Nanotechnology approaches for ocular drug delivery

Modern Therapeutic Approaches for Noninfectious Ocular Diseases Involving Inflammation

Dry eye disease, age-related macular degeneration, and uveitis are ocular diseases that significantly affect the quality of life of millions of people each year. In these diseases, the action of chemokines, proinflammatory cytokines, and immune cells drives a local inflammatory response that results in ocular tissue damage. Multiple therapeutic strategies are developed to either address the symptoms or abate the underlying cause of these diseases. Herein, the challenges to deliver drugs to the relevant location in the eye for each of these diseases are reviewed along with current and innovative therapeutic approaches that attempt to restore homeostasis within the ocular microenvironment.

Nanogel-based natural polymers as smart carriers for the controlled delivery of Timolol Maleate through the cornea for glaucoma

Despite frequent scientific efforts, efficient ocular drug delivery is a major challenge for pharmaceutical scientists. Poor bioavailability of ophthalmic solutions can be overcome by using smart ophthalmic drug-delivery systems. In this research, loading and delivery of Timolol Maleate (TM) through the cornea by synthesized nanoparticles based on biopolymers (chitosan-alginate) were studied. The physico-chemical properties of these nanoparticles were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and dynamic light scattering (DLS). Loading and release were evaluated by a UV-vis spectrometer and the ex vivo permeation study was carried out using the Franz Diffusion Cell and fluorescent microscopy studies. The results indicated that morphology and size of nanoparticles were spherical and in the range of 80-100nm. The loading capacity and encapsulation efficiency were about 42% and 94% respectively. They illustrated a burst release in the first hour followed by a slower and more sustained drug release during the next 24h. Also, the results indicated that the cornea penetration of TM loaded in nanoparticles was twice than that of TM. Hence, this nanocarrier can be considered as a suitable candidate for controlled TM delivery and release through the cornea.

Efficacy of biogenic silver nanoparticles against clinical isolates of fungi causing mycotic keratitis in humans

Mycotic keratitis is mainly responsible for vision loss caused by various fungi. Sometimes, proper treatment of such infection is not possible due to unavailability of effective antifungal agents and development of resistance of such fungi to antimycotic drugs. Hence, it is necessary to search for potential antifungal agents, which can effectively eradicate fungal infection of eyes. Nanoparticles‐based antifungal drugs overcome this problem by increasing permeability and properties of drug molecules. In the present study, silver nanoparticles were synthesised by using Helminthosporium sp. and Chaetomium sp. following sequential reduction technique. The synthesised silver nanoparticles were detected primarily by UV‐visible spectrophotometer showing absorption spectra at 424 and 433 nm, respectively. Nanoparticles tracking analysis confirmed the mean particle size of silver nanoparticles as 45 and 55 nm. The synthesised AgNPs showed significant antifungal activity against fungi causing mycotic keratitis, when used alone and in combination with ketoconazole and amphotericin B in the range of 30–70 microgram per millilitre of minimum inhibitory concentration. Thus, the synthesised AgNPs can be used to enhance the activities of ketoconazole and amphotericin B.

Subconjunctival injectable dendrimer-dexamethasone gel for the treatment of corneal inflammation

Corneal inflammation is often encountered as a key pathological event in many corneal diseases. Current treatments involve topical corticosteroids which require frequent instillations due to rapid tear turnover, causing side-effects such as corneal toxicity and elevated intraocular pressure (IOP). Hence, new interventions that can reduce side effects, dosing frequency, and increase patient compliance can be highly beneficial. In this study, we explore a subconjunctival injectable gel based on G4-PAMAM dendrimer and hyaluronic acid, cross-linked using thiol-ene click chemistry, incorporated with dendrimer dexamethasone (D-Dex) conjugates as a potential strategy for sustained delivery and enhanced bioavailability of corticosteroids. The efficacy of the injectable gel formulation was evaluated in a rat mild alkali burn model. Fluorescently-labelled dendrimers (D-Cy5) incorporated in the gel release D-Cy5 in vivo. The released D-Cy5 selectively targets and localizes within corneal macrophages in inflamed rat cornea but not in healthy controls. This pathology dependent biodistribution was exploited for drug delivery, by incorporating D-Dex in the injectable gel. The attenuation of corneal inflammation by D-Dex gels was assessed using various clinical and biochemical parameters over a 2-week period. Subconjunctival D-Dex gel treatment resulted in favorable clinically-relevant outcomes with reduced central corneal thickness and improved corneal clarity compared to free-Dex and placebo gel controls. The extent of corneal neovascularization was significantly reduced in the D-Dex group. These findings suggest that D-Dex attenuates corneal inflammation more effectively than free-Dex by attenuating macrophage infiltration and pro-inflammatory cytokines expression. A significant elevation in IOP was not observed in the D-Dex group but was observed in the free-Dex group. This novel injectable D-Dex gel may be a potential drug delivery platform for the treatment of many inflammatory ocular surface disorders such as dry eye, auto-immune keratitis and post-surgical complications where frequent steroid administration is required.

Potential of CeCl3@mSiO2 nanoparticles in alleviating diabetic cataract development and progression

Cataract is a major cause of visual impairment for diabetic patients. It is imperative to develop efficient therapeutic agents against diabetic cataract (DC) because diabetes confers higher risk for complications after cataract surgery. We have previously reported the role of CeCl₃ loaded mesoporous silica (CeCl₃@mSiO₂) nanoparticles in reducing the oxidative stress of lens epithelial cells. However, the potential of CeCl₃@mSiO₂ in preventing diabetic cataract development remains unclear. In this study, we applied CeCl₃@mSiO₂ nanoparticles with a size of 87.6±8.9nm to streptozotocin-induced diabetic cataract rat model by intraperitoneal injection. Our results showed that CeCl₃@mSiO₂ efficiently ameliorated the progression of DC. Consistent with antioxidant effect of CeCl₃@mSiO₂in vitro, administration of CeCl₃@mSiO₂ significantly abrogated hyperglycemia-mediated upregulation of advanced glycation end products, lipid peroxidation and protein carbonylation in animal lens. Taken together, our study provides a potential nanodrug to manage the development of DC.

Two-dimensional transition metal dichalcogenide nanomaterials for combination cancer therapy

In this review, we mainly summarize the latest advances in the utilization of 2D TMDCs for PTT combination cancer therapy and imaging-guided cancer combination therapy, as well as their toxicity bothin vitroandin vivo.

PLGA nanoparticles for intravitreal peptide delivery: statistical optimization, characterization and toxicity evaluation

Frequent intravitreal injections are currently used to overcome the ocular barriers and provide sufficient drug to the posterior eye segment. However, intravitreal injections have been associated with a number of complications and high treatment costs. To overcome these limitations, peptide-loaded poly(d,l-lactic-co-glycolic acid) nanoparticles (PLGA NPs) were developed using the nanoprecipitation technique and were optimized via Box-Behnken Design (BBD) and Response Surface Methodology (RSM). Developed NPs were evaluated for potential toxicity and cell apoptosis using the zebrafish embryo toxicity (ZET) model with titanium dioxide NPs and ethanol (1% v/v) serving as positive controls. Developed NPs had a size of 75.6-153.8 nm, a polydispersity index between 0.11 and 0.25 and a zeta potential of -9.4 to -46.0 mV. Loaded peptide was found to be stable under various experimental conditions tested. BBD and RSM were validated through the characterization of optimized formulations. Survival and hatching rates of NP-treated zebrafish 0-144 h post-fertilization were found to be normal with no significant malformations. Cellular apoptosis studies also endorsed the non-cytotoxic nature of the NPs. The overall results indicate that optimized PLGA nanoparticles could be a promising platform for efficient peptide delivery to the posterior segment of the eye.

Dendrimers as a promising tool in ocular therapeutics: Latest advances and perspectives

Dendrimers have called the attention of scientists in the area of drug and gene delivery over the last two decades for their versatility, complexity and multibranching properties. Some strategies for optimizing drug pharmacokinetics and site-specific targeting using dendrimers have been proposed. Among them, those related to treating and managing ocular diseases are of special interest. Ocular therapies suffer from significant disadvantages, including frequent administration, poor penetration and/or rapid elimination. This review provides an overview of the recent and promising progress in the dendrimers field, focusing on both the anterior and posterior segments of the eye ocular targets, the use of dendrimers as a strategy for overcoming obstacles to the traditional treatment of ocular diseases and an outlook on future directions. Finally, a first approach to ocular safety with dendrimers is intended that accounts for the state-of-the-art science to date.

Therapeutic effect of apatinib-loaded nanoparticles on diabetes-induced retinal vascular leakage

Apatinib, a novel and selective inhibitor of vascular endothelial growth factor (VEGF) receptor 2, has been demonstrated recently to exhibit anticancer efficacy by inhibiting the VEGF signaling pathway. Given the importance of VEGF in retinal vascular leakage, the present study was designed to investigate whether apatinib-loaded polymeric nanoparticles inhibit VEGF-mediated retinal vascular hyperpermeability and block diabetes-induced retinal vascular leakage. For the delivery of water-insoluble apatinib, the drug was encapsulated in nanoparticles composed of human serum albumin (HSA)-conjugated polyethylene glycol (PEG). In vitro paracellular permeability and transendothelial electric resistance assays showed that apatinib-loaded HSA-PEG (Apa-HSA-PEG) nanoparticles significantly inhibited VEGF-induced endothelial hyperpermeability in human retinal microvascular endothelial cells. In addition, they substantially reduced the VEGF-induced junctional loss and internalization of vascular endothelial-cadherin, a major component of endothelial junction complexes. In vivo intravitreal injection of Apa-HSA-PEG nanoparticles in mice blocked VEGF-induced retinal vascular leakage. These in vitro and in vivo data indicated that Apa-HSA-PEG nanoparticles efficiently blocked VEGF-induced breakdown of the blood–retinal barrier. In vivo experiments with streptozotocin-induced diabetic mice showed that an intravitreal injection of Apa-HSA-PEG nanoparticles substantially inhibited diabetes-induced retinal vascular leakage. These results demonstrated, for the first time, that apatinib-loaded nanoparticles may be a promising therapeutic agent for the prevention and treatment of diabetes-induced retinal vascular disorders.

Facets of Nanotechnology as Seen in Food Processing, Packaging, and Preservation Industry

Nanotechnology has proven its competence in almost all possible fields we are aware of. However, today nanotechnology has evolved in true sense by contributing to a very large extent to the food industry. With the growing number of mouths to feed, production of food is not adequate. It has to be preserved in order to reach to the masses on a global scale. Nanotechnology made the idea a reality by increasing the shelf life of different kinds of food materials. It is not an entirely full-proof measure; however it has brought down the extent of wastage of food due to microbial infestation. Not only fresh food but also healthier food is being designed with the help of nano-delivery systems which act as a carrier for the food supplements. There are regulations to follow however as several of them pose serious threats to the wellbeing of the population. In coming days, newer modes of safeguarding food are going to be developed with the help of nanotechnology. In this paper, an overview has been given of the different methods of food processing, packaging, and preservation techniques and the role nanotechnology plays in the food processing, packaging, and preservation industry.

The role of nanotechnology in control of human diseases: perspectives in ocular surface diseases

Nanotechnology is the creation and use of materials and devices on the same scale as molecules and intracellular structures, typically less than 100 nm in size. It is an emerging science and has made its way into pharmaceuticals to significantly improve the delivery and efficacy of drugs in a number of therapeutic areas, due to development of various nanoparticle-based products. In recent years, there has been increasing evidence that nanotechnology can help to overcome many of the ocular diseases and hence researchers are keenly interested in this science. Nanomedicines offer promise as viable alternatives to conventional drops, gels or ointments to improve drug delivery to the eye. Because of their small size, they are well tolerated, thus preventing washout, increase bioavailability and also help in specific drug delivery. This review describes the application of nanotechnology in the control of human diseases with special emphasis on various eye and ocular surfaces diseases.

Nanoengineering of therapeutics for retinal vascular disease

Retinal vascular diseases, including diabetic retinopathy, neovascular age related macular degeneration, and retinal vein occlusion, are leading causes of blindness in the Western world. These diseases share several common disease mechanisms, including vascular endothelial growth factor (VEGF) signaling, hypoxia, and inflammation, which provide opportunities for common therapeutic strategies. Treatment of these diseases using laser therapy, anti-VEGF injections, and/or steroids has significantly improved clinical outcomes. However, these strategies do not address the underlying root causes of pathology, and may have deleterious side effects. Furthermore, many patients continue to progress toward legal blindness despite receiving regular therapy. Nanomedicine, the engineering of therapeutics at the 1-100 nm scale, is a promising approach for improving clinical management of retinal vascular diseases. Nanomedicine-based technologies have the potential to revolutionize the treatment of ophthalmology, through enabling sustained release of drugs over several months, reducing side effects due to specific targeting of dysfunctional cells, and interfacing with currently "undruggable" targets. We will discuss emerging nanomedicine-based applications for the treatment of complications associated with retinal vascular diseases, including angiogenesis and inflammation.

Corticosteroid-loaded biodegradable nanoparticles for prevention of corneal allograft rejection in rats

Immunologic graft rejection is one of the main causes of short and long-term graft failure in corneal transplantation. Steroids are the most commonly used immunosuppressive agents for postoperative management and prevention of corneal graft rejection. However, steroids delivered in eye drops are rapidly cleared from the surface of the eye, so the required frequency of dosing for corneal graft rejection management can be as high as once every 2h. Additionally, these eye drops are often prescribed for daily use for 1 year or longer, which can result in poor patient compliance and steroid-related side effects. Here, we report a biodegradable nanoparticle system composed of Generally Regarded as Safe (GRAS) materials that can provide sustained release of corticosteroids to prevent corneal graft rejection following subconjunctival injection provided initially during transplant surgery. Poly(lactic-co-glycolic acid) (PLGA) nanoparticles containing dexamethasone sodium phosphate (DSP) exhibited a size of 200 nm, 8 wt.% drug loading, and sustained drug release over 15 days in vitro under sink conditions. DSP-loaded nanoparticles provided sustained ocular drug levels for at least 7 days after subconjunctival administration in rats, and prevented corneal allograft rejection over the entire 9-week study when administered weekly. In contrast, control treatment groups that received weekly injections of either placebo nanoparticles, saline, or DSP in solution demonstrated corneal graft rejection accompanied by severe corneal edema, neovascularization and opacity that occurred in ≤ 4 weeks. Local controlled release of corticosteroids may reduce the rate of corneal graft rejection, perhaps especially in the days immediately following surgery when risk of rejection is highest and when typical steroid eye drop administration requirements are particularly onerous.

Current nanotechnology approaches for the treatment and management of diabetic retinopathy

Diabetic retinopathy (DR) is a consequence of diabetes mellitus at the ocular level, leading to vision loss, and contributing to the decrease of patient's life quality. The biochemical and anatomic abnormalities that occur in DR are discussed in this review to better understand and manage the development of new therapeutic strategies. The use of new drug delivery systems based on nanoparticles (e.g. liposomes, dendrimers, cationic nanoemulsions, lipid and polymeric nanoparticles) is discussed along with the current traditional treatments, pointing out the advantages of the proposed nanomedicines to target this ocular disease. Despite the multifactorial nature of DR, which is not entirely understood, some strategies based on nanoparticles are being exploited for a more efficient drug delivery to the posterior segment of the eye. On the other hand, the use of some nanoparticles also seems to contribute to the development of DR symptoms (e.g. retinal neovascularization), which are also discussed in light of an efficient management of this ocular chronic disease.

Conducting polymer nanoparticles decorated with collagen mimetic peptides for collagen targeting

We report on the formation of conducting polymer nanoparticles (CPNs), stabilized by a collagen mimetic peptide (CMP)-polymer amphiphile. CPNs ranging from ∼15 to 40 nm were readily accessible upon modifying the amphiphile concentration. Surface presentation of CMPs on CPN precluded intra-/inter-particle trimerization, while preserving their ability to target collagen without pre-activation.

Drug targeting using solid lipid nanoparticles

The present review aims to show the features of solid lipid nanoparticles (SLNs) which are at the forefront of the rapidly developing field of nanotechnology with several potential applications in drug delivery and research. Because of some unique features of SLNs such as their unique size dependent properties it offers possibility to develop new therapeutics. A common denominator of all these SLN-based platforms is to deliver drugs into specific tissues or cells in a pathological setting with minimal adverse effects on bystander cells. SLNs are capable to incorporate drugs into nanocarriers which lead to a new prototype in drug delivery which maybe used for drug targeting. Hence solid lipid nanoparticles hold great promise for reaching the goal of controlled and site specific drug delivery and hence attracted wide attention of researchers. This review presents a broad treatment of targeted solid lipid nanoparticles discussing their types such as antibody SLN, magnetic SLN, pH sensitive SLN and cationic SLN.

Cyclosporine A Loaded PLGA Nanoparticles for Dry Eye Disease:In VitroCharacterization Studies

Dry eye disease is a common disease of the tear film caused by decreased tear production or increased evaporation. The objective of this study was to develop and evaluate poly (dl-lactide-co-glycolide) (PLGA) nanoparticles for CsA (CsA) ophthalmic delivery, for the treatment of dry eye disease. Topical CsA is currently the only and safe pharmacologic treatment of severe dry eye symptoms. Nanoparticles (NPs) were prepared by W/O solvent evaporation technique followed by probe sonicator and characterized for various properties such as particle size, entrapment efficiency, zeta potential,in vitrodrug release,in vitropermeation studies by Franz diffusion cells, XRD, DSC, SEM, and stability studies. The developed nanosuspension showed a mean particle size in the range from 128 to 253.50 nm before freeze drying and after freeze drying 145.60 to 260.0 nm. The drug entrapment efficiency was from 58.35 to 95.69% and production yield was found between52.29±2.4and85.30±2.1% in all preparations. The zeta potential of the Eudragit RL containing nanoparticles was positive, that is, 20.3 mV to 34.5 mV. The NPs formulations exhibited a biphasic drug release with initial burst followed by a very slow drug release and total cumulative release up to 24 h ranged from 69.83 to 91.92%. Kinetically, the release profiles of CsA from NPs appeared to fit best with the Higuchi model. The change of surface characteristics of NPs represents a useful approach for improvement of ocular retention and drug availability.

Nanomedicine in cerebral palsy

Cerebral palsy is a chronic childhood disorder that can have diverse etiologies. Injury to the developing brain that occurs either in utero or soon after birth can result in the motor, sensory, and cognitive deficits seen in cerebral palsy. Although the etiologies for cerebral palsy are variable, neuroinflammation plays a key role in the pathophysiology of the brain injury irrespective of the etiology. Currently, there is no effective cure for cerebral palsy. Nanomedicine offers a new frontier in the development of therapies for prevention and treatment of brain injury resulting in cerebral palsy. Nanomaterials such as dendrimers provide opportunities for the targeted delivery of multiple drugs that can mitigate several pathways involved in injury and can be delivered specifically to the cells that are responsible for neuroinflammation and injury. These materials also offer the opportunity to deliver agents that would promote repair and regeneration in the brain, resulting not only in attenuation of injury, but also enabling normal growth. In this review, the current advances in nanotechnology for treatment of brain injury are discussed with specific relevance to cerebral palsy. Future directions that would facilitate clinical translation in neonates and children are also addressed.

Efficacy and safety of dendrimer nanoparticles with coexpression of tumor necrosis factor-α and herpes simplex virus thymidine kinase in gene radiotherapy of the human uveal melanoma OCM-1 cell line

Human uveal melanoma is the most common primary intraocular tumor, and brachytherapy is one of the most common and effective treatment strategies. In order to find a safer and more effective way to increase the radio sensitivity of the tumor, we tried to use the dendrimer nanoparticle performing coexpression gene radiotherapy. In this study, we constructed recombinant DNA plasmids (early growth response-1 tumor necrosis factor-α [pEgr1-TNFα], pEgr1 thymidine kinase [TK], and pEgr1-TNFα-TK) according to the Egr1 promoter sequence. The sequences of human TNFα and herpes simplex virus (HSV) TK that were published by GenBank. Agarose gel electrophoresis and DNA sequencing had proven that we constructed the double-gene recombined plasmids pEgr1-TNF-TK correctly, as well as the plasmids pEgr1-TNFα and pEgr1-TK. The dendrimer nanoparticles combined with plasmid DNA as dendriplexes were verified with agarose gel electrophoresis and observed by transmission electron microscopy (TEM) and scanning electron microscopy to define size and shape. Zeta potential was measured using a Zetasizer analyzer. Optimal size and neutral zeta-potential characteristics of dendriplexes were achieved for the transfection studies. DNase I examination proved that the dendriplexes could protect plasmid DNA for at least 6 hours. The recombinant plasmids were transfected with dendrimer nanoparticles into the human choroidal melanoma OCM-1 cell line, followed by exposure to iodine-125 ((125)I) after transfection. After transfection with dendrimer nanoparticles and the irradiation of (125)I, the gene expressions of TNFα and HSV1-TK were significantly increased at the protein level by enzyme-linked immunosorbent assay and Western blot analysis in OCM-1 cells. The cellular morphology of OCM-1 cells altering was observed by TEM, and a decrease in cell proliferation was revealed in cell-growth curves. Flow cytometry of annexin V/propidium iodide double-dyeing apoptosis and caspase-3 fluorescence staining showed that this treatment method could turn transfected OCM-1 cells into apoptosis and necrosis by the effects of the gene expression. This study indicated that the dendrimer nanoparticles with coexpression of TNF-α and HSV1-TK gene therapy are effective and safe and can provide us with a novel strategy to treat human uveal melanoma in the future.