as a promising approach.

KEY FINDINGS

This review explores the potential of liposomal-based medications, with a particular focus on topical administration as a superior alternative to enhance therapeutic efficacy and improve patient compliance compared to existing treatments. This writing delves into the therapeutic prospects of liposomal formulations across different administration routes, as evidenced by ongoing clinical trials. Additionally, critical aspects of liposomal production and market strategies are discussed herein.

SUMMARY

By overcoming ocular barriers and optimizing drug delivery, liposomal topical administration holds the key to significantly improving glaucoma treatment outcomes.

Nanotechnology-based non-invasive strategies in ocular therapeutics: Approaches, limitations to clinical translation, and safety concerns

The eye is a highly sensitive and vital component that significantly affects human quality of life. Diseases that affect the eye are major contributors to visual impairment and blindness and can have a profound effect on an individual's well-being. Ocular drug delivery is challenging because of physiological and anatomical barriers. Invasive Intravitreal administration is primarily used for the treatment and management of posterior segmental disease. However, frequent intravitreal administration is associated with adverse effects. Furthermore, topical administration results in less than 5% ocular bioavailability, leading to a void in the safe and efficacious management of posterior segment diseases. Nanocarrier-based systems have been well explored as ocular therapeutics to overcome the sub-therapeutic management attributed to conventional eye drops and physiological and anatomical barriers. Since the first report of nanoparticles to date, the nanocarrier system has come a long way with the simplicity and versatility offered by the system. Significant progress has been made in the development of noninvasive nanocarrier systems and their interactions with the ocular surface. The nanocarrier system enhances precorneal retention, limits nontherapeutic absorption, and offers controlled drug release. This review aims to provide an overview of the recent advancements in noninvasive nanocarrier-based topical ocular drug delivery systems, including their interaction with the ocular surface, the barriers to their translation to clinical settings, and the associated scale-up challenges.

Bringing ophthalmology into the scientific world: Novel nanoparticle-based strategies for ocular drug delivery

The distinctive benefits and drawbacks of various drug delivery strategies to supply corneal tissue improvement for sense organs have been the attention of studies worldwide in recent decades. Static and dynamic barriers of ocular tissue prevent foreign chemicals from entering and inhibit the active absorption of therapeutic medicines. The distribution of different medications to ocular tissue is one of the most appealing and demanding tasks for investigators in pharmacology, biomaterials, and ophthalmology, and it is critical for cornea wound healing due to the controlled release rate and increased drug bioavailability. It should be mentioned that the transport of various types of medications into the different sections of the eye, particularly the cornea, is exceedingly challenging because of its distinctive structure and various barriers throughout the eye. Nanoparticles are being studied to improve medicine delivery strategies for ocular disease. Repetitive corneal drug delivery using biodegradable nanocarriers allows a medicine to remain in different parts of the cornea for extended periods of time and thus improve administration route effectiveness. In this review, we discussed eye anatomy, ocular delivery barriers, as well as the emphasis on the biodegradable nanomaterials ranging from organic nanostructures, such as nanomicelles, polymers, liposomes, niosomes, nanowafers, nanoemulsions, nanosuspensions, nanocrystals, cubosomes, olaminosomes, hybridized NPs, dendrimers, bilosomes, solid lipid NPs, nanostructured lipid carriers, and nanofiber to organic nanomaterials like silver, gold, and mesoporous silica nanoparticles. In addition, we describe the nanotechnology-based ophthalmic medications that are presently on the market or in clinical studies. Finally, drawing on current trends and therapeutic approaches, we discuss the challenges that innovative optical drug delivery systems confront and propose future research routes. We hope that this review will serve as a source of motivation and inspiration for developing innovative ophthalmic formulations.

Unlocking the Potential of Antimicrobial Peptides: Cutting-Edge Advances and Therapeutic Potential in Combating Bacterial Keratitis

Bacterial keratitis is a prevalent, and severe corneal illness resulting from bacterial pathogens. Failure to administer a timely and suitable therapy may lead to corneal opacity, ulceration, significant vision impairment, or potential blindness. Current clinical interventions for bacterial keratitis involve the administration of topical antimicrobial agents and systemic antibiotics. However, the misuse and overuse of antibiotics have led to the rapid emergence of antibiotic-resistant bacteria. Additionally, the restricted antibacterial spectrum and possible adverse effects of antibiotics have provided considerable obstacles to traditional therapies. This highlights the urgent need for novel and highly effective antimicrobial agents. Antimicrobial peptides (AMPs) are a class of naturally occurring or synthetically designed small molecules that have gained significant attention due to their unique antimicrobial mechanisms and low risk of resistance development. AMPs exhibit promising potential in treating bacterial keratitis through direct antibacterial mechanisms, such as inhibiting cell wall synthesis, disrupting cell membranes, and interfering with nucleic acid metabolism, as well as indirect mechanisms, including modulation of the host immune response. This review provides a comprehensive overview of the antibacterial mechanisms of AMPs and their advancements in the treatment of bacterial keratitis. It emphasizes the role of various modification strategies and artificial-intelligence-assisted design in enhancing the antibacterial efficacy, stability, and biocompatibility of AMPs. Furthermore, this review discusses the latest progress in combining AMPs with delivery systems for improved therapeutic outcomes. Finally, the review highlights the current challenges and future perspectives of AMPs in bacterial keratitis treatment, providing valuable insights for developing novel AMPs with high antibacterial efficacy, stability, and safety for bacterial keratitis therapies.

Implications of nanotechnology for the treatment of Dry Eye Disease: Recent advances

Managing Dry Eye Disease (DED), a prevalent condition affecting the ocular surface, remains challenging despite advancements in diagnostics and therapies. Current treatments primarily involve lubricating eye drops and anti-inflammatory medications, which often require prolonged use and generally provide only symptomatic relief. The current study focuses on improving DED treatments through nano-drug delivery technologies and advanced formulations. These systems aim to address the limitations of conventional therapies by providing extended, targeted, and sustained drug release. The development of innovative nanomaterials offers improved precision, control, and customization for DED management. By enabling controlled and sustained drug release, these nano-drug delivery systems could offer longer-lasting relief, addressing the chronic nature of DED more effectively than current symptomatic therapies. Future research should focus on integrating multiple therapeutic agents within these systems to simultaneously target inflammation and tear film instability. This review examines the potential of nano-based materials for DED treatment, with a particular emphasis on lipid-based, polymer-based and polysaccharide-based systems.

Antibacterial Lecithin/Chitosan Nanoparticles for the Sustained Release of Ciprofloxacin to Treat Ocular Bacterial Infections

Ocular drug-delivery is one of the most challenging areas owing to nature of ocular tissues. Various nanoformulations have been designed and investigated for drug-delivery to achieve high drug bioavailability. The major focus of these preparations available in market is to utilize nanomaterial as drug-carrier only, with less focus on developing functional-nanomaterials, which is a key knowledge gap in the field. To address this, we developed a nanoparticulate system from bioactive-polymers, having intrinsic antimicrobial and mucoadhesiveness, loaded with ciprofloxacin (cipro) to treat ocular bacterial infections. Cipro-loaded lecithin/chitosan nanoparticles were prepared and characterized for their physiochemical properties. They exhibited good drug loading efficiency and showed sustained drug-release for 72 h, with slow release for first 4 h followed by a burst release in phosphate buffered saline and simulated tear fluid. Cipro-loaded nanoparticles were assessed for their antibacterial potential against Staphylococcus aureus (96 %) and Pseudomonas aeruginosa (72 %) using optical density, disc-diffusion method, live-dead assay, and demonstrated promising antibacterial properties. The drug-loaded nanoparticles showed good cytocompatibility (~90 %) towards murine fibroblasts and rabbit corneal cells. Being amphiphilic in nature, the nanoparticles exhibited mucoadhesiveness, hemocompatibility (<4 %) and, thus, proving to be a promising candidate for treating ocular infections. This approach ensures efficient drug delivery and synergic/additive therapeutic effects.

