Sustained Release of Brimonidine from a New Composite Drug Delivery System for Treatment of Glaucoma

Emerging trends in long-acting sustained drug delivery for glaucoma management

Glaucoma is an optic neuropathy in which progressive degeneration of retinal ganglion cells and the optic nerve leads to irreversible visual loss. Glaucoma is one of the leading causes of blindness. The pathogenesis of glaucoma is determined by different pathogenetic mechanisms, including increased intraocular pressure, mechanical stress, excitotoxicity, resistance to aqueous drainage and oxidative stress. Topical formulations are often used in glaucoma treatment, whereas surgical measures are used in acute glaucoma cases. For most patients, long-term glaucoma treatments are given. Poor patient compliance and low bioavailability are often associated with topical therapy, which suggests that sustained-release, long-acting drug delivery systems could be beneficial in managing glaucoma. This review summarizes the eye's physiology, the pathogenesis of glaucoma, current treatments, including both pharmacological and nonpharmacological interventions, and recent advances in long-acting drug delivery systems for the treatment of glaucoma.

Treatment of glaucoma with drug-loaded contact lenses: A systematic review and meta-analysis

OBJECTIVE

This study is a systematical review regarding the glaucoma treatment with drug-loaded contact lenses. The effectiveness and safety about that were summarized, which providing effective suggestions and guidance for clinical research.

METHODS

The studies published up to May 1, 2024 on the treatment of glaucoma with sustained-release contact lenses were searched from CNKI, Wanfang Data, VIP, PubMed, Embase, Cochrane Library, and Medline. CAMARADES was used to evaluate literature quality. The safety, endpoints of intraocular pressure reduction (IOPR) and duration of intraocular pressure (IOP) decline during glaucoma treatment were analyzed by means of qualitative and quantitative methods. The protocol registration number is CRD42024487157.

RESULTS

47 studies were included. In clinical trials, glaucoma patients showed a 50% reduction in IOP and no corneal tissue destruction after wearing contact lenses. In animal experiments, the endpoint IOPR [MD = 0.58, 95%CI (0.37, 0.80), P < 0.00001] of the medicated contact lenses group was significantly better than that of the eye drops group. Subgroup analysis showed that contact lenses loaded with timolol (TML), with TML + dorzolamide, and with TML + latanoprost, which compared to eye drops, had a better effect on reducing IOP, while contact lenses loaded with puerarin, latanoprost, and TML + bimatoprost showed no statistical difference. Most studies demonstrated the duration of IOP reduction and drugs release in vitro for ≥3 days during contact lenses treatment.

CONCLUSION

Most drug-loaded contact lenses exhibit excellent effectiveness and safety. The nanoparticle-loaded contact lenses containing TML for glaucoma treatment is recommended in future clinical research.

Drug releasing contact lenses and their application to disease presentations

Eye drops, the most common method for anterior segment treatment, face challenges of inefficiency, with less than 7% instilled drugs typically reaching target tissues of interest. The advent of contact lens drug delivery systems offers a paradigm shift, enhancing drug residence time and bioavailability on the ocular surface. This review focuses on the considerations and challenges in developing contact lenses for drug delivery, particularly for managing four categories of ocular diseases: anterior segment infections, dry eye disease, ocular allergies, and glaucoma. Each disease category requires tailored therapeutic approaches, and the technical intricacies of drug-releasing contact lenses must address concerns related to lens properties, drug release duration, and safety. The aim of this review is to provide insights into the therapeutic needs of ocular diseases and offer a comprehensive overview of the progress made in this innovative approach. The emergence of a commercially available ketotifen fumarate-releasing lens serves as a testament to the feasibility and potential benefits of this innovative approach, paving the way for further refinement and targeted applications in ocular therapeutics.

Current research and future potential of thermogels for sustained drug delivery

INTRODUCTION

Drug administration is ubiquitous in the healthcare field, and it is crucial to optimize drug delivery methods to improve drug efficacy, reduce systemic toxicity, and enhance patient compliance Thermogels have shown immense potential in drug delivery due to their injectability, biocompatibility, and ability to provide localized and sustained drug release.

AREA COVERED

This paper discusses the unique properties of thermogel in relation to drug kinetics and their suitability as a carrier. Different considerations and applications of thermogel drug delivery systems (DDS) were highlighted and their challenges to enter the market discussed. A comprehensive literature search was conducted using major databases such as PubMed, Scopus, and Web of Science. The search employed relevant keywords to identify studies on thermogel DDS. Clinicaltrials.gov was also utilized to determine the current state of clinical studies.

EXPERT OPINION

Nonetheless, thermogel holds great promise for the future in DDS with research achieving greater heights in terms of complexity and clinical pursuits. Their flexibility in fabrication and modularity manner makes it a great material to tailor to different drug delivery applications and to be integrated into various biomedical disciplinaries.

Smart theranostic contact lenses

Although smart contact lenses have demonstrated great potential in theranostics, there remain critical challenges and opportunities in their commercial development. In this Perspective, the current status and capability of smart theranostic contact lenses are highlighted, focusing on their application as sensing systems for detecting biomarkers such as glucose, intraocular pressure (IOP), and inflammatory cytokines, and as drug delivery systems (DDS) for precise and controlled therapy. Additionally, key challenges associated with clinical development and commercialization of smart theranostic contact lenses are discussed, to optimize diagnostic and therapeutic interventions. Considering the rapid evolution of the field, we finally also discuss the need for systematic studies on safety, efficacy, and mass-production, and we spark new ideas for advancing smart theranostic contact lenses into versatile platforms for personalized medicine.

Fish Fin-Derived Non-Invasive Flexible Bioinspired Contact Lens for Continuous Ophthalmic Drug Delivery

Efficient drug delivery is crucial for glaucoma patients. Flexible biomedical devices that enable sustained ocular drug delivery and can regulate the drug release rate according to physiological conditions are highly desirable for glaucoma treatments, addressing both low drug bioavailability and poor patient compliance from manual drug administration, and improving treatment outcomes. Inspired by the structure and reciprocating motion of fish dorsal fins, a drug-eluting contact lens based on deformable microstructures for non-invasive ocular surface drug delivery is developed. Liquid drugs are stored within the interstices of the deformable microstructural units, allowing for continuous drug release through diffusion upon contact with the ocular surface. Finite element analysis is utilized to study the intraocular drug transport dynamics of glaucoma and optimize the overall layout of the device. Microstructural units undergo deformation under loading, altering the interstitial spaces and modulating the drug release rate. This device can adaptively adjust its drug release rate based on changes in intraocular pressure (IOP) and can be proactively regulated in response to cyclic eye loads, accommodating elevated IOP caused by varying body postures and activities. As a flexible, non-invasive, highly dynamic, and adaptive drug delivery platform, it holds significant potential for future biomedical applications.

