Preparation of the Potential Ocular Inserts by Electrospinning Method to Achieve the Prolong Release Profile of Triamcinolone Acetonide

Nanofibers in Ocular Drug Targeting and Tissue Engineering: Their Importance, Advantages, Advances, and Future Perspectives

Nanofibers are frequently encountered in daily life as a modern material with a wide range of applications. The important advantages of production techniques, such as being easy, cost effective, and industrially applicable are important factors in the preference for nanofibers. Nanofibers, which have a broad scope of use in the field of health, are preferred both in drug delivery systems and tissue engineering. Due to the biocompatible materials used in their construction, they are also frequently preferred in ocular applications. The fact that they have a long drug release time as a drug delivery system and have been used in corneal tissue studies, which have been successfully developed in tissue engineering, stand out as important advantages of nanofibers. This review examines nanofibers, their production techniques and general information, nanofiber-based ocular drug delivery systems, and tissue engineering concepts in detail.

Formation of Hydrophilic Nanofibers from Nanostructural Design in the Co-Encapsulation of Celecoxib through Electrospinning

This study presents a method for a one-step co-encapsulation of PLGA nanoparticles in hydrophilic nanofibers. The aim is to effectively deliver the drug to the lesion site and achieve a longer release time. The celecoxib nanofiber membrane (Cel-NPs-NFs) was prepared by emulsion solvent evaporation and electrospinning with celecoxib as a model drug. By this method, nanodroplets of celecoxib PLGA are entrapped within polymer nanofibers during an electrospinning process. Moreover, Cel-NPs-NFs exhibited good mechanical strength and hydrophilicity, with a cumulative release of 67.74% for seven days, and the cell uptake at 0.5 h was 2.7 times higher than that of pure nanoparticles. Furthermore, pathological sections of the joint exhibited an apparent therapeutic effect on rat OA, and the drug was delivered effectively. According to the results, this solid matrix containing nanodroplets or nanoparticles could use hydrophilic materials as carriers to prolong drug release time.

Modified Potato Starch as a Potential Retardant for Prolonged Release of Lidocaine Hydrochloride from Methylcellulose Hydrophilic Gel

The problem of drug delivery often concentrates on the prolongation of drug activity. Application of natural polymers which are biodegradable and inexpensive is in the interest of many researchers. The aim of this study was the application of newly synthesized starch derivatives as potential functional excipients proposed for hydrophilic gel with lidocaine hydrochloride (LH) to prolong drug release from the hydrogel matrix. In our study, we investigated the effect of starch modified with citric acid on the release kinetics of LH using UV-VIS and Fourier-transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), as well as viscosity and pH measurements. We demonstrated the effectiveness of citric-acid-modified starch in prolonging the release of LH from methylcellulose gel.

Recent advancements in polymeric nanofibers for ophthalmic drug delivery and ophthalmic tissue engineering

Nanofibers due to their unique properties such as high surface-to-volume ratio, porous structure, mechanical strength, flexibility and their resemblance to the extracellular matrix, have been researched extensively in the field of ocular drug delivery and tissue engineering. Further, different modifications considering the formulation and process parameters have been carried out to alter the drug release profile and its interaction with the surrounding biological environment. Electrospinning is the most commonly used technique for preparing nanofibers with industrial scalability. Advanced techniques such as co-axial electrospinning and combined system such as embedding nanoparticles in nanofiber provide an alternative approach to enhance the performance of the scaffold. Electrospun nanofibers offers a matrix like structure for cell regeneration. Nanofibers have been used for ocular delivery of various drugs like antibiotics, anti-inflammatory and various proteins. In addition, lens-coated medical devices provide new insights into the clinical use of nanofibers. Through fabricating the nanofibers researchers have overcome the issues of low bioavailability and compatibility with ocular tissue. Therefore, nanofibers have great potential in ocular drug delivery and tissue engineering and have the capacity to revolutionize these therapeutic areas in the field of ophthalmology. This review is mainly focused on the recent advances in the preparation of nanofibers and their applications in ocular drug delivery and tissue engineering. The authors have attempted to emphasize the processing challenges and future perspectives along with an overview of the safety and toxicity aspects of nanofibers.