Nanotechnology in Ocular Drug Delivery: The Potential of Polymeric Micelles as a Drug Delivery Vehicle

Conventional ocular drug delivery systems face challenges like rapid clearance, high dosages, low compliance, and poor bioavailability. A novel solution utilizes mucoadhesive polymers for controlled release, enhancing drug effectiveness while reducing dosages and frequency. Polymeric micelles, nanosized colloidal DDS, are set to modify drug delivery for challenging drugs mainly belonging to Biopharmaceutical Classification System class II (low solubility and high permeability), class III (high solubility and low permeability), and class IV (low solubility and low permeability). Micelles solubilize poorly soluble drugs, shielding them from degradation and macrophage uptake and extending drug action. Their small size enables them to breach ocular barriers, elevating therapeutic impact and bioavailability. This review explores polymeric micelles' potential in ocular drug delivery, covering their introduction, formulation, preparation, characterization, applications, recent progress, and challenges through critical analysis of all possible research communications so far. The review also scrutinizes the transition from lab to clinical use. Polymeric micelles revolutionize ocular drug delivery by surmounting limitations through enhanced solubilization, protection, and sustained release. This comprehensive review highlights their potential to improve ocular drug delivery practices.

Thiolated gellan gum/polyethylene glycol diacrylate hydrogels containing timolol maleate-loaded chitosan nanoparticles for ophthalmic delivery

The combination of hydrogels with nanoformulations can significantly enhance the delivery and effectiveness of drugs in ophthalmic drug delivery systems. In the current study, the polyethylene glycol diacrylate (PEGDA)/thiolated gellan gum (GGSH) hydrogels based on GGSH and PEGDA were prepared via thiol-ene reaction using Irgacure 2959 as a photoinitiator. To this end, the modification of GG was achieved by esterification of the hydroxyl groups of GG with the carboxyl group of mercaptopropionic acid with a free thiol amount of 95.5 μmol g-1. To provide sustained release, chitosan nanoparticles (CSNPs) containing timolol maleate (TM) with 56.4% entrapment efficiency were synthesized by the desolvation method and encapsulated in the developed hydrogel. The values of zeta potential and particle size of CSNPs were +26.0 mV and 182.4 nm, respectively. The physico/chemical properties of the hydrogels were investigated via texture analyzer, FT-IR, XRD, and SEM. Thein vitrodegradation, swelling behavior, rheological assessments, cell viability testing, and porosity determination were evaluated. With the increase in PEGDA concentration, the mechanical properties were increased. While the rate of swelling, degradation, and drug release were decreased. Thein vitrobiocompatibility of hydrogels was confirmed using the MTT test. According to anex vivostudy, ocular drug delivery using the obtained transparent hydrogels is promising due to improved drug permeation and sustained release of TM via CSNPs.

Nanotechnological approaches to improve corticosteroids ocular therapy

The administration of corticosteroids is the first-line treatment of the clinical conditions with ocular inflammation. Nonetheless, ocular physiological mechanisms, anatomical barriers and corticosteroid properties prevent it from reaching the target site. Thus, frequent topical administered doses or ocular injections are required, leading to a higher risk of adverse events and poor patient compliance. Designing novel drug delivery systems based on nanotechnological tools is a useful approach to overcome disadvantages associated with the ocular delivery of corticosteroids. Nanoparticle-based drug delivery systems represent an alternative to the current dosage forms for the ocular administration of corticosteroids, since due to their particle size and the properties of their materials, they can increase their solubility, improve ocular permeability, control their release and increase bioavailability after their ocular administration. In this way, lipid and polymer-based nanoparticles have been the main strategies developed, giving rise to novel patent applications to protect these innovative drug delivery systems as a product, its preparation or administration method. Additionally, it should be noted that at least 10 clinical trials are being carried out to evaluate the ocular application of different pharmaceutical formulations based on corticosteroid-loaded nanoparticles. Through a comprehensive and extensive analysis, this review highlights the impact of nanotechnology applications in ocular inflammation therapy with corticosteroids.

The role of metal nanocarriers, liposomes and chitosan-based nanoparticles in diabetic retinopathy treatment: A review study

Diabetic Retinopathy (DR) is a significant and progressive eye complication associated with diabetes mellitus, leading to potential vision loss. The pathophysiology of DR involves complex neurovascular changes due to prolonged hyperglycemia, resulting in microangiopathy and neurodegeneration. Current treatment modalities come with limitations such as low bioavailability of therapeutic agents, risk of side effects, and surgical complications. Consequently, the prevention and management of DR, particularly in its advanced stages, present ongoing challenges. This review investigates recent advancements in nanotechnology as a novel approach to enhance the treatment of DR. A comprehensive literature review of recent studies focusing on nanocarriers for drug delivery in DR treatment and an analysis of their efficacy compared to traditional methods was conducted for this study. The findings indicate that nanotechnology can significantly enhance the bioavailability of therapeutic agents while minimizing systemic exposure and associated side effects. The novelty of this study lies in its focus on the intersection of nanotechnology and ophthalmology, exploring innovative solutions that extend beyond existing literature on DR treatments. By highlighting recent advancements in this field, the study paves the way for future research aimed at developing more effective therapeutic strategies for managing DR.

Drug delivery strategies to improve the treatment of corneal disorders

Anterior eye disorders including dry eye syndrome, keratitis, chemical burns, and trauma have varying prevalence rates in the world. Classical dosage forms based-topical ophthalmic drugs are popular treatments for managing corneal diseases. However, current dosage forms of ocular drugs can be associated with major challenges such as the short retention time in the presence of ocular barriers. Developing alternative therapeutic methods is required to overcome drug bioavailability from ocular barriers. Nanocarriers are major platforms and promising candidates for the administration of ophthalmic drugs in an adjustable manner. This paper briefly introduces the advantages, disadvantages, and characteristics of delivery systems for the treatment of corneal diseases. Additionally, advanced technologies such as 3D printing are being considered to fabricate ocular drug carriers and determine drug dosages for personalized treatment. This comprehensive review is gathered through multiple databases such as Google Scholar, PubMed, and Web of Science. It explores information around "ocular drug delivery systems'', "nano-based drug delivery systems'', "engineered nanocarriers'', and "advanced technologies to fabricate personalized drug delivery systems''.

Recent updates on drug delivery approaches for improved ocular delivery with an insight into nanostructured drug delivery carriers for anterior and posterior segment disorders

Ocular diseases have a major impact on patient's vision and quality of life, with approximately 2.2 billion people have visual impairment worldwide according to the findings from the World Health Organization (WHO). The eye is a complex organ with unique morphology and physiology consisting of numerous ocular barriers which hinders the entry of exogenous substances and impedes drug absorption. This in turn has a substantial impact on effective drug delivery to treat ocular diseases, especially intraocular disorders which has consistently presented a challenge to eye care professionals. The most common method of delivering medications to the eye is topical instillation of eye drops. Although this approach is a viable option for treating many ocular diseases remains a major challenge for the effective treatment of posterior ocular conditions. Up till now, incessant efforts have been committed to design innovative drug delivery systems with the hopes of potential clinical application. Modern developments in nanocarrier's technology present a potential chance to overcome these obstacles by enabling targeted delivery of the loaded medication to the eyes with improved solubility, delayed release, higher penetration and increased retention. This review covers the anatomy of eye with associated ocular barriers, ocular diseases and administration routes. In addition it primarily focuses on the latest progress and contemporary applications of ophthalmic formulations providing specific insight on nanostructured drug delivery carriers reported over the past 5 years highlighting their values in achieving efficient ocular drug delivery to both anterior and posterior segments. Most importantly, we outlined in this review the macro and nanotechnology based ophthalmic drug formulations that are being patented or marketed so far for treating ocular diseases. Finally, based on current trends and therapeutic concepts, we highlighted the challenges faced by novel ocular drug delivery systems and provided prospective future developments for further research in these directions. We hope that this review will serve as a source of motivation and ideas for formulation scientists in improving the design of innovative ophthalmic formulations.

Advances in dorzolamide hydrochloride delivery: harnessing nanotechnology for enhanced ocular drug delivery in glaucoma management

Dorzolamide hydrochloride (DRZ) is a carbonic anhydrase inhibitor utilized in managing elevated intraocular pressure (IOP) associated with glaucoma. However, its clinical effectiveness is hindered by a short half-life, low residence time, and the need for frequent dosing, highlighting the necessity for innovative delivery systems. This work reviews recent advancements in DRZ delivery, particularly focusing on cyclodextrin complexation and nanotechnology applications. It explores the potential of cyclodextrin derivatives to enhance DRZ's bioavailability. DRZ cyclodextrin complexes or nanoparticulate systems maintain high drug concentrations in the eye while minimizing irritation and viscosity-related issues. Nanotechnology introduces nanoparticle-based carriers such as polymeric nanoparticles, solid lipid nanoparticles, liposomes, niosomes, and nanoemulsions. These formulations enable sustained drug release, improved corneal permeation, and enhanced patient compliance. Clinical trials have shown that DRZ nanoparticle eye drops and nanoliposome formulations offer efficacy comparable to conventional therapies, with the potential for better tolerability. Overall, this review highlights significant progress in DRZ delivery systems, suggesting their potential to transform glaucoma treatment by addressing current limitations and improving therapeutic outcomes.