Preparation, Characterization and In vitro Evaluation of Insulin-PHBV Nanoparticles/Alginate Hydrogel Composite System for Prolonged Delivery of Insulin

PURPOSE

In the present study, biodegradable poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) nanoparticles (NPs) containing insulin were loaded in sodium alginate/jeffamine (ALG/jeff) hydrogel for prolonged delivery of insulin. The main aim of this work was to fabricate an efficient insulin delivery system to improve patient adherence by decreasing the repetition of injections.

METHODS

Swelling and morphological properties and crosslinking efficiency of ALG/jeff hydrogel were assessed. The composite hydrogel was prepared by adding PHBV NPs to ALG/jeff hydrogel concurrently with crosslinking process. The morphology and loading capacity of composite hydrogel were analyzed.

RESULTS

Circular dichroism measurement demonstrated that insulin remains stable following fabrication process. The release profile exhibited 54.6 % insulin release from composite hydrogel within 31 days with minor initial burst release equated to nanoparticles and hydrogels. MTT cell viability analysis was performed by applying L-929 cell line and no cytotoxic effect was observed.

CONCLUSIONS

Favorable results clearly introduced fabricated composite hydrogel as an excellent candidate for drug delivery systems and also paves the route for prolonged delivery systems of other proteins.

Research progress of nano delivery systems for intraocular pressure lowering drugs

Glaucoma is a chronic ocular disease characterized by optic atrophy and visual field defect. The main risk factor for glaucoma onset and progression is elevated intraocular pressure, which is caused by increased aqueous humor outflow resistance. Currently, the primary method for glaucoma therapy is the use of intraocular pressure lowering drugs. However, these drugs, when administered through eye drops, have low bioavailability, require frequent administration, and often result in adverse effects. To overcome these challenges, the application of nanotechnology for drug delivery has emerged as a promising approach. Nanoparticles can physically adsorb, encapsulate, or chemically graft drugs, thereby improving their efficacy, retention time, and reducing adverse reactions. Moreover, nanotechnology has opened up new avenues for ocular administration. This article provides a comprehensive review of nano systems for intraocular pressure lowering drugs, encompassing cholinergic agonists, β-adrenergic antagonists, α-adrenergic agonists, prostaglandin analogs, carbonic anhydrase inhibitors, Rho kinase inhibitors, and complex preparations. The aim is to offer novel insights for the development of nanotechnology in the field of intraocular pressure lowering drugs.

Sustained release of brimonidine from conjunctival sac insert to reduce intraocular pressure for glaucoma treatment

BACKGROUND

Glaucoma is one of the major irreversible blinding eye diseases in the world. Reducing intraocular pressure (IOP) is the primary treatment option, and taking eye drops daily is the common method. However, short drug duration and poor bioavailability of eye drops may lead to unsatisfied therapeutic effects and inadequate patient compliance.

METHODS

A brimonidine-loaded silicone rubber insert (BRI@SR@PT) was prepared by loading brimonidine into a surface-modified silicone rubber ring, followed by polydopamine/thermoplastic polyurethane coatings. The physical properties, in vitro cytocompatibility and drug release of BRI@SR@PT were investigated. The BRI@SR@PT was administrated in the conjunctival sac of rabbit eyes, and its in vivo drug release, IOP-lowering efficacy and biosafety were assessed.

RESULTS

The BRI@SR@PT presented great thermal stability and excellent elasticity. The BRI@SR@PT was able to release BRI sustainably for 28 days with little toxicity in vitro. Compared to BRI eye drops, the BRI@SR@PT effectively lowered IOP for 21 days based on the sustained BRI release with great biosafety when administrated in conjunctival sac of rabbit eyes in a noninvasive fashion.

CONCLUSIONS

The conjunctival sac insert (BRI@SR@PT), as a promising drug-delivery platform, may provide a sustained IOP-lowering treatment for patients with ocular hypertension or glaucoma, without the need for invasive procedures.

Next generation therapeutics for retinal neurodegenerative diseases

Neurodegenerative diseases affecting the visual system encompass glaucoma, macular degeneration, retinopathies, and inherited genetic disorders such as retinitis pigmentosa. These ocular pathologies pose a serious burden of visual impairment and blindness worldwide. Current treatment modalities include small molecule drugs, biologics, or gene therapies, most of which are administered topically as eye drops or as injectables. However, the topical route of administration faces challenges in effectively reaching the posterior segment and achieving desired concentrations at the target site, while injections and implants risk severe complications, such as retinal detachment and endophthalmitis. This necessitates the development of innovative therapeutic strategies that can prolong drug release, deliver effective concentrations to the back of the eye with minimal systemic exposure, and improve patient compliance and safety. In this review, we introduce retinal degenerative diseases, followed by a discussion of the existing clinical standard of care. We then delve into detail about drug and gene delivery systems currently in preclinical and clinical development, including formulation and delivery advantages/drawbacks, with a special emphasis on potential for clinical translation.

Novel frontiers in neuroprotective therapies in glaucoma: Molecular and clinical aspects

In the last years, neuroprotective therapies have attracted the researcher interests as modern and challenging approach for the treatment of neurodegenerative diseases, aimed at protecting the nervous system from injuries. Glaucoma is a neurodegenerative disease characterized by progressive excavation of the optic nerve head, retinal axonal injury and corresponding vision loss that affects millions of people on a global scale. The molecular basis of the pathology is largely uncharacterized yet, and the therapeutic approaches available do not change the natural course of the disease. Therefore, in accordance with the therapeutic regimens proposed for other neurodegenerative diseases, a modern strategy to treat glaucoma includes prescription of drugs with neuroprotective activities. With respect to this, several preclinical and clinical investigations on a plethora of different drugs are currently ongoing. In this review, first, the conceptualization of the rationale for the adoption of neuroprotective strategies for retina is summarized. Second, the molecular aspects highlighting glaucoma as a neurodegenerative disease are reported. In conclusion, the molecular and pharmacological properties of most promising direct neuroprotective drugs used to delay glaucoma progression are examined, including: neurotrophic factors, NMDA receptor antagonists, the α2-adrenergic agonist, brimonidine, calcium channel blockers, antioxidant agents, nicotinamide and statins.

