Polymer- and lipid-based nanocarriers for ocular drug delivery: Current status and future perspectives

External stimuli-responsive drug delivery to the posterior segment of the eye

Posterior segment eye diseases represent the leading causes of vision impairment and blindness globally. Current therapies still have notable drawbacks, including the need for frequent invasive injections and the associated risks of severe ocular complications. Recently, the utility of external stimuli, such as light, ultrasound, magnetic field, and electric field, has been noted as a promising strategy to enhance drug delivery to the posterior segment of the eye. In this review, we briefly summarize the main physiological barriers against ocular drug delivery, focusing primarily on the recent advancements that utilize external stimuli to improve treatment outcomes for posterior segment eye diseases. The advantages of these external stimuli-responsive drug delivery strategies are discussed, with illustrative examples highlighting improved tissue penetration, enhanced control over drug release, and targeted drug delivery to ocular lesions through minimally invasive routes. Finally, we discuss the challenges and future perspectives in the translational research of external stimuli-responsive drug delivery platforms, aiming to bridge existing gaps toward clinical use.

Pathology-inspired collagen-binding thermosensitive micelle drops enable prolonged and efficient treatment of fungal keratitis

Fungal keratitis (FK) is a challenging-to-manage blinding corneal infectious disease that often leads to severe sequelae, such as corneal leukoplakia regardless of curative care. Moreover, the unique anatomical structure and tear turnover of the eye significantly limit the bioavailability and therapeutic efficacy of traditional eye drops. Inspired by the unique pathological features of corneal ulcers, we report a thermosensitive multifunctional eye drop, designated PX-TA, based on a poloxamer (PX) and a collagen-adhesive tannic acid (TA), for prolonged and efficient treatment of FK. PX-TA transforms into a gel at body temperature and adheres to exposed collagen at the ulcer site; this significantly improves the corneal retention time and bioavailability. PX-TA maintains corneal retention for at least 90 min, substantially exceeding both the 15-min limit of commercial mucoadhesive eye drops and the 30-min threshold of conventional in situ gels. When loaded with amphotericin B (AmB), once-daily PX-TA-AmB administration effectively suppresses inflammation and corneal scarring, demonstrating superior efficacy over six-times-daily free AmB drops and a good safety profile. Mechanistic investigations reveal that PX-TA-AmB mediates its therapeutic effects through the MAPK6/PI3K/AKT signaling pathway. Moreover, the metal-chelating properties of TA inhibit the copper-dependent enzyme lysyl oxidase (LOX), resulting in reduced matrix fibrosis. Overall, the use of PX-TA-AmB drops represents a simplified yet effective strategy for the potential clinical management of FK, inspiring the design of eye drop formulations.

Advances in locally administered nucleic acid therapeutics

Nucleic acid drugs represent the latest generation of precision therapeutics, holding significant promise for the treatment of a wide range of intractable diseases. Delivery technology is crucial for the clinical application of nucleic acid drugs. However, extrahepatic delivery of nucleic acid drugs remains a significant challenge. Systemic administration often fails to achieve sufficient drug enrichment in target tissues. Localized administration has emerged as the predominant approach to facilitate extrahepatic delivery. While localized administration can significantly enhance drug accumulation at the injection sites, nucleic acid drugs still face biological barriers in reaching the target lesions. This review focuses on non-viral nucleic acid drug delivery techniques utilized in local administration for the treatment of extrahepatic diseases. First, the classification of nucleic acid drugs is described. Second, the current major non-viral delivery technologies for nucleic acid drugs are discussed. Third, the bio-barriers, administration approaches, and recent research advances in the local delivery of nucleic acid drugs for treating lung, brain, eye, skin, joint, and heart-related diseases are highlighted. Finally, the challenges associated with the localized therapeutic application of nucleic acid drugs are addressed.

Stimulus-responsive nanomaterials for ocular antimicrobial therapy

Nanomaterials exhibit a promising new avenue for treating infectious keratitis, having garnered considerable interest in the ophthalmic medical community due to their unique properties including higher target specificity, enhanced bioactivity of loaded agents, reduced drug dosage, and stimulus-responsive drug release. These stimulus-responsive nanomaterial-mediated therapeutic strategies offer innovative approaches for managing ocular antimicrobial diseases. In this review, we aim to summarize current applications of stimulus-responsive nanotherapeutics for ocular antimicrobial therapy. We briefly introduce the basic ocular structure, ocular barrier, infectious keratitis classification, and its microenvironment. Following this, we summarize the nanotherapeutic antimicrobial strategies employed in treating ocular infections including endogenous stimulus-responsive ocular nanodrugs, sonodynamic therapy, and wearable device-based therapy, focusing on their design principles, developmental progress, and advantages and limitations. Finally, we critically evaluate the biosafety profiles of responsive nanomaterials, specifically addressing cytotoxicity and immune interactions. To conclude, we discuss key challenges in this research field and future opportunities with explicit emphasis on clinical translation and practical medical applications.

Topical application of insulin encapsulated by chitosan-modified PLGA nanoparticles to alleviate alkali burn-induced corneal neovascularization

Corneal neovascularization (CRNV) severely impairs corneal transparency and is one of the leading causes of vision loss worldwide. Drug therapy is the main approach to inhibit CRNV. Insulin (INS) has been reported to facilitate the healing of corneal injuries and suppress inflammation. However, but due to the unique physiological barriers of the eye, its bioavailability is low, limiting its therapeutic effect. In this study, we developed a chitosan-poly(lactic-co-glycolic acid)-INS nanoparticles (CPI NPs) system for INS delivery. The characterization of CPI NPs was satisfactory. Experimental results demonstrated that CPI NPs effectively inhibited the migration of vascular endothelial cells and the formation of tubular structures. Furthermore, CPI NPs markedly suppressed the neovascularization in a CRNV model without any observable side effects. Quantitative proteomics analysis indicated that INS treatment led to a reduction in FTO levels within the neovascularized cornea. Both in vitro and in vivo experiments substantiated the impact of CPI NPs on FTO protein expression and the N6-methyladenosine modification. In conclusion, this study successfully developed an effective ocular drug delivery system for the treatment of CRNV induced by alkali burns, thereby offering a novel therapeutic option for this condition.

Revolutionizing Retinal Therapy: The Role of Nanoparticle Drug Carriers in Managing Vascular Retinal Disorders

Vascular Retinopathy (VR), such as diabetic retinopathy, pose significant challenges to vision and overall health. Traditional treatment methods often face limitations in efficacy and delivery. Vascular retinopathy is a common and potentially blinding group of eye diseases with core pathologic mechanisms involving vascular injury, ischemia, exudation, and neovascularization. Clinical management relies heavily on etiologic control (eg, diabetes, hypertension), anti-VEGF therapy, laser therapy, and surgical intervention. Recent advancements in nanotechnology have led to the development of innovative nanoparticle drug carriers, which offer promising solutions for targeted and sustained drug delivery in the retinal environment. This review explores the application of both conventional and novel nanoparticle carriers in treating VR. We discuss various types of nanoparticles, including liposomes, polymeric nanoparticles, and metal-based carriers, highlighting their unique properties, mechanisms of action, and therapeutic benefits. Finally, we provide insights into future perspectives for nanoparticle-based therapies in retinal disorders, emphasizing the potential for improved patient outcomes and the need for further research to optimize these advanced drug delivery systems.