Recent Nanotechnological Trends in the Management of Microbial Keratitis

Microbial keratitis (MK) is a sight-threatening ocular disease that needs rapid diagnosis and treatment to prevent more serious outcomes. The broad-spectrum topical antimicrobial treatment is currently the main pharmacological approach for MK management, yet its efficacy is increasingly challenged by evolving antimicrobial resistance, including multidrug resistance. Also, the ocular surface presents numerous challenges for standard topical drug delivery. The failure and ineffectiveness of current therapies have necessitated the development of novel therapeutic strategies to manage MK. With advances in nanotechnology in the biomedical field, various nanomaterials can be employed to control MK. The primary determinants of nanoparticles' vast range of applications are their size, surface properties, and chemical makeup, which also happen to be the same elements that give rise to their poisonous and dangerous effects. In this study, we provide a perspective on the contact lens-associated corneal illnesses such as MK and explore how nanotechnology might help address this significant clinical issue. In addition, safety and toxicological concerns about the increasingly widespread use of contact lenses are also discussed.

Quality by design steered approach for co-encapsulation of timolol maleate and dorzolamide hydrochloride in injectable liposomes

Glaucoma is caused by high intraocular pressure, which can causes blindness. Combinations of timolol and dorzolamide are used for its treatment with a requirement of multiple dosing with dosing being twice or four times a day. Conventional eye drops have poor pre-corneal retention and is thus less available for action. This study utilizes principles of Quality by Design for formulation of injectable liposomes coloaded with timolol maleate and dorzolamide HCl, which overcomes limitations of conventional eye drops. For implementation of Quality by Design principles a systematic approach involving defining Quality Target Product Profile, identification of Critical Quality Attributes, mapping Critical Quality Attributes to Critical Process Parameters and Critical Material Attributes, Failure Mode and Effect Analysis based risk assessment, Taguchi screening, and 32 full factorial Design of Experiments design were utilized. A robust model for formulation of coloaded liposomes was successfully developed. Design of Experiments approach allowed to obtain optimized batch having particle size of 116.1 nm, encapsulation efficiency of dorzolamide HCl of 72.12 % and encapsulation efficiency of timolol maleate of 71.94 %. In-vitro drug release showed a sustained release for 4 days. The prepared formulation was in the desired osmolarity range. Biosafety was proved using histopathological characterization. In-vivo studies for assessing the Intra Ocular Pressure reduction showed that there was no significant difference in Intra Ocular Pressure reduction between prepared liposomes and marketed formulation but were superior than marketed formulation because of less fluctuations in Intra Ocular Pressure. Prepared coloaded injectable liposomes lays the foundation for further research in the area and can be translated from to bench side for commercial clinical use.

Age-Related Macular Degeneration (AMD): Pathophysiology, Drug Targeting Approaches, and Recent Developments in Nanotherapeutics

The most prevalent reason for vision impairment in aging inhabitants is age-related macular degeneration (AMD), a posterior ocular disease with a poor understanding of the anatomic, genetic, and pathophysiological progression of the disease. Recently, new insights exploring the role of atrophic changes in the retinal pigment epithelium, extracellular drusen deposits, lysosomal lipofuscin, and various genes have been investigated in the progression of AMD. Hence, this review explores the incidence and risk factors for AMD, such as oxidative stress, inflammation, the complement system, and the involvement of bioactive lipids and their role in angiogenesis. In addition to intravitreal anti-vascular endothelial growth factor (VEGF) therapy and other therapeutic interventions such as oral kinase inhibitors, photodynamic, gene, and antioxidant therapy, as well as their benefits and drawbacks as AMD treatment options, strategic drug delivery methods, including drug delivery routes with a focus on intravitreal pharmacokinetics, are investigated. Further, the recent advancements in nanoformulations such as polymeric and lipid nanocarriers, liposomes, etc., intended for ocular drug delivery with pros and cons are too summarized. Therefore, the purpose of this review is to give new researchers an understanding of AMD pathophysiology, with an emphasis on angiogenesis, inflammation, the function of bioactive lipids, and therapy options. Additionally, drug delivery options that focus on the development of drug delivery system(s) via several routes of delivery can aid in the advancement of therapeutic choices.

Nanomedicine in glaucoma treatment; Current challenges and future perspectives

Glaucoma presents a significant global health concern and affects millions of individuals worldwide and predicted a high increase in prevalence of about 111 million by 2040. The current standard treatment involves hypotensive eye drops; however, challenges such as patient adherence and limited drug bioavailability hinder the treatment effectiveness. Nanopharmaceuticals or nanomedicines offer promising solutions to overcome these obstacles. In this manuscript, we summarized the current limitations of conventional antiglaucoma treatment, role of nanomedicine in glaucoma treatment, rational design, factors effecting the performance of nanomedicine and different types of nanocarriers in designing of nanomedicine along with their applications in glaucoma treatment from recent literature. Current clinical challenges that hinder real-time application of antiglaucoma nanomedicine are highlighted. Lastly, future directions are identified for improving the therapeutic potential and translation of antiglaucoma nanomedicine into clinic.

Lipid nanoparticle technology-mediated therapeutic gene manipulation in the eyes

Millions of people worldwide have hereditary genetic disorders, trauma, infectious diseases, or cancer of the eyes, and many of these eye diseases lead to irreversible blindness, which is a major public health burden. The eye is a relatively small and immune-privileged organ. The use of nucleic acid-based drugs to manipulate malfunctioning genes that target the root of ocular diseases is regarded as a therapeutic approach with great promise. However, there are still some challenges for utilizing nucleic acid therapeutics in vivo because of certain unfavorable characteristics, such as instability, biological carrier-dependent cellular uptake, short pharmacokinetic profiles in vivo (RNA), and on-target and off-target side effects (DNA). The development of lipid nanoparticles (LNPs) as gene vehicles is revolutionary progress that has contributed the clinical application of nucleic acid therapeutics. LNPs have the capability to entrap and transport various genetic materials such as small interfering RNA, mRNA, DNA, and gene editing complexes. This opens up avenues for addressing ocular diseases through the suppression of pathogenic genes, the expression of therapeutic proteins, or the correction of genetic defects. Here, we delve into the cutting-edge LNP technology for ocular gene therapy, encompassing formulation designs, preclinical development, and clinical translation.

Review: Neuroprotective Nanocarriers in Glaucoma

Glaucoma stands as a primary cause of irreversible blindness globally, characterized by the progressive dysfunction and loss of retinal ganglion cells (RGCs). While current treatments primarily focus on controlling intraocular pressure (IOP), many patients continue to experience vision loss. Therefore, the research focus has shifted to therapeutic targets aimed at preventing or delaying RGC death and optic nerve degeneration to slow or halt disease progression. Traditional ocular drug administration, such as eye drops or oral medications, face significant challenges due to the eye's unique structural and physiological barriers, which limit effective drug delivery. Invasive methods like intravitreal injections can cause side effects such as bleeding, inflammation, and infection, making non-invasive delivery methods with high bioavailability very desirable. Nanotechnology presents a promising approach to addressing these limitations in glaucoma treatment. This review summarizes current approaches involving neuroprotective drugs combined with nanocarriers, and their impact for future use.

Advances in the development of lipid nanoparticles for ophthalmic therapeutics

Previously, researchers have employed Lipid nanoparticles (LNPs) to directly encapsulate medicines. In the realm of gene therapy, researchers have begun to employ lipid nanoparticles to encapsulate nucleic acids such as messenger RNA, small interfering RNA, and plasmid DNA, which are known as nucleic acid lipid nanoparticles. Recent breakthroughs in LNP-based medicine have provided significant prospects for the treatment of ocular disorders, such as corneal, choroidal, and retinal diseases. The use of LNP as a delivery mechanism for medicines and therapeutic genes can increase their effectiveness while avoiding undesired immune reactions. However, LNP-based medicines may pose ocular concerns. In this review, we discuss the general framework of LNP. Additionally, we review adjustable approaches and evaluate their possible risks. In addition, we examine newly described ocular illnesses in which LNP was utilized as a delivery mechanism. Finally, we provide perspectives for solving these potential issues.