Recent advancements in nanomaterial-laden contact lenses for diagnosis and treatment of glaucoma, review and update

Despite the existence of numerous eye drops in the market, most of them are not sufficiently effective because of quick clearance and the barriers within the eye. To increase the delivery of the drugs to the eye, various new formulations have been explored in recent decades. These formulations aim to enhance drug retention and penetration, while enabling sustained drug release over extended periods. One such innovative approach is the utilization of contact lenses, which were originally designed for cosmetic purposes and vision correction. Contact lenses have appeared as a promising formulation for ocular drug delivery, as they can increase the bioavailability of drugs in the eye and diminish unwanted side effects. They are specifically appropriate for treating chronic eye conditions, making them an area of interest for researchers in the field of ophthalmology. This review outlines the promising potential of nanomaterial-laden contact lenses for diagnosis and treatment of glaucoma. It classifies therapeutic approaches based on nanomaterial type, summarizes diagnostic advances, discusses improvement of contact lenses properties, covers marketing perspectives, and acknowledges the challenges of these innovative contact lenses for glaucoma management.

Combined Therapy of Experimental Autoimmune Uveitis by a Dual-Drug Nanocomposite Formulation with Berberine and Dexamethasone

Purpose

Autoimmune uveitis is a kind of sight-threatening ocular and systemic disorders. Recent treatments on autoimmune uveitis still remain many limitations due to extreme complexity and undetermined pathogenesis. In this study, a novel dual-drug nanocomposite formulation is developed to treat experimental autoimmune uveitis by a combined and sustained therapy method.

Methods

The dual-drug nanocomposite formulation is constructed by integrating berberine (BBR)-loaded mesoporous silica nanoparticles (MSNs) into dexamethasone (DEX)-loaded thermogel (BBR@MSN-DEX@Gel). The BBR@MSN-DEX@Gel is characterized by transmission electron microscopy, dynamic light scattering, Fourier transform infrared spectrometer and rheometer. The in vitro drug release profile, cytotoxicity and anti-inflammation effectiveness of BBR@MSN-DEX@Gel on lipopolysaccharide-stimulated human conjunctival epithelial cells are investigated. After the in vivo drug release profile and biosafety of the dual-drug nanocomposite formulation are confirmed, its treatment effectiveness is fully assessed based on the induced experimental autoimmune uveitis (EAU) Lewis rat's model.

Results

The dual-drug nanocomposite formulation has good injectability and thermosensitivity, suitable for administration by an intravitreal injection. The BBR@MSN-DEX@Gel has been found to sustainably release both drugs for up to 4 weeks. The carrier materials have minimal in vitro cytotoxicity and high in vivo biosafety. BBR@MSN-DEX@Gel presents obviously anti-inflammatory effectiveness in vitro. After administration of BBR@MSN-DEX@Gel into Lewis rat's eye with EAU by an intravitreal injection, the nanocomposite formulation significantly suppresses inflammatory reaction of autoimmune uveitis via a dual-drug combined and sustained therapy method, compared with the equivalent dose of single-component formulations.

Conclusion

BBR@MSN-DEX@Gel serves as a promising dual-drug nanocomposite formulation for future treatment of autoimmune uveitis.

Recent Advances of Ocular Drug Delivery Systems: Prominence of Ocular Implants for Chronic Eye Diseases

Chronic ocular diseases can seriously impact the eyes and could potentially result in blindness or serious vision loss. According to the most recent data from the WHO, there are more than 2 billion visually impaired people in the world. Therefore, it is pivotal to develop more sophisticated, long-acting drug delivery systems/devices to treat chronic eye conditions. This review covers several drug delivery nanocarriers that can control chronic eye disorders non-invasively. However, most of the developed nanocarriers are still in preclinical or clinical stages. Long-acting drug delivery systems, such as inserts and implants, constitute the majority of the clinically used methods for the treatment of chronic eye diseases due to their steady state release, persistent therapeutic activity, and ability to bypass most ocular barriers. However, implants are considered invasive drug delivery technologies, especially those that are nonbiodegradable. Furthermore, in vitro characterization approaches, although useful, are limited in mimicking or truly representing the in vivo environment. This review focuses on long-acting drug delivery systems (LADDS), particularly implantable drug delivery systems (IDDS), their formulation, methods of characterization, and clinical application for the treatment of eye diseases.

Novel long-acting brimonidine tartrate loaded-PCL/PVP nanofibers for versatile biomedical applications: fabrication, characterization and antimicrobial evaluation

The global state of antibiotic resistance highlights the necessity for new drugs that can treat a wide range of microbial infections. Drug repurposing has several advantages, including lower costs and improved safety compared to developing a new compound. The aim of the current study is to evaluate the repurposed antimicrobial activity of Brimonidine tartrate (BT), a well-known antiglaucoma drug, and to potentiate its antimicrobial effect by using electrospun nanofibrous scaffolds. BT-loaded nanofibers were fabricated in different drug concentrations (1.5, 3, 6, and 9%) via the electrospinning technique using two biopolymers (PCL and PVP). Then, the prepared nanofibers were characterized by SEM, XRD, FTIR, swelling ratio, and in vitro drug release. Afterward, the antimicrobial activities of the prepared nanofibers were investigated in vitro using different methods against several human pathogens and compared to the free BT. The results showed that all nanofibers were prepared successfully with a smooth surface. The diameters of nanofibers were reduced after loading of BT compared to the unloaded ones. In addition, scaffolds showed controlled-drug release profiles that were maintained for more than 7 days. The in vitro antimicrobial assessments revealed good activities for all scaffolds against most of the investigated human pathogens, particularly the one prepared with 9% BT which showed superiority in the antimicrobial effect over other scaffolds. To conclude, our findings proved the capability of nanofibers in loading BT and improving its repurposed antimicrobial efficacy. Therefore, it could be a promising carrier for BT to be used in combating numerous human pathogens.

Sustained release of brimonidine from polydimethylsiloxane-coating silicone rubber implant to reduce intraocular pressure in glaucoma

Glaucoma is the leading cause of irreversible blindness, affecting 111 million people by 2040 worldwide. Intraocular pressure (IOP) is the only controllable risk factor for the disease and current treatment options seek to reduce IOP via daily taking eye drops. However, shortcomings of eye drops, such as poor bioavailability and unsatisfied therapeutic effects, may lead to inadequate patient compliance. In this study, an effective brimonidine (BRI)-loaded silicone rubber (SR) implant coated with polydimethylsiloxane (BRI@SR@PDMS) is designed and fully investigated for IOP reduction treatment. The in vitro BRI release from BRI@SR@PDMS implant reveals a more sustainable trend lasting over 1 month, with a gradually declined immediate drug concentration. The carrier materials show no cytotoxicity on human corneal epithelial cells and mice corneal epithelial cells in vitro. After administrated into rabbit's conjunctival sac, the BRI@SR@PDMS implant releases BRI in a sustained fashion and effectively reduces IOP for 18 days with great biosafety. In contrast, BRI eye drops only maintain IOP-lowering effect for 6 h. Therefore, as a substitute of eye drops, the BRI@SR@PDMS implant can be applied as a promising non-invasive platform to achieve long-term IOP-lowering in patients suffering from ocular hypertension or glaucoma.

