Gel-Based Materials for Ophthalmic Drug Delivery

Controlled Release of Molecules to Enhance Cell Survival and Regeneration

Controlled release or controlled drug delivery comprises the set of techniques and approaches to improve bioavailability through improved safety and/or efficacy using a carrier material for the molecule of interest. The predictability and tunability of these carriers make them ideal for protection, localization, and sustained presentation of a wide range of therapeutics, including growth factors implicated in cell survival and regeneration. Here we provide a method for encapsulating epidermal growth factor in a degradable polymer matrix for delivery to the cornea. Additional notes are included to demonstrate the wide-ranging capabilities of such methods for other materials, therapeutic agents, and sites of action within the eye.

Recent advances and strategies for nanocarrier-mediated topical therapy and theranostic for posterior eye disease

Posterior eye disorders, such as age-related macular degeneration, diabetic retinopathy, and glaucoma, have a significant impact on human quality of life and are the primary cause of age-related retinal diseases among adults. There is a pressing need for innovative topical approaches to treat posterior eye disorders, as current methods often rely on invasive procedures with inherent risks. Limited success was attained in the realm of topical ophthalmic delivery through non-invasive means. Additionally, there exists a dearth of literature that delves into the potential of this approach for drug delivery and theranostic purposes, or that offers comprehensive design strategies for nanocarrier developers to surmount the significant physiological ocular barriers. This review offers a thorough and up-to-date state-of-the-art overview of 40 studies on therapeutic loaded nanocarriers and theranostic devices that, to the best of our knowledge, represent all successful works that reached posterior eye segments through a topical non-invasive administration. Most importantly, based on the successful literature studies, this review provides a comprehensive summary of the potential design strategies that can be implemented during nanocarrier development to overcome each ocular barrier.

Transforming Medicinal Oil into Advanced Gel: An Update on Advancements

The present study delves into the evolution of traditional Ayurvedic oil preparations through innovative strategies to develop advanced gel formulations, aiming at amplifying their therapeutic efficacy. Ayurvedic oils have a rich historical context in healing practices, yet their conversion into contemporary gel-based formulations represents a revolutionary approach to augment their medicinal potential. The primary objective of this transformation is to leverage scientific advancements and modern pharmaceutical techniques to enhance the application, absorption, and overall therapeutic impact of these traditional remedies. By encapsulating the essential constituents of Ayurvedic oils within gel matrices, these novel strategies endeavor to improve their stability, bioavailability, and targeted delivery mechanisms. This review highlights the fusion of traditional Ayurvedic wisdom with cutting-edge pharmaceutical technology, paving the way for more effective and accessible utilization of these revered remedies in modern healthcare.

Advancements in Regenerative Hydrogels in Skin Wound Treatment: A Comprehensive Review

This state-of-the-art review explores the emerging field of regenerative hydrogels and their profound impact on the treatment of skin wounds. Regenerative hydrogels, composed mainly of water-absorbing polymers, have garnered attention in wound healing, particularly for skin wounds. Their unique properties make them well suited for tissue regeneration. Notable benefits include excellent water retention, creating a crucially moist wound environment for optimal healing, and facilitating cell migration, and proliferation. Biocompatibility is a key feature, minimizing adverse reactions and promoting the natural healing process. Acting as a supportive scaffold for cell growth, hydrogels mimic the extracellular matrix, aiding the attachment and proliferation of cells like fibroblasts and keratinocytes. Engineered for controlled drug release, hydrogels enhance wound healing by promoting angiogenesis, reducing inflammation, and preventing infection. The demonstrated acceleration of the wound healing process, particularly beneficial for chronic or impaired healing wounds, adds to their appeal. Easy application and conformity to various wound shapes make hydrogels practical, including in irregular or challenging areas. Scar minimization through tissue regeneration is crucial, especially in cosmetic and functional regions. Hydrogels contribute to pain management by creating a protective barrier, reducing friction, and fostering a soothing environment. Some hydrogels, with inherent antimicrobial properties, aid in infection prevention, which is a crucial aspect of successful wound healing. Their flexibility and ability to conform to wound contours ensure optimal tissue contact, enhancing overall treatment effectiveness. In summary, regenerative hydrogels present a promising approach for improving skin wound healing outcomes across diverse clinical scenarios. This review provides a comprehensive analysis of the benefits, mechanisms, and challenges associated with the use of regenerative hydrogels in the treatment of skin wounds. In this review, the authors likely delve into the application of rational design principles to enhance the efficacy and performance of hydrogels in promoting wound healing. Through an exploration of various methodologies and approaches, this paper is poised to highlight how these principles have been instrumental in refining the design of hydrogels, potentially revolutionizing their therapeutic potential in addressing skin wounds. By synthesizing current knowledge and highlighting potential avenues for future research, this review aims to contribute to the advancement of regenerative medicine and ultimately improve clinical outcomes for patients with skin wounds.