Exploring the potential of silymarin-loaded nanovesicles as an effective drug delivery system for cancer therapy: in vivo, in vitro, and in silico experiments

We aimed to perform a comprehensive study on the development and characterization of silymarin (Syl)-loaded niosomes as potential drug delivery systems. The results demonstrate significant novelty and promising outcomes in terms of morphology, size distribution, encapsulation efficiency, in vitro release behavior, free energy profiles of Syl across the niosome bilayer, hydrogen bonding interactions, antimicrobial properties, cytotoxicity, and in vivo evaluations. The physical appearance, size, and morphology assessment of free niosomes and Syl-loaded niosomes indicated stable and well-formed vesicular structures suitable for drug delivery. Transmission electron microscopy (TEM) analysis revealed spherical shapes with distinct sizes for each formulation, confirming uniform distribution. Dynamic light scattering (DLS) analysis confirmed the size distribution results with higher polydispersity index for Syl-loaded niosomes. The encapsulation efficiency of Syl in the niosomes was remarkable at approximately 91%, ensuring protection and controlled release of the drug. In vitro release studies showed a sustained release profile for Syl-loaded niosomes, enhancing therapeutic efficacy over time. Free energy profiles analysis identified energy barriers hindering Syl permeation through the niosome bilayer, emphasizing challenges in drug delivery system design. Hydrogen bonding interactions between Syl and niosome components contributed to energy barriers, impacting drug permeability. Antimicrobial assessments revealed significant differences in inhibitory effects against S. aureus and E. coli. Cytotoxicity evaluations demonstrated the superior tumor-killing potential of Syl-loaded niosomes compared to free Syl. In vivo studies indicated niosome formulations' safety profiles in terms of liver and kidney parameters compared to bulk Syl, showcasing potential for clinical applications. Overall, this research highlights the promising potential of Syl-loaded niosomes as effective drug delivery systems with enhanced stability, controlled release, and improved therapeutic outcomes.

Nanomedicines for Dry Eye Syndrome: Targeting Oxidative Stress with Modern Nanomaterial Strategies

Dry eye syndrome (DES) is a dynamic, chronic disease of the ocular surface and ocular appendages caused by inflammation. The most common symptoms include redness, itching, and blurred vision, resulting from dysfunction of the meibomian glands and impaired tear-film production. Factors contributing to the development of DES include environmental elements, such as UV radiation, and internal elements, such as hormonal imbalances. These factors increase oxidative stress, which exacerbates inflammation on the surface of the eye and accelerates the development of DES. In recent years, the incidence of DES has risen, leading to a greater need to develop effective treatments. Current treatments for dry eye are limited and primarily focus on alleviating individual symptoms, such as reducing inflammation of the ocular surface. However, it is crucial to understand the pathomechanism of the disease and tailor treatment to address the underlying causes to achieve the best possible therapeutic outcomes. Therefore, in this review, we analyzed the impact of oxidative stress on the development of DES to gain a better understanding of its pathomechanism and examined recently developed nanosystems that allow drugs to be delivered directly to the disease site.

Advancing Ocular Medication Delivery with Nano-Engineered Solutions: A Comprehensive Review of Innovations, Obstacles, and Clinical Impact

Recent advancements in ocular drug delivery have led to the introduction of a range of nanotechnology-based systems, such as polymeric nanoparticles, solid lipid nanoparticles, nanostructured lipid carriers, inorganic nanoparticles, niosomes, liposomes, nanosuspensions, dendrimers, nanoemulsions, and microemulsions. These systems enhance drug retention, penetration, bioavailability, and targeted delivery, promising prolonged drug release, and improved patient compliance. However, their interactions with biological systems pose potential toxicity risks, necessitating a careful evaluation of nanoparticle size, shape, surface charge, and coating. Traditional ocular drug delivery methods, like topical applications and injections, face challenges due to anatomical and physiological barriers, leading to frequent dosing and systemic toxicity risks. Nanocarriers offer solutions by improving drug permeation and targeted delivery, yet translating these innovations from research to clinical practice involves overcoming hurdles related to manufacturing scale-up, quality control, regulatory approval, and cost-effectiveness. The quality by design (QbD) framework provides a systematic approach to optimize nanocarrier formulation and process design, ensuring safety and efficacy. Assessing the safety of nanocarriers through in vivo and in vitro studies is crucial for their clinical application. This review explores the use of various nanomedicines in ocular drug delivery, highlighting the current state of ocular medication delivery and considering critical aspects such as scaling up and clinical applications.

Treatment avenues for age-related macular degeneration: Breakthroughs and bottlenecks

Age-related macular degeneration (AMD) is a significant factor contributing to serious vision loss in adults above 50. The presence of posterior segment barriers serves as chief roadblocks in the delivery of drugs to treat AMD. The conventional treatment strategies use is limited due to its off-targeted distribution in the eye, shorter drug residence, poor penetration and bioavailability, fatal side effects, etc. The above-mentioned downside necessitates drug delivery using some cutting-edge technology including diverse nanoparticulate systems and microneedles (MNs) which provide the best therapeutic delivery alternative to treat AMD efficiently. Furthermore, cutting-edge treatment modalities including gene therapy and stem cell therapy can control AMD effectively by reducing the boundaries of conventional therapies with a single dose. This review discusses AMD overview, conventional therapies for AMD and their restrictions, repurposed therapeutics and their anti-AMD activity through different mechanisms, and diverse barriers in drug delivery for AMD. Various nanoparticulate-based approaches including polymeric NPs, lipidic NPs, exosomes, active targeted NPs, stimuli-sensitive NPs, cell membrane-coated NPs, inorganic NPs, and MNs are explained. Gene therapy, stem cell therapy, and therapies in clinical trials to treat AMD are also discussed. Further, bottlenecks of cutting-edge (nanoparticulate) technology-based drug delivery are briefed. In a nutshell, cutting-edge technology-based therapies can be an effective way to treat AMD.

Recent advances and strategies for nanocarrier-mediated topical therapy and theranostic for posterior eye disease

Posterior eye disorders, such as age-related macular degeneration, diabetic retinopathy, and glaucoma, have a significant impact on human quality of life and are the primary cause of age-related retinal diseases among adults. There is a pressing need for innovative topical approaches to treat posterior eye disorders, as current methods often rely on invasive procedures with inherent risks. Limited success was attained in the realm of topical ophthalmic delivery through non-invasive means. Additionally, there exists a dearth of literature that delves into the potential of this approach for drug delivery and theranostic purposes, or that offers comprehensive design strategies for nanocarrier developers to surmount the significant physiological ocular barriers. This review offers a thorough and up-to-date state-of-the-art overview of 40 studies on therapeutic loaded nanocarriers and theranostic devices that, to the best of our knowledge, represent all successful works that reached posterior eye segments through a topical non-invasive administration. Most importantly, based on the successful literature studies, this review provides a comprehensive summary of the potential design strategies that can be implemented during nanocarrier development to overcome each ocular barrier.

Development of ophthalmic nanoemulsions of β-caryophyllene for the treatment of Acanthamoeba keratitis

Although rare, amoebic keratitis (AK) is a disease caused by Acanthamoeba spp. that can lead to blindness. The drugs currently available for its treatment are very toxic, which has motivated the investigation for more effective and safe therapeutic options. In this study, the in vitro activity of ß-caryophyllene (BCP) was exploited taking into account its action against other protozoans as well as its well-known healing and anti-inflammatory properties (aspects relevant for the AK pathogenesis). On the other hand, high volatilization and oxidation phenomena are found for this compound, which led to its incorporation into nanoemulsions (NEs). Two emulsifying agents were tested, resulting in monodisperse systems with reduced droplet size (<265 nm) and high surface charge (positive and negative for NEs prepared with cetrimonium bromide -CTAB and Phosal® 50+, respectively). NEs prepared with CTAB were shown to be more stable after long-term storage at 4 and 25 °C than those prepared with Phosal®. Pure BCP, at the highest concentration (500 µM), resulted in a level of inhibition of Acanthamoeba trophozoites equivalent to that of reference drug (chlorhexidine). This activity was even greater after oil nanoencapsulation. The reduced droplet size could improve the interaction of the oil with the microorganism, justifying this finding. Changes in surface charge did not impact the activity. Positively charged NEs improved the interaction and retention of BCP in the cornea and thus should be prioritized for further studies.