Eudragit® L100/Polyvinyl Alcohol Nanoparticles Impregnated Mucoadhesive Films as Ocular Inserts for Controlled Delivery of Erythromycin: Development, Characterization and In Vivo Evaluation

The fast elimination of drugs from the cornea is one of many challenges associated with the topical administration of conventional dosage forms. The present manuscript aimed to prepare modified-release inserts containing erythromycin (ERY) to enhance drug delivery and address the aforementioned limitation. Film formulations were developed using Eudragit^® L100 (EUD) and Polyvinyl Alcohol (PVA) polymers. ERY-loaded EUD-based nanoparticles were developed by the colloidal dispersion method using PVA as the emulsifier. The film-casting method was applied to form the mucoadhesive films using sodium alginate, gelatin, cyclodextrin-α, and β as polymeric film matrices. Different physicochemical properties of the optimized formulations and in vitro release profiles were evaluated. The in vivo evaluation was performed by collecting tear samples of rabbits using a novel, non-invasive method following the administration of inserts in the cul-de-sac. The ERY amount was assayed using a microbiological assay. The developed films showed prolonged in vitro and in vivo release profiles over five to six days; they had suitable physicochemical properties and a tensile strength of 2–3 MPa. All formulations exhibited antibacterial efficacy against E. coli and S. aureus with more than 20 mm diameter of inhibited growth zones. None of the formulations caused irritation to the rabbit’s eye. The inserts showed promising pharmacokinetics with AUC_0–120 of 30,000–36,000 µg·h/mL, a C_max of more than 1800 µg/mL at 4 h, and maintained drug concentration over the threshold of 5 µg/mL during the following 120 h of study. Nanoparticle-containing, mucoadhesive films could be fabricated as ocular inserts and can prolong the topical ocular delivery of ERY.

Polysaccharide-based nanofibers for pharmaceutical and biomedical applications: A review

Nanofibers are fibrous nanocarriers that can be synthesized from natural polymers, synthetic polymers, semiconducting materials, composite materials, and carbon-based materials. Recently, natural polysaccharides-based nanofibers are gaining attention in the field of pharmaceuticals and biomedical as these are biocompatible, biodegradable, non-toxic, and economic. Nanofibers can deliver a significant amount of drug to the targeted site and provide effective interaction of therapeutic agent at the site of action due to a larger surface area. Other important advantages of nanofibers are low density, high porosity, small pore size, high mechanical strength, and low cost. In this review, natural polysaccharides such as alginate, pullulan, hyaluronic acid, dextran, cellulose, chondroitin sulfate, chitosan, xanthan gum, and gellan gum are discussed for their characteristics, pharmaceutical utility, and biomedical applications. The authors have given particular emphasis to the several fabrication processes that utilize these polysaccharides to form nanofibers, and their recent updates in pharmaceutical applications such as drug delivery, tissue engineering, skin disorders, wound-healing dressings, cancer therapy, bioactive molecules delivery, anti-infectives, and solubility enhancement. Despite these many advantages, nanofibers have been explored less for their scale-up and applications in advanced therapeutic delivery.

Considerations for Polymers Used in Ocular Drug Delivery

PURPOSE

Age-related eye diseases are becoming more prevalent. A notable increase has been seen in the most common causes including glaucoma, age-related macular degeneration (AMD), and cataract. Current clinical treatments vary from tissue replacement with polymers to topical eye drops and intravitreal injections. Research and development efforts have increased using polymers for sustained release to the eye to overcome treatment challenges, showing promise in improving drug release and delivery, patient experience, and treatment compliance. Polymers provide unique properties that allow for specific engineered devices to provide improved treatment options. Recent work has shown the utilization of synthetic and biopolymer derived biomaterials in various forms, with this review containing a focus on polymers Food and Drug Administration (FDA) approved for ocular use.

METHODS

This provides an overview of some prevalent synthetic polymers and biopolymers used in ocular delivery and their benefits, brief discussion of the various types and synthesis methods used, and administration techniques. Polymers approved by the FDA for different applications in the eye are listed and compared to new polymers being explored in the literature. This article summarizes research findings using polymers for ocular drug delivery from various stages: laboratory, preclinical studies, clinical trials, and currently approved. This review also focuses on some of the challenges to bringing these new innovations to the clinic, including limited selection of approved polymers.

RESULTS

Polymers help improve drug delivery by increasing solubility, controlling pharmacokinetics, and extending release. Several polymer classes including synthetic, biopolymer, and combinations were discussed along with the benefits and challenges of each class. The ways both polymer synthesis and processing techniques can influence drug release in the eye were discussed.

CONCLUSION

The use of biomaterials, specifically polymers, is a well-studied field for drug delivery, and polymers have been used as implants in the eye for over 75 years. Promising new ocular drug delivery systems are emerging using polymers an innovative option for treating ocular diseases because of their tunable properties. This review touches on important considerations and challenges of using polymers for sustained ocular drug delivery with the goal translating research to the clinic.

In Situ Gelling Electrospun Ocular Films Sustain the Intraocular Pressure-Lowering Effect of Timolol Maleate: In Vitro, Ex Vivo, and Pharmacodynamic Assessment

Most common intraocular pressure (IOP) reduction regimens for the management of glaucoma include the topical use of eye drops, a dosage form that is associated with short residence time at the site of action, increased dosing frequency, and reduced patient compliance. In situ gelling nanofiber films comprising poly(vinyl alcohol) and Poloxamer 407 were fabricated via electrospinning for the ocular delivery of timolol maleate (TM), aiming to sustain the IOP-lowering effect of the β-blocker, compared to conventional eye drops. The electrospinning process was optimized, and the physicochemical properties of the developed formulations were thoroughly investigated. The fiber diameters of the drug-loaded films ranged between 123 and 145 nm and the drug content between 5.85 and 7.83% w/w. Total in vitro drug release from the ocular films was attained within 15 min following first-order kinetics, showing higher apparent permeability (P_app) values across porcine corneas compared to the drug's solution. The fabricated films did not induce any ocular irritation as evidenced by both the hen's egg test on chorioallantoic membrane and the in vivo Draize test. In vivo administration of the ocular films in rabbits induced a faster onset of action and a sustained IOP-lowering effect up to 24 h compared to TM solution, suggesting that the proposed ocular films are promising systems for the sustained topical delivery of TM.

Design of Novel Nanoemulsion Formulations for Topical Ocular Delivery of Itraconazole: Development, Characterization and In Vitro Bioassay

Purpose: The objective of this study was to design and develop nanoemulsion formulations of Itraconazole (ITZ), a water-insoluble, potent antifungal drug using the spontaneous emulsification method, to improve the ocular delivery and achieve a sustained release of the drug. Methods: The oil was selected on the basis of the ITZ solubility while the surfactant and co-surfactant were selected based on the thermodynamic stability and globule size. Following the selection of components, a pseudo-ternary phase diagram was constructed for the most promising formulation (F11) using benzyl benzoate (BB) as the oil, Eumulgin CO40 as the surfactant, and propylene glycol as the co-surfactant, by the design of experiments (DoE). Results: F7 and F11 formulations were found to have an average globule size of 223.5 ± 10.7 nm and 157.5 ± 14.2 nm, besides thermodynamic stability and suitable physicochemical properties. F11 possessed an almost seven-fold higher cumulative percentage of in vitro released ITZ, in comparison to ITZ aqueous suspension after 24 hours. The release data suggested that the best fitted kinetical model for F11 and F7 was the Higuchi and Korsmeyer-Peppas model. Conclusion: The extended-release of the drug beside an acceptable amount of loaded ITZ suggested that nanoemulsion is suitable for the delivery of the ITZ.

Preparation and functional evaluation of electrospun polymeric nanofibers as a new system for sustained topical ocular delivery of itraconazole

Due to the rapid clearance of external agents from the surface of the cornea, conventional ocular formulations usually require frequent and long duration of administration to achieve a therapeutic level of the drug on the cornea which can be conquered using prolonged-release nanofibrous inserts. In the present study, for the first time, polymeric nanofibers of itraconazole (ITZ), a potent triazole antifungal agent, were prepared as ocular inserts to enhance the topical ocular delivery of the drug. Three different nanofibers were prepared by electrospinning using polyvinyl alcohol-cellulose acetate and polycaprolactone-polyethylene glycol 12 000 polymeric blends. Nanofibers indicated uniform structures with the mean diameter ranging between 137 and 180 nm. Differential scanning calorimetry and Fourier-transform infrared spectroscopy confirmed the amorphous state of the drug in the formulations and the no drug-polymer interaction. Appropriate stability, suitable flexibility, and 2.2-3.9 MPa tensile strength were observed. Formulations indicated antifungal efficacy against Candida albicans and Aspergillus fumigatus and cell viability >70% at different concentrations. Results of bioassay against Candida albicans exhibited prolonged in vitro release of 50-70% of ITZ for almost 55 days. The results suggested that the nanofibers could be considered suitable for prolonged delivery of the ITZ as an antifungal requiring frequent and long duration of administration.