Application of Poloxamer for In Situ Eye Drop Modeling by Enrichment with Propolis and Balsam Poplar Buds Phenolic Compounds

In situ poloxamer-based gels are increasingly being explored as ocular drug delivery carriers to extend the release of active substances, thereby enhancing bioavailability. The objective of this study was to develop thermally stable in situ gels incorporating balsam poplar bud extract, propolis extract, and p-coumaric acid solution and to evaluate the physicochemical parameters of these gelified eye drops. This research assessed the compatibility of poloxamer-based eye drops with active components, their physicochemical properties, stability post-sterilization and during storage, and the release profiles of the active compounds. Fifteen eye drop formulations were prepared and categorized into three groups based on active components. One of the active components was propolis extract. As an alternative to propolis, eye drops containing the plant precursor, balsam poplar bud extract, were developed. The third group's active component was p-coumaric acid, a dominant phenolic acid in propolis and balsam poplar bud extracts. The study reported phenolic contents of 76.63 CAE mg/g for propolis and 83.25 CAE mg/g for balsam poplar bud aqueous extracts, with balsam poplar bud extracts showing higher SPF values (14.0) compared to propolis (12.7), while p-coumaric acid solution exhibited the highest SPF values (25.5). All eye drops were transparent, with pH values meeting the requirements for ocular drops. Formulations containing 8-10% poloxamer 407 met the criteria for in situ gels. All formulations remained stable for 90 days. Conclusion: The study results indicate that the formulated gels possess suitable physicochemical properties, are resistant to applied autoclaving conditions, and exhibit an extended release of active compounds with an increase in poloxamer content.

Overview of processed excipients in ocular drug delivery: Opportunities so far and bottlenecks

Ocular drug delivery presents a unique set of challenges owing to the complex anatomy and physiology of the eye. Processed excipients have emerged as crucial components in overcoming these challenges and improving the efficacy and safety of ocular drug delivery systems. This comprehensive overview examines the opportunities that processed excipients offer in enhancing drug delivery to the eye. By analyzing the current landscape, this review highlights the successful applications of processed excipients, such as micro- and nano-formulations, sustained-release systems, and targeted delivery strategies. Furthermore, this article delves into the bottlenecks that have impeded the widespread adoption of these excipients, including formulation stability, biocompatibility, regulatory constraints, and cost-effectiveness. Through a critical evaluation of existing research and industry practices, this review aims to provide insights into the potential avenues for innovation and development in ocular drug delivery, with a focus on addressing the existing challenges associated with processed excipients. This synthesis contributes to a deeper understanding of the promising role of processed excipients in improving ocular drug delivery systems and encourages further research and development in this rapidly evolving field.