Fostering the unleashing potential of nanocarriers-mediated delivery of ocular therapeutics

Ocular delivery is the most challenging aspect in the field of pharmaceutical research. The major hurdle for the controlled delivery of drugs to the eye includes the physiological static barriers such as the complex layers of the cornea, sclera and retina which restrict the drug from permeating into the anterior and posterior segments of the eye. Recent years have witnessed inventions in the field of conventional and nanocarrier drug delivery which have shown considerable enhancement in delivering small to large molecules across the eye. The dynamic challenges associated with conventional systems include limited drug contact time and inadequate ocular bioavailability resulting from solution drainage, tear turnover, and dilution or lacrimation. To this end, various bioactive-based nanosized carriers including liposomes, ethosomes, niosomes, dendrimer, nanogel, nanofibers, contact lenses, nanoprobes, selenium nanobells, nanosponge, polymeric micelles, silver nanoparticles, and gold nanoparticles among others have been developed to circumvent the limitations associated with the conventional dosage forms. These nanocarriers have been shown to achieve enhanced drug permeation or retention and prolong drug release in the ocular tissue due to their better tissue adherence. The surface charge and the size of nanocarriers (10-1000 nm) are the important key factors to overcome ocular barriers. Various nanocarriers have been shown to deliver active therapeutic molecules including timolol maleate, ampicillin, natamycin, voriconazole, cyclosporine A, dexamethasone, moxifloxacin, and fluconazole among others for the treatment of anterior and posterior eye diseases. Taken together, in a nutshell, this extensive review provides a comprehensive perspective on the numerous facets of ocular drug delivery with a special focus on bioactive nanocarrier-based approaches, including the difficulties and constraints involved in the fabrication of nanocarriers. This also provides the detailed invention, applications, biodistribution and safety-toxicity of nanocarriers-based therapeutcis for the ophthalmic delivery.

Nanosuspensions in ophthalmology: Overcoming challenges and enhancing drug delivery for eye diseases

This review article provides a comprehensive overview of the advancements in using nanosuspensions for controlled drug delivery in ophthalmology. It highlights the significance of ophthalmic drug delivery due to the prevalence of eye diseases and delves into various aspects of this field. The article explores molecular mechanisms, drugs used, and physiological factors affecting drug absorption. It also addresses challenges in treating both anterior and posterior eye segments and investigates the role of mucus in obstructing micro- and nanosuspensions. Nanosuspensions are presented as a promising approach to enhance drug solubility and absorption, covering formulation, stability, properties, and functionalization. The review discusses the pros and cons of using nanosuspensions for ocular drug delivery and covers their structure, preparation, characterization, and applications. Several graphical representations illustrate their role in treating various eye conditions. Specific drug categories like anti-inflammatory drugs, antihistamines, glucocorticoids, and more are discussed in detail, with relevant studies. The article also addresses current challenges and future directions, emphasizing the need for improved nanosuspension stability and exploring potential technologies. Nanosuspensions have shown substantial potential in advancing ophthalmic drug delivery by enhancing solubility and absorption. This article is a valuable resource for researchers, clinicians, and pharmaceutical professionals in this field, offering insights into recent developments, challenges, and future prospects in nanosuspension use for ocular drug delivery.

Moxifloxacin-loaded nanoparticles of thiolated xyloglucan for ocular drug delivery: Permeation, mucoadhesion and pharmacokinetic evaluation

The current study goal was to improve mucoadhesive potential and ocular pharmacokinetics of nanoparticles of thiolated xyloglucan (TXGN) containing moxifloxacin (MXF). Thiolation of xyloglucan (XGN) was achieved with esterification with 3-mercaptopropionic acid. TXGN was characterized by NMR and FTIR analysis. The nanoparticles of TXGN were prepared using ionic-gelation method and evaluate the antibacterial properties. TXGN and nanoparticles were determined to possess 0.06 and 0.08 mmol of thiol groups/mg of polymer by Ellman's method. The ex-vivo bioadhesion time of TXGN and nanoparticles was higher than XGN in a comparative assessment of their mucoadhesive properties. The creation of a disulfide link between mucus and TXGN is responsible for the enhanced mucoadhesive properties of TXGN (1-fold) and nanoparticles (2-fold) over XGN. Improved MXF penetration in nanoparticulate formulation (80 %) based on TXGN was demonstrated in an ex-vivo permeation research utilizing rabbit cornea. Dissolution study showed 95 % release of MXF from nanoparticles. SEM images of nanoparticles showed spherical shape and cell viability assay showed nontoxic behavior when tested on RPE cell line. Antibacterial analysis revealed a zone of inhibition of 31.5 ± 0.5 mm for MXF, while NXM3 exhibited an expanded zone of 35.5 ± 0.4 mm (p < 0.001). In conclusion, thiolation of XGN improves its bioadhesion, permeation, ocular-retention and pharmacokinetics of MXF.

Can (Natural) deep eutectic systems increase the efficacy of ocular therapeutics?

The eye is one of the most complex organs in the human body, with a unique anatomy and physiology, being divided into anterior and posterior segments. Ocular diseases can occur in both segments, but different diseases affect different segments. Glaucoma and cataracts affect the anterior segment, while macular degeneration and diabetic retinopathy occur in the posterior segment. The easiest approach to treat ocular diseases, especially in the anterior segment, is through the administration of topical eye drops, but this route presents many constraints, namely precorneal dynamic and static ocular barriers. On the other hand, the delivery of drugs to the posterior segment of the eye is far more challenging and is mainly performed by the intravitreal route. However, it can lead to severe complications such as retinal detachment, endophthalmitis, increased intraocular pressure and haemorrhage. The design of new drug delivery systems for the anterior segment is very challenging, but targeting the posterior one is even more difficult and little progress has been made. In this review we will discuss various strategies including the incorporation of additives in the formulations, such as viscosity, permeability, and solubility enhancers, namely based on Deep eutectic systems (DES). Natural deep eutectic systems (NADES) have emerged to solve several problems encountered in pharmaceutical industry, regarding the pharmacokinetic and pharmacodynamic properties of drugs. NADES can contribute to the design of advanced technologies for ocular therapeutics, including hydrogels and nanomaterials. Here in, we revise some applications of (NA)DES in the development of new drug delivery systems that can be translated into the ophthalmology field.

Physiochemical Characterization of Lipidic Nanoformulations Encapsulating the Antifungal Drug Natamycin

Natamycin is a tetraene polyene that exploits its antifungal properties by irreversibly binding components of fungal cell walls, blocking the growth of infections. However, topical ocular treatments with natamycin require frequent application due to the low ability of this molecule to permeate the ocular membrane. This limitation has limited the use of natamycin as an antimycotic drug, despite it being one of the most powerful known antimycotic agents. In this work, different lipidic nanoformulations consisting of transethosomes or lipid nanoparticles containing natamycin are proposed as carriers for optical topical administration. Size, stability and zeta potential were characterized via dynamic light scattering, the supramolecular structure was investigated via small- and wide-angle X-ray scattering and 1H-NMR, and the encapsulation efficiencies of the four proposed formulations were determined via HPLC-DAD.

Oil-in-water nanoemulsions for glaucoma treatment: An insight into the latest trends

Glaucoma is a serious eye disease characterized by elevated intraocular pressure, which can ultimately lead to blindness, making it the second leading cause of blindness worldwide, following cataracts. The condition is associated with various risk factors and primarily affects the optic nerve. To treat glaucoma, a range of approaches, both traditional and innovative, have been employed. Recently, there has been a significant focus on nanoemulsions as a promising avenue for treatment. This review underscores the advantages of using oil-in-water nanoemulsions for ocular drug delivery, showcasing their superiority in terms of enhanced bioavailability and stability compared with other dispersion systems. This review also delves into the limitations inherent in traditional drug formulations, elucidates the mechanisms governing drug release, explores the pivotal role of surfactants, and examines the landscape of granted patents in this domain. By addressing these critical aspects, the review offers invaluable insights into the treatment of glaucoma, shedding light on innovative approaches that hold great promise in the fight against this debilitating eye condition. During our search, it was noticed that despite the existence of commendable research in the field of ocular nanoemulsions, particularly in the context of glaucoma along with granted patents, the commercialized nanoemulsion formulations for glaucoma is not yet exist.