Record Ultralarge-Pores, Low Density Three-Dimensional Covalent Organic Framework for Controlled Drug Delivery

The unique structural characteristics of three-dimensional (3D) covalent organic frameworks (COFs) like high surface areas, interconnected pore system and readily accessible active sites render them promising platforms for a wide set of functional applications. Albeit promising, the reticular construction of 3D COFs with large pores is a very demanding task owing to the formation of interpenetrated frameworks. Herein we report the designed synthesis of a 3D non-interpenetrated stp net COF, namely TUS-64, with the largest pore size of all 3D COFs (47 Å) and record-low density (0.106 g cm^-3 ) by reticulating a 6-connected triptycene-based linker with a 4-connected porphyrin-based linker. Characterized with a highly interconnected mesoporous scaffold and good stability, TUS-64 shows efficient drug loading and controlled release for five different drugs in simulated body fluid environment, demonstrating the competency of TUS-64 as drug nanocarriers.

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.

Advances in innovative delivery systems for antiglaucoma drugs

PURPOSE OF REVIEW

Currently, glaucoma treatment drugs are facing problems such as low bioavailability, poor patient compliance, discontinuous administration affecting the efficacy of intraocular pressure (IOP) lowering and chronic damage to the eye caused by side effects of drugs. In order to solve these problems and to better meet clinical needs, various new dosage forms have been developed and applied in the clinical setting.

RECENT FINDINGS

A number of nano formulations and extended-release gels are in successive animal trials, some tear plugs, implants and contact lenses are in clinical trials, and it is believed that more new carrier materials and formulations to improve the bioavailability of drugs are being developed.

SUMMARY

Novel delivery systems for antiglaucoma drugs offer patients more and better therapeutic options, and ongoing or completed studies are providing clear directions for subsequent research to improve clinical applications.

Biomaterials Based on Organic Polymers and Layered Double Hydroxides Nanocomposites: Drug Delivery and Tissue Engineering

The development of biomaterials has a substantial role in pharmaceutical and medical strategies for the enhancement of life quality. This review work focused on versatile biomaterials based on nanocomposites comprising organic polymers and a class of layered inorganic nanoparticles, aiming for drug delivery (oral, transdermal, and ocular delivery) and tissue engineering (skin and bone therapies). Layered double hydroxides (LDHs) are 2D nanomaterials that can intercalate anionic bioactive species between the layers. The layers can hold metal cations that confer intrinsic biological activity to LDHs as well as biocompatibility. The intercalation of bioactive species between the layers allows the formation of drug delivery systems with elevated loading capacity and modified release profiles promoted by ion exchange and/or solubilization. The capacity of tissue integration, antigenicity, and stimulation of collagen formation, among other beneficial characteristics of LDH, have been observed by in vivo assays. The association between the properties of biocompatible polymers and LDH-drug nanohybrids produces multifunctional nanocomposites compatible with living matter. Such nanocomposites are stimuli-responsive, show appropriate mechanical properties, and can be prepared by creative methods that allow a fine-tuning of drug release. They are processed in the end form of films, beads, gels, monoliths etc., to reach orientated therapeutic applications. Several studies attest to the higher performance of polymer/LDH-drug nanocomposite compared to the LDH-drug hybrid or the free drug.

Sustained release glaucoma therapies: Novel modalities for overcoming key treatment barriers associated with topical medications

Glaucoma is a progressive optic neuropathy and a leading cause of irreversible blindness. The disease has conventionally been characterized by an elevated intraocular pressure (IOP); however, recent research has built the consensus that glaucoma is not only dependent on IOP but rather represents a multifactorial optic neuropathy. Although many risk factors have been identified ranging from demographics to co-morbidities to ocular structural predispositions, IOP is currently the only modifiable risk factor, most often treated by topical IOP-lowering medications. However, topical hypotensive regimens are prone to non-adherence and are largely inefficient, leading to disease progression in spite of treatment. As a result, several companies are developing sustained release (SR) drug delivery systems as alternatives to topical delivery to potentially overcome these barriers. Currently, Bimatoprost SR (Durysta^TM) from Allergan plc is the only FDA-approved SR therapy for POAG. Other SR therapies under investigation include: bimatoprost ocular ring (Allergan) (ClinicalTrials.gov identifier: NCT01915940), iDose^® (Glaukos Corporation) (NCT03519386), ENV515 (Envisia Therapeutics) (NCT02371746), OTX-TP (Ocular Therapeutix) (NCT02914509), OTX-TIC (Ocular Therapeutix) (NCT04060144), and latanoprost free acid SR (PolyActiva) (NCT04060758). Additionally, a wide variety of technologies for SR therapeutics are under investigation including ocular surface drug delivery systems such as contact lenses and nanotechnology. While challenges remain for SR drug delivery technology in POAG management, this technology may shift treatment paradigms and dramatically improve outcomes.

Intravitreal Injectable Hydrogels for Sustained Drug Delivery in Glaucoma Treatment and Therapy

Glaucoma is extensively treated with topical eye drops containing drugs. However, the retention time of the loaded drugs and the in vivo bioavailability of the drugs are highly influenced before reaching the targeted area sufficiently, due to physiological and anatomical barriers of the eye, such as rapid nasolacrimal drainage. Poor intraocular penetration and frequent administration may also cause ocular cytotoxicity. A novel approach to overcome these drawbacks is the use of injectable hydrogels administered intravitreously for sustained drug delivery to the target site. These injectable hydrogels are used as nanocarriers to intimately interact with specific diseased ocular tissues to increase the therapeutic efficacy and drug bioavailability of the anti-glaucomic drugs. The human eye is very delicate, and is sensitive to contact with any foreign body material. However, natural biopolymers are non-reactive, biocompatible, biodegradable, and lack immunogenic and inflammatory responses to the host whenever they are incorporated in drug delivery systems. These favorable biomaterial properties have made them widely applicable in biomedical applications, with minimal adversity. This review highlights the importance of using natural biopolymer-based intravitreal hydrogel drug delivery systems for glaucoma treatment over conventional methods.

Lab-on-a-Contact Lens: Recent Advances and Future Opportunities in Diagnostics and Therapeutics

The eye is one of the most complex organs in the human body, containing rich and critical physiological information (e.g., intraocular pressure, corneal temperature, and pH) as well as a library of metabolite biomarkers (e.g., glucose, proteins, and specific ions). Smart contact lenses (SCLs) can serve as a wearable intelligent ocular prosthetic device capable of noninvasive and continuous monitoring of various essential physical/biochemical parameters and drug loading/delivery for the treatment of ocular diseases. Advances in SCL technologies and the growing public interest in personalized health are accelerating SCL research more than ever before. Here, the current status and potential of SCL development through a comprehensive review from fabrication to applications to commercialization are discussed. First, the material, fabrication, and platform designs of the SCLs for the diagnostic and therapeutic applications are discussed. Then, the latest advances in diagnostic and therapeutic SCLs for clinical translation are reviewed. Later, the established techniques for wearable power transfer and wireless data transmission applied to current SCL devices are summarized. An outlook, future opportunities, and challenges for developing next-generation SCL devices are also provided. With the rise in interest of SCL development, this comprehensive and essential review can serve as a new paradigm for the SCL devices.

In vitro and in vivo evaluation of brimonidine loaded silica nanoparticles-laden silicone contact lenses to manage glaucoma

Glaucoma is treated by frequent instillation of 0.2% w/v brimonidine tartrate eye drop solution, which showed poor ocular bioavailability of 1-3%. Medicated contact lenses can be used to improve the ocular drug bioavailability. However, drug loading in the contact lens matrix showed high burst release and changes the optophysical properties of the contact lens material. In this paper, a novel brimonidine loaded silica nanoparticles-laden silicone contact lenses (Bri-Si) were designed to achieve controlled drug delivery without altering the optophysical properties of the contact lens. Silica nanoparticles were prepared by polymerizing octadecyltrimethoxysilane (OTMS) molecules at the oil/water interface of microemulsion. Traditional soaking method (Bri-SM), direct brimonidine-loading method (Bri-DL) and microemulsion-laden contact lens (Bri-ME) were developed for comparison. The Bri-Si lens showed improved swelling, transmittance, oxygen permeability and lysozyme adherence compared to Bri-SM, Bri-DL and Bri-ME lenses. The Bri-DL lens showed high brimonidine leaching during extraction and sterilization steps, with low cumulative drug release. While, Bri-Si lens show controlled brimonidine release for 144 h. In a rabbit tear fluid model, the Bri-Si lens showed high brimonidine concentration for 96 h compared to Bri-ME lens and eye drop therapy. Based on histopathological studies of cornea, the Bri-Si lens was found to be safe for human applications. The data demonstrated the novel application of silica nanoparticles to control brimonidine release from the contact lens without altering the optophysical properties of the contact lens.

Sustained release of brimonidine from BRI@SR@TPU implant for treatment of glaucoma

Glaucoma is the leading cause of irreversible vision loss worldwide, and reduction of intraocular pressure (IOP) is the only factor that can be interfered to delay disease progression. As the first line and preferred method to treat glaucoma, eye drops have many shortcomings, such as low bioavailability, poor patient compliance, and unsustainable therapeutic effect. In this study, a highly efficient brimonidine (BRI) silicone rubber implant (BRI@SR@TPU implant) has been designed, prepared, characterized, and administrated for sustained relief of IOP to treat glaucoma. The in vitro BRI release from BRI@SR@TPU implants shows a sustainable release profile for up to 35 d, with decreased burst release and increased immediate drug concentration. The carrier materials are not cytotoxic to human corneal epithelial cells and conjunctival epithelial cells, and show good biocompatibility, which can be safely administrated into rabbit’s conjunctival sac. The BRI@SR@TPU implant sustainably released BRI and effectively reduced IOP for 18 d (72 times) compared to the commercial BRI eye drops (6 h). The BRI@SR@TPU implant is thus a promising noninvasive platform product for long-term IOP-reducing in patients with glaucoma and ocular hypertension.

Imaging Methods for the Assessment of a Complex Hydrogel as an Ocular Drug Delivery System for Glaucoma Treatment: Opportunities and Challenges in Preclinical Evaluation

Glaucoma is one of the leading causes of loss of vision. The problems associated with the marketed formulations of anti-glaucoma drugs are low bioavailability, unwanted side effects, and low patient compliance. Hydrogels are an important class of soft materials that play a crucial role in developing an ocular drug delivery system. They assume a special significance in addressing the problems associated with the marketed formulations of eyedrops. An appropriate design of the hydrogel system capable of encapsulating single or multiple drugs for glaucoma has emerged in recent times to overcome such challenges. Although various modes of imaging play critical roles in assessing the efficacy of these formulations, evaluating hydrogels for drug permeation and retention remains challenging. Especially, the assessment of dual drugs in the hydrogel system is not straightforward due to the complexity in measuring drug penetration and retention for in vivo or ex vivo systems. There is a need to develop tools for the fabrication and validation of hydrogel-based systems that give insight into precorneal retention, biocompatibility, cellular uptake, and cell permeation. The current review highlights some of the complexities in formulating hydrogel and benchmarking technologies, including confocal laser scanning microscopy, fluorescent microscopy, slit-lamp biomicroscopy, and camera-based imaging. This review also summarizes recent evaluations of various hydrogel formulations using in vitro and in vivo models. Further the article will help researchers from various disciplines, including formulation scientists and biologists, set up preclinical protocols for evaluating polymeric hydrogels.

Molecular bases for temperature sensitivity in supramolecular assemblies and their applications as thermoresponsive soft materials

Thermoresponsive supramolecular assemblies have been extensively explored in diverse formats, from injectable hydrogels to nanoscale carriers, for a variety of applications including drug delivery, tissue engineering and thermo-controlled catalysis. Understanding the molecular bases behind thermal sensitivity of materials is fundamentally important for the rational design of assemblies with optimal combination of properties and predictable tunability for specific applications. In this review, we summarize the recent advances in this area with a specific focus on the parameters and factors that influence thermoresponsive properties of soft materials. We summarize and analyze the effects of structures and architectures of molecules, hydrophilic and lipophilic balance, concentration, components and external additives upon the thermoresponsiveness of the corresponding molecular assemblies.

MnO2 Coated Nanotheranostic LDH for Synergistic Cascade Chemo/Chemodynamic Cancer Therapy under the Guidance of MRI-Targeted Diagnosis

Integrating magnetic resonance imaging (MRI)-targeted diagnosis with synergistic cascade treatments, such as chemo/chemodynamic therapy (CT/CDT), is highly desired to promote the antitumor performance; However, the rational design of such “all-in-one”...

Polydopamine nanoparticles attenuate retina ganglion cell degeneration and restore visual function after optic nerve injury

Background

Oxidative stress contributes to retina ganglion cells (RGCs) loss in variety of ocular diseases, including ocular trauma, ocular vein occlusion, and glaucoma. Scavenging the excessed reactive oxygen species (ROS) in retinal neurovascular unit could be beneficial to RGCs survival. In this study, a polydopamine (PDA)-based nanoplatform is developed to protect RGCs.

Results

The PDA nanoparticles efficiently eliminate multi-types of ROS, protect endothelia and neuronal cells from oxidative damage, and inhibit microglia activation in retinas. In an optic nerve crush (ONC) model, single intravitreal injection of PDA nanoparticles could significantly attenuate RGCs loss via eliminating ROS in retinas, reducing the inflammatory response and maintaining barrier function of retinal vascular endothelia. Comparative transcriptome analysis of the retina implied that PDA nanoparticles improve RGCs survival probably by altering the expression of genes involved in inflammation and ROS production. Importantly, as a versatile drug carrier, PDA nanoparticles could deliver brimonidine (a neuroprotection drug) to synergistically attenuate RGCs loss and promote axon regeneration, thus restore visual function.

Conclusions

The PDA nanoparticle-based therapeutic nanoplatform displayed excellent performance in ROS elimination, providing a promising probability for treating retinal degeneration diseases.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-01199-3.

Two-dimensional biomaterials: material science, biological effect and biomedical engineering applications

To date, nanotechnology has increasingly been identified as a promising and efficient means to address a number of challenges associated with public health. In the past decade, two-dimensional (2D) biomaterials, as a unique nanoplatform with planar topology, have attracted explosive interest in various fields such as biomedicine due to their unique morphology, physicochemical properties and biological effect. Motivated by the progress of graphene in biomedicine, dozens of types of ultrathin 2D biomaterials have found versatile bio-applications, including biosensing, biomedical imaging, delivery of therapeutic agents, cancer theranostics, tissue engineering, as well as others. The effective utilization of 2D biomaterials stems from the in-depth knowledge of structure-property-bioactivity-biosafety-application-performance relationships. A comprehensive summary of 2D biomaterials for biomedicine is still lacking. In this comprehensive review, we aim to concentrate on the state-of-the-art 2D biomaterials with a particular focus on their versatile biomedical applications. In particular, we discuss the design, fabrication and functionalization of 2D biomaterials used for diverse biomedical applications based on the up-to-date progress. Furthermore, the interactions between 2D biomaterials and biological systems on the spatial-temporal scale are highlighted, which will deepen the understanding of the underlying action mechanism of 2D biomaterials aiding their design with improved functionalities. Finally, taking the bench-to-bedside as a focus, we conclude this review by proposing the current crucial issues/challenges and presenting the future development directions to advance the clinical translation of these emerging 2D biomaterials.

Novel Contact Lenses Embedded with Drug-Loaded Zwitterionic Nanogels for Extended Ophthalmic Drug Delivery

Therapeutic ophthalmic contact lenses with prolonged drug release and improved bioavailability have been developed to circumvent tedious eye drop instillation. In this work, zwitterionic nanogels based on poly(sulfobetaine methacrylate) (PSBMA) were easily fabricated by one-step reflux-precipitation polymerization, with the advantages of being surfactant-free and morphology controlled. Then, the ophthalmic drug levofloxacin (LEV) was encapsulated into the nanogels. A set of contact lenses with varied nanogel-loading content was fabricated by the cast molding method, with the drug-loaded nanogels dispersed in pre-monomer solutions composed of 2-hydroxyethyl methacrylate (HEMA) and N-vinyl-2-pyrrolidone (NVP). The structure, surface morphology, water contact angle (WCA), equilibrium water content (EWC), transmittance, and mechanical properties of the contact lenses were subsequently investigated, and in vitro drug release and biocompatibility were further evaluated. As a result, the optimized contact lens with nanogel-loading content of 8 wt% could sustainably deliver LEV for ten days, with critical lens properties within the range of recommended values for commercial contact lenses. Moreover, cell viability assays revealed that the prepared contact lenses were cytocompatible, suggesting their significant potential as an alternative to traditional eye drops or ointment formulations for long-term oculopathy treatment.

Inhibiting corneal neovascularization by sustainably releasing anti-VEGF and anti-inflammation drugs from silica-thermogel nanohybrids

Corneal neovascularization (CNV) is one of the main factors that induce blindness worldwide. To effectively inhibit CNV, a novel nanohybrid has been developed by incorporating anti-VEGF bevacizumab (BEV)-loaded mesoporous silica nanoparticles (BEV@MSN) into the thermogel matrix with anti-inflammation cyclosporine A (CsA) (BEV@MSN-CsA@Thermogel). This nanohybrid regulates the in vitro release of both bevacizumab and cyclosporine A in a sustainable way for up to four weeks to enhance CNV inhibition through the synergistic anti-VEGF and anti-inflammation. The carrier materials (i.e. silica and thermogel) in this nanohybrid do not show any cytotoxicity to human Tenon's fibroblasts, corneal epithelial cells and corneal endothelial cells. BEV@MSN-CsA@Thermogel effectively prevents proliferation, migration, and tube-like structure formation of human umbilical vein endothelial cells. Moreover, subconjunctival injection of BEV@MSN-CsA@Thermogel significantly inhibits corneal neovascularization in terms of the CNV area, the new vessel length, the corneal opaque area, the corneal inflammation and abnormal fibrosis in a rabbit model. This nanohybrid is thus a promising alternative for effective CNV treatment.

Lollipop-Inspired Multilayered Drug Delivery Hydrogel for Dual Effective, Long-Term, and NIR-Defined Glaucoma Treatment

Glaucoma is an ophthalmic disease that is characterized by elevated intraocular pressure (IOP). Eye drops are the preferred choice to reduce IOP for the treatment of glaucoma. However, the bioavailability of eye drops is low (<5%). Their long-term frequent administration cannot ensure patient compliance, which is the main reason for treatment failure. Inspired by lollipop, herein, a multilayered sodium alginate-chitosan (SA-CS) hydrogel ball (HB) decorated by zinc oxide-modified biochar (ZnO-BC) is developed as a new drug delivery system. The multilayer structure encapsulate timolol maleate (TM) and levofloxacin inside the different layers to realize the sustained release of drugs, which can control ocular hypertension and prevent infection effectively. The results show that the release of TM can be sustained in vitro for longer than 2 weeks. Moreover, IOP is also effectively reduced in vivo. Meanwhile, the photothermal conversion activity of ZnO-BC can regulate drug release on demand after stimulation by near-infrared irradiation. More importantly, the designed HB also shows good biocompatibility and antibacterial properties in vitro and in vivo. In summary, ZnO-BC-SA-CS HB can effectively reduce IOP and is expected to replace the classical tedious eye drop strategy, having potential utilization value in the treatment of glaucoma.

Encapsulation of a highly hydrophilic drug in polymeric particles: A comparative study of batch and microfluidic processes

The objective of this work was to investigate the effect of microfluidics on the quality attributes of metformin hydrochloride-loaded poly lactic-co-glycolic acid polymeric particles (MFH-PLGA PPs) when compared to a traditional double emulsion batch method. The relationship of encapsulation and loading efficiencies, yield %, particle size, surface morphology, and release profile with process and formulation variables were determined using design of experiments (DoE). The effects of the dispersal method of the primary (sonication vs. vortex) or secondary emulsion (microfluidics vs. batch), polyvinyl alcohol concentration (PVA), and drug to polymer ratio were investigated. The PPs' size was impacted by both the PVA concentration and the type of primary and secondary emulsion dispersion methods. Microfluidics significantly increased the PPs' yield %, particle size, encapsulation, and loading efficiencies. The higher loaded microfluidic-based PPs had more burst release, following first-order release kinetics when compared to the lower loaded batch-based particles, which followed the Korsmeyer-Peppas model for release kinetics. Microfluidic-based PPs exhibited a smooth, porous, more uniform, and larger particle size with hollow structure than the batch-based PPs with a matrix-like structure. In conclusion, we have elucidated the effect of microfluidics on the quality attributes of MFH-PLGA PPs and their comparison to the traditional batch technique.

Soft Materials by Design: Unconventional Polymer Networks Give Extreme Properties

Hydrogels are polymer networks infiltrated with water. Many biological hydrogels in animal bodies such as muscles, heart valves, cartilages, and tendons possess extreme mechanical properties including being extremely tough, strong, resilient, adhesive, and fatigue-resistant. These mechanical properties are also critical for hydrogels' diverse applications ranging from drug delivery, tissue engineering, medical implants, wound dressings, and contact lenses to sensors, actuators, electronic devices, optical devices, batteries, water harvesters, and soft robots. Whereas numerous hydrogels have been developed over the last few decades, a set of general principles that can rationally guide the design of hydrogels using different materials and fabrication methods for various applications remain a central need in the field of soft materials. This review is aimed at synergistically reporting: (i) general design principles for hydrogels to achieve extreme mechanical and physical properties, (ii) implementation strategies for the design principles using unconventional polymer networks, and (iii) future directions for the orthogonal design of hydrogels to achieve multiple combined mechanical, physical, chemical, and biological properties. Because these design principles and implementation strategies are based on generic polymer networks, they are also applicable to other soft materials including elastomers and organogels. Overall, the review will not only provide comprehensive and systematic guidelines on the rational design of soft materials, but also provoke interdisciplinary discussions on a fundamental question: why does nature select soft materials with unconventional polymer networks to constitute the major parts of animal bodies?

Improved Treatment Options for Glaucoma with Brimonidine-Loaded Lipid DNA Nanoparticles

Glaucoma is the second leading cause of irreversible blindness worldwide. Among others, elevated intraocular pressure (IOP) is one of the hallmarks of the disease. Antiglaucoma drugs such as brimonidine can lower the IOP but their adherence to the ocular surface is low, leading to a low drug uptake. This results in a frequent dropping regime causing low compliance by the patients. Lipid DNA nanoparticles (NPs) have the intrinsic ability to bind to the ocular surface and can be loaded with different drugs. Here, we report DNA NPs functionalized for loading of brimonidine through specific aptamers and via hydrophobic interactions with double stranded micelles. Both NP systems exhibited improved affinity toward the cornea and retained release of the drug as compared to controls both in vitro and in vivo. Both NP types were able to lower the IOP in living animals significantly more than pristine brimonidine. Importantly, the brimonidine-loaded NPs showed no toxicity and improved efficacy and hence should improve compliance. In conclusion, this drug-delivery system offers high chances of an improved treatment for glaucoma and thus preserving vision in the aging population.

Micro/nanodevices for assessment and treatment in stomatology and ophthalmology

Micro/nanodevices have been widely applied for the real-time monitoring of intracellular activities and the delivery of exogenous substances in the past few years. This review focuses on miniaturized micro/nanodevices for assessment and treatment in stomatology and ophthalmology. We first summarize the recent progress in this field by examining the available materials and fabrication techniques, device design principles, mechanisms, and biosafety aspects of micro/nanodevices. Following a discussion of biochemical sensing technology from the cellular level to the tissue level for disease assessment, we then summarize the use of microneedles and other micro/nanodevices in the treatment of oral and ocular diseases and conditions, including oral cancer, eye wrinkles, keratitis, and infections. Along with the identified key challenges, this review concludes with future directions as a small fraction of vast opportunities, calling for joint efforts between clinicians and engineers with diverse backgrounds to help facilitate the rapid development of this burgeoning field in stomatology and ophthalmology.

Advanced drug delivery applications of layered double hydroxide

Layered double hydroxides (LDHs), also known as anionic clays or hydrotalcite-like compounds, are a class of nanomaterials that attained great attention as a carrier for drug delivery applications. The lamellar structure of this compound exhibits a high surface-to-volume ratio which enables the intercalation of therapeutic agents and releases them at the target site, thereby reducing the adverse effect. Moreover, the intercalated drug can be released in a sustained manner, and hence the frequency of drug administration can be decreased. The co-precipitation, ion exchange, manual grinding, and sol-gel methods are the most employed for their synthesis. The unique properties like the ease of synthesis, low cost, high biocompatibility, and low toxicity render them suitable for biomedical applications. This review presents the advances in the structure, properties, method of preparation, types, functionalization, and drug delivery applications of LDH. Also, this review provides various new conceptual insights that can form the basis for new research questions related to the drug delivery applications of LDH.

Novel Drug Delivery Systems Fighting Glaucoma: Formulation Obstacles and Solutions

Glaucoma is considered to be one of the biggest health problems in the world. It is the main cause of preventable blindness due to its asymptomatic nature in the early stages on the one hand and patients' non-adherence on the other. There are several approaches in glaucoma treatment, whereby this has to be individually designed for each patient. The first-line treatment is medication therapy. However, taking into account numerous disadvantages of conventional ophthalmic dosage forms, intensive work has been carried out on the development of novel drug delivery systems for glaucoma. This review aims to provide an overview of formulation solutions and strategies in the development of in situ gel systems, nanosystems, ocular inserts, contact lenses, collagen corneal shields, ocular implants, microneedles, and iontophoretic devices. The results of studies confirming the effectiveness of the aforementioned drug delivery systems were also briefly presented.

Ophthalmic Drops with Nanoparticles Derived from a Natural Product for Treating Age-Related Macular Degeneration

There is a continuing, urgent need for an ophthalmic (eye) drop for the clinical therapy of age-related macular degeneration (AMD), a leading cause of blindness. Here, we report the first formulation of an eye drop that is effective via autophagy for AMD treatment. This eye drop is based on a single natural product derivative (ACD), which is an amphiphilic molecule containing a 6-aminohexanoate group (H₂N(CH₂)₅COO-). We demonstrate that this eye drop reverses the abnormal angiogenesis induced in a primate model of AMD that has the pathological characteristics close to that of human AMD. The ACD molecule was self-assembled in an aqueous environment leading to nanoparticles (NPs) about 9.0 nm in diameter. These NPs were encapsulated in calcium alginate hydrogel. The resulting eye drop effectively slowed the release of ACD and displayed extended release periods in both simulated blood (pH 7.4) and inflammatory (pH 5.2) environments. We show that the eye drop penetrated both the corneal and blood-eye barriers and reached the fundus. With low cellular toxicity, the drop targeted S1,25D₃-membrane-associated rapid response steroid-binding protein (1,25D₃-MARRS) promoting autophagy in a dose-dependent manner. In addition, the drop inhibited cell migration and tubular formation. On the other hand, when protein 1,25D₃-MARRS was knocked down, the eye drop did not exhibit such inhibition functionalities. Our study indicates that the 6-aminohexanoate group on self-assembled NPs encapsulated in hydrogel leads to the positive in vivo outcomes. The present formulation offers a promising approach for clinical treatment of human AMD.

Glaucoma: Management and Future Perspectives for Nanotechnology-Based Treatment Modalities

Glaucoma, being asymptomatic for relatively late stage, is recognized as a worldwide cause of irreversible vision loss. The eye is an impervious organ that exhibits natural anatomical and physiological barriers which renders the design of an efficient ocular delivery system a formidable task and challenge scientists to find alternative formulation approaches. In the field of glaucoma treatment, smart delivery systems for targeting have aroused interest in the topical ocular delivery field owing to its potentiality to oppress many treatment challenges associated with many of glaucoma types. The current momentum of nano-pharmaceuticals, in the development of advanced drug delivery systems, hold promises for much improved therapies for glaucoma to reduce its impact on vision loss. In this review, a brief about glaucoma; its etiology, predisposing factors and different treatment modalities has been reviewed. The diverse ocular drug delivery systems currently available or under investigations have been presented. Additionally, future foreseeing of new drug delivery systems that may represent potential means for more efficient glaucoma management are overviewed. Finally, a gab-analysis for the required investigation to pave the road for commercialization of ocular novel-delivery systems based on the nano-technology are discussed.

Brimonidine-LAPONITE® intravitreal formulation has an ocular hypotensive and neuroprotective effect throughout 6 months of follow-up in a glaucoma animal model

Intravitreal administration is widely used in ophthalmological practice to maintain therapeutic drug levels near the neuroretina and because drug delivery systems are necessary to avoid reinjections and sight-threatening side effects. However, currently there is no intravitreal treatment for glaucoma. The brimonidine-LAPONITE® formulation was created with the aim of treating glaucoma for extended periods with a single intravitreal injection. Glaucoma was induced by producing ocular hypertension in two rat cohorts: [BRI-LAP] and [non-bri], with and without treatment, respectively. Eyes treated with brimonidine-LAPONITE® showed lower ocular pressure levels up to week 8 (p < 0.001), functional neuroprotection explored by scotopic and photopic negative response electroretinography (p = 0.042), and structural protection of the retina, retinal nerve fibre layer and ganglion cell layer (p = 0.038), especially on the superior-inferior axis explored by optical coherence tomography, which was corroborated by a higher retinal ganglion cell count (p = 0.040) using immunohistochemistry (Brn3a antibody) up to the end of the study (week 24). Furthermore, delayed neuroprotection was detected in the contralateral eye. Brimonidine was detected in treated rat eyes for up to 6 months. Brimonidine-LAPONITE® seems to be a potential sustained-delivery intravitreal drug for glaucoma treatment.

Ion Exchange Controlled Drug Release from Polymerized Ionic Liquids

In this work ion functionalized hydrogels as potent drug delivery systems are presented. The ion functionalization of the hydrogel enables the retention of ionic drug molecules and thus a reduction of burst release effects. Timolol maleate in combination with polymerized anionic 3-sulfopropylmethacrylate potassium and ibuprofen combined with cationic poly-[2-(methacryloyloxy)ethyl] trimethylammonium chloride are investigated in respect to their drug release profile. The results are showing an ion exchange depending release behavior instead of a diffusion-controlled drug release as it is known from common drug delivery systems. Furthermore, the suitability of such hydrogels for standard methods for sterilization is investigated.

MOF-Based Polymeric Nanocomposite Films as Potential Materials for Drug Delivery Devices in Ocular Therapeutics

Novel MOF-based polymer nanocomposite films were successfully prepared using Zr-based UiO-67 as a metal-organic framework (MOF) and polyurethane (PU) as a polymeric matrix. Synchrotron X-ray powder diffraction (SXRPD) analysis confirms the improved stability of the UiO-67 embedded nanocrystals, and scanning electron microscopy images confirm their homogeneous distribution (average crystal size ∼100-200 nm) within the 50 μm thick film. Accessibility to the inner porous structure of the embedded MOFs was completely suppressed for N₂ at cryogenic temperatures. However, ethylene adsorption measurements at 25 °C confirm that at least 45% of the MOF crystals are fully accessible for gas-phase adsorption of nonpolar molecules. Although this partial blockage limits the adsorption performance of the embedded MOFs for ocular drugs (e.g., brimonidine tartrate) compared to the pure MOF, an almost 60-fold improvement in the adsorption capacity was observed for the PU matrix after incorporation of the UiO-67 nanocrystals. The UiO-67@PU nanocomposite exhibits a prolonged release of brimonidine (up to 14 days were quantified). Finally, the combined use of SXRPD, thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR) analyses confirmed the presence of the drug in the nanocomposite film, the stability of the MOF framework and the drug upon loading, and the presence of brimonidine in an amorphous phase once adsorbed. These results open the gate toward the application of these polymeric nanocomposite films for drug delivery in ocular therapeutics, either as a component of a contact lens, in the composition of lacrimal stoppers (e.g., punctal plugs), or in subtenon inserts.

An injectable recombinant human milk fat globule-epidermal growth factor 8-loaded copolymer system for spinal cord injury reduces inflammation through NF-κB and neuronal cell death

Spinal cord injury (SCI) is a common disease and a major cause of paralysis, carrying much burden around the world. Despite the progress made with growth factors therapy, the response rate of acute SCI treatment still remains unsatisfactory, due largely to complex and severe inflammatory reactions. Herein, we prepare a MFG-E8-loaded copolymer system-based anti-inflammation therapy for SCI treatment. It is shown that the MFG-E8-loaded copolymer system can decrease pro-inflammatory cytokine expression and neuron death. In a rat model of crush-caused SCI, the copolymer system shows significant therapeutic efficacy by ameliorating inflammation, decreasing fibrotic scar, promoting myelin regeneration and suppressing overall SCI severity.