Cypate-loaded hollow mesoporous Prussian blue nanoparticle/hydrogel system for efficient photodynamic therapy/photothermal therapy dual-modal antibacterial therapy

Infectious diseases caused by pathogenic microorganisms are a significant burden on public health and the economic stability of societies all over the world. The appearance of drug-resistant bacteria has severely blocked the effectiveness of conventional antibiotics. Therefore, developing novel antibiotic-free strategies to combat bacteria holds huge potential for maximizing validity and minimizing the risk of enhancing bacterial resistance. Herein, a cypate-loaded hollow mesoporous Prussian blue nanoparticles (Cy-HMPBs) was built to achieve the PDT/PTT synergistic antimicrobial therapy. The carbomer hydrogel (CH) was combined with the Cy-HMPBs to form a nanoparticle/hydrogel therapeutic system (Cy-HMPBs/CH) to reach the goal of local delivery of antimicrobial cargo. The low concentration of Cy-HMPBs/CH receives over 99% of antimicrobial ability against Escherichia coli and Staphylococcus aureus upon near-infrared (NIR) irradiation. More importantly, Cy-HMPBs/CH has favorable biocompatibility and can play therapeutic effects only after laser irradiation, indicating the on-demand therapy at the targeted region to avert side effects on healthy tissue. This study provides ideas for the design of an antibiotic-free antimicrobial strategy against infectious diseases.

Aflibercept Loaded Eye-Drop Hydrogel Mediated with Cell-Penetrating Peptide for Corneal Neovascularization Treatment

Corneal neovascularization (CoNV) is a major cause of visual impairment worldwide. Currently, available treatment options have limited efficacy and are associated with adverse effects due to biological barriers and clearance mechanisms. To address this challenge, a novel topical delivery system is developed-Gel 2_1&Eylea-an aflibercept-loaded eye-drop hydrogel mediated with cell-penetrating peptide 1. Gel 2_1&Eylea demonstrates superior membrane permeability, increased stability, and prolonged drug retention time on the ocular surface, and thus may improve drug efficacy. In a rabbit CoNV model, Gel 2_1&Eylea significantly reduces the density of neovascularization with no adverse effects on normal corneoscleral limbal vessels, demonstrating high efficacy and biocompatibility. This work identifies a promising treatment for CoNV which has the potential to benefit other ocular neovascular diseases.

Factors affecting on in vitro release of miconazole from in situ ocular gel

The reason for conducting this study is to prolong release of miconazole in the ocular site of action by ocular-based gels (OBGs) formulations. The formulation factors affecting on the release from OBG should be studied using various gelling agents in various concentrations to achieve the improvement in retention and residence time in response to prolonged release. In this study, the formulations were prepared using carbopol 940, pectin, sodium alginate, poloxamer 407, and poly(methacrylic acid) at 0.5%, 1%, and 1.5% w/v, respectively. Hydroxypropyl methylcellulose E5 (HPMC E5) 1% was added as thickening agent/viscosity builder. The formulation containing carbopol 940, pectin and sodium alginate at 1.5% w/v, displayed a noticable improvement in viscosity, gelling capacity, and extended release for 7 h in comparison with the reference drug. Overall, the release showed that the sodium alginate with HPMC E5 form in situ gel which had longer time of release reach to 12 h compared with other polymers. the release of miconazole from the OBGs affected significantly by two factors includes gelling capacity and viscosity builder. The novelty of this study is supporting the delivery of ocular drugs through a cornea as an important key of the eye instead of dependence on an internal blood supply using an oral or a parental administration.

QbD Design, Formulation, Optimization and Evaluation of Trans-Tympanic Reverse Gelatination Gel of Norfloxacin: Investigating Gene-Gene Interactions to Enhance Therapeutic Efficacy

Traditional otic drug delivery methods lack controlled release capabilities, making reverse gelatination gels a promising alternative. Reverse gelatination gels are colloidal systems that transition from a sol to a gel phase at the target site, providing controlled drug release over an extended period. Thermosensitive norfloxacin reverse gelatination gels were developed using a Quality by Design (QbD)-based optimization approach. The formulations were evaluated for their in vitro release profile, rheological behavior, visual appearance, pH, gelling time, and sol-gel transition temperature. The results show that the gelation temperatures of the formulations ranged from 33 to 37 °C, with gelling durations between 35 and 90 s. The drug content in the formulations was uniform, with entrapment efficiency ranging from 55% to 95%. Among the formulations, F10 exhibited the most favorable properties and was selected for a stability study lasting 60 days. Ex-vivo release data demonstrate that the F10 formulation achieved 95.6percentage of drug release at 360 min. This study successfully developed thermosensitive norfloxacin reverse gelatination gels using a QbD-based optimization approach. The selected formulation, F10, exhibited desirable properties in terms of gelling temperature, drug content, and release profile. These gels hold potential for the controlled delivery of norfloxacin in the treatment of ear infections.

Ophthalmic nano-bioconjugates: critical challenges and technological advances

Ophthalmic disease can cause permanent loss of vision and blindness. Easy-to-administer topical and systemic treatments are preferred for treating sight-threatening disorders. Typical ocular anatomy makes topical and systemic ophthalmic drug delivery challenging. Various novel nano-drug delivery approaches are developed to attain the desired bioavailability in the eye by increasing residence time and improved permeability across the cornea. The review focuses on novel methods that are biocompatible, safe and highly therapeutic. Novelty in nanocarrier design and modification can overcome their drawbacks and make them potential drug carriers for eye disorders in both the anterior and posterior eye segments. This review briefly discussed technologies, patented developments, and clinical trial data to support nanocarriers' use in ocular drug delivery.

Recent advancements in nanotechnology-based bacteriophage delivery strategies against bacterial ocular infections

Antibiotic resistance is growing as a critical challenge in a variety of disease conditions including ocular infections leading to disastrous effects on the human eyes. Staphylococcus aureus (S. aureus) mediated ocular infections are very common affecting different parts of the eye viz. vitreous chamber, conjunctiva, cornea, anterior and posterior chambers, tear duct, and eyelids. Blepharitis, dacryocystitis, conjunctivitis, keratitis, endophthalmitis, and orbital cellulitis are some of the commonly known ocular infections caused by S. aureus. Some of these infections are so fatal that they could cause bilateral blindness like panophthalmitis and orbital cellulitis, which is caused by methicillin-resistant S. aureus (MRSA) and vancomycin-resistance S. aureus (VRSA). The treatment of S. aureus infections with known antibiotics is becoming gradually difficult because of the development of resistance against multiple antibiotics. Apart from the different combinations and formulation strategies, bacteriophage therapy is growing as an effective alternative to treat such infections. Although the superiority of bacteriophage therapy is well established, yet physical factors (high temperatures, acidic pH, UV-rays, and ionic strength) and pharmaceutical barriers (poor stability, low in-vivo retention, controlled and targeted delivery, immune system neutralization, etc.) have the greatest influence on the viability of phage virions (also phage proteins). A variety of Nanotechnology based formulations such as polymeric nanoparticles, liposomes, dendrimers, nanoemulsions, and nanofibres have been recently reported to overcome the above-mentioned obstacles. In this review, we have compiled all these recent reports and discussed bacteriophage-based nanoformulations techniques for the successful treatment of ocular infections caused by multidrug-resistant S. aureus and other bacteria.

Trans-corneal drug delivery strategies in the treatment of ocular diseases

The cornea is a remarkable tissue that possesses specialized structures designed to safeguard the eye against foreign objects. However, its unique properties also make it challenging to deliver drugs in a non-invasive manner. This review highlights recent advancements in achieving highly efficient drug transport across the cornea, focusing on nanomaterials. We have classified these strategies into three main categories based on their mechanisms and have analyzed their success and limitations in a systematic manner. The purpose of this review is to examine potential general principles that could improve drug penetration through the cornea and other natural barriers in the eye. We hope it will inspire the development of more effective drug delivery systems that can better treat ocular diseases.

Structural Strategies for Supramolecular Hydrogels and Their Applications

Supramolecular structures are of great interest due to their applicability in various scientific and industrial fields. The sensible definition of supramolecular molecules is being set by investigators who, because of the different sensitivities of their methods and observational timescales, may have different views on as to what constitutes these supramolecular structures. Furthermore, diverse polymers have been found to offer unique avenues for multifunctional systems with properties in industrial medicine applications. Aspects of this review provide different conceptual strategies to address the molecular design, properties, and potential applications of self-assembly materials and the use of metal coordination as a feasible and useful strategy for constructing complex supramolecular structures. This review also addresses systems that are based on hydrogel chemistry and the enormous opportunities to design specific structures for applications that demand enormous specificity. According to the current research status on supramolecular hydrogels, the central ideas in the present review are classic topics that, however, are and will be of great importance, especially the hydrogels that have substantial potential applications in drug delivery systems, ophthalmic products, adhesive hydrogels, and electrically conductive hydrogels. The potential interest shown in the technology involving supramolecular hydrogels is clear from what we can retrieve from the Web of Science.

Intraocular delivery considerations of ocular biologic products and key preclinical determinations

INTRODUCTION

Ophthalmic diseases of the retina are a significant cause of vision loss globally. Despite much progress, there remains an unmet need for durable, long-acting treatment options. While biologic therapies show great promise, they present many challenges, including complexities in biochemical properties, mechanism of action, manufacturing considerations, preclinical evaluation, and delivery mechanism; these are confounded by the unique anatomy and physiology of the eye itself.

AREAS COVERED

This review describes the current development status of intravitreally administered drugs for the treatment of ophthalmic disease, outlines the range of approaches that can be considered for sustained drug delivery to the eye, and discusses key preclinical considerations for the evaluation of ocular biologics.

EXPERT OPINION

The required frequency of dosing in the eye results in a great burden on both patients and the health care system, with direct intraocular administration remaining the most reliable and predictable route. Sustained and controlled ophthalmic drug delivery systems will go a long way in reducing this burden. Sustained delivery can directly dose target tissues, improving bioavailability and reducing off-target systemic effects. Maintaining stability and activity of compounds can prevent aggregation and enable extended duration of release, while sustaining dosage and preventing residual polymer after drug depletion.

Urinary excretion patterns and potential risks of beta-blocker ophthalmic drops in sports

Beta-blockers have been prohibited by the World Anti-Doping Agency (WADA) in certain sports, but insufficient research data make it difficult to distinguish between therapeutic uses or misuses. This study aimed at investigating the urinary excretion pattern following beta-blocker ophthalmic drops and the potential risk of constituting an adverse analytical finding (AAF) in sports. Prescribed timolol and carteolol ophthalmic drops were used in healthy participants and glaucoma patients. The urine samples were then collected to investigate the urinary excretion pattern following acute and chronic administration of the above beta-blocker ophthalmic drops. The liquid chromatograph-tandem mass spectrometry method was applied for measuring urinary beta-blockers. Our results demonstrated that the levels of both urinary timolol and carteolol exceeded the minimum reporting levels (MRL) following acute and chronic administration. The highest levels of urinary timolol and carteolol observed in the present study were 255.7 and 923.8 ng/ml, respectively. Regarding the acute administration of timolol ophthalmic drop, 26.19 (11/42) of urine samples were detected with timolol higher than the MRL in timed and random sampling. In contrast, the acute administration of carteolol ophthalmic drops made the carteolol levels higher than the MRL among most urine samples. On the other hand, 36.36% (4/11) of urine samples were detected with beta-blockers higher than the MRL during the chronic administration of timolol and carteolol ophthalmic drops. In the context of receiving ophthalmic beta-blocker medications, the present study has highlighted the potential risk of constituting an AAF in specific sports and suggests strengthening athletes' awareness of therapeutic use exemptions.

Can We Structure Biomaterials to Spray Well Whilst Maintaining Functionality?

Structured fluid biomaterials, including gels, creams, emulsions and particle suspensions, are used extensively across many industries, including great interest within the medical field as controlled release vehicles to improve the therapeutic benefit of delivered drugs and cells. Colloidal forces within these materials create multiscale cohesive interactions, giving rise to intricate microstructures and physical properties, exemplified by increasingly complex mathematical descriptions. Yield stresses and viscoelasticity, typically arising through the material microstructure, vastly improve site-specific retention, and protect valuable therapeutics during application. One powerful application route is spraying, a convenient delivery method capable of applying a thin layer of material over geometrically uneven surfaces and hard-to-reach anatomical locations. The process of spraying is inherently disruptive, breaking a bulk fluid in successive steps into smaller elements, applying multiple forces over several length scales. Historically, spray research has focused on simple, inviscid solutions and dispersions, far from the complex microstructures and highly viscoelastic properties of concentrated colloidal biomaterials. The cohesive forces in colloidal biomaterials appear to conflict with the disruptive forces that occur during spraying. This review explores the physical bass and mathematical models of both the multifarious material properties engineered into structured fluid biomaterials and the disruptive forces imparted during the spray process, in order to elucidate the challenges and identify opportunities for rational design of sprayable, structured fluid biomaterials.

The Development and Evaluation of Phase Transition Microemulsion for Ocular Delivery of Acetazolamide for Glaucoma Treatment

The aim of this study was to develop microemulsion (ME) formulation with possible phase transition into liquid crystals upon ocular application to enhance acetazolamide bioavailability. Pseudoternary phase diagrams were constructed using olive oil or castor oil (oily phase), Tween 80 (surfactant), and sodium carbonate solution (aqueous phase). Microemulsion and liquid crystal (LC) formulations were selected from the constructed phase diagrams and were evaluated for rheological properties and in vitro drug release. The efficacy of the developed formulations in reducing intraocular pressure (IOP) was assessed in vivo. In vitro release study showed slower release rate from LC and ME compared with drug solution with the release from LC being the slowest. Ocular application of acetazolamide ME formulations or aqueous solution resulted in significant reduction in IOP from baseline. The recorded T_max values indicated faster onset of action for acetazolamide aqueous solution (1 h) compared with ME systems (3 h). However, the duration of action was prolonged and the reduction in IOP continued for up to 10 h in case of MEs, while that of aqueous solution was only for 4-5 h. The study suggested ME formulations for ocular delivery of acetazolamide with enhanced efficacy and prolonged duration of action.

Efficacy of Autologous Serum Gel in Neurotrophic Persistent Corneal Epithelial Defects Combined with Lagophthalmos

INTRODUCTION

To investigate the efficacy of autologous serum gel in patients with lagophthalmos combined with neurotrophic persistent corneal epithelial defects (PEDs).

METHODS

This is retrospective, case-series study enrolled 15 patients with lagophthalmos complicated by neurotrophic PEDs refractory to medical treatment including autologous serum eye drops. They were treated with autologous serum gel in conjunction with conservative treatment. The following information was collected from medical records: demographics, underlying diseases, and past ocular history. PEDs healing time was evaluated with visual acuity, visual analog scale (VAS) scores, esthesiometer scores, and the areas of the epithelial defects.

RESULTS

Six men and nine women with a mean age of 63.3 ± 9.9 years were included. The most common cause of the neurotrophic PEDs and lagophthalmos in this group was postherpetic infection (46.7%) and cerebral hemorrhage (26.7%) each. Two months following treatment with autologous serum gel, there was a reduction in the area of the epithelial defects (from 19.2 ± 9.9 to 0.6 ± 1.5 mm²) and a significant improvement in best-corrected visual acuity (BCVA) (from 0.8 ± 0.5 to 0.5 ± 0.4 logMAR) and VAS scores (from 5.1 ± 1.1 to 2.1 ± 0.6) in 13 eyes (87%). Among the 11 completely healed eyes, the mean epithelial healing time was 3.2 ± 1.8 weeks.

CONCLUSIONS

Autologous serum gel reduces symptoms and promotes corneal epithelialization of refractory neurotrophic PEDs in patients with lagophthalmos. Therefore, it may be well tolerated and a beneficial addition in the management of neurotrophic PEDs in patients with lagophthalmos.

Advances and Challenges in Intranasal Delivery of Antipsychotic Agents Targeting the Central Nervous System

Treatment of central nervous system (CNS) disorders is challenging using conventional delivery strategies and routes of administration because of the presence of the blood–brain barrier (BBB). This BBB restricts the permeation of most of the therapeutics targeting the brain because of its impervious characteristics. Thus, the challenges of delivering the therapeutic agents across the BBB to the brain overcoming the issue of insufficient entry of neurotherapeutics require immediate attention for recovering from the issues by the use of modern platforms of drug delivery and novel routes of administration. Therefore, the advancement of drug delivery tools and delivering these tools using the intranasal route of drug administration have shown the potential of circumventing the BBB, thereby delivering the therapeutics to the brain at a significant concentration with minimal exposure to systemic circulation. These novel strategies could lead to improved efficacy of antipsychotic agents using several advanced drug delivery tools while delivered via the intranasal route. This review emphasized the present challenges of delivering the neurotherapeutics to the brain using conventional routes of administration and overcoming the issues by exploring the intranasal route of drug administration to deliver the therapeutics circumventing the biological barrier of the brain. An overview of different problems with corresponding solutions in administering therapeutics via the intranasal route with special emphasis on advanced drug delivery systems targeting to deliver CNS therapeutics has been focused. Furthermore, preclinical and clinical advancements on the delivery of antipsychotics using this intranasal route have also been emphasized.

Hybrid thermosensitive-mucoadhesive in situ forming gels for enhanced corneal wound healing effect of L-carnosine

Purpose

Thermosensitive in situ gels have been around for decades but only a few have been translated into ophthalmic pharmaceuticals. The aim of this study was to combine the thermo-gelling polymer poloxamer 407 and mucoadhesive polymers chitosan (CS) and methyl cellulose (MC) for developing effective and long-acting ophthalmic delivery systems for L-carnosine (a natural dipeptide drug) for corneal wound healing.

Methods

The effect of different polymer combinations on parameters like gelation time and temperature, rheological properties, texture, spreading coefficients, mucoadhesion, conjunctival irritation potential, in vitro release, and ex vivo permeation were studied. Healing of corneal epithelium ulcers was investigated in a rabbit’s eye model.

Results

Both gelation time and temperature were significantly dependent on the concentrations of poloxamer 407 and additive polymers (chitosan and methyl cellulose), where it ranged from <10 s to several minutes. Mechanical properties investigated through texture analysis (hardness, adhesiveness, and cohesiveness) were dependent on composition. Promising spreading-ability, mucoadhesion, transcorneal permeation of L-carnosine, high ocular tolerability, and enhanced corneal epithelium wound healing were recorded for poloxamer 407/chitosan systems.

Conclusion

In situ gelling systems comprising combinations of poloxamer-chitosan exhibited superior gelation time and temperature, mucoadhesion, and rheological characteristics suitable for effective long-acting drug delivery systems for corneal wounds.

Applications of Chitosan-Alginate-Based Nanoparticles-An Up-to-Date Review

Chitosan and alginate are two of the most studied natural polymers that have attracted interest for multiple uses in their nano form. The biomedical field is one of the domains benefiting the most from the development of nanotechnology, as increasing research interest has been oriented to developing chitosan-alginate biocompatible delivery vehicles, antimicrobial agents, and vaccine adjuvants. Moreover, these nanomaterials of natural origin have also become appealing for environmental protection (e.g., water treatment, environmental-friendly fertilizers, herbicides, and pesticides) and the food industry. In this respect, the present paper aims to discuss some of the newest applications of chitosan-alginate-based nanomaterials and serve as an inception point for further research in the field.