Evaluation of curcumin-based ophthalmic nano-emulsion on atropine-induced dry eye in mice

Background

One of the most efficient treatments for dry eye syndrome (DES) is to use nanocarriers as a potential delivery system. We aim to evaluate curcumin in a nano emulsion formulation.

Methods

A new formulation containing 5.5% curcuminoid was used. DLS, Zeta potential, TEM, and HPLC tests were performed to determine the size and morphology. First, 30 mice were selected as atropine-induced dry eye models. Next, 25 mice in 5 groups were treated with the nano emulsion at different doses, and corneal tissues were separated for evaluation.

Results

The DLS test results were indicative of the particles' stability. Nano curcumin appeared to be thoroughly effective in all groups, with the highest dose showing the most similarity to the healthy control group.

Conclusions

Curcumin-based nano emulsion eye drop is a promising candidate for DES management. However, further investigation is required to evaluate the possible risks in humans.

Novel Biomaterials in Glaucoma Treatment

Glaucoma is a significant cause of blindness worldwide, and its treatment remains challenging. The disease progressively leads to damage to the optic disc and thus loss of visual acuity and visual field. High intraocular pressure (IOP) is a common risk factor. There are three major methods to treat this disease: topical, laser, and surgical. None of these are completely satisfactory; therefore, alternatives using new biomaterials are being sought. Since biomaterial engineering has experienced significant growth in recent decades, its products are gradually being introduced to various branches of medicine, with the exception of ophthalmology. Biomaterials, such as glaucoma drainage implants, have been successfully used to treat glaucoma. There is significant ongoing research on biomaterials as drug delivery systems that could overcome the disadvantages of topical glaucoma treatment, such as poor intraocular penetration or frequent drug administration. This article summarizes the use of novel biomaterials for glaucoma treatment presented in the literature. The literature search was based on articles published in English on PubMed.gov, Cochranelibrary.com, and Scopus.com between 2018 and 2023 using the following term "biomaterials in glaucoma." A total of 103 published articles, including twenty-two reviews, were included. Fifty-nine articles were excluded on the basis of their titles and abstracts.

M2-type macrophage-targeted delivery of IKKβ siRNA induces M2-to-M1 repolarization for CNV gene therapy

Choroidal Neovascularization (CNV) is capable of inciting recurrent hemorrhage in the macular region, severely impairing patients' visual acuity. During the onset of CNV, infiltrating M2 macrophages play a crucial role in promoting angiogenesis. To control this disease, our study utilizes the RNA interference (RNAi)-based gene therapy to reprogram M2 macrophages to the M1 phenotype in CNV lesions. We synthesize the mannose-modified siRNA-loaded liposome specifically targeting M2 macrophages to inhibit the inhibitory kappa B kinase β (IKKβ) gene involved in the polarization of macrophages, consequently modulating macrophage polarization state. In vitro and in vivo, the mannose-modified IKKβ siRNA-loaded liposome (siIKKβ-ML) has been proven to effectively target M2 macrophages to repolarize them to M1 phenotype, and inhibit the progression of CNV. Collectively, our findings elucidate that siIKKβ-ML holds the potential to control CNV by reprogramming the macrophage phenotype, indicating a promising therapeutic avenue for CNV management.

Chitosan nanoparticles improve the effectivity of miltefosine against Acanthamoeba

BACKGROUND

Acanthamoeba keratitis (AK) is a corneal sight-threatening infection caused by the free-living amoebae of the genus Acanthamoeba. Early and appropriate treatment significantly impacts visual outcomes. Mucoadhesive polymers such as chitosan are a potential strategy to prolong the residence time and bioavailability of the encapsulated drugs in the cornea. Regarding the recent administration of miltefosine (MF) for treating resistant AK, in the present study, we synthesized miltefosine-loaded chitosan nanoparticles (MF-CS-NPs) and evaluated them against Acanthamoeba.

METHODOLOGY/PRINCIPAL FINDINGS

Chitosan nanoparticles (CNPs) were prepared using the ionic gelation method with negatively charged tripolyphosphate (TPP). The zeta-potential (ZP) and the particle size of MF-CS-NPs were 21.8±3.2 mV and 46.61±18.16 nm, respectively. The release profile of MF-CS-NPs indicated linearity with sustained drug release. The cytotoxicity of MF-CS-NPs on the Vero cell line was 2.67 and 1.64 times lower than free MF at 24 and 48 hours. This formulation exhibited no hemolytic activity in vitro and ocular irritation in rabbit eyes. The IC50 of MF-CS-NPs showed a significant reduction by 2.06 and 1.69-fold in trophozoites at 24 and 48 hours compared to free MF. Also, the MF-CS-NPs IC50 in the cysts form was slightly decreased by 1.26 and 1.21-fold at 24 and 48 hours compared to free MF.

CONCLUSIONS

The MF-CS-NPs were more effective against the trophozoites and cysts than free MF. The nano-chitosan formulation was more effective on trophozoites than the cysts form. MF-CS-NPs reduced toxicity and improved the amoebicidal effect of MF. Nano-chitosan could be an ideal carrier that decreases the cytotoxicity of miltefosine. Further analysis in animal settings is needed to evaluate this nano-formulation for clinical ocular drug delivery.

Nanomicellar eye drops: a review of recent advances

INTRODUCTION

Research on nanotechnology in medicine has also involved the ocular field and nanomicelles are among the applications developed. This approach is used to increase both the water solubility of hydrophobic drugs and their penetration/permeation within/through the ocular tissues since nanomicelles are able to encapsulate insoluble drug into their core and their small size allows them to penetrate and/or diffuse through the aqueous pores of ocular tissues.

AREAS COVERED

The present review reports the most significant and recent literature on the use of nanomicelles, made up of both surfactants and amphiphilic polymers, to overcome limitations imposed by the physiology of the eye in achieving a high bioavailability of drugs intended for the therapeutic areas of greatest commercial interest: dry eye, inflammation, and glaucoma.

EXPERT OPINION

The results of the numerous studies in this field are encouraging and demonstrate that nanomicelles may be the answer to some of the challenges of ocular therapy. In the future, new molecules self-assembling into micelles will be able to meet the regulatory requirements for marketing authorization for their use in ophthalmic formulations.

Topical Ophthalmic Liposomes Dual-Modified with Penetratin and Hyaluronic Acid for the Noninvasive Treatment of Neovascular Age-Related Macular Degeneration

Introduction

Since intrinsic ocular barrier limits the intraocular penetration of therapeutic protein through eye drops, repeated intravitreal injections of anti-vascular endothelial growth factor (anti-VEGF) agents are the standard therapy for neovascular age-related macular degeneration (nAMD), which are highly invasive and may cause particular ocular complications, leading to poor patient compliance.

Methods

Using Penetratin (Pen) as the ocular penetration enhancer and hyaluronic acid (HA) as the retina-targeting ligand, a dual-modified ophthalmic liposome (Penetratin hyaluronic acid-liposome/Conbercept, PenHA-Lip/Conb) eye drop was designed to non-invasively penetrate the ocular barrier and deliver anti-VEGF therapeutic agents to the targeted intraocular tissue.

Results

PenHA-Lip effectively penetrates the ocular barrier and targets the retinal pigment epithelium via corneal and non-corneal pathways. After a single topical administration of conbercept-loaded PenHA-Lip (PenHA-Lip/Conb), the intraocular concentration of conbercept peaked at 18.74 ± 1.09 ng/mL at 4 h, which is 11.55-fold higher than unmodified conbercept. In a laser-induced choroidal neovascularization (CNV) mouse model, PenHA-Lip/Conb eye drops three times daily for seven days inhibited CNV formation and progression without any significant tissue toxicity and achieved an equivalent effect to a single intravitreal conbercept injection.

Conclusion

PenHA-Lip efficiently and safely delivered conbercept to the posterior eye segment and may be a promising noninvasive therapeutic option for nAMD.

Enhancing Ocular Drug Delivery: The Effect of Physicochemical Properties of Nanoparticles on the Mechanism of Their Uptake by Human Cornea Epithelial Cells

This study investigates the effect of nanoparticle size and surface chemistry on interactions of the nanoparticles with human cornea epithelial cells (HCECs). Poly(lactic-co-glycolic) acid (PLGA) nanoparticles were synthesized using the emulsion-solvent evaporation method and surface modified with mucoadhesive (alginate [ALG] and chitosan [CHS]) and mucopenetrative (polyethylene glycol [PEG]) polymers. Particles were found to be monodisperse (polydispersity index (PDI) below 0.2), spherical, and with size and zeta potential ranging from 100 to 250 nm and from -25 to +15 mV, respectively. Evaluation of cytotoxicity with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay indicated that incubating cells with nanoparticles for 24 h at concentrations up to 100 μg/mL caused only mild toxicity (70-100% cell viability). Cellular uptake studies were conducted using an in vitro model developed with a monolayer of HCECs integrated with simulated mucosal solution. Evaluation of nanoparticle uptake revealed that energy-dependent endocytosis is the primary uptake mechanism. Among the different nanoparticles studied, 100 nm PLGA NPs and PEG-PLGA-150 NPs showed the highest levels of uptake by HCECs. Additionally, uptake studies in the presence of various inhibitors suggested that macropinocytosis and caveolae-mediated endocytosis are the dominant pathways. While clathrin-mediated endocytosis was found to also be partially responsible for nanoparticle uptake, phagocytosis did not play a role within the studied ranges of size and surface chemistries. These important findings could lead to improved nanoparticle-based formulations that could improve therapies for ocular diseases.

Ophthalmic wild olive (ACEBUCHE) oil nanoemulsions exert oculoprotective effects against oxidative stress induced by arterial hypertension

Oxidative stress plays a key role in several systemic and ocular diseases, including hypertensive eye diseases. In this context, we previously showed that oral administration of wild olive (acebuche, ACE) oil from Olea europaea var. sylvestris can counteract ocular damage secondary to arterial hypertension by modulating excess reactive oxygen species (ROS) produced by the enzyme nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. Therefore, this work describes the development of an ACE oil-based formulation for ocular administration as a local therapy to counteract hypertension-related oxidative damage. Specifically, ACE oil nanoemulsions (NEs) were successfully produced and characterized, exhibiting appropriate features for ophthalmic administration, including a nanometer size (<200 nm), moderate negative ZP, adequate osmolality and pH, and colloidal stability in biorelevant fluids. Likewise, the NEs presented a shear thinning behavior, especially convenient for ocular instillation. In vivo evaluation was performed through either intravitreal injection or topical ophthalmic administration in mice with hypertension induced via administration of Nω-nitro-L-arginine-methyl-ester (L-NAME). Both routes of administration reduced hypertensive morphological alterations and demonstrated a noticeable antioxidant effect thanks to the reduction of the activity/expression of NADPH oxidase in cornea and retina. Thus, an ACE oil ophthalmic formulation represent a promising therapy for ocular pathologies associated with arterial hypertension.

Overview of Spanlastics: A Groundbreaking Elastic Medication Delivery Device with Versatile Prospects for Administration via Various Routes

When compared to the challenges associated with traditional dosage forms, medication delivery systems based on nanotechnology have been a huge boon. One such candidate for medication delivery is spanlastics, an elastic nanovesicle that can transport a diverse array of medicinal compounds. The use of spanlastics has been associated with an increase in interest in alternative administration methods. The non-ionic surfactant or surfactant blend is the main component of spanlastics. The purpose of this review was primarily to examine the potential of spanlastics as a delivery system for a variety of medication classes administered via diverse routes. Science Direct, Google Scholar, and Pubmed were utilized to search the academic literature for this review. Several studies have demonstrated that spanlastics greatly improve therapeutic effectiveness, increase medication absorption, and decrease drug toxicity. This paper provides a summary of the composition and structure of spanlastics along with their utility in the delivery of various therapeutic agents by adopting different routes. Additionally, it provides an overview of the numerous disorders that may be treated using drugs that are contained in spanlastic vesicles.

An Updated Review on Nanoemulsion: Factory for Food and Drug Delivery

BACKGROUND

A nanoemulsion is a colloidal system of small droplets dispersed in another liquid. It has attracted considerable attention due to its unique properties and various applications. Throughout this review, we provide an overview of nanoemulsions and how they can be applied to various applications such as drug delivery, food applications, and pesticide formulations.

OBJECTIVE

This updated review aims to comprehensively overview nanoemulsions and their applications as a versatile platform for drug delivery, food applications, and pesticide formulations.

METHODS

Research relevant scientific literature across various databases, including PubMed, Scopus, and Web of Science. Suitable keywords for this purpose include "nanoemulsion," "drug delivery," and "food applications." Ensure the search criteria include recent publications to ensure current knowledge is included.

RESULTS

Several benefits have been demonstrated in the delivery of drugs using nanoemulsions, including improved solubility, increased bioavailability, and controlled delivery. Nanoemulsions have improved some bioactive compounds in food applications, including vitamins and antioxidants. At the same time, pesticide formulations based on nanoemulsions have also improved solubility, shelf life, and effectiveness.

CONCLUSION

The versatility of nanoemulsions makes them ideal for drug delivery, food, and pesticide formulation applications. These products are highly soluble, bioavailable, and targeted, providing significant advantages. More research and development are required to implement nanoemulsion-based products on a commercial scale.

Ocular antibacterial chitosan-maleic acid hydrogels: In vitro and in vivo studies for a promising approach with enhanced mucoadhesion

The aim was to design and evaluate a chitosan-based conjugate providing high mucoadhesiveness and antibacterial activity for ocular infections treatment. Chitosan was conjugated with maleic acid via amide bond formation and infrared spectroscopy. Furthermore, 2,4,6-Trinitrobenzene sulfonic acid (TNBS) allowed characterization and quantification of conjugated groups, respectively. Biocompatibility was tested via hemolysis assay and Hen's Egg-Chorioallantoic membrane test. Characterization of the pH and osmolarity of hydrogels was followed by mucoadhesion assessment utilizing rheology. In addition, antibacterial studies were carried out towards Escherichia coli by broth microdilution test and agar-disk diffusion assay. In vivo studies were carried out following the already established Draize test and determining pharmacokinetic profile of dexamethasone in aqueous humour. The conjugate exhibited a degree of modification of 50.05 % and no toxicity or irritability. Moreover, mucoadhesive properties were enhanced in 2.68-fold and 1.81-fold for elastic and viscous modulus, respectively. Furthermore, rheological synergism revealed the presence of a gel-like structure. Additionally, broth microdilution and agar disk diffusion studies exhibited enhancement in antibacterial activity. Finally, in vivo studies manifested that hydrogels were highly tolerated, evidencing promising characteristics of the developed conjugate. The conjugate presented promising antimicrobial, long lasting mucoadhesive features and highly improved pharmacokinetics, leading to a revolutionizing approach in the treatment of ocular bacterial infections.

Advanced Technologies of Drug Delivery to the Posterior Eye Segment Targeting Angiogenesis and Ocular Cancer

Retinoblastoma (RB), a childhood retinal cancer is caused due to RB1 gene mutation which affects the child below 5 years of age. Angiogenesis has been proven its role in RB metastasis due to the presence of vascular endothelial growth factor (VEGF) in RB cells. Therefore, exploring angiogenic pathway by inhibiting VEGF in treating RB would pave the way for future treatment. In preclinical studies, anti-VEGF molecule have shown their efficacy in treating RB. However, treatment requires recurrent intra-vitreal injections causing various side effects along with patient nonadherence. As a result, delivery of anti-VEGF agent to retina requires an ocular delivery system that can transport it in a non-invasive manner to achieve patient compliance. Moreover, development of these type of systems are challenging due to the complicated physiological barriers of eye. Adopting a non-invasive or minimally invasive approach for delivery of anti-VEGF agents would not only address the bioavailability issues but also improve patient adherence to therapy overcoming the side effects associated with invasive approach. The present review focuses on the eye cancer, angiogenesis and various novel ocular drug delivery systems that can facilitate inhibition of VEGF in the posterior eye segment by overcoming the eye barriers.

Applications of Nanotechnology-mediated Herbal Nanosystems for Ophthalmic Drug

In recent years, herbal nanomedicines have gained tremendous popularity for novel drug discovery. Nanotechnology has provided several advances in the healthcare sector, emerging several novel nanocarriers that potentiate the bioavailability and therapeutic efficacy of the herbal drug. The recent advances in nanotechnology with accelerated strategies of ophthalmic nanosystems have paved a new path for overcoming the limitations associated with ocular drug delivery systems, such as low bioavailability, poor absorption, stability, and precorneal drug loss. Ophthalmic drug delivery is challenging due to anatomical and physiological barriers. Due to the presence of these barriers, the herbal drug entry into the eyes can be affected when administered by following multiple routes, i.e., topical, injectables, or systemic. However, the advancement of nanotechnology with intelligent systems enables the herbal active constituent to successfully entrap within the system, which is usually difficult to reach employing conventional herbal formulations. Herbal-loaded nanocarrier drug delivery systems demonstrated enhanced herbal drug permeation and prolonged herbal drug delivery. In this current manuscript, an extensive search is conducted for original research papers using databases Viz., PubMed, Google Scholar, Science Direct, Web of Science, etc. Further painstaking efforts are made to compile and update the novel herbal nanocarriers such as liposomes, polymeric nanoparticles, solid lipid nanoparticles, nanostructure lipid carriers, micelles, niosomes, nanoemulsions, dendrimers, etc., which are mostly used for ophthalmic drug delivery system. This article presents a comprehensive survey of diverse applications used for the preventative measures and treatment therapy of varied eye disorders. Further, this article highlights the recent findings that the innovators are exclusively working on ophthalmic nanosystems for herbal drug delivery systems. The nanocarriers are promising drug delivery systems that enable an effective and supreme therapeutic potential circumventing the limitations associated with conventional ocular drug delivery systems. The nanotechnology-based approach is useful to encapsulate the herbal bioactive and prevent them from degradation and therefore providing them for controlled and sustained release with enhanced herbal drug permeation. Extensive research is still being carried out in the field of herbal nanotechnology to design an ophthalmic nanosystem with improved biopharmaceutical properties.

The Effect of High-Pressure Homogenization Conditions on the Physicochemical Properties and Stability of Designed Fluconazole-Loaded Ocular Nanoemulsions

The growing interest in high-energy emulsification is a result of its scalability, which is important from an industrial perspective and allows for a more reproducible and efficient production of pharmaceutical formulations. The aim of this study was to evaluate the effect of composition, mainly a fixed surfactant/cosurfactant (Smix) ratio, their concentration, and the parameters of high-pressure homogenization (HPH) processing on the quality and stability of ophthalmic fluconazole-loaded nanoemulsions. After a physicochemical analysis of nanoemulsions containing 20% w/w of oil, as optimal conditions for the HPH process, three cycles at a pressure of 1000 bar were established, obtaining formulations with an average droplet diameter size in the range of 80.63-129.68 nm and PDI values below 0.25. While it was expected that an increasing cosurfactant concentration decreased the droplet size, in the case of formulations containing Tween 20 and 10% w/w of cosurfactants, "over-processing" was observed, identified by the droplet size and polydispersity index increase. Consecutively, the selected formulations were evaluated for in vitro drug release in Franz's cell, antifungal activity, and 30-day stability using NMR spectroscopy. An antifungal activity test showed no significant difference in the antifungal activity between optimal fluconazole-loaded nanoemulsions and a 0.3% aqueous drug solution, but previously, research showed that prepared formulations were characterized by a higher viscosity and satisfactory prolonged release compared to a control. In a 30-day stability study, it was observed that higher HLB values of the used surfactants decreased the stability of the formulations in the following order: Kolliphor EL, Tween 80, Tween 20. The NMR spectra confirmed that Kolliphor EL-based formulations ensured the higher stability of the nanoemulsion composition in comparison to Tween 80 and a better stabilizing effect of propylene glycol as a cosurfactant in comparison to PEG 200. Therefore, the optimization of HPH technology should be focused on the selection of Smix and the Smix:oil ratio in order to prepare stable formulations of high quality.

PLGA Nanoparticles Containing Natural Flavanones for Ocular Inflammation

Flavanones are natural compounds that display anti-inflammatory activity. The aim of this work was to prepare PLGA nanoparticles (NPs) containing natural flavanones I ((2S)-5,7-dihydroxy-6-methyl-8-(3-methyl-2-buten-1-il)-2-phenyl-2,3-dihydro-4H-1-Benzopyran-4-one) and II (2S)-5,7-dihydroxy-2-(4'-methoxyphenyl)-6-methyl-8-(3-methyl-2-buten-1-yl)-2,3-dihydro-4H-1-Benzopyran-4-one) (NP I and NP II, respectively) so as to evaluate their potential for topical anti-inflammatory ocular therapy. An in silico study was carried out using the Molinspiration® and PASS Online web platforms before evaluating the in vitro release study and the ex vivo porcine cornea and sclera permeation. The HPLC analytical method was also established and validated. Finally, the in vitro anti-inflammatory efficacy of NPs was studied in the HCE-2 model. The flavanones I and II could be released following a kinetic hyperbolic model. Neither of the two NPs was able to permeate through the tissues. NP I and NP II were found to be respectful of any changes in the tissues' morphology, as evidenced by histological studies. In HCE-2 cells, NP I and NP II were not cytotoxic at concentrations up to 25 µM. NP I showed higher anti-inflammatory activity than NP II, being able to significantly reduce IL-8 production in LPS-treated HCE-2 cells. In summary, ocular treatment with NP I and NP II could be used as a promising therapy for the inhibition of ocular inflammation.

Organic and Biogenic Nanocarriers as Bio-Friendly Systems for Bioactive Compounds' Delivery: State-of-the Art and Challenges

"Green" strategies to build up novel organic nanocarriers with bioperformance are modern trends in nanotechnology. In this way, the valorization of bio-wastes and the use of living systems to develop multifunctional organic and biogenic nanocarriers (OBNs) have revolutionized the nanotechnological and biomedical fields. This paper is a comprehensive review related to OBNs for bioactives' delivery, providing an overview of the reports on the past two decades. In the first part, several classes of bioactive compounds and their therapeutic role are briefly presented. A broad section is dedicated to the main categories of organic and biogenic nanocarriers. The major challenges regarding the eco-design and the fate of OBNs are suggested to overcome some toxicity-related drawbacks. Future directions and opportunities, and finding "green" solutions for solving the problems related to nanocarriers, are outlined in the final of this paper. We believe that through this review, we will capture the attention of the readers and will open new perspectives for new solutions/ideas for the discovery of more efficient and "green" ways in developing novel bioperformant nanocarriers for transporting bioactive agents.

Drug delivery methods based on nanotechnology for the treatment of eye diseases

One of the most difficult tasks among the numerous medication delivery methods is ocular drug delivery. Despite having effective medications for treating ocular illness, we have not yet managed to develop an appropriate drug delivery strategy with the fewest side effects. Nanotechnology has the potential to significantly address the drawbacks of current ocular delivery systems, such as their insufficient therapeutic effectiveness and unfavourable side effects from invasive surgery or systemic exposure. The objective of the current research is to highlight and update the most recent developments in nano-based technologies for the detection and treatment of ocular diseases. Even if more work has to be done, the advancements shown here might lead to brand-new, very practical ocular nanomedicines.

NAD+-associated-hyaluronic acid and poly(L-lysine) polyelectrolyte complexes: An evaluation of their potential for ocular drug delivery

This study details the formation and characterisation of a novel nicotinamide adenine dinucleotide (NAD+)-associated polymeric nanoparticle system. The development of a polyelectrolyte complex (PEC) composed of two natural polyelectrolytes, hyaluronic acid and poly(L-lysine), and an evaluation of its suitability for NAD+ ocular delivery, primarily based on its physicochemical properties and in vitro release profile under physiological ocular flow rates, were of key focus. Following optimisation of formulation method conditions such as complexation pH, mode of addition, and charge ratio, the PEC was successfully formulated under mild formulation conditions via polyelectrolyte complexation. With a size of 235.1 ± 19.0 nm, a PDI value of 0.214 ± 0.140, and a zeta potential value of - 38.0 ± 1.1 mV, the chosen PEC, loaded with 430 µg of NAD+ per mg of PEC, exhibited non-Fickian, sustained release at physiological flowrates of 10.9 ± 0.2 mg of NAD+ over 14 h. PECs containing up to 200 µM of NAD+ did not induce any significant cytotoxic effects on an immortalised human corneal epithelial cell line. Using fluorescent labeling, the NAD+-associated PECs demonstrated retention within the corneal epithelium layer of a porcine model up to 6 h post incubation under physiological conditions. A study of the physicochemical behaviour of the PECs, in terms of size, zeta potential and NAD+ complexation in response to environmental stimuli,highlighted the dynamic nature of the PEC matrix and its dependence on both pH and ionic condition. Considering the successful formation of reproducible NAD+-associated PECs with suitable characteristics for ocular drug delivery via an inexpensive formulation method, they provide a promising platform for NAD+ ocular delivery with a strong potential to improve ocular health.