Preparation of triamcinolone acetonide-loaded chitosan/fucoidan hydrogel and its potential application as an oral mucosa patch

Oral inflammatory diseases (OIDs) are among the most common lesions in the oral cavity, affecting the quality of human life and even causing oral cancer. However, most of the current oral mucosa patches still have some limitations, particularly instant, poor mechanical strength and conformability, low adhesion to tissue, and foreign body sensation. Herein, triamcinolone acetonide (TA)-loaded chitosan/fucoidan (CF) composite hydrogels were prepared via chemical crosslinking. The macro/microscopic morphologies and (bio)physicochemical properties of composite hydrogels were investigated. Incorporating fucoidan in chitosan hydrogels greatly enhanced their swelling behavior, mechanical strength, and adhesion properties. Further, the addition of TA in CF hydrogels improved their elastic feature, inhibited inflammatory response, and promoted the formation of mature and well-organized collagen fibers. The developed composite hydrogels displayed not only good antibacterial properties but also good cytocompatibility and histocompatibility. Thus, the designed hydrogels allow the development of oral mucosa patches as a potential treatment for OIDs.

Enhanced topical corticosteroids delivery to the eye: A trade-off in strategy choice

Topical corticosteroids are the primary treatment of ocular inflammation caused by surgery, injury, or other conditions. Drug pre-corneal residence time, drug water solubility, and drug corneal permeability coefficient are the major factors that determine the ocular drug bioavailability after topical administration. Although growing research successfully enhanced local delivery of corticosteroids utilizing various strategies, rational and dynamic approaches to strategy selection are still lacking. Within this review, an overview of the various strategies as well as their performance in retention, solubility, and permeability coefficient of corticosteroids are provided. On this basis, the tradeoff of strategy selection is discussed, which may shed light on the rational choice and application of ophthalmic delivery enhancement strategies.

Recent advances in ophthalmic preparations: Ocular barriers, dosage forms and routes of administration

The human eye is a complex organ with unique anatomy and physiology that restricts the delivery of drugs to target ocular tissues/sites. Recent advances in the field of pharmacy, biotechnology and material science have led to development of novel ophthalmic dosage forms which can provide sustained drug delivery, reduce dosing frequency and improve the ocular bioavailability of drugs. This review highlights the different anatomical and physiological factors which affect ocular bioavailability of drugs and explores advancements from 2016 to 2020 in various ophthalmic preparations. Different routes of drug administration such as topical, intravitreal, intraocular, juxtascleral, subconjunctival, intracameral and retrobulbar are discussed with their advances and limitations.

A Systematic Review of Drug-Loaded Electrospun Nanofiber-Based Ophthalmic Inserts

Currently, ocular inserts and nanoparticles have received much attention due to the limited bioavailability of conventional eye preparations and the toxicity problems of systemic drug administration. The current systematic review aims to present recent studies on the use of electrospun nanofiber-based ocular inserts to improve the bioavailability of drugs used for different ophthalmic diseases. A systematic search was performed in PubMed, Ovid Medline, Web of Science, ScienceDirect, Scopus, Reaxys, Google Scholar, and Google Patents/Espacenet taking "drug-loaded", "nanofibers", and "ophthalmic inserts" and their equivalent terms as keywords. The search was limited to original and peer-reviewed studies published in 2011-2021 in English language. Only 13 out of 795 articles and 15 out of 197 patents were included. All results revealed the success of nanofiber-based ocular inserts in targeting and improved bioavailability. Ocular inserts based on nanofibers can be used as safe, efficient carriers for the treatment of anterior and posterior eye diseases.

Metronidazole- and Amoxicillin-Loaded PLGA and PCL Nanofibers as Potential Drug Delivery Systems for the Treatment of Periodontitis: In Vitro and In Vivo Evaluations

The purpose of this study was to prepare poly (D-L) lactide-co-glycolide (PLGA) and poly ε-caprolactone (PCL) nanofibers containing metronidazole and amoxicillin using an electrospinning process as intrapocket sustained-release drug delivery systems for the treatment of periodontal diseases. Scanning electron microscopy showed that the drug containing PLGA and PCL nanofibers produced from the electrospinning process was uniform and bead-free in morphology. The obtained nanofibers had a strong structure and resisted external tension according to the tensiometry results. The cytotoxicity results indicated acceptable cell viability (>80%). Quantification by high-performance liquid chromatography showed almost complete in vitro drug release between 7 and 9 days, whereas 14 days were required for complete drug release in vivo. No significant signs of irritation or inflammatory reaction were detected after three weeks of subcutaneous implantation of nanofibers in the animal models, thus indicating suitable compatibility. The results therefore suggest that the designed nanofibers can be used as potential commercial formulations in the treatment of periodontitis as controlled-release intrapocket drug delivery systems that can increase patient compliance. This is due to their ability to reduce the frequency of administration from three times daily in a systemic manner to once weekly as local delivery.

Design and Development of Antibacterial/Anti-inflammatory Dual Drug-Loaded Nanofibrous Inserts for Ophthalmic Sustained Delivery of Gentamicin and Methylprednisolone: In Vitro Bioassay, Solvent, and Method Effects’ Evaluation

Purpose: To overcome the challenges caused by the use of conventional ophthalmic dosage forms such as the fast elimination of the drug from the surface of the eye, in this study, dual drug-loaded nanofibers were developed for sustained ophthalmic delivery of gentamicin (GNT) and methylprednisolone (MP). Moreover, the solvent effects, polymer mixtures, and method of preparation on the release profile of the prepared nanofibers, were evaluated.

Methods: The nanofibers were prepared using polycaprolactone (PCL), poly (lactic-co-glycolic acid) (PLGA), and polyvinyl alcohol (PVA) using electrospinning technique. Thereafter, seven optimized formulations were developed with different solvent mixtures and polymer concentrations using various electrospinning methods. The physicochemical and mechanical properties of nanofibers were also evaluated, and the morphology of formulations was observed. The antibacterial efficacy was investigated and the in vitro release amounts of GNT and MP from nanofibers were estimated using the bioassay and ultraviolet-visible (UV-Vis) spectroscopy.

Results: The developed G1, G4, G5, G6, and G7 had suitable mechanical properties and morphologies with diameter ranging between 70-350 nm. The 1:1 v/v ratio of DMF/DCM in the solvent mixture and using core-shell technique for the preparation, formed nanofibers with more favorable release profiles. The optimized formulations indicated sustained-release manner for both drugs during 3-9 days and the antibacterial efficacy against Staphylococcus aureus.

Conclusion: Among all the prepared formulations, the nanofiber with core-shell structure possessed the best sustained-release profiles of GNT and MP. The obtained results suggest that these nanofibers have a potential to be used as an insert in the eye for long-term release of the drug.

Polyvinyl Alcohol/Chitosan Single-Layered and Polyvinyl Alcohol/Chitosan/Eudragit RL100 Multi-layered Electrospun Nanofibers as an Ocular Matrix for the Controlled Release of Ofloxacin: an In Vitro and In Vivo Evaluation

A novel nanofiber insert was prepared with a modified electrospinning method to enhance the ocular residence time of ofloxacin (OFX) and to provide a sustained release pattern by covering hydrophilic polymers, chitosan/polyvinyl alcohol (CS/PVA) nanofibers, with a hydrophobic polymer, Eudragit RL100 in layers, and by glutaraldehyde (GA) cross-linking of CS-PVA nanofibers for the treatment of infectious conjunctivitis. The morphology of the prepared nanofibers was studied using scanning electron microscopy (SEM). The average fiber diameter was found to be 123 ± 23 nm for the single electrospun nanofiber with no cross-linking (OFX-O). The single nanofibers, cross-linked for 10 h with GA (OFX-OG), had an average fiber diameter of 159 ± 30 nm. The amount of OFX released from the nanofibers was measured in vitro and in vivo using UV spectroscopy and microbial assay methods against Staphylococcus aureus, respectively. The antimicrobial efficiency of OFX formulated in cross-linked and non-cross-linked nanofibers was affirmed by observing the inhibition zones of Staphylococcus aureus and Escherichia coli. In vivo studies using the OFX nanofibrous inserts on a rabbit eye confirmed a sustained release pattern for up to 96 h. It was found that the cross-linking of the nanofibers by GA vapor could reduce the burst release of OFX from OFX-loaded CS/PVA in one layer and multi-layered nanofibers. In vivo results showed that the AUC_0–96 for the nanofibers was 9–20-folds higher compared to the OFX solution. This study thus demonstrates the potential of the nanofiber technology is being utilized to sustained drug release in ocular drug delivery systems.

