Nanotherapy for posterior eye diseases

A review on revolutionizing ophthalmic therapy: Unveiling the potential of chitosan, hyaluronic acid, cellulose, cyclodextrin, and poloxamer in eye disease treatments

Ocular disorders, encompassing both common ailments like dry eye syndrome and more severe situations for instance age-related macular degeneration, present significant challenges to effective treatment due to the intricate architecture and physiological barriers of the eye. Polysaccharides are emerging as potential solutions for drug delivery to the eyes due to their compatibility with living organisms, natural biodegradability, and adhesive properties. In this review, we explore not only the recent advancements in polysaccharide-based technologies and their transformative potential in treating ocular illnesses, offering renewed optimism for both patients and professionals but also anatomy of the eye and the significant obstacles hindering drug transportation, followed by an investigation into various drug administration methods and their ability to overcome ocular-specific challenges. Our focus lies on biological adhesive polymers, including chitosan, hyaluronic acid, cellulose, cyclodextrin, and poloxamer, known for their adhesive characteristics enhancing drug retention on ocular surfaces and increasing bioavailability. A detailed analysis of material designs used in ophthalmic formulations, such as gels, lenses, eye drops, nanofibers, microneedles, microspheres, and nanoparticles, their advantages and limitations, the potential of formulations in improving therapeutic outcomes for various eye conditions. Moreover, we underscore the discovery of novel polysaccharides and their potential uses in ocular drug delivery.

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.

In-situ forming biodegradable implants for sustained Fluocinolone acetonide release to the posterior eye: In-vitro and in-vivo investigations in rabbits

Delivering medication to the posterior segment of the eye presents a significant challenge. Intravitreal injection has emerged as the preferred method for drug delivery to this area. However, current injectable non-biodegradable implants for fluocinolone acetonide (FA) require surgical removal after prolonged drug release, potentially affecting patient compliance. This study aimed to develop an in-situ forming biodegradable implant (ISFBI) optimal formulation containing PLGA504H and PLGA756S (50:50 w/w%) with the additive NMP solvent. The goal was to achieve slow and controlled release of FA over a two-month period with lower burst release, following a single intravitreal injection. Through morphology, rheology, stability and in-vitro release evaluations, the optimal formulation demonstrated low viscosity (0.12-1.25 Pa. s) and sustained release of FA at a rate of 0.36 µg/day from the third day up to two months. Furthermore, histopathology and in-vivo studies were conducted after intravitreal injection of the optimal formulation in rabbits' eye. Pharmacokinetic analysis demonstrated mean residence time (MRT) of 20.02 ± 0.6 days, half-life (t1/2) of 18.80 ± 0.4 days, and clearance (Cl) of 0.29 ± 0.03 ml/h for FA in the vitreous humor, indicating sustained and slow absorption of FA by the targeted retinal tissue from vitrea over the two-month period and eliminating through the anterior section of the eye, as revealed by its presence in the aqueous humor. Additionally, FA exhibited no detection in the blood and no evidence of systemic side effects or damage on the retinal layer and other organs. Based on these findings, it can be concluded that in-situ forming injectable biodegradable PLGA implants can show promise as a long-acting and controlled-release system for intraocular drug delivery.

Chitosan as a promising materials for the construction of nanocarriers for diabetic retinopathy: an updated review

Diabetic retinopathy (DR) is a condition that causes swelling of the blood vessels of the retina and leaks blood and fluids. It is the most severe form of diabetic eye disease. It causes vision loss in its advanced stage. Diabetic retinopathy is responsible for causing 26% of blindness. Very insufficient therapies are accessible for the treatment of DR. As compared to the conventional therapies, there should be enhanced research on the controlled release, shorter duration, and cost-effective therapy of diabetic retinopathy. The expansion of advanced nanocarriers-based drug delivery systems has been now employed to exploit as well as regulate the transport of many therapeutic agents to target sites via the increase in penetration or the extension of the duration of contact employing production by enclosing as well as distributing tiny molecules in nanostructured formulation. Various polymers have been utilized for the manufacturing of these nanostructured formulations. Chitosan possesses incredible biological and chemical properties, that have led to its extensive use in pharmaceutical and biomedical applications. Chitosan has been used in many studies because of its enhanced mucoadhesiveness and non-toxicity. Multiple studies have used chitosan as the best candidate for manufacturing nanocarriers and treating diabetic retinopathy. Numerous nanocarriers have been formulated by using chitosan such as nanostructured lipid carriers, solid lipid nanoparticles, liposomes, and dendrimers for treating diabetic retinopathy. This current review elaborates on the recent advancements of chitosan as a promising approach for the manufacturing of nanocarriers that can be used for treating diabetic retinopathy.

A novel lipophenol quercetin derivative to prevent macular degeneration: Intravenous and oral formulations for preclinical pharmacological evaluation

Drugs with properties against oxidative and carbonyl stresses are potential candidates to prevent dry age-related macular degeneration (Dry-AMD) and inherited Stargardt disease (STGD1). Previous studies have demonstrated the capacity of a new lipophenol drug: 3-O-DHA-7-O-isopropyl-quercetin (Q-IP-DHA) to protect ARPE19 and primary rat RPE cells respectively from A2E toxicity and under oxidative and carbonyl stress conditions. In this study, first, a new methodology has been developed to access gram scale of Q-IP-DHA. After classification of the lipophenol as BCS Class IV according to physico-chemical and biopharmaceutical properties, an intravenous formulation with micelles (M) and an oral formulation using lipid nanocapsules (LNC) were developed. M were formed with Kolliphor® HS 15 and saline solution 0.9 % (mean size of 16 nm, drug loading of 95 %). The oral formulation was optimized and successfully allowed the formation of LNC (25 nm, 96 %). The evaluation of the therapeutic potency of Q-IP-DHA was performed after IV administration of micelles loaded with Q-IP-DHA (M-Q-IP-DHA) at 30 mg/kg and after oral administration of LNC loaded with Q-IP-DHA (LNC-Q-IP-DHA) at 100 mg/kg in mice. Results demonstrated photoreceptor protection after induction of retinal degeneration by acute light stress making Q-IP-DHA a promising preventive candidate against dry-AMD and STGD1.

Selectively coated contact lenses by nanoelectrospray (nES) to fabricate drug-eluting contact lenses for treating ocular diseases

Drug-eluting contact lenses (DECLs) incorporated with poly(lactic-co-glycolic acid) (PLGA) and various model drugs (ketotifen fumarate, bimatoprost and latanoprost) were fabricated using nanoelectrospray (nES) approach. The resulting DECLs demonstrated outstanding optical transmittance within the optical zone, indicating that the employed coating procedure did not compromise visual acuity under the prescribed spraying parameters. In vitro drug release assessments of the model drugs (ketotifen fumarate (KF), bimatoprost (BIM), and latanoprost (LN)) revealed a strong correlation between the model drug's hydrophobicity and the duration of drug release. Changing the drug loading of the more hydrophilic model drugs, BIM and KF, showed no impact on the drug release kinetics of DECLs loaded with BIM and KF. However, for the hydrophobic model drug, LN, the highest LN loading led to the most extended drug release. The conventional steam sterilisation method was found to damage the PLGA coating on the DECLs fabricated by nES. An alternative sterilisation strategy, such as radiation sterilisation may need to be investigated in the future study to minimise potential harm to the coating.

Mathematical Modeling of Drug Delivery from Bi-Layered Core-Shell Polymeric Microspheres

Chronic diseases usually require repetitive dosing. Depending on factors such as dosing frequency, mode of administration, and associated costs this can result in poor patient compliance. A better alternative involves using drug delivery systems to reduce the frequency of dosing and extend drug release. However, reaching the market stage is a time-consuming process. In this study, we used two numerical approaches for estimating the values of the critical parameters that govern the diffusion-controlled drug release within bilayered core-shell microspheres. Specifically, the estimated parameters include burst release, drug diffusion coefficient in two polymers, and the drug partition coefficient. Estimating these parameters provides insight for optimizing device design, guiding experimental efforts, and improving the device's effectiveness. We obtained good agreement between the models and the experimental data. The methods explored in this work apply not only to bi-layered spherical systems but can also be extended to multi-layered spherical systems.

Current Insights into Targeting Strategies for the Effective Therapy of Diseases of the Posterior Eye Segment

The eye is one a unique sophisticated human sense organ with a complex anatomical structure. It is encased by variety of protective barriers as responsible for vision. There has been a paradigm shift in the prevalence of several major vision threatening ocular conditions with enhanced reliance on computer-based technologies in our workaday life and work-from-home modalities although aging, pollution, injury, harmful chemicals, lifestyle changes will always remain the root cause. Treating posterior eye diseases is a challenge faced by clinicians worldwide. The clinical use of conventional drug delivery systems for posterior eye targeting is restricted by the ocular barriers. Indeed, for overcoming various ocular barriers for efficient delivery of the therapeutic moiety and prolonged therapeutic effect requires prudent and target-specific approaches. Therefore, for efficient drug delivery to the posterior ocular segment, advancements in the development of sustained release and nanotechnology-based ocular drug delivery systems have gained immense importance. Therapeutic efficacy and patient compliance are of paramount importance in clinical translation of these investigative drug delivery systems. This review provides an insight into the various strategies employed for improving the treatment efficacies of the posterior eye diseases. Various drug delivery systems such as systemic and intraocular injections, implants have demonstrated promising outcomes, along with that they have also exhibited side-effects, limitations and strategies employed to overcome them are discussed in this review. The application of artificial intelligence-based technologies along with an appreciation of disease, delivery systems, and patient-specific outcomes will likely enable more effective therapy for targeting the posterior eye segment.

Recent Updates on Nanocarriers for Drug Delivery in Posterior Segment Diseases with Emphasis on Diabetic Retinopathy

In recent years, various conventional formulations have been used for the treatment and/or management of ocular medical conditions. Diabetic retinopathy, a microvascular disease of the retina, remains the leading cause of visual disability in patients with diabetes. Currently, for treating diabetic retinopathy, only intraocular, intravitreal, periocular injections, and laser photocoagulation are widely used. Frequent administration of these drugs by injections may lead to serious complications, including retinal detachment and endophthalmitis. Although conventional ophthalmic formulations like eye drops, ointments, and suspensions are available globally, these formulations fail to achieve optimum drug therapeutic profile due to immediate nasolacrimal drainage, rapid tearing, and systemic tearing toxicity of the drugs. To achieve better therapeutic outcomes with prolonged release of the therapeutic agents, nano-drug delivery materials have been investigated. These nanocarriers include nanoparticles, solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC), dendrimers, nanofibers, in-situ gel, vesicular carriers, niosomes, and mucoadhesive systems, among others. The nanocarriers carry the potential benefits of site-specific delivery and controlled and sustained drug release profile. In the present article, various nanomaterials explored for treating diabetic retinopathy are reviewed.

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.

Noninvasive Framework Nucleic Acid Eye Drops for Retinal Administration

Intravitreal injection is widely employed for the treatment of retinal diseases. However, it suffers from various drawbacks, including ocular trauma, risk of infection, and poor patient compliance due to frequent administrations. Due to the presence of barriers such as the cornea, it has been a challenge to develop efficient noninvasive ophthalmic eye drops that can reach the retina. Framework nucleic acids (FNAs), known for their excellent biocompatibility and precise, controllable shape and size, have been extensively utilized in drug delivery application. Here, we report the development of size- and shape-resolved fluorescent DNA frameworks for noninvasive retinal administration. Results show that tetrahedral DNA nanostructures (TDNs) with an edge length of 20 bp can reach the retina within 6 h with the highest efficiency. Moreover, this delivery method exhibits excellent biocompatibility. Our findings provide an approach for the development of localized treatment strategies for retinal diseases using FNA-based nanocarriers.

Effectiveness of carbonic anhydrase inhibitor loaded nanoparticles in the treatment of diabetic retinopathy

Diabetic Retinopathy (DRP) is a disease consisting of all the structural and functional changes that develop in the retinal layer of the eye due to diabetes. DRP is the most important cause of blindness between the ages of 20-74 in the world, and the most successful standard treatment option in the treatment of DRP is intravitreal injections. To synthesize acetazolamide loaded nanoparticles to be applied intravitreal treatment of DRP and to examine thein vitroefficacy of the nanoparticles. ACZ loaded PHBV nanoparticles (PHBV-ACZ NPs) formulations were prepared. Nanoparticles with a particle size of 253.20 ± 0.55 nm. A DRP model was established and characterized in HRMEC cells. The effect of the nanoparticles on permeability has been investigated and carrier proteins in BRB due to the development of DRP has been investigated. To establish thein vitroDRP model, HRMEC was stimulated with Recombinant human 165 Vascular Endothelial Growth Factor (VEGF), thereby temporarily reducing the expression levels of endothelial junction proteins, increasing the number of intercellular spaces in the monolayers of HRMECs. It was determined that after the cells were exposed to Carbonic anhydrase inhibitors (CAI) loaded nanoparticles, permeability decreased and protein expression increased.

Design, optimization, in vitro and in vivo evaluation of triamcinolone acetonide nanocrystals loaded in situ gel for topical ocular delivery

Triamcinolone acetonide (TAA), a long-acting synthetic glucocorticoid, is commonly used for the management of posterior uveitis (PU) because of its anti-inflammatory and immunosuppressive characteristics. The commercially available formulation is in the suspension form advised for intravitreal injection, which has a number of serious problems. In the present research work, we prepared TAA nanocrystals (TAA-NCs) using the principles of design of experiments (DoE). The optimized TAA-NCs had a particle size of 243.0 ± 6.5 nm and a yield (%) of 89.4 ± 4.3%. The optimized TAA-NCs were suspended in a dual-responsive in situ gelling system, which has been previously reported by our team. The TAA-NCs loaded in situ gel (TAA-NC-ISG) formulations were evaluated for rheology, stability, in vitro and in vivo characteristics. The ocular pharmacokinetic investigations revealed that TAA-NCs loaded in situ gel achieved higher concentrations (Cmax of TAA-NC-ISG = 854.9 ng/mL) of the drug in vitreous humor and sustained (MRT0-∞ of TAA-NC-ISG = 11.2 h) the drug concentrations for longer duration compared to aqueous suspension of TAA-NCs (TAA-NC-Susp) and aqueous suspension of TAA with 20% hydroxypropyl β-cyclodextrin(TAA-HP-β-CD-Susp) reported in our previous work. This higher exposure of TAA by TAA-NC-ISG is due to the combined effect of the nanometric size of the TAA nanocrystals and the in situ gelling properties of the formulation.

Experimental and mathematical approaches for drug delivery for the treatment of wet age-related macular degeneration

Several chronic eye diseases affect the posterior segment of the eye. Among them age-related macular degeneration can cause vision loss if left untreated and is one of the leading causes of visual impairment in the world. Most treatments are based on intravitreally injected therapeutics that inhibit the action of vascular endothelial growth factor. However, due to the need for monthly injections, this method is associated with poor patient compliance. To address this problem, numerous drug delivery systems (DDSs) have been developed. This review covers a selection of particulate systems, non-stimuli responsive hydrogels, implants, and composite systems that have been developed in the last few decades. Depending on the type of DDS, polymer material, and preparation method, different mechanical properties and drug release profiles can be achieved. Furthermore, DDS development can be optimized by implementing mathematical modeling of both drug release and pharmacokinetic aspects. Several existing mathematical models for diffusion-controlled, swelling-controlled, and erosion-controlled drug delivery from polymeric systems are summarized. Compartmental and physiologically based models for ocular drug transport and pharmacokinetics that have studied drug concentration profiles after intravitreal delivery or release from a DDS are also reviewed. The coupling of drug release models with ocular pharmacokinetic models can lead to obtaining much more efficient DDSs for the treatment of age-related macular degeneration and other diseases of the posterior segment of the eye.

Ocular pharmacokinetics and toxicity of nanoparticular acetazolamide: In vivo distribution and safety of PHBV-ACZ nanoparticle

Diabetic macular edema (DME) is defined as fluid accumulation in the macular region, between the retinal layers, due to many diseases, especially diabetes. DME is one of the major complications of diabetic retinopathy (DRP). Carbonic anhydrase inhibitors (CAI) are a pharmaceutical agent used in different fields, especially glaucoma treatment. Acetazolamide (ACZ), which is a CAI, is an active substance that has been used off-label for many years in the treatment of macular edema due to diabetes and many other diseases. The low solubility and bioavailability of ACZ limit its use in the treatment of DME. In this study, a nanoparticulate formulation was developed that would increase the solubility and bioavailability of ACZ and allow it to be administered intravitreally. ACZ was loaded on poly(3-hydroxybutyrate-co-3-Hydroxyvalerate) (PHBV) nanoparticles and the loading efficiency was 71.58 ± 1.22%. Toxicity of nanoparticles after intravitreal application was evaluated with anterior segment and posterior segment examination findings, intraocular pressure (IOP) measurements and electrophysiological tests. At the end of the 3-month follow-up, electroretinography (ERG) measurements demonstrated that ACZ loaded PHBV (PHBV-ACZ) nanoparticles did not cause loss of function in retinal cells. On histological examination, rare degenerative changes were observed in several cell groups. In addition, pharmacokinetic studies were performed to determine the tissue distribution of ACZ at various periods. ACZ was identified in vitreous humor and retina at the highest concentration. Based on our results, the prepared nanoparticle formulation can release long-term CAI for DRP therapy and accordingly can reduce the need for monthly intravitreal injections.

Challenges and strategies for ocular posterior diseases therapy via non-invasive advanced drug delivery

Posterior segment diseases, such as age-related macular degeneration (AMD) and diabetic retinopathy (DR) are vital factor that seriously threatens human vision health and quality of life, the treatment of which poses a great challenge to ophthalmologists and ophthalmic scientists. In particular, ocular posterior drug delivery in a non-invasive manner is highly desired but still faces many difficulties such as rapid drug clearance, limited permeability and low drug accumulation at the target site. At present, many novel non-invasive topical ocular drug delivery systems are under development aiming to improve drug delivery efficiency and biocompatibility for better therapy of posterior segment oculopathy. The purpose of this review is to present the challenges in the noninvasive treatment of posterior segment diseases, and to propose strategies to tackle these bottlenecks. First of all, barriers to ocular administration were introduced based on ocular physiological structure and behavior, including analysis and discussion on the influence of ocular structures on noninvasive posterior segment delivery. Thereafter, various routes of posterior drug delivery, both invasive and noninvasive, were illustrated, along with the respective anatomical obstacles that need to be overcome. The widespread and risky application of invasive drug delivery, and the need to develop non-invasive local drug delivery with alternative to injectable therapy were described. Absorption routes through topical administration and strategies to enhance ocular posterior drug delivery were then discussed. As a follow-up, an up-to-date research advances in non-invasive delivery systems for the therapy of ocular fundus lesions were presented, including different nanocarriers, contact lenses, and several other carriers. In conclusion, it seems feasible and promising to treat posterior oculopathy via non-invasive local preparations or in combination with appropriate devices.

Cannabidiol nanoemulsion for eye treatment - Anti-inflammatory, wound healing activity and its bioavailability using in vitro human corneal substitute

Cannabidiol (CBD) is the non-psychoactive component of the plant Cannabis sativa (L.) that has great anti-inflammatory benefits and wound healing effects. However, its high lipophilicity, chemical instability, and extensive metabolism impair its bioavailability and clinical use. Here, we report on the preparation of a human cornea substitute in vitro and validate this substitute for the evaluation of drug penetration. CBD nanoemulsion was developed and evaluated for stability and biological activity. The physicochemical properties of CBD nanoemulsion were maintained during storage for 90 days under room conditions. In the scratch assay, nanoformulation showed significantly ameliorated wound closure rates compared to the control and pure CBD. Due to the lower cytotoxicity of nanoformulated CBD, a higher anti-inflammatory activity was demonstrated. Neither nanoemulsion nor pure CBD can penetrate the cornea after the four-hour apical treatment. For nanoemulsion, 94 % of the initial amount of CBD remained in the apical compartment while only 54 % of the original amount of pure CBD was detected in the apical medium, and 7 % in the cornea, the rest was most likely metabolized. In summary, the nanoemulsion developed in this study enhanced the stability and biological activity of CBD.

The Evolution of Triamcinolone Acetonide Therapeutic Use in Retinal Diseases: From Off-Label Intravitreal Injection to Advanced Nano-Drug Delivery Systems

Ophthalmic drug delivery to the posterior segment of the eye has been challenging due to the complex ocular anatomy. Intravitreal injection of drugs was introduced to deliver therapeutic doses in the posterior segment. Different posterior segment diseases including age-related macular degeneration, diabetic macular edema, retinal vein occlusions, uveitis, and cystoid macular edema, among others, have been historically treated with intravitreal corticosteroids injections, and more recently with intravitreal corticosteroids drug implants. Triamcinolone acetonide (TA) is the most frequently used intraocular synthetic corticosteroid. Using nanoparticle-based TA delivery systems has been proposed as an alternative to intravitreal injections in the treatment of posterior segment diseases. From these novel delivery systems, topical liposomes have been the most promising strategy. This review is oriented to exhibit triamcinolone acetonide drug evolution and its results in treating posterior segment diseases using diverse delivery platforms.

Innovative Strategies for Drug Delivery to the Ocular Posterior Segment

Innovative and new drug delivery systems (DDSs) have recently been developed to vehicle treatments and drugs to the ocular posterior segment and the retina. New formulations and technological developments, such as nanotechnology, novel matrices, and non-traditional treatment strategies, open new perspectives in this field. The aim of this mini-review is to highlight promising strategies reported in the current literature based on innovative routes to overcome the anatomical and physiological barriers of the vitreoretinal structures. The paper also describes the challenges in finding appropriate and pertinent treatments that provide safety and efficacy and the problems related to patient compliance, acceptability, effectiveness, and sustained drug delivery. The clinical application of these experimental approaches can help pave the way for standardizing the use of DDSs in developing enhanced treatment strategies and personalized therapeutic options for ocular pathologies.

Application of organic nanocarriers for intraocular drug delivery

The application of intraocular drug delivery is usually limited due to special anatomical and physiological barriers, and the elimination mechanisms in the eye. Organic nano-drug delivery carriers exhibit excellent adhesion, permeability, targeted modification and controlled release abilities to overcome the obstacles and improve the efficiency of drug delivery and bioavailability. Solid lipid nanoparticles can entrap the active components in the lipid structure to improve the stability of drugs and reduce the production cost. Liposomes can transport hydrophobic or hydrophilic molecules, including small molecules, proteins and nucleic acids. Compared with linear macromolecules, dendrimers have a regular structure and well-defined molecular mass and size, which can precisely control the molecular shape and functional groups. Degradable polymer materials endow nano-delivery systems a variety of size, potential, morphology and other characteristics, which enable controlled release of drugs and are easy to modify with a variety of ligands and functional molecules. Organic biomimetic nanocarriers are highly optimized through evolution of natural particles, showing better biocompatibility and lower toxicity. In this article, we summarize the advantages of organic nanocarriers in overcoming multiple barriers and improving the bioavailability of drugs, and highlight the latest research progresses on the application of organic nanocarriers for treatment of ocular diseases.

Effective Treatment of Haemophilus influenzae-Induced Bacterial Conjunctivitis by a Bioadhesive Nanoparticle Reticulate Structure

Ocular formulations should provide an effective antibiotic concentration at the site of infection to treat bacterial eye infections. However, tears and frequent blinking accelerate the drug clearance rate and limit drug residence time on the ocular surface. This study describes a biological adhesion reticulate structure (BNP/CA-PEG) consisting of antibiotic-loaded bioadhesion nanoparticles (BNP/CA), with an average 500-600 nm diameter, and eight-arm NH₂-PEG-NH₂ for local and extended ocular drug delivery. This retention-prolonging effect is a function of the Schiff base reaction between groups on the surface of BNP and amidogen on PEG. BNP/CA-PEG showed significantly higher adhesion properties and better treatment efficacy in an ocular rat model with conjunctivitis in comparison to non-adhesive nanoparticles, BNP, or free antibiotics. Both in vivo safety experiment and in vitro cytotoxicity test verified the biocompatibility and biosafety of the biological adhesion reticulate structure, indicating a promising translational prospect for further clinical use.

Topical Treatment for Retinal Degenerative Pathologies: A Systematic Review

The topical administration of medicines is the preferred route in ocular therapy, at least for the anterior segment of the eye. However, the eye's inherent functional and biological barriers all work against the active pharmaceutical ingredient (API) to efficiently reach the targeted retinal structures. The main objective of this article is to offer a systematic review of the scientific literature in recent years, focusing on the latest developments of topical treatment intended for retinal degenerative diseases. Database search returned 102 clinical studies, focused on topical treatment for age macular degeneration, macular edemas (in diabetic retinopathy, surgery related or in retinal dystrophies) or glaucoma. After the exclusion of low-powered studies and those combining vitreo-retinal surgery, 35 articles remained for analysis. Currently, the topical treatment of retinal degenerative diseases is limited by the difficulty to deliver effective drug concentrations to the posterior eye structures. However, in the case of drug classes like NSAIDs, the presence of certain molecular and metabolic features for specific representatives makes the topical administration currently feasible in several clinical contexts. For other drug classes, either a fine-tuning of the API's pharmacokinetic profile or the use of more advanced formulation strategies, such as rationally designed nanostructured drugs and vehicles, crystalline polymorphs or supramolecular complexes, could bring the much awaited breakthrough for a more predictable and controlled delivery towards the retinal structures and could eventually be employed in the future for the development of more effective ways of delivering drugs to the posterior eye, with the ultimate goal of improving their clinical efficacy.

Ocular permeability, intraocular biodistribution of lipid nanocapsule formulation intended for retinal drug delivery

Recently, cGMP analogues have been investigated for the treatment of inherited retinal degenerations (IRD) using intravitreal injections. However, higher vitreous elimination rates limit the possibility to treat the retina with small molecule drugs. Here, we investigated the potential of lipid nanocapsules (LNCs) as vehicles to reduce clearance and prolong the delivery of cGMP analogue, CN03 to the retinal photoreceptors. Initially LNCs were investigated for both topical/periocular and intravitreal administration routes. While LNC-mediated drug permeation through the cornea proved to be too low for clinical applications, intravitreal application showed significant promise. Intravitreally administered LNCs containing fluorescent tracer in ex vivo porcine eyes showed complete intravitreal dispersal within 24 h. Ocular bio-distribution on histological sections showed that around 10 % of the LNCs had reached the retina, and 40 % accumulated in the ciliary body. For comparison, we used fluorescently labeled liposomes and these showed a different intraocular distribution with 48 % accumulated in the retina, and almost none were in the ciliary body. LNCs were then tested in retinal explants prepared from wild-type (WT) and rd1 mouse. In WT retina LNCs showed no significant toxic effects up to a concentration of 5 mg/mL. In rd1 retina, the LNC/CN03 formulation protected rd1 photoreceptors with similar efficacy to that of free CN03, demonstrating the usefulness of LNC/CN03 formulation in the treatment of IRD. Overall, our results indicate the suitability of LNCs for intraocular administration and drug delivery to both the retina and the ciliary body.

Intraocular nano-microscale drug delivery systems for glaucoma treatment: design strategies and recent progress

Glaucoma is a leading cause of irreversible visual impairment and blindness, affecting over 76.0 million people worldwide in 2020, with a predicted increase to 111.8 million by 2040. Hypotensive eye drops remain the gold standard for glaucoma treatment, while inadequate patient adherence to medication regimens and poor bioavailability of drugs to target tissues are major obstacles to effective treatment outcomes. Nano/micro-pharmaceuticals, with diverse spectra and abilities, may represent a hope of removing these obstacles. This review describes a set of intraocular nano/micro drug delivery systems involved in glaucoma treatment. Particularly, it investigates the structures, properties, and preclinical evidence supporting the use of these systems in glaucoma, followed by discussing the route of administration, the design of systems, and factors affecting in vivo performance. Finally, it concludes by highlighting the emerging notion as an attractive approach to address the unmet needs for managing glaucoma.

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

Ocular diseases seriously affect patients' vision and life quality, with a global morbidity of over 43 million blindness. However, efficient drug delivery to treat ocular diseases, particularly intraocular disorders, remains a huge challenge due to multiple ocular barriers that significantly affect the ultimate therapeutic efficacy of drugs. Recent advances in nanocarrier technology offer a promising opportunity to overcome these barriers by providing enhanced penetration, increased retention, improved solubility, reduced toxicity, prolonged release, and targeted delivery of the loaded drug to the eyes. This review primarily provides an overview of the progress and contemporary applications of nanocarriers, mainly polymer- and lipid-based nanocarriers, in treating various eye diseases, highlighting their value in achieving efficient ocular drug delivery. Additionally, the review covers the ocular barriers and administration routes, as well as the prospective future developments and challenges in the field of nanocarriers for treating ocular diseases.

Innovation in the Development of Synthetic and Natural Ocular Drug Delivery Systems for Eye Diseases Treatment: Focusing on Drug-Loaded Ocular Inserts, Contacts, and Intraocular Lenses

Nowadays, ocular drug delivery still remains a challenge, since the conventional dosage forms used for anterior and posterior ocular disease treatments, such as topical, systemic, and intraocular administration methods, present important limitations mainly related to the anatomical complexity of the eye. In particular, the blood-ocular barrier along with the corneal barrier, ocular surface, and lacrimal fluid secretion reduce the availability of the administered active compounds and their efficacy. These limitations have increased the need to develop safe and effective ocular delivery systems able to sustain the drug release in the interested ocular segment over time. In the last few years, thanks to the innovations in the materials and technologies employed, different ocular drug delivery systems have been developed. Therefore, this review aims to summarize the synthetic and natural drug-loaded ocular inserts, contacts, and intraocular lenses that have been recently developed, emphasizing the characteristics that make them promising for future ocular clinical applications.

High-Capacity Mesoporous Silica Nanocarriers of siRNA for Applications in Retinal Delivery

The main cause of subretinal neovascularisation in wet age-related macular degeneration (AMD) is an abnormal expression in the retinal pigment epithelium (RPE) of the vascular endothelial growth factor (VEGF). Current approaches for the treatment of AMD present considerable issues that could be overcome by encapsulating anti-VEGF drugs in suitable nanocarriers, thus providing better penetration, higher retention times, and sustained release. In this work, the ability of large pore mesoporous silica nanoparticles (LP-MSNs) to transport and protect nucleic acid molecules is exploited to develop an innovative LP-MSN-based nanosystem for the topical administration of anti-VEGF siRNA molecules to RPE cells. siRNA is loaded into LP-MSN mesopores, while the external surface of the nanodevices is functionalised with polyethylenimine (PEI) chains that allow the controlled release of siRNA and promote endosomal escape to facilitate cytosolic delivery of the cargo. The successful results obtained for VEGF silencing in ARPE-19 RPE cells demonstrate that the designed nanodevice is suitable as an siRNA transporter.

Tailoring surface properties of liposomes for dexamethasone intraocular administration

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

Decorating hexahistidine-metal assemblies with tyrosine enhances the ability of proteins to pass through corneal biobarriers

In recent decades, the use of protein drugs has increased dramatically for almost every clinical indication, including autoimmunity and cancer infection, given their high specificity and limited side effects. However, their easy deactivation by the surrounding microenvironment and limited ability to pass through biological barriers pose large challenges to the use of these agents for therapeutic effects; these deficits could be greatly improved by nanodelivery using platforms with suitable physicochemical properties. Here, to assess the effect of the hydrophilicity of nanoparticles on their ability to penetrate biological barriers, the hydrophobic amino acid tyrosine (Y) was decorated onto hexahistidine peptide, and two nanosized YHmA and HmA particles were generated, in which Avastin (Ava, a protein drug) was encapsulated by a coassembly strategy. In vitro and in vivo tests demonstrated that these nanoparticles effectively retained the bioactivity of Ava and protected Ava from proteinase K hydrolysis. Importantly, YHmA displayed a considerably higher affinity to the ocular surface than HmA, and YHmA also exhibited the ability to transfer proteins across the barriers of the anterior segment, which greatly improved the bioavailability of the encapsulated Ava and produced surprisingly good therapeutic outcomes in a model of corneal neovascularization. STATEMENT OF SIGNIFICANCE: Improving the ability to penetrate tissue barriers and averting inactivation caused by surrounding environments, are the keys to broaden the application of protein drugs. By decorating hydrophobic amino acid, tyrosine (Y), on hexahistidine peptide, YHmA encapsulated protein drug Ava with high efficiency by co-assembly strategy. YHmA displayed promising ability to maintain bioactivity of Ava during encapsulation and delivery, and protected Ava from proteinase K hydrolysis. Importantly, YHmA transferred Ava across the corneal epithelial barrier and greatly improved its bioavailability, producing surprisingly good therapeutic outcomes in a model of corneal neovascularization. Our results contributed to not only the strategy to overcome shortcomings of protein drugs, but also suggestion on hydrophilicity as a nonnegligible factor in nanodrug penetration through biobarriers.

Nanoscale Delivery Systems of Lutein: An Updated Review from a Pharmaceutical Perspective

Carotenoids are natural lipid-soluble pigments that produce yellow to red colors in plants as well as providing bright coloration in vegetables and fruits. Lutein belongs to the xanthophyll subgroup of the carotenoid family, which plays an essential role in photosynthesis and photoprotection in nature. In the human body, lutein, together with its isomer zeaxanthin and its metabolite meso-zeaxanthin, accumulates in the macula of the eye retina, which is responsible for central, high-resolution, and color vision. As a bioactive phytochemical, lutein has essential physiological functions, providing photoprotection against damaging blue light, along with the neutralization of oxidants and the preservation of the structural and functional integrity of cellular membranes. As a potent antioxidant and anti-inflammatory agent, lutein unfortunately has a low bioavailability because of its lipophilicity and a low stability as a result of its conjugated double bonds. In order to enhance lutein stability and bioavailability and achieve its controlled delivery to a target, nanoscale delivery systems, which have great potential for the delivery of bioactive compounds, are starting to be employed. The current review highlights the advantages and innovations associated with incorporating lutein within promising nanoscale delivery systems, such as liposomes, nanoemulsions, polymer nanoparticles, and polymer–lipid hybrid nanoparticles, as well as their unique physiochemical properties.

Targeted drug delivery to the retinal pigment epithelium: Untapped therapeutic potential for retinal diseases

The retinal pigment epithelium (RPE) plays a crucial part in sight-threatening diseases. In this review, we shed light on the pivotal implication of the RPE in age-related macular degeneration, diabetic retinopathy and retinopathy of prematurity; and explain why a paradigm shift toward targeted RPE therapy is needed to efficiently fight these retinal diseases. We provide guidance for the development of RPE-specific nanotherapeutics by giving a comprehensive overview of the possibilities and challenges of drug delivery to the RPE and highlight successful nanotherapeutic approaches targeting the RPE.

Delivery of Hydrophobic Drugs to the Posterior Ocular Region by Gel-in-Water Nanoemulsion

Purpose

The aim of this study was to develop a nanogel emulsion as a minimally invasive, safe, and effective treatment alternative for posterior ocular diseases.

Methods

A gel-in-water (G/W) nanoemulsion was developed by ultrasonication using beeswax as an organogelator. Different physicochemical properties were evaluated along with particle size analysis by dynamic light scattering. In vitro biocompatibility of G/W nanoemulsion using rat hepatocytes and human umbilical vein endothelial cells (HUVECs) and in vivo corneal permeability as eye drops were investigated.

Results

The nanogel emulsion was monodispersed with a polydispersity index and particle diameter of approximately 0.2 and 200 nm, respectively. The zeta potential value of −8.1 mV suggested enhanced stability and improved retinal permeability of nanoparticles. The prepared nanoemulsion was found to be biocompatible with hepatocytes and HUVECs in vitro. Moreover, in vivo study demonstrated high permeability of G/W nanoemulsion to the retinal layer with no ocular irritation.

Conclusions

G/W nanoemulsions have the potential for topical drug delivery in the posterior eye segment with maximum therapeutic efficacy.

Translational Relevance

Organogel nanodispersion is a new concept to deliver hydrophobic drugs to the posterior segment of eyes as a novel drug delivery system.

The dose-dependent effect of a stabilized cannabidiol nanoemulsion on ocular surface inflammation and intraocular pressure

Cannabidiol (CBD) is a phytocannabinoid that has a great clinical therapeutic potential. Few studies have been published on its efficacy in ocular inflammations while its impact on intraocular pressure (IOP), a major risk factor for glaucoma, remains unclear. Moreover, due to its lability and high lipophilicity, its formulation within a prolonged stable topical ophthalmic solution or emulsion able to penetrate the highly selective corneal barrier is challenging. Therefore, various CBD nanoemulsions (NEs) were designed and evaluated for stability in accelerated conditions. Further, the optimal formulation was tested on a murine LPS-induced keratitis inflammation model. Lastly, increasing CBD concentrations were topically applied, for two weeks, on mice eyes, for IOP measurement. CBD NEs exhibited optimal physicochemical characteristics for ocular delivery. A specific antioxidant was required to obtain the stable, final, formulation. In vivo, 0.4 to 1.6% CBD w/v reduced the levels of key inflammatory cytokines, depending on the concentration applied. These concentrations decreased or did not affect the IOP. Our results showed that a well-designed CBD ocular dosage form can be stabilized for an extended shelf life. Furthermore, the significant decrease in inflammatory cytokines levels could be exploited, provided that an adequate therapeutic dosage regimen is identified in humans.

Pharmacological Role of Functionalized Gold Nanoparticles in Disease Applications

Gold has always been regarded as a symbol of nobility, and its shiny golden appearance has always attracted the attention of many people. Gold has good ductility, molecular recognition properties, and good biocompatibility. At present, gold is being used in many fields. When gold particles are as small as several nanometers, their physical and chemical properties vary with their size in nanometers. The surface area of a nano-sized gold surface has a special effect. Therefore, gold nanoparticles can, directly and indirectly, give rise to different biological activities. For example, if the surface of the gold is sulfided. Various substances have a strong chemical reactivity and are easy to combine with sulfhydryl groups; hence, nanogold is often used in biomedical testing, disease diagnosis, and gene detection. Nanogold is easy to bind to proteins, such as antibodies, enzymes, or cytokines. In fact, scientists use nanogold to bind special antibodies, as a tool for targeting cancer cells. Gold nanoparticles are also directly cytotoxic to cancer cells. For diseases caused by inflammation and oxidative damage, gold nanoparticles also have antioxidant and anti-inflammatory effects. Based on these unique properties, gold nanoparticles have become the most widely studied metal nanomaterials. Many recent studies have further demonstrated that gold nanoparticles are beneficial for humans, due to their functional pharmacological properties in a variety of diseases. The content of this review will be the application of gold nanoparticles in treating or diagnosing pressing diseases, such as cancers, retinopathy, neurological diseases, skin disorders, bowel diseases, bone cartilage disorders, cardiovascular diseases, infections, and metabolic syndrome. Gold nanoparticles have shown very obvious therapeutic and application potential.

Periplocin ameliorates mouse age-related meibomian gland dysfunction through up-regulation of Na/K-ATPase via SRC pathway

Age-related meibomian gland dysfunction (MGD) is the main cause of evaporative dry eye disease in an aging population. Decreased meibocyte cell renewal and lipid synthesis are associated with age-related MGD. Here, we found an obvious decline of Ki67, ΔNp63, and Na+/K+ ATPase expression in aged meibomian glands. Potential Na+/K+ ATPase agonist periplocin, a naturally occurring compound extracted from the traditional herbal medicine cortex periplocae, could promote the proliferation and stem cell activity of meibocyte cells in vitro. Moreover, we observed that periplocin treatment effectively increased the expression of Na+ /K+ ATPase, accompanied with the enhanced expression of Ki67 and ΔNp63 in aged meibomian glands, indicating that periplocin may accelerate meibocyte cell renewal in aged mice. LipidTox staining showed increased lipid accumulation after periplocin treatment in cultured meibomian gland cells and aged meibomian glands. Furthermore, we demonstrated that the SRC pathway was inhibited in aged meibomian glands; however, it was activated by periplocin. Accordingly, the inhibition of the SRC signaling pathway by saracatinib blocked periplocin-induced proliferation and lipid accumulation in meibomian gland cells. In sum, we suggest periplocin-ameliorated meibocyte cell renewal and lipid synthesis in aged meibomian glands via the SRC pathway, which could be a promising candidate for age-related MGD.

Microneedle scleral patch for minimally invasive delivery of triamcinolone to the posterior segment of eye

The delivery of therapeutics to the posterior segment of the eye is achieved by invasive procedures, including intravitreal injections and implants. The topically applied formulations would not permeate through different tissue barriers of the eye to reach the posterior segment. Here, we demonstrate the effectiveness of microneedle scleral patch in delivering the model molecule, triamcinolone acetonide, to the posterior segment of the eye. Microneedle scleral patch (MSP) and microneedle corneal patch (MCP) were fabricated through the micromolding technique using rapidly dissolvable polyvinylpyrrolidone. The patches containing 25 microneedles were characterized for physical and mechanical properties, drug loading and release behavior in vitro and ex vivo porcine eye globe model. The distribution of TA administered using MSP and MCP in different ocular tissues was evaluated in the rabbit eye model. The results showed that microneedles with 545 ± 8 µm length and 279 ± 26 µm width at the base in MSP penetrate the scleral membrane with the application of 0.35 ± 0.06 N force. The needles dissolved within 60 s after insertion in the corneal and scleral tissue. The 5 min application of MSP showed a significantly (p < 0.05) greater TA disposition in the vitreous humor and choroid-retinal complex in excised porcine eye globe compared with MCP and TA nanosuspension eye drops. In rabbit model studies, the TA concentration was greatest in the choroid-retinal complex and sclera after administration through intravitreal injection and MSP, respectively. The TA disposition in the sclera was significantly (p < 0.05) greater after MSP application compared with intravitreal injection and MCP application for up to 24 h. MSP application provided a greater safety score compared with intravitreal injection. In conclusion, MSP can be developed as a minimally invasive drug delivery system to target the posterior segment of the eye.

Topical drug delivery to the retina: obstacles and routes to success

INTRODUCTION

Retinal diseases are one of the main reasons for vision loss where all available drug treatments are based on invasive drug administration such as intravitreal injections. Despite huge efforts and some promising results in animal models, almost all delivery technologies tested have failed in human trials. There are however examples of clinically effective topical delivery systems such as fast dissolving aqueous eye drop suspensions.

AREAS COVERED

Six obstacles to topical drug delivery to the eye have been identified and discussed in some details. These obstacles consist of static membrane barriers to drug permeation into the eye, dynamic barriers such as the lacrimal drainage and physiochemical barriers such as low thermodynamic activity. It is explained how and why these obstacles hamper drug permeation and how different technologies, both those that are applied in marketed drug products and those that are under investigation, have addressed these obstacles.

EXPERT OPINION

The reason that most topical drug delivery systems have failed to deliver therapeutic drug concentrations to the retina is that they do not address physiochemical barriers such as the thermodynamic activity of the permeating drug molecules. Topical drug delivery to the retina has only been successful when the static, dynamic, and physiochemical barriers are addressed simultaneously.

Anti-aging properties of phytoconstituents and phyto-nanoemulsions and their application in managing aging-related diseases

Aging is spontaneous and inevitable process in all living beings. It is a complex natural phenomenon that manifests as a gradual decline of physiological functions and homeostasis. Aging inevitably leads to age-associated injuries, diseases, and eventually death. The research on aging-associated diseases aimed at delaying, preventing or even reversing the aging process are of great significance for healthy aging and also for scientific progress. Numerous plant-derived compounds have anti-aging effects, but their therapeutic potential is limited due to their short shelf-life and low bioavailability. As the novel delivery system, nanoemulsion can effectively improve this defect. Nanoemulsions enhance the delivery of drugs to the target site, maintain the plasma concentration for a longer period, and minimize adverse reaction and side effects. This review describes the importance of nanoemulsions for the delivery of phyto-derived compounds and highlights the importance of nanoemulsions in the treatment of aging-related diseases. It also covers the methods of preparation, fate and safety of nanoemulsions, which will provide valuable information for the development of new strategies in treatment of aging-related diseases.

A Long-Acting Curcumin Nanoparticle/In Situ Hydrogel Composite for the Treatment of Uveal Melanoma

Uveal melanoma (UM) is the most common primary intraocular tumor in adults with high mortality. In order to improve prognosis and survival of UM patients, it is critical to inhibit tumor progression and metastasis as early as possible after the initial presentation/diagnosis of the disease. Sustained local delivery of antitumor therapeutics in the posterior region can potentially achieve long-term UM inhibition, improve target therapeutic delivery to the posterior segments, as well as reduce injection frequency and hence improved patient compliance. To address the highly unmet medical need in UM therapy, a bioinspired in situ gelling hydrogel system composed of naturally occurring biopolymers collagen and hyaluronic acid was developed in the present research. Curcumin with anti-cancer progression, anti-metastasis effects, and good ocular safety was chosen as the model therapeutic. The developed in situ gelling delivery system gelled at 37 °C within two minutes and demonstrated excellent biocompatibility and slow degradation. The curcumin-loaded nanoparticle/hydrogel composite was able to sustain release payload for up to four weeks. The optimized nanoparticle/hydrogel composite showed effective inhibition of human UM cell proliferation. This novel nanoparticle/in situ hydrogel composite demonstrated a great potential for the treatment of the rare and devastating intraocular cancer.

Emerging Applications of Nanotechnology in Healthcare Systems: Grand Challenges and Perspectives

Healthcare, as a basic human right, has often become the focus of the development of innovative technologies. Technological progress has significantly contributed to the provision of high-quality, on-time, acceptable, and affordable healthcare. Advancements in nanoscience have led to the emergence of a new generation of nanostructures. Each of them has a unique set of properties that account for their astonishing applications. Since its inception, nanotechnology has continuously affected healthcare and has exerted a tremendous influence on its transformation, contributing to better outcomes. In the last two decades, the world has seen nanotechnology taking steps towards its omnipresence and the process has been accelerated by extensive research in various healthcare sectors. The inclusion of nanotechnology and its allied nanocarriers/nanosystems in medicine is known as nanomedicine, a field that has brought about numerous benefits in disease prevention, diagnosis, and treatment. Various nanosystems have been found to be better candidates for theranostic purposes, in contrast to conventional ones. This review paper will shed light on medically significant nanosystems, as well as their applications and limitations in areas such as gene therapy, targeted drug delivery, and in the treatment of cancer and various genetic diseases. Although nanotechnology holds immense potential, it is yet to be exploited. More efforts need to be directed to overcome these limitations and make full use of its potential in order to revolutionize the healthcare sector in near future.

Lipid-Based Nanocarriers as Topical Drug Delivery Systems for Intraocular Diseases

Effective drug delivery to intraocular tissues remains a great challenge due to complex anatomical and physiological barriers that selectively limit the entry of drugs into the eye. To overcome these challenges, frequent topical application and regular intravitreal injections are currently used to achieve the desired drug concentrations into the eye. However, the repetitive installation or recurrent injections may result in several side effects. Recent advancements in the field of nanoparticle-based drug delivery have demonstrated promising results for topical ophthalmic nanotherapies in the treatment of intraocular diseases. Studies have revealed that nanocarriers enhance the intraocular half-life and bioavailability of several therapies including proteins, peptides and genetic material. Amongst the array of nanoparticles available nowadays, lipid-based nanosystems have shown an increased efficiency and feasibility in topical formulations, making them an important target for constant and thorough research in both preclinical and clinical practice. In this review, we will cover the promising lipid-based nanocarriers used in topical ophthalmic formulations for intraocular drug delivery.

The utility and risks of therapeutic nanotechnology in the retina

The clinical application of nanotechnology in medicine is promising for therapeutic, diagnostic, and surgical improvements in the near future. Nanotechnologies in nano-ophthalmology are in the early stages of application in clinical contexts, including ocular drug and gene delivery systems addressing eye disorders, particularly retinopathies. Retinal diseases are challenging to treat as current interventions, such as intravitreal injections, are limited by their invasive nature. This review examines nanotechnological approaches to retinal diseases in a clinical context. Nanotechnology has the potential to transform pharmacological and surgical interventions by overcoming limitations posed by the protective anatomical and physiological barriers that limit access to the retina. Preclinical research in the application of nanoparticles in diagnostics indicates that nanoparticles can enhance existing diagnostic and screening tools to detect diseases earlier and more easily and improve disease progression monitoring precision.

Injectable bio-responsive hydrogel for therapy of inflammation related eyelid diseases

Eyelid plays a vital role in protecting the eye from injury or infection. Inflammation related eyelid diseases, such as blepharitis, are the most common ocular disorders that affect human's vision and quality of life. Due to the physiological barriers and anatomical structures of the eye, the bioavailability of topical administrated therapeutics is typically less than 5%. Herein, we developed a bio-responsive hydrogel drug delivery system using a generally recognized as safe compound, triglycerol monostearate (TG-18), for in-situ eyelid injection with sustained therapeutics release. In vitro, drug release and disassembly time of Rosiglitazone loaded hydrogel (Rosi-hydrogel) were estimated in the presence or absence of MMP-9, respectively. Moreover, the disassembly of TG-18 hydrogel was evaluated with 9-month-old and 12-month-old mice in vivo. Owing to the bio-responsive nature of Rosi-hydrogel, the on-demand Rosiglitazone release is achieved in response to local enzymes. These findings are proved by further evaluation in the age-related meibomian gland dysfunction mice model, and the bio-responsive hydrogel is used as an in-situ injection to treat eyelid diseases. Taken together, the in-situ eyelid injection with sustained drug release opens a window for the therapy of inflammation related eyelid diseases.

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This study is the first application of injectable bio-responsive hydrogel for therapy of inflammation related eyelid diseases.

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The enzyme response characteristic is extremely suitable for enhancing drug bioavailability in ocular drug delivery.

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In-situ release of rosiglitazone can effectively treat age-related meibomian gland dysfunction in the mice model.

Lipo-PEG nano-ocular formulation successfully encapsulates hydrophilic fluconazole and traverses corneal and non-corneal path to reach posterior eye segment

The present study describes a special lipid-polyethylene glycol matrix solid lipid nanoparticles (SLNs; 138 nm; -2.07 mV) for ocular delivery. Success of this matrix to encapsulate (entrapment efficiency - 62.09%) a hydrophilic drug, fluconazole (FCZ-SLNs), with no burst release (67% release in 24 h) usually observed with most water-soluble drugs, is described presently. The system showed 164.64% higher flux than the marketed drops (Zocon^®) through porcine cornea. Encapsulation within SLNs and slow release did not compromise efficacy of FCZ-SLNs. Latter showed in vitro and in vivo antifungal effects, including antibiofilm effects comparable to free FCZ solution. Developed system was safe and stable (even to sterilisation by autoclaving); and showed optimal viscosity, refractive index and osmotic pressure. These SLNs could reach up to retina following application as drops. The mechanism of transport via corneal and non-corneal transcellular pathways is described by fluorescent and TEM images of mice eye cross sections. Particles streamed through the vitreous, crossed inner limiting membrane and reached the outer retinal layers.