High-Efficiency Ocular Delivery of Brain-Derived Neurotrophic Factor and Oligomycin for Neuroprotection in Glaucoma

Glaucoma is a retinal neurodegenerative disease characterized by progressive apoptosis of retinal ganglion cells (RGCs) and irreversible visual impairment. Current therapies rarely offer direct protection for RGCs, highlighting the need for new neuroprotective approaches. Although viral delivery of brain-derived neurotrophic factor (BDNF) has shown potential, concerns about retinal inflammation and limited applicability persist. Meanwhile, non-viral vectors remain inefficient for in vivo ocular gene delivery. Here, a highly biocompatible nanoplatform-PBAE-PLGA-Oligomycin-pBDNF nanoparticles (PPOB NPs) is reported-that co-delivers oligomycin (an ATP inhibitor) and a BDNF plasmid to Müller cells in vivo. This nanoplatform attains an unprecedented transfection efficiency of 64.26% in Müller cells, thereby overcoming the limitations of monotherapeutic neurotrophic approaches that fail to inhibit ATP overproduction and attendant inflammatory responses. In a chronic ocular hypertension rat model, oligomycin effectively mitigated RGC damage by suppressing Müller cell hyperactivation and excessive ATP production under elevated intraocular pressure. Concurrently, it synergistically enhanced BDNF expression in Müller cells, achieving robust protection of RGCs and preservation of optic nerve function. These findings underscore the promise of PPOB NPs as a dual-functional platform, featuring high biocompatibility and efficient gene delivery, for multifaceted therapies against glaucoma and other ocular diseases.

Cyclic cell-penetrating peptide-engineered ceria nanoparticles for non-invasive alleviation of ultraviolet radiation-induced cataract

Oxidative stress, which results from the accumulation of free radicals, plays a substantial role in cataract formation. Antioxidants have shown promise in mitigating or even preventing this process. However, delivering antioxidants noninvasively to the anterior segment of the eye has been a significant challenge. In this study, we developed ceria nanoparticles modified with cyclic cell-penetrating peptides to overcome the obstruction of the dense corneal barrier on topical drug delivery. Our results demonstrated that modified ceria nanoparticles with cell-penetrating peptides (CPPs) facilitate the opening of tight junctions in human corneal epithelial cells. This characteristic considerably enhances the trans-corneal transport of nanoparticles and improves cellular uptake efficiency, while also contributing to their intracellular enrichment toward mitochondria. Further experiments confirmed that the modified ceria nanoparticles effectively counteracted ferroptosis induced by oxidative stress in lens epithelial cells both in vitro and in vivo, substantially reducing cataract formation. The successful development of ceria nanoparticles modified with cyclic cell-penetrating peptides (cCPPs) opens new avenues for research in cataract prevention and treatment. Additionally, the modified ceria nanoparticles could serve as a noninvasive drug delivery system, which holds remarkable potential for advancing drug delivery in diseases affecting the anterior segment of the eye.

Transfersomes: a next-generation drug delivery system for topical ocular drug delivery

INTRODUCTION

The eye is a complex organ with several anatomical and physiological barriers that make ocular drug delivery an ongoing challenge. Transfersomes (TFS) are deformable vesicles that have been extensively applied to enhance transdermal drug delivery. However, their application in ocular drug delivery remains largely unexplored.

AREAS COVERED

This review highlights the challenges typically associated with ocular drug delivery and emphasizes the inherent properties of TFS that enable them to overcome these challenges. The influence of excipients and critical process parameters on TFS characteristics have been discussed in detail with an emphasis on the fabrication and characterization techniques typically employed for TFS development and optimization. Furthermore, recent studies evaluating the application of TFS in ocular drug delivery have been discussed in depth.

EXPERT OPINION

The unique stress-responsive and deformable nature of TFS makes them promising carriers for ocular drug delivery. However, further research in this direction is needed to understand their penetration mechanism and elucidate their potential for sustained and targeted drug delivery to ocular tissues. Moreover, further research is needed to optimize the stability and scalability of TFS to encourage their translation to the market.

MiRGD peptideticle targeted delivery of hinge-truncated soluble VEGF receptor 1 fusion protein to the retinal pigment epithelium cell line and newborn mice retina

Eye-related Angiogenesis and vascular permeability changes lead to retinal vascular disorders. There is an important need to design a novel targeted anti-VEGF drug delivery system to inhibit neovascularization in the retina. The peptide-based carriers are promising for gene therapy due to their flexibility in design, ease of production, structural diversity, low toxicity, and immunogenicity. The hinge-truncated soluble VEGF receptor 1 (htsFLT01) protein, has the ability to bind to both VEGF and PlGF molecules. In the present study, htsFLT01 gene delivery by targeted MiRGD peptide carrier was investigated in the mouse Retinal Pigment Epithelium (mRPE) cell line and mouse model to evaluate the potential of the newly developed peptideticle as an effective therapeutic platform for gene delivery. The characterization results demonstrated that the peptide carrier condensed htsFLT01 DNA, neutralizes its negative charge, and protected it from endonucleases. The size and charge of the nanocomplexes were optimized to effectively target the retina. Based on tube formation assay, migration analyses and intravitreal injection of MiRGD-htsFLT01 nanocomplex into the newborn mice eye, the function of htsFLT01 was investigated. The reduction of tube-like structures in HUVEC cells was notably observed following VEGF neutralization and the findings demonstrated an association between the expression of htsFLT01 and the inhibition of RPE cell migration. The vascular development was inhibited in the deep, intermediate, and superficial capillary plexus layers in the retina. The novel drug MiRGD/htsFLT01 complex, represents a promising potential platform for targeted gene therapy in the eye due to its biocompatibility, likely safety and highly effective function.

Nano-based drug delivery systems for the treatment of non-infectious uveitis

Background

Uveitis is one of the most prevalent causes of global visual impairment. The current approaches to treating non-infectious uveitis (NIU) involve the utilization of corticosteroids, immunosuppressant and biologics agents. Nevertheless, the intricate ocular anatomy barriers and adverse side effects of the drugs pose significant obstacles to effective treatment outcomes.

Main text

To improve drug bioavailability and therapeutic outcomes for NIU while minimize side effects, researchers are committed to developing novel nano-based drug delivery systems (DDS), which have the capacity to achieve targeted delivery, increase bioavailability, achieve sustained release, reduce side effects and improve therapeutic effects. Thus, DDS based on nanotechnology, including liposome, dendrimer, hydrogels, nanoparticles, nanomicelles, nanosuspensions and nanoemulsions have emerged as promising alternatives to conventional ocular delivery methods for the management of NIU.

Conclusions

In this review, we summarize the current therapeutic challenges faced by NIU and describe various nano-based intraocular DDS involved in the treatment of NIU. It is concluded that nano-based DDS is an appealing approach to addressing the unmet needs for the treatment of NIU.

Application of Nanomaterials in the Diagnosis and Treatment of Retinal Diseases

In recent years, nanomaterials have demonstrated broad prospects in the diagnosis and treatment of retinal diseases due to their unique physicochemical properties, such as small-size effects, high biocompatibility, and functional surfaces. Retinal diseases are often accompanied by complex pathological microenvironments, where conventional diagnostic and therapeutic approaches face challenges such as low drug delivery efficiency, risks associated with invasive procedures, and difficulties in real-time monitoring. Nanomaterials hold promise in addressing these limitations of traditional therapies, thereby improving treatment precision and efficacy. The applications of nanomaterials in diagnostics are summarized, where they enable high-resolution retinal imaging by carrying fluorescent probes or contrast agents or act as biosensors to sensitively detect disease-related biomarkers, facilitating early diagnosis and dynamic monitoring. In therapeutics, functionalized nanocarriers can precisely deliver drugs, genes, or antioxidant molecules to retinal target cells, significantly enhancing therapeutic outcomes while reducing systemic toxicity. Additionally, nanofiber materials possess unique properties that make them particularly suitable for retinal regeneration in tissue engineering. By loading neurotrophic factors into nanofiber scaffolds, their regenerative effects can be amplified, promoting the repair of retinal neurons. Despite their immense potential, clinical translation of nanomaterials still requires addressing challenges such as long-term biosafety, scalable manufacturing processes, and optimization of targeting efficiency.

MicroRNA-loaded antioxidant nanoplatforms for prevention and treatment of experimental acute and chronic uveitis

Uveitis, a frequently recurrent inflammatory condition of the uvea, poses a significant risk of visual impairment and blindness, primarily due to the excessive generation of reactive oxygen species (ROS) and the activation of signaling pathways that propagate inflammatory responses. Despite the widespread use of corticosteroid eye drops as a standard treatment, these therapies are hindered by limited efficacy, adverse side effects, and poor ocular bioavailability. To address these challenges, polyethyleneimine (PEI)-modified polydopamine (PDA) carrying microRNA-132-3p (miR-132), namely PEI/PDA@miR-132, was developed to simultaneously neutralize ROS and attenuate inflammation in experimental models of acute and chronic uveitis. Mechanistically, PEI/PDA@miR-132 demonstrated remarkable efficacy by suppressing ROS production, inhibiting the pro-inflammatory polarization of macrophages, and downregulating the IκBα/nuclear factor-kappa B (NF-κB) p65 signaling pathway. These effects culminated in the reduction of pro-inflammatory cytokines and mitigation of apoptosis. Therapeutically, PEI/PDA@miR-132 provided significant relief from hallmark symptoms of uveitis, including iris congestion, inflammatory exudation, and retinal folds, while exhibiting superior retinal safety compared to commercially available dexamethasone. Furthermore, it showcased excellent biocompatibility, positioning it as a promising therapeutic strategy for managing oxidative stress- and inflammation-driven diseases such as acute and chronic uveitis.

Quercetin loaded biogenic squalene nano-lipid carriers for the treatment of dry eye syndrome

In this study, quercetin-incorporated squalene nanostructured lipid carriers (QS-NLCs) were developed to mitigate the pathological conditions of dry eye disease (DED). The melt emulsification method was used to prepare QS-NLCs. The resulting NLCs have 93.74 ± 9.32 nm particle size, 43.8 ± 5.42 % drug loading and showed good stability for 90 days at different storage conditions. The structural characterization of NLCs was carried out through DSC, FTIR, and XRD, and the morphological study was conducted using TEM analysis. The morphological study emphasised no agglomeration was present in the formulation, and further -31.47 ± 2.18 mV zeta potential supported the TEM analysis. Also, the QS-NLCs showed a release pattern in which more than 70 % of the drug was released in the medium in 1 h. After that, a sustained release pattern was observed for 6 h. However, QS-NLCs also showed higher ex-vivo corneal permeation, i.e., ∼2.5-fold, as compared to free quercetin. Also, no significant difference was observed in the moisture retention capacity of NLCs when compared with control glycerin. Further, the QS-NLCs showed good anti-inflammatory and cytotoxicity activities against RAW 264.7 and HCECs cell lines, respectively. Furthermore, 18.22 ± 1.23 mm of Schirmer score in a 5-day tear production study and a 2.79-fold increased half-life (T1/2), 3.02-fold enhanced area under the curve (AUC0-∞), and 2.88-fold higher mean retention time (MRT0-∞) were obtained which signified the higher bioavailability of QS-NLCs with higher ocular tolerance ensured by modified Draize test. Most importantly, the proposed QS-NLCs improved the pharmacological activities of quercetin against DED.

Insights into nano-ZrO2 reinforced self-antibacterial Ti-3Cu composites via laser metal deposition: content-optimized bioactive nano-ZrO2 integrated for wear resistance, in vitro antibacterial and biological properties

Ti alloys are sensitive to fretting wear, which leads to early failure of their implants. Wear is a major factor in determining the long-term clinical performance. This work explored the increase of wear resistance in antibacterial Ti-Cu alloys, by incorporating biocompatible nano-ZrO2 using laser metal deposition (LMD). The content of the reinforcing nano-ZrO2 played a crucial role in performance. There was good densification quality for ≤3 wt%. The densification quality declined and there were macrocracks for ≥5 wt%. Both the prior β grains and the α grains initially decreased in size followed by coarsening as the ZrO2 content increased, with the minimum at 3 wt%. The yield strength increased with increasing ZrO2 content, and the elastic modulus increased from 5 wt%. The wear rate decreased initially and then increased with increasing ZrO2 contents, reaching the lowest wear rate at 3 wt%. The corrosion resistance in body fluid was a minimum between 3 and 5 wt%, with less or more leading to a decrease in corrosion resistance. In vitro antibacterial tests and MC3T3-E1 cell culture assays indicated that ZrO2 contents of up to 10 wt% achieved good antibacterial effects while maintaining good biocompatibility. The comprehensive test results allowed screening and optimization of the processability and wear-related performance. 3 wt% ZrO2 contents provided the best overall performance. The mechanisms for various content bioactive nano-ZrO2 integrated for wear resistance, in vitro antibacterial and biological properties were explored. This work aimed to understand how ZrO2 concentrations influenced the overall performance and to identify the optimal content for wear resistance and related biofunctionality.

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.

Formulation Advances in Posterior Segment Ocular Drug Delivery

Posterior segment ocular diseases, such as diabetic retinopathy, age-related macular degeneration, and retinal vein occlusion, are leading causes of vision impairment and blindness worldwide. Effective management of these conditions remains a formidable challenge due to the unique anatomical and physiological barriers of the eye, including the blood-retinal barrier and rapid drug clearance mechanisms. To address these hurdles, nanostructured drug delivery systems are proposed to overcome ocular barriers, target the retina, and enhance permeation while ensuring controlled release. Traditional therapeutic approaches, such as intravitreal injections, pose significant drawbacks, including patient discomfort, poor compliance, and potential complications. Therefore, understanding the physiology and clearance mechanism of eye could aid in the design of novel formulations that could be noninvasive and deliver drugs to reach the target site is pivotal for effective treatment strategies. This review focuses on recent advances in formulation strategies for posterior segment ocular drug delivery, highlighting their potential to overcome these limitations. Furthermore, the potential of nanocarrier systems such as in-situ gel, niosomes, hydrogels, dendrimers, liposomes, nanoparticles, and nanoemulsions for drug delivery more effectively and selectively is explored, and supplemented with illustrative examples, figures, and tables. This review aims to provide insights into the current state of posterior segment drug delivery, emphasizing the need for interdisciplinary approaches to develop patient-centric, minimally invasive, and effective therapeutic solutions.

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.

Innovative approaches to treatment of eye diseases: advances in stem cell therapy use in ophthalmology

INTRODUCTION

The human eye, a photo-sensory organ with an array of neuronal and tissue networks, remains susceptible to damage from various diseases and disorders despite its being a flawless masterpiece. It is estimated that over 2 billion people suffer from vision loss with common causative factors such as; age-related macular degeneration (AMD), glaucoma, cataracts, diabetic retinopathy, and infections amongst others. The use of Orthodox procedures has only helped mitigate the pathology; however, it doesn't serve any substantial curative purpose. More recently, the incorporation of new therapies via ocular delivery of nanomaterials and stem cell intervention has helped to change tides in the treatment of various ophthalmic pathologies.

MAIN TEXT

This review provides an overview of the current trends and breakthroughs in ophthalmology via stem cell therapy, with emphasis on its types, mechanisms, applications, and benefits. Mesenchymal stem cells which can arise from embryonic or adult origin possess some immunomodulatory effects that contribute to the therapeutic relevance of the MSCs and the ability to evade rejection from the host. However, the major drawback has been uncontrolled growth which can result in unintended side effects. Moreso, religious and ethical issues concerning the employment of MSCs from embryonic origin have also hindered clinical progression with its use. The use of stem cell therapy in the treatment of eye pathologies which is still undergoing clinical trials has shown to be a more viable treatment approach in ophthalmology as it targets retinal degenerative diseases thereby offering novel pathways for vision restoration. And also serves as a revolutionary alternative for treating severe ocular diseases. Stem cell delivery techniques might be quite cumbersome as the eye is a very delicate organ. The therapeutic interventional technique employed is aimed to ensure the reduction or absence of undesired effects in the deposition of the active pharmaceutical ingredient (API) being the stem cells. Techniques such as hydrogel-based injectables, which offer delivery of the APIs to the desired site of action without change in the physicochemical properties of the drug molecule, the scaffold delivery techniques, and the use of 3D bio-printing which can be used to develop scaffolds for retinal degeneration. The employment of artificial intelligence and machine learning in stem cell therapy has shown to be very fast and efficient in stem cell delivery and preventing likely human errors.

CONCLUSIONS

Unlike conventional treatments that often focus on managing symptoms, stem cells have the unique ability to repair and regenerate damaged tissues, addressing the root causes of the diseases. However, limitations due to economic, regulatory, and ethical challenges have posed barriers to advancing stem cell therapies.

Nanoemulsion-based pseudopolyrotaxane hydrogel for enhanced corneal bioavailability and treatment of corneal inflammation

Corneal inflammation, a condition that can potentially lead to blindness, is often treated with topical eye drops. However, the limited ocular drug bioavailability of the eye drops necessitates frequent dosing. Herein, a nanoemulsion-based pseudopolyrotaxane hydrogel was fabricated to improve corneal bioavailability and thereby suppress inflammation. In this approach, dexamethasone was encapsulated into a nanoemulsion emulsified by Tween 80. The nanoemulsion was then mixed with γ-Cyclodextrin (γ-CD) aqueous solution to produce dexamethasone-loaded nanoemulsion-based pseudopolyrotaxane hydrogel (DEX-NPH) via host-guest interaction between Tween 80 and γ-CD. The hydrogel exhibited a shear-thinning and thixotropy character. In vitro drug release and hydrogel dissolution studies showed that drugs released from hydrogel predominantly in the form of nanoemulsion. The ocular surface fluorescence imaging and tear pharmacokinetics indicated that the hydrogel could significantly prolong precorneal residence time. The corneal pharmacokinetics suggested that DEX-NPH with 35 % γ-CD improved corneal bioavailability by 1.29-fold compared with nanoemulsion and by 4.09-fold compared with free drug solution. In particular, the precorneal retention capacity and corneal bioavailability could be adjusted by changing the γ-CD content in the hydrogel. Moreover, ocular irritation evaluation confirmed the excellent safety of such hydrogel. In an alkali burn-induced corneal inflammation model, the hydrogel exhibited a superior anti-inflammatory effect compared to nanoemulsion or free drug solution alone. In summary, the nanoemulsion-based pseudopolyrotaxane hydrogel is promising for enhancing corneal bioavailability and treating corneal inflammation.

Fluorinated multifunctional polymer vesicles for enhanced ocular surface penetration and synergistic treatment of dry eye disease

Current pharmacotherapy for DED is limited by a vicious inflammatory cycle in which reactive oxygen species (ROS) play a critical role. Additionally, topical eye drop therapy for DED often suffers from poor ocular availability due to multiple ocular surface barriers. Considering the key role of the ROS-NLRP3-IL-1β signaling axis in DED, in this investigation, fluorinated multifunctional polymer vesicles were developed for enhanced ocular surface penetration and synergistic DED therapy by combining ROS scavenging and immunomodulation. MCC950, an NLRP3-IL-1β inhibitor, was loaded in situ during vesicle preparation. The results demonstrated that fluorocarbon units randomly distributed in the corona layer significantly enhanced ocular surface penetration. Furthermore, the vesicle membrane, composed of polyphenylborate ester blocks, efficiently scavenged excess ROS in inflamed corneal tissue. In response to excessive ROS, a hydrophobic-to-hydrophilic conversion of the vesicle membrane facilitated the efficient release of MCC950 to modulate the NLRP3-caspase-1-IL1β pathway. We believe that this work will provide insightful guidance to achieve effective treatment of DED by enhancing ocular surface penetration.

Hybrid Biomembrane-Functionalized Nanorobots Penetrate the Vitreous Body of the Eye for the Treatment of Retinal Vein Occlusion

Intravitreal injections of antivascular endothelial growth factor (VEGF) agents are the primary method for treating retinal vein occlusion (RVO). However, the complex structure of eye anatomy presents ocular barriers that impede drug delivery. Additionally, these drugs only manage the complications associated with RVO and fail to address the underlying cause of vessel occlusions. Here, we describe a method that utilizes functionalized magnetically driven nanorobots to overcome ocular barriers and treat RVO. These nanorobots are developed using a hybrid biomembrane that combines stem cell membranes with liposome-derived membranes, enveloping perfluorohexane, iron oxide nanoparticles, and l-arginine. After intravitreal injection, the nanorobots can move directionally through and penetrate the vitreous body to reach the retina, driven by an external magnetic field. Subsequently, the nanorobots actively target the inflammation sites at occluded vessels due to the presence of stem cell membranes. In a rat model of RVO, enhanced targeting and accumulation in ischemic retinal vessels were demonstrated following intravitreal injections. Furthermore, the application of ultrasound triggers the release of l-arginine at the site of occlusion, stimulating the production of nitric oxide, which promotes vasodilation and restores blood flow, thereby achieving excellent therapeutic efficacy for RVO. We believe these methods hold significant promise for overcoming challenges in ocular drug delivery and effectively treating RVO in clinical applications.

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.

Supramolecular Engineering of Nanoceria for Management and Amelioration of Age-Related Macular Degeneration via the Two-Level Blocking of Oxidative Stress and Inflammation

Age-related macular degeneration (AMD), characterized by choroidal neovascularization (CNV), is the global leading cause of irreversible blindness. Current first-line therapeutics, vascular endothelial growth factor (VEGF) antagonists, often yield incomplete and suboptimal vision improvement, necessitating the exploration of novel and efficacious therapeutic approaches. Herein, a supramolecular engineering strategy to construct moringin (MOR) loaded α-cyclodextrin (α-CD) coated nanoceria (M@CCNP) is constructed, where the hydroxy and newly formed carbonyl groups of α-CD interact with the nanoceria surface via O─Ce conjunction and the isothiocyanate group of MOR inserts deeply into the α-CD cavity via host-guest interaction. By exploiting the recycling reactive oxygen species (ROS) scavenging capability of nanoceria and the anti-inflammation properties of MOR, the two-level strike during AMD pathogenesis can be precisely blocked by M@CCNP. Remarkably, excellent therapeutic efficacy to CNV is observed in vivo, achieving over 80% reduction in neovascularization and over 60% reduction in leakage area. In summary, the supramolecular engineered nanoceria provides an efficient approach for amelioration of AMD by blocking the two-level strike, and presents significant potential as an exceptional drug delivery platform, particularly for ROS-related diseases.

The use of nanocarriers in treating Batten disease: A systematic review

The neuronal ceroid lipofuscinoses, commonly known as Batten disease, are a group of lysosomal storage disorders affecting children. There is extensive central nervous system and retinal degeneration, resulting in seizures, vision loss and a progressive cognitive and motor decline. Enzyme replacement and gene therapies are being developed, and mRNA and oligonucleotide therapies are more recently being considered. Overcoming the challenges of the blood-brain barrier and blood-ocular barrier is crucial for effectively targeting the brain and eye, whatever the therapeutic approach. Nanoparticles and extracellular vesicles are small carriers that can encapsulate a cargo and pass through these cell barriers. They have been investigated as drug carriers for other pathologies and could be a promising treatment strategy for Batten disease. Their use in gene, enzyme, or mRNA replacement therapy of all lysosomal storage disorders, including Mucopolysaccharidoses, Niemann-Pick diseases, and Fabry disease, is investigated in this systematic review. Different nanocarriers can efficiently target the lysosome and cross the barriers into the brain and eyes. This supports continued exploration of nanocarriers as potential future treatment options for Batten disease.

Chondroitin Sulphate-Chitosan Based Nanogels Loaded with Naringenin-β-Cyclodextrin Complex as Potential Tool for the Treatment of Diabetic Retinopathy: A Formulation Study

Purpose

The main purpose of the study was the formulation development of nanogels (NHs) composed of chondroitin sulfate (CS) and low molecular weight chitosan (lCH), loaded with a naringenin-β-cyclodextrin complex (NAR/β-CD), as a potential treatment for early-stage diabetic retinopathy.

Methods

Different formulations of NHs were prepared by varying polymer concentration, lCH ratio, and pH and, then, characterized for particle size, zeta potential, particle concentration (particles/mL) and morphology. Cytotoxicity and internalization were assessed in vitro using Human Umbilical Vein Endothelial Cells (HUVEC). The NAR/β-CD complex was prepared and evaluated for morphology, complexation efficiency, and solubility. Finally, the most promising NH prototype was loaded with NAR/β-CD (NH@NAR/β-CD) and further characterized for encapsulation efficiency, loading capacity, opacity and cytotoxicity on HUVEC; in vitro release test and DPPH assay were performed to investigate NH capability to sustain NAR release and NH@NAR/β-CD antioxidant properties, respectively.

Results

NH properties were influenced by polymer concentration, lCH ratio, and pH. N3 (0.5 mg/mL; lCH=1.5:1; pH = 5) and N9 (0.5 mg/mL; lCH=1:1; pH = 5) showed optimal characteristics, including small size (<350 nm) and positive zeta potential, facilitating cellular uptake. The NAR/β-CD complex showed 71% complexation efficiency and enhanced NAR solubility. Since characterized by superior properties and better in vitro biocompatibility, N3 was loaded with NAR/β-CD. N3@NAR/β-CD capability to sustain in vitro NAR release, radical scavenging activity and in vitro biocompatibility were finally demonstrated.

Conclusion

The physico-chemical properties of N3@NAR/β-CD were responsible for their cell uptake, suggesting their potential to target retinal endothelial cells. The high NAR/β-CD complexation efficiency and the sustained NAR release over 72 hours could guarantee the maintenance of an effective drug concentration at the damage site while reducing the injection number. Further studies about the safety and the effectiveness of the intravitreal injection of NHs@NAR/β-CD will be performed on a diabetic animal model.

Drug in Drug: Quorum Sensing Inhibitor in Star-Shaped Antibacterial Polypeptides for Inhibiting and Eradicating Corneal Bacterial Biofilms

Biofilm-related bacterial keratitis is a severe ocular infection that can result in drastic vision impairment and even blindness. However, the therapeutic efficiency of clinical antibiotic eyedrops is often compromised because the bacteria in the biofilms resist bactericide via the community genetic regulation, namely, bacterial quorum sensing. Herein, quercetin (QCT)-loaded star-shaped antibacterial peptide polymer (SAPP), QCT@SAPP, is developed based on a "drug" in a "drug" strategy for inhibiting and eradicating Pseudomonas aeruginosa biofilms on the cornea. The natural antibacterial peptide-mimic SAPP with the positively charged amphipathic structure not only enables QCT@SAPP to penetrate the biofilms readily but also selectively adheres to the highly negatively charged P. aeruginosa, releasing the loaded QCT into the bacteria to regulate quorum sensing by inhibiting lasI, lasR, rhlR, and rhlI. Thanks to its robust bactericidal ability from SAPP, QCT@SAPP can eliminate more than 99.99% of biofilms. Additionally, QCT@SAPP displayed outstanding performance in relieving ocular inflammation by significantly downregulating pro-inflammatory cytokines and profiting from scavenging reactive oxygen species by releasing QCT, which finally helps to restore visual function. In conclusion, QCT@SAPP, with good compatibility, exerts excellent therapeutic effects in a bacterial keratitis mice model, making it a promising candidate for controlling bacterial biofilm-induced infections, including bacterial keratitis.

Subconjunctival injection of microcrystalline prodrug of dexamethasone for long-acting anti-inflammation after phacoemulsification surgery

Long-acting injectable formulations of dexamethasone with minimal invasiveness are highly desired to manage chronic ocular inflammatory conditions. Here, we applied microcrystals (MCs) of a hydrophobic acetone-based ketal-linked prodrug of dexamethasone (SKD) to treat postoperative ocular inflammation. We compared the efficacy and safety of SKD MCs through subconjunctival (SC) injection with that of Maxidex (a topical suspension of dexamethasone MCs) through SC injection and eye drops in the phacoemulsification combined with intraocular lens implantation (Phaco-IOL) rabbit model. In Phaco-IOL rabbit eyes, a single SC injection of SKD MCs (0.4 mg dexamethasone equiv.) showed anti-inflammatory effects comparable to Maxidex eye drops and completely alleviated the inflammation within 28 days, while an SC injection of Maxidex at the same dose only provided anti-inflammatory effects for 7 days. The study on the dose-dependent anti-inflammatory effects of SKD MCs showed no significant difference in anti-inflammatory effects for the high dosage (0.8 mg dexamethasone equiv.) and the low dosage (0.4 mg dexamethasone equiv.) in 28 days. Nevertheless, systematic drug distribution of SKD MCs and Maxidex in normal rabbits after SC injection demonstrates that the drug concentration in conjunctiva was higher for the high dosage and that a considerable amount of prodrug and dexamethasone could still be detected in the cornea and iris-ciliary body at least 84 days for SKD MCs at high dosage. Furthermore, no persistent elevated intraocular pressure and abnormality in retinal structure and thickness were observed, confirming the excellent safety of long-acting SKD MCs post-SC injection. Our findings provide valuable insights into using prodrug-based MCs for treating ocular postoperative inflammation, and the detailed drug distribution analysis would promote the clinical translation of these MCs in ocular diseases.

Active trans-corneal drug delivery with ocular adhesive micelles for efficient glaucoma therapy

Efficient and noninvasive drug delivery for glaucoma therapy necessitates prolonged retention on the ocular surface and deep penetration into the cornea. However, inherent physiological defenses such as rapid tear clearance and low cornea permeability present significant challenges that hinder the effectiveness of trans-corneal drug delivery. In this study, we demonstrate the potential of zwitterionic micelles composed of poly(2-(N-oxide-N,N-diethylamino)ethyl methacrylate)-block-poly(ε-caprolactone) (OPDEA-PCL) amphiphiles as a biocompatible carrier for trans-corneal drug delivery. These micelles exhibit enhanced adhesion to ocular tissues and resistance to tear clearance due to their unique affinity for cell membranes. These characteristics facilitate adsorptive-mediated transcytosis, significantly augmenting trans-corneal transport and intraocular accumulation of the glaucoma medication brinzolamide (BRZ). As a result, OPDEA-PCL/BRZ formulations effectively normalize intraocular pressure in an open-angle glaucoma rat model, surpassing PEGylated and free BRZ formulations. This research underscores the potential utility of OPDEA-PCL micelles as a promising vehicle for noninvasive topical trans-corneal drug delivery in glaucoma therapy.

Co-delivery of antioxidants and siRNA-VEGF: promising treatment for age-related macular degeneration

Current treatments for retinal disorders are anti-angiogenic agents, laser photocoagulation, and photodynamic therapies. These conventional treatments focus on reducing abnormal blood vessel formation in the retina, which, in a low-oxygen environment, can lead to harmful proliferation of endothelial cells. This results in dysfunctional, leaky blood vessels that cause retinal edema, hemorrhage, and vision loss. Age-related Macular Degeneration is a primary cause of vision loss and blindness in the elderly, impacting around 20% of those over 50 years old. This complex disease is also closely related to oxidative stress in retina. In this review, we explore the challenge of treating retinal diseases, alternatives and possibilities of enhancing the effectiveness of therapies using co-delivery systems containing both antiangiogenic and antioxidant therapeutic agents. Despite recent proposals potential, the lack of extensive clinical studies on the long-term outcomes and optimal combinations of therapies means that the full risk profile and effectiveness of combined therapy are not yet completely understood. These factors must be carefully considered and managed by healthcare providers to optimize treatment outcomes and ensure patient safety.

Applications and latest research progress of liposomes in the treatment of ocular diseases

The special structure of eyes and the existence of various physiological barriers make ocular drug delivery one of the most difficult problems in the pharmaceutical field. Considering the problems of patient compliance, local administration remains the preferred method of drug administration in the anterior part of eyes. However, local administration suffers from poor bioavailability, need for frequent administration, and systemic toxicity. Administration in the posterior part of the eye is more difficult, and intravitreal injection is often used. But intravitreal injection faces the problems of poor patient compliance and likely side effects after multiple injections. The development of nanocarrier technology provides an effective way to solve these problems. Among them, liposomes, as the most widely used carrier in clinical application, have the characteristics of amphiphilic nanostructure, easy surface modification, extended release time, good biocompatibility, etc. The liposomes are expected to overcome obstacles and effectively deliver drugs to the target site to improve ocular drug bioavailability. This review summarized the various controllable properties of liposomes for ocular delivery as well as the application and research progress of liposomes in various ocular diseases. In addition, we summarized the physiological barriers and routes of administration contained in eyes, as well as the prospects of liposomes in the treatment of ocular diseases.

Corneal Mucin-Targeting Liposome Nanoplatforms Enable Effective Treatment of Dry Eye Diseases by Integrated Regulation of Ferroptosis and Inflammation

The incidence of dry eye disease (DED) has been increasing annually worldwide, creating an urgent need for new therapies. Due to the multifactorial mechanism underlying DED, traditional medications focused on decreasing ocular surface inflammation have been unable to address all the harmful factors and fail to achieve a complete clinical cure. Ferroptosis, a new form of programmed cell death characterized by lipid peroxidation, has become a pivotal contributor to dry eye oxidative stress-driven pathology. Therefore, therapeutic targeting of ferroptosis may be an attractive option for dry eye management. Herein, a sialic acid-targeting peptide-modified liposome loaded with Cyclosporine A (CsA), a typical anti-inflammatory drug, and Ferrostatin-1 (Fer-1), a selective ferroptosis inhibitor, is developed termed as CF@SNPs, for combing and sustaining DED treatment. This multifunctional liposomal encapsulation demonstrates excellent aqueous solubility; moreover, the sialic acid-targeting peptide prolongs ocular surface retention, further enhancing therapeutic efficacy. The CF@SNPs treatment comprehensively alleviates DED symptoms, including improving corneal defects, augmenting goblet cell count, and restoring tear secretion. Specifically, CF@SNPs attenuate dry eye pathology by suppressing p53-SLC7A11-GSH-dependent ferroptosis and TNF-α-associated inflammatory cascades, accompanied by favorable biocompatibility in vivo. These results underscore the promising potential of this superior nano-formulation for DED pharmacotherapy.

In Situ Crystallized Ceria-Vesicle Nanohybrid Therapeutic for Effective Treatment of Inflammatory Intraocular Disease

Posterior uveitis is a leading cause of vision impairment and blindness globally due to its detrimental effects on the choroid and retina. The condition is worsened by oxidative stress, which heightens inflammation and perpetuates a cycle of damage that current treatments only temporarily relieve. To address this, a novel treatment involving the in situ crystallization of ultrasmall cerium oxide nanoparticles (≈3 nm) on mesenchymal stem cell (MSC) extracellular vesicles (EVs) for the management of primed mycobacterial uveitis (PMU) is developed. This nanohybrid leverages the individual and synergistic effects of its components for a comprehensive therapeutic approach. The cerium oxide nanoparticles act as a nanozyme to reduce inflammation and scavenge excessive reactive oxygen species (ROS), while the MSC EVs, with their biocompatibility, modulate inflammatory cell infiltration and alleviate tissue damage. This synergistic system offers a promising new treatment strategy for ocular diseases characterized by oxidative stress and inflammation.

A hyaluronic acid-modified cyclodextrin self-assembly system for the delivery of β-carotene in the treatment of dry eye disease

Dry eye disease (DED) is a multifactorial ocular disease, the core mechanism of which is the tear film instability caused by ocular oxidative stress damage and inflammation. Although various pharmaceutical agents are available for DED treatment, their effectiveness is often limited by the eyes' unique biological barriers, and the long-term use of steroid hormones can lead to several adverse effects. This study reported a nano-supramolecular delivery system consisting of a polycyclodextrin (PCD), hyaluronic acid (HA) and the natural compound β-carotene (BC) for the DED treatment. Our findings indicate that the HA/PCD@BC eye drops effectively distribute on the ocular surface, retain BC, and significantly enhance the corneal penetration of BC. The excellent biocompatibility of HA/PCD@BC was demonstrated through viability testing on different cell lines, the Draize eye test, as well as the hematoxylin-eosin staining (H&E) sections of cornea and conjunctiva. Both in vitro oxidative stress assays and in vivo DED model evaluations demonstrated that the HA/PCD@BC delivery system significantly reduced abnormal oxidative stress levels on the ocular surface, inhibited the secretion of inflammatory factors, and increased the secretion of tear film stabilizing mucin. These effects collectively improved pathological changes in eye tissues and minimized damage to the ocular surface. It is of particular importance to note that HA/PCD@BC eye drops showed superior efficacy in comparison to cyclosporine A (CsA), an FDA-approved first-line drug. To sum up, the HA/PCD@BC nanodelivery system provides a natural, safe and effective therapeutic strategy for the treatment of DED and various ocular diseases.

Unraveling Neurological Drug Delivery: Polymeric Nanocarriers for Enhanced Blood-Brain Barrier Penetration

Treating neurological illnesses is challenging because the blood-brain barrier hinders therapeutic medications from reaching the brain. Recent advances in polymeric nanocarriers (PNCs), which improve medication permeability across the blood-brain barrier, may influence therapy strategies for neurological diseases. PNCs have several ways to deliver medications to the nervous system. This review article provides a summary of the parts and manufacturing methods involved in making PNCs. Additionally, it highlights the elements that result in PNCs having enhanced blood-brain barrier penetration. A combination of passive and active targeting strategies is used by PNCs intended to overcome the blood-brain barrier. Among these are micellar structures, nanogels, nanoparticles, cubosomes, and dendrimers. These nanocarriers, which are functionalized with certain ligands that target BBB transporters, enable the direct delivery of drugs to the brain. Mainly, the BBB prevents medications from entering the brain. Understanding the BBB's physiological and anatomical characteristics is necessary to get over this obstacle. Preclinical and clinical research demonstrates the safety and effectiveness of these PNCs, and their potential use in the treatment of neurological illnesses, including brain tumors, Parkinson's disease, and Alzheimer's disease, is discussed. Concerns that PNCs may have about their biocompatibility and possible toxicity are also covered in this review article. This study examines the revolutionary potential of PNCs in CNS drug delivery, potential roadblocks, ongoing research, and future opportunities for PNC design progress. PNCs open the door to more focused and efficient treatment for neurological illnesses by comprehending the subtleties of BBB penetration.

India's Pink-Eye Mystery: Decoding the 2023 Conjunctivitis Outbreak

The pink eye outbreak in 2023 was caused due to humid weather conditions in most regions of India. The most affected states include Delhi, Gujrat (21% cases), Maharashtra (30%), Himachal Pradesh (4%) and Karnataka (4%). The epidemiological data indicates that males have a high prevalence rate as compared to females; urban areas were most affected, and professionals as well as students were the population group that had the highest prevalence rate. The most common clinical manifestations were the presence of red eye, eye discharge, grittiness, and eyelashes being stuck together. One of the hallmarks of histopathology is a cobblestone formation of flattened nodules with central vascular centers. Conjunctivitis is a virusmediated immune response accompanied by inflammation, which proceeds the immune reaction, giving rise to vasodilation, pseudo membrane formation, and conjunctivital discharge. The gold standard for the diagnosis of Conjunctivitis is the Adenoplus kit using PCR technology; apart from this slit lamp biomicroscope can be used for the evaluation. It is the need of the hour to spread awareness about the Pink Eye disease and the measures to prevent it.

Targeted Drug Nanodelivery and Immunotherapy for Combating Tumor Resistance

Chemotherapy resistance is a common cause of tumor treatment failure. Various molecular responses, such as increased expression of efflux transporter proteins, including Pglycoprotein (P-gp), changes in the tumor microenvironment (TME), the role of platelets, and the effects of cancer stem cells (CSCs), can lead to drug resistance. Through extensive research on the mechanisms of drug resistance, more effective anti-resistance drugs and therapeutic approaches are being developed. This review explores drug resistance mechanisms and summarizes relevant anti-resistance drugs. In addition, due to the therapeutic limitations of the aforementioned treatments, new advances in nanocarrier-based combination immunotherapy to address the challenge of drug resistance have been described. Nanocarriers combined with immunotherapy can not only target tumor sites for targeted drug release but also modulate the autoimmune system and enhance immune efficacy, thereby overcoming tumor drug resistance. This review suggests new strategies for overcoming tumor drug resistance and is expected to inform tumor treatment and prognosis.

Suprachoroidal Delivery of Viral and Nonviral Vectors for Treatment of Retinal and Choroidal Vascular Diseases

PURPOSE

Current treatments for retinal and choroidal neovascular diseases suffer from insufficient durability, including anti-vascular endothelial growth factor-A agents. It is, therefore, of interest to explore alternative methods that could allow for robust improvement in visual acuity with fewer injections required.

DESIGN

Literature review.

RESULTS

Among various preclinical and clinical studies in the literature, a promising approach is the use of suprachoroidal injection with viral and nonviral gene delivery vectors. Compared with other ocular injection methods, suprachoroidal injection has demonstrated wide biodistribution of injected agents and safety as an outpatient procedure. In terms of viral vectors, suprachoroidal injection of an adeno-associated virus 8 vector expressing an anti-vascular endothelial growth factor-A antibody fragment has shown an excellent safety profile and evidence of biological activity. In terms of nonviral vectors, lipid nanoparticles and polymeric nanoparticles both demonstrate strong promise for ocular gene therapy in large animal models. In particular, biodegradable poly(β-amino ester) nanoparticles show excellent biodistribution, safety, and efficacy for gene therapy via the suprachoroidal route. Nonviral nanoparticle approaches can have notable advantages over viral vectors in terms of carrying capacity, redosability, and manufacturing costs. An advantage of gene therapy is that once a delivery vector has been optimized, genetic cargos can be readily tailored without changing the safety, efficacy, and pharmacokinetic properties of the delivery vector.

CONCLUSIONS

This review highlights recent progress that has been made and compares viral and nonviral suprachoroidal gene delivery for the treatment of retinal and choroidal vascular diseases. Suprachoroidal gene therapy is an emerging biotechnology that holds substantial potential to make a translational impact in treating these diseases.

From Preformulative Design to In Vivo Tests: A Complex Path of Requisites and Studies for Nanoparticle Ocular Application. Part 1: Design, Characterization, and Preliminary In Vitro Studies

Ocular pathologies are widely diffused worldwide, and their effective treatment, combined with a high patient compliance, is sometimes challenging to achieve due to the barriers of the eye; in this context, the use of nanoparticles for topical ophthalmic application could represent a successful strategy. Aiming to develop nanoplatforms with potential clinical applications, great attention has to be paid to their features, in relation to the route of administration and to the pharmacopoeial requirements. This review (part 1) thus embraces the preliminary steps of nanoparticle development and characterization. At the beginning, the main barriers of the eye and the different administration routes are resumed, followed by a general description of the advantages of the employment of nanoparticles for ocular topical administration. Subsequently, the preformulative steps are discussed, deepening the choice of raw materials and determining the quantitative composition. Then, a detailed report of the physicochemical and technological characterization of nanoparticles is presented, analyzing the most relevant tests that should be performed on nanoparticles to verify their properties and the requisites (both mandatory and suggested) demanded by regulatory agencies. In conclusion, some preliminary noncellular in vitro evaluation methods are described. Studies from in vitro cellular assays to in vivo tests will be discussed in a separate (part 2) review paper. Hence, this overview aims to offer a comprehensive tool to guide researchers in the choice of the most relevant studies to develop a nanoplatform for ophthalmic drug administration.

From Preformulative Design to in Vivo Tests: A Complex Path of Requisites and Studies for Nanoparticle Ocular Application. Part 2: In Vitro, Ex Vivo, and In Vivo Studies

The incidence of ocular pathologies is constantly increasing, as is the interest of the researchers in developing new strategies to ameliorate the treatment of these conditions. Nowadays, drug delivery systems are considered among the most relevant approaches due to their applicability in the treatment of a great variety of inner and outer eye pathologies through painless topical administrations. The design of such nanocarriers requires a deep study of many aspects related to the administration route but also a consideration of the authorities and pharmacopeial requirements, in order to achieve a clinical outcome. On such bases, the scope of this review is to describe the path of the analyses that could be performed on nanoparticles, along with the assessment of their applicability for ophthalmic treatments. Preformulation studies, physicochemical and technological characterization, and preliminary noncellular in vitro studies have been described in part 1 of this review. Herein, first the in vitro cellular assays are described; subsequently, nonocular organotypic tests and ex vivo studies are reported, as to present the various analyses to which the formulations can be subjected before in vivo studies, described in the last part. In each step, the models that could be used are presented and compared, highlighting the pros and cons. Moreover, their reliability and eventual acceptance by regulatory agencies are discussed. Hence, this review provides an overview of the most relevant assays applicable for nanocarriers intended for ophthalmic administration to guide researchers in the experimental decision process.

Promising Pharmacological Interventions for Posterior Capsule Opacification: A Review

Phacoemulsification combined with intraocular lens implantation is the primary treatment for cataract. Although this treatment strategy benefits patients with cataracts, posterior capsule opacification (PCO) remains a common complication that impairs vision and affects treatment outcomes. The pathogenesis of PCO is associated with the proliferation, migration, and fibrogenesis activity of residual lens epithelial cells, with epithelial-mesenchymal transition (EMT) serving as a key mechanism underlying the condition. Transforming growth factor-beta 2 (TGF-β2) is a major promotor of EMT, thereby driving PCO development. Most studies have shown that drugs and miRNAs mitigate EMT by inhibiting, clearing, or eliminating LECs. In addition, targeting EMT-related signaling pathways in TGF-β2-stimulated LECs has garnered attention as a research focus. This review highlights potential treatments for PCO and details the mechanisms by which drugs and miRNAs counter EMT.

Metal-phenolic nanoparticles enhance low temperature photothermal therapy for bacterial biofilm in superficial infections

Bacterial infections, especially induced by multidrug-resistant pathogens, have become a significant global health concern. In the infected tissues, biofilms not only serve as a source of nutrients but also act as protective barriers that impede antibiotic penetration. Herein, we developed tea polyphenols epigallocatechin gallate (EGCG) Au nanoparticles (E-Au NPs) through direct one-step self-assembly methods by EGCG chelating with Au ions to eradicate antibiotic-resistant bacteria methicillin-resistant Staphylococcus aureus (MRSA) and prevent the formation of biofilm under near-infrared (NIR) irradiation. The outstanding antibacterial effect involved in mild photothermal therapy, reactive oxygen species production, pathogenicity-related genes regulation, and quinoprotein formation that were specific to the polyphenol-based NPs. The excellent antibacterial and anti-inflammatory therapeutic efficacy of E-Au NPs was validated and topically applied in murine MRSA-infected skin wounds and keratitis model in vivo to kill bacteria, reduce the inflammation response and promote wound healing. Furthermore, the ophthalmic and systemic biosafety profiles were thoroughly evaluated while no significant side effects were revealed achieving a balance between high-efficiency antibacterial properties and biocompatibility. This study provides an effective therapeutic agent of metal-phenolic materials for superficial tissue infection with favorable prognosis and potential in clinical translation.

Targeting reactive oxygen species to ameliorate T cell-mediated inflammation in dry eye syndrome: a novel therapeutic approach

Dry eye syndrome (DES) is a prevalent condition linked to oxidative stress from Orthokeratology (OK) lens use, causing significant discomfort and impacting quality of life. Herein, this study investigates the role of Reactive Oxygen Species (ROS) in modulating T cell responses, particularly Th17 cells and IL-17A production, which are central to DES pathogenesis. We propose a novel therapeutic strategy using ceria nanoparticles (CeNPs) for ocular ROS clearance, hypothesized to attenuate Th17 activation and IL-1β and IL-17A production, thereby reducing DES symptoms. We developed a hybrid coating for OK lenses using Schiff base reactions to link tannic acid with CeNPs, aiming to neutralize ROS and mitigate inflammation. This approach could offer a transformative treatment for DES, especially among OK lens users. In comparison to existing therapies, our approach demonstrated a 70% reduction in corneal inflammation markers and a 2.5-fold increase in tear secretion, offering a transformative treatment for DES, especially among OK lens users.

Cutting-edge advances in nano/biomedicine: A review on transforming thrombolytic therapy

Thrombotic blockages within blood vessels give rise to critical cardiovascular disorders, including ischemic stroke, venous thromboembolism, and myocardial infarction. The current approach to the therapy of thrombolysis involves administering Plasminogen Activators (PA), but it is hindered by fast drug elimination, narrow treatment window, and the potential for bleeding complications. Leveraging nanomedicine to encapsulate and deliver PA offers a solution by improving the efficacy of therapy, safeguarding the medicine from proteinase biodegradation, and reducing unwanted effects in in vivo trials. In this review, we delve into the underlying venous as well as arterial thrombus pathophysiology and provide an overview of clinically approved PA used to address acute thrombotic conditions. We explore the existing challenges and potential directions within recent pivotal research on a variety of targeted nanocarriers, such as lipid, polymeric, inorganic, and biological carriers, designed for precise delivery of PA to specific sites. We also discuss the promising role of microbubbles and ultrasound-assisted Sono thrombolysis, which have exhibited enhanced thrombolysis in clinical studies. Furthermore, our review delves into approaches for the strategic development of nano-based carriers tailored for targeting thrombolytic action and efficient encapsulation of PA, considering the intricate interaction in biology systems as well as nanomaterials. In conclusion, the field of nanomedicine offers a valuable method for the exact and effective therapy of severe thrombus conditions, presenting a pathway toward improved patient outcomes and reduced complications.

Solubilization techniques used for poorly water-soluble drugs

About 40% of approved drugs and nearly 90% of drug candidates are poorly water-soluble drugs. Low solubility reduces the drugability. Effectively improving the solubility and bioavailability of poorly water-soluble drugs is a critical issue that needs to be urgently addressed in drug development and application. This review briefly introduces the conventional solubilization techniques such as solubilizers, hydrotropes, cosolvents, prodrugs, salt modification, micronization, cyclodextrin inclusion, solid dispersions, and details the crystallization strategies, ionic liquids, and polymer-based, lipid-based, and inorganic-based carriers in improving solubility and bioavailability. Some of the most commonly used approved carrier materials for solubilization techniques are presented. Several approved poorly water-soluble drugs using solubilization techniques are summarized. Furthermore, this review summarizes the solubilization mechanism of each solubilization technique, reviews the latest research advances and challenges, and evaluates the potential for clinical translation. This review could guide the selection of a solubilization approach, dosage form, and administration route for poorly water-soluble drugs. Moreover, we discuss several promising solubilization techniques attracting increasing attention worldwide.

Ocular RNA nanomedicine: engineered delivery nanoplatforms in treating eye diseases

Ocular disorders remain a major global health challenge with unmet medical needs. RNA nanomedicine has shown significant therapeutic benefits and safety profiles in patients with complex eye disorders, already benefiting numerous patients with gene-related eye disorders. The effective delivery of RNA to the unique structure of the eye is challenging owing to RNA instability, off-target effects, and ocular physiological barriers. Specifically tailored RNA medication, coupled with sophisticated engineered delivery platforms, is crucial to guide and advance developments in treatments for oculopathy. Herein we review recent advances in RNA-based nanomedicine, innovative delivery strategies, and current clinical progress and present challenges in ocular disease therapy.

Absorption enhancement strategies in chitosan-based nanosystems and hydrogels intended for ocular delivery: Latest advances for optimization of drug permeation

Ophthalmic diseases can be presented as acute diseases like allergies, ocular infections, etc., or chronic ones that can be manifested as a result of systemic disorders, like diabetes mellitus, thyroid, rheumatic disorders, and others. Chitosan (CS) and its derivatives have been widely investigated as nanocarriers in the delivery of drugs, genes, and many biological products. The biocompatibility and biodegradability of CS made it a good candidate for ocular delivery of many ingredients, including immunomodulating agents, antibiotics, ocular hypertension medications, etc. CS-based nanosystems have been successfully reported to modulate ocular diseases by penetrating biological ocular barriers and targeting and controlling drug release. This review provides guidance to drug delivery formulators on the most recently published strategies that can enhance drug permeation to the ocular tissues in CS-based nanosystems, thus improving therapeutic effects through enhancing drug bioavailability. This review will highlight the main ocular barriers to drug delivery observed in the nano-delivery system. In addition, the CS physicochemical properties that contribute to formulation aspects are discussed. It also categorized the permeation enhancement strategies that can be optimized in CS-based nanosystems into four aspects: CS-related physicochemical properties, formulation components, fabrication conditions, and adopting a novel delivery system like implants, inserts, etc. as described in the published literature within the last ten years. Finally, challenges encountered in CS-based nanosystems and future perspectives are mentioned.

Enhanced Ocular Drug Delivery of Dexamethasone Using a Chitosan-Coated Soluplus®-Based Mixed Micellar System

BACKGROUND

This study introduces a novel dexamethasone (DEX) mixed micellar system (DEX-MM) using Soluplus® and Pluronic F-127 (PF127) to enhance ocular drug delivery. The enhancement of ocular application properties was achieved by creating a chitosan-coated DEX-MM (DEX-CMM), which promotes better adherence to the ocular surface, thereby improving drug absorption.

METHODS

Using the solvent evaporation method, a formulation was developed with a Soluplus®-to-drug ratio of 1:10, enhanced with 0.25% PF127. After dispersing in water, 1% chitosan (CS) was added. The stability and integrity of DEX within the micelles were verified using attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and differential scanning calorimetry (DSC). Additionally, in vitro and ex vivo drug release studies were conducted.

RESULTS

DEX-CMM (F6) demonstrated a particle size of 151.9 ± 1 nm and a polydispersity index (PDI) of 0.168 ± 0.003, suggesting uniformity and high electrostatic stability with a zeta potential of +35.96 ± 2.13 mV. The non-Fickian drug release mechanism indicated prolonged drug retention. Comparative analyses showed DEX-CMM outperforming a standard DEX suspension in drug release and ocular tissue permeation, with flux measurements significantly higher than the DEX suspension.

CONCLUSION

The study confirmed the efficacy of DEX-CMM in enhancing drug delivery to ocular tissues, evidenced by improved permeability. Safety evaluations using the HET-CAM test demonstrated that DEX-CMM was non-irritant, supporting its potential for effective ocular drug delivery.

Piezoelectric PVDF and its copolymers in biomedicine: innovations and applications

In recent years, poly(vinylidene fluoride) (PVDF) has emerged as a versatile polymer with a wide range of applications across various fields. PVDF's piezosensitivity, versatility, crystalline structure, and tunable parameters have established it as a highly sought-after material. Furthermore, PVDF and its copolymers exhibit excellent processability and chemical resistance to a diverse array of substances. Of particular significance is its remarkable structural stability in physiological media, which highlights its potential for use in the development of biomedical products. This review offers a comprehensive overview of the latest advancements in PVDF-based biomedical systems. It examines the fabrication of stimulus-responsive delivery systems, bioelectric therapy devices, and tissue-regenerating scaffolds, all of which harness the piezosensitivity of PVDF. Moreover, the potential of PVDF in the fabrication of both invasive and non-invasive diagnostic tools is investigated, with particular emphasis on its flexibility, transparency, and piezoelectric efficiency. The material's high biocompatibility and physiological stability are of paramount importance in the development of implantable sensors for long-term health monitoring, which is crucial for the management of chronic diseases and postoperative care. Additionally, we discuss a novel approach to photoacoustic microscopy that employs a PVDF sensor, thereby eliminating the necessity for external contrast agents. This technique provides a new avenue for non-invasive imaging in biomedical applications. Finally, we explore the challenges and prospects for the development of PVDF-based systems for a range of biomedical applications. This review is distinctive in comparison to other reviews on PVDF due to its concentrated examination of biomedical applications, including pioneering imaging techniques, long-term health monitoring, and a detailed account of advancements in the field. Collectively, these elements illustrate the potential of PVDF to markedly influence biomedical engineering and patient care, distinguishing it from existing literature. By leveraging the distinctive attributes of PVDF and its copolymers, researchers can continue to advance the frontiers of biomedical engineering, with the potential to transform patient care and treatment outcomes.