In vitro and in vivo biological assessment of dual drug-loaded coaxial nanofibers for the treatment of corneal abrasion

The treatment of corneal abrasion currently involves the topical administration of antibiotics, with moxifloxacin HCl (0.5% w/v) eye drops being one of the most widely used treatments. Our previous work (Tawfik et al., 2020) involved the development of coaxial poly-lactic-co-glycolic acid (PLGA) and polyvinylpyrrolidone (PVP) nanofibers loaded with the antibiotic moxifloxacin HCl and the anti-scarring agent pirfenidone in the core (PVP) and shell (PLGA) respectively, with a view to the system comprising an ocular insert for the combination therapy of corneal abrasion. In this study, we examine the antimicrobial, anti-scarring and pharmacokinetic properties of the fibers alongside consideration of their toxicity and propensity for irritation. Minimum inhibitory concentration and zone of inhibition studies against S. aureus and P. aeruginosa were performed, while fibroblast cell viability and α-smooth muscle actin (α-SMA, a biomarker for scar formation) were measured using MTT and Western Blot assays, respectively. Pharmacokinetic studies and efficacy against infection were performed using a rabbit model, while ocular irritancy was assessed using the Draize test. The studies demonstrated that the antimicrobial activity of the moxifloxacin HCl was preserved following encapsulation into the nanofibers, while the downregulation of α-SMA was demonstrated using concentrations below the IC₂₀ values (concentration required to decrease corneal fibroblast viability by no more than 20%). The pharmacokinetic study showed retention and sustained release of the moxifloxacin HCl over a 24-hour period, in contrast to equivalent eye drops which required four times daily dosing. Evidence of low level (according to the MMTS scale) irritation was detected for the nanofiber systems. Overall, the study has demonstrated that the dual drug-loaded nanofiber system shows potential for once daily dosing as an ocular insert for the treatment of corneal abrasion.

Recent Biomedical Approaches for Chitosan Based Materials as Drug Delivery Nanocarriers

In recent decades, drug delivery systems (DDSs) based on nanotechnology have been attracting substantial interest in the pharmaceutical field, especially those developed based on natural polymers such as chitosan, cellulose, starch, collagen, gelatin, alginate and elastin. Nanomaterials based on chitosan (CS) or chitosan derivatives are broadly investigated as promising nanocarriers due to their biodegradability, good biocompatibility, non-toxicity, low immunogenicity, great versatility and beneficial biological effects. CS, either alone or as composites, are suitable substrates in the fabrication of different types of products like hydrogels, membranes, beads, porous foams, nanoparticles, in-situ gel, microparticles, sponges and nanofibers/scaffolds. Currently, the CS based nanocarriers are intensely studied as controlled and targeted drug release systems for different drugs (anti-inflammatory, antibiotic, anticancer etc.) as well as for proteins/peptides, growth factors, vaccines, small DNA (DNAs) and short interfering RNA (siRNA). This review targets the latest biomedical approaches for CS based nanocarriers such as nanoparticles (NPs) nanofibers (NFs), nanogels (NGs) and chitosan coated liposomes (LPs) and their potential applications for medical and pharmaceutical fields. The advantages and challenges of reviewed CS based nanocarriers for different routes of administration (oral, transmucosal, pulmonary and transdermal) with reference to classical formulations are also emphasized.

A Review on Ocular Novel Drug Delivery Systems of Antifungal Drugs: Functional Evaluation and Comparison of Conventional and Novel Dosage Forms

Ocular fungal infections affect more than one million people annually worldwide. They can lead to impaired vision or even complete blindness, so they should be treated immediately to prevent such consequences. Although topical administration has always been the most common route of ocular drug delivery owing to high patient acceptance, reduced side effects, and the possibility of self-administration, its limited ocular bioavailability poses a major challenge. As a result, attention has recently been drawn to the design and development of novel drug delivery systems (NDDS) that can overcome the challenges of conventional dosage forms. This research is the first to review and classify the studies which have designed and developed topical ocular NDDS with the aim to compare the performance and antifungal activity of these novel systems with conventional forms. According to the results, all studies seemed to confirm the superiority of NDDS over conventional forms in cases of released and permeated drug and antifungal activity. The NDDS were used specifically to improve ocular delivery by slowing down the release rate, increasing drug permeation, and subsequently increasing the antifungal effects of the active pharmaceutical ingredients. Hence, further studies on NDDS may aid the optimization of ocular drug delivery of antifungal drugs.

Polysaccharide-Based Nanomaterials for Ocular Drug Delivery: A Perspective

Ocular drug delivery is one of the most challenging issues in ophthalmology because of the complex physiological structure of the eye. Polysaccharide-based nanomaterials have been extensively investigated in recent years as ideal carriers for enhancing the bioavailability of drugs in the ocular system because of their biocompatibility and drug solubilization. From this perspective, we discuss the structural instability of polysaccharides and its impