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

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

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

Recent advances in photothermal nanomaterials for ophthalmic applications

The human eye, with its remarkable resolution of up to 576 million pixels, grants us the ability to perceive the world with astonishing accuracy. Despite this, over 2 billion people globally suffer from visual impairments or blindness, primarily because of the limitations of current ophthalmic treatment technologies. This underscores an urgent need for more advanced therapeutic approaches to effectively halt or even reverse the progression of eye diseases. The rapid advancement of nanotechnology offers promising pathways for the development of novel ophthalmic therapies. Notably, photothermal nanomaterials, particularly well-suited for the transparent tissues of the eye, have emerged as a potential game changer. These materials enable precise and controllable photothermal therapy by effectively manipulating the distribution of the thermal field. Moreover, they extend beyond the conventional boundaries of thermal therapy, achieving unparalleled therapeutic effects through their diverse composite structures and demonstrating enormous potential in promoting retinal drug delivery and photoacoustic imaging. This paper provides a comprehensive summary of the structure-activity relationship between the photothermal properties of these nanomaterials and their innovative therapeutic mechanisms. We review the latest research on photothermal nanomaterial-based treatments for various eye diseases. Additionally, we discuss the current challenges and future perspectives in this field, with a focus on enhancing global visual health.

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.

Construction of a thermosensitive gel based on hydroxypropyl-β-cyclodextrin/meloxicam inclusion complexes for improving meloxicam solubility and prolonging drug retention time in the cornea

The eyes are easily stimulated by external factors, which can cause inflammation. Anti-inflammatory drugs are usually used to inhibit the production of inflammatory factors. Many nonsteroidal anti-inflammatory drugs have been used for the eye, but due to the poor solubility of meloxicam, there are currently no marketed meloxicam preparations for the treatment of eye diseases. This article uses hydroxypropyl-β-CD (HP-β-CD) to encapsulate meloxicam and combined with thermosensitive gel to prepare an HP-β-CD/meloxicam inclusion complex eye thermosensitive gel, which can improved the water solubility of meloxicam and extend the retention time of the drug in the cornea, and achieve the goal of slow release through continuous dissolution. It not only has the advantages of convenient administration and accurate dosage of eye drops, but also overcomes the disadvantage of easy loss of eye drops, showing the advantages of long retention time and fewer administration times, and provides a basis for the development of other dosage forms of meloxicam.

Recent Advances in Ocular Drug Delivery: Insights into Lyotropic Liquid Crystals

Background/Objectives: This review examines the evolution of lyotropic liquid crystals (LLCs) in ocular drug delivery, focusing on their ability to address the challenges associated with traditional ophthalmic formulations. This study aims to underscore the enhanced bioavailability, prolonged retention, and controlled release properties of LLCs that significantly improve therapeutic outcomes. Methods: This review synthesizes data from various studies on both bulk-forming LLCs and liquid crystal nanoparticles (LCNPs). It also considers advanced analytical techniques, including the use of machine learning and AI-driven predictive modeling, to forecast the phase behavior and molecular structuring of LLC systems. Emerging technologies in biosensing and real-time diagnostics are discussed to illustrate the broader applicability of LLCs in ocular health. Results: LLCs are identified as pivotal in promoting targeted drug delivery across different regions of the eye, with specific emphasis on the tailored optimization of LCNPs. This review highlights principal categories of LLCs used in ocular applications, each facilitating unique interactions with physiological systems to enhance drug efficacy and safety. Additionally, novel applications in biosensing demonstrate LLCs' capacity to improve diagnostic processes. Conclusions: Lyotropic liquid crystals offer transformative potential in ocular drug delivery by overcoming significant limitations of conventional delivery methods. The integration of predictive technologies and biosensing applications further enriches the utility of LLCs, indicating a promising future for their use in clinical settings. This review points to continued advancements and encourages further research in LLC technology to maximize its therapeutic benefits.

Polysaccharides polymers for glaucoma treatment-a review

One of the major challenges in preventing glaucoma progression is patient compliance with medication regimens. Since conventional ophthalmic dosage forms have numerous limitations, researchers have been intensively working on developing polymers-based delivery systems for glaucoma drugs. Specifically, research and development efforts have increased using polysaccharide polymers such as sodium alginate, cellulose, β-cyclodextrin, hyaluronic acid, chitosan, pectin, gellan gum, galactomannans for sustained release to the eye to overcome treatment challenges, showing promise in improving drug release and delivery, patient experience, and treatment compliance. In the recent past, multiple research groups have successfully designed sustained drug delivery systems, promoting the efficacy as well as the feasibility of glaucoma drugs with single/combinations of polysaccharides to eliminate the drawbacks associated with the glaucoma treatment. Naturally available polysaccharides, when used as drug vehicles can increase the retention time of eye drops on the ocular surface, leading to improved drug absorption and bioavailability. Additionally, some polysaccharides can form gels or matrices that can release drugs slowly over time, providing sustained drug delivery and reducing the need for frequent dosing. Thus, this review aims to provide an overview of the pre-clinical and clinical studies of polysaccharide polymers applied for glaucoma treatment along with their therapeutic outcomes.

Oxidized Dextran/Chitosan Hydrogel Engineered with Tetrasulfide-Bridged Silica Nanoparticles for Postsurgical Treatment

Tumor recurrence and wound microbial infection after tumor excision are serious threats to patients. Thus, the strategy to supply a sufficient and sustained release of cancer drugs and simultaneously engineer antibacterial properties and satisfactory mechanical strength is highly desired for tumor postsurgical treatment. Herein, A novel double-sensitive composite hydrogel embedded with tetrasulfide-bridged mesoporous silica (4S-MSNs) is developed. The incorporation of 4S-MSNs into oxidized dextran/chitosan hydrogel network, not only enhances the mechanical properties of hydrogels, but also can increase the specificity of drug with dual pH/redox sensitivity, thereby allowing more efficient and safer therapy. Besides, 4S-MSNs hydrogel preserves the favorable physicochemical properties of polysaccharide hydrogel, such as high hydrophilicity, satisfactory antibacterial activity, and excellent biocompatibility. Thus, the prepared 4S-MSNs hydrogel can be served as an efficient strategy for postsurgical bacterial infection and inhibition of tumor recurrence.

Polymer-Based Self-Assembled Drug Delivery Systems for Glaucoma Treatment: Design Strategies and Recent Advances

Glaucoma has become the world's leading cause of irreversible blindness, and one of its main characteristics is high intraocular pressure. Currently, the non-surgical drug treatment scheme to reduce intraocular pressure is a priority method for glaucoma treatment. However, the complex and special structure of the eye poses significant challenges to the treatment effect and safety adherence of this drug treatment approach. To address these challenges, the application of polymer-based self-assembled drug delivery systems in glaucoma treatment has emerged. This review focuses on the utilization of polymer-based self-assembled structures or materials as important functional and intelligent carriers for drug delivery in glaucoma treatment. Various drug delivery systems, such as eye drops, hydrogels, and contact lenses, are discussed. Additionally, the review primarily summarizes the design strategies and methods used to enhance the treatment effect and safety compliance of these polymer-based drug delivery systems. Finally, the discussion delves into the new challenges and prospects of employing polymer-based self-assembled drug delivery systems for the treatment of glaucoma.

Photothermal nanohybrid hydrogels for biomedical applications

In the past decades, diseases such as wound infection, cancer, bone defect and osteoarthritis have constantly threatened the public health. However, the traditional treatment has many insufficiencies, such as high cost, easy recurrence and high biological toxicity. Hydrogel is a material with three-dimensional network structure, which has a series of advantages, such as injectability, self-heal ability, easy loading and controllability of drug release, and excellent biocompatibility. Therefore, it is extensively used in drug delivery, antibacterial, anti-cancer and other fields. However, the traditional hydrogels have the single performance, and therapeutic efficacy is often rely on the drugs loaded on them to cure diseases, which cannot achieve sustainable therapeutic effect. In order to solve this problem, photothermal nano hydrogel with photothermal agent (PTA) has become an ideal material due to its excellent physical and chemical properties. Photothermal nano hydrogels used in photothermal therapy (PTT) can exploit the photothermal effect of photothermal agent to increase local temperature and control the sol-gel phase transition behavior of hydrogels, so they are widely used in drug release, photothermal sterilization, photothermal inhibition of cancer cells and enhancement of bone repair. To sum up, this paper introduces the preparation of hydrogels with photothermal nanomaterials, and discusses their applications in the fields of drug release, photothermal sterilization, photothermal cancer cell inhibition and enhanced bone repair.

Glaucoma Treatment and Hydrogel: Current Insights and State of the Art

Aqueous gels formulated using hydrophilic polymers (hydrogels) and those based on stimuli-responsive polymers (in situ gelling or gel-forming systems) attract increasing interest in the treatment of several eye diseases. Their chemical structure enables them to incorporate various ophthalmic medications, achieving their optimal therapeutic doses and providing more clinically relevant time courses (weeks or months as opposed to hours and days), which will inevitably reduce dose frequency, thereby improving patient compliance and clinical outcomes. Due to its chronic course, the treatment of glaucoma may benefit from applying gel technologies as drug-delivering systems and as antifibrotic treatment during and after surgery. Therefore, our purpose is to review current applications of ophthalmic gelling systems with particular emphasis on glaucoma.

Mussel-Inspired Microgel Encapsulated NLRP3 Inhibitor as a Synergistic Strategy Against Dry Eye

The inflammatory response mediated by oxidative stress is the main pathogenesis of dry eye, but clinical observations have shown that scavenging oxygen-free radicals alone has limited therapeutic effect. Moreover, the unique anatomy and physiology of the ocular surface result in low bioavailability of drugs, and higher concentration is required to achieve the desired efficacy, which, however, may bring systemic side effects. These problems pose a challenge, but the revelation of the ROS-NLRP3-IL-1β signaling axis opens up new possibilities. In this investigation, an NLRP3 inhibitor was successfully encapsulated in polydopamine-based microgels and used for dry eye treatment. It was demonstrated that the well-designed microgels exhibited good biocompatibility, prolonged drug retention time on the ocular surface, and effective inhibition of corneal epithelial damage and cell apoptosis. In addition, due to the synergistic effect, the NLRP3 inhibitor–loaded microgels could exert enhanced oxygen radical scavenging and inflammation-inhibiting effects at a lower dose than monotherapy. These findings suggest that polydopamine-based microgels have advantages as ocular surface drug delivery platforms and have promising applications in oxidative damage–related inflammatory diseases in synergy with anti-inflammatory drugs.

Tubular chitosan hydrogels with a tuneable lamellar structure programmed by electrical signals

The discovery of facile methods to create complex lamellar structures in hydrogels, which mimic the exquisite structures in nature, remains a great challenge. In this work, an ordered lamellar structured hydrogel from the stimuli-responsive amino-polysaccharide chitosan is fabricated by an electro-assembly process, during which the diffusion of OH^- and the electrophoresis of the chitosan chains play important roles. Importantly, a complex ordered/disordered structure of chitosan hydrogel can be regulated with high fidelity by programming the input electrical signals.

Current situation and progress of drugs for reducing intraocular pressure

Glaucoma, the most common cause of irreversible blindness worldwide, usually causes characteristic optic nerve damage. Pathological intraocular pressure (IOP) elevation is a major risk factor. Drug reduction of IOP is the preferred treatment for clinicians because it can delay the progression of disease. However, the traditional IOP-lowering drugs currently used by patients may be poorly tolerated. Therefore, in recent years, some new drugs have been put into clinical application or in clinical phase I–III studies. They have a better IOP-lowering effect and fewer adverse reactions. Because glaucoma is a chronic disease, drugs need to be administered continuously for a long time. For patients, good compliance and high drug bioavailability have a positive effect on the prognosis of the disease. Therefore, clinicians and scientists have developed drug delivery systems to solve this complex problem. In addition, natural compounds and dietary supplements have a good effect of reducing IOP, and they can also protect the optic nerve through antioxidant action. We summarize the current traditional drugs, new drugs, sustained-release drug delivery systems, and complementary drugs and outline the mechanism of action and clinical effects of these drugs on glaucoma and their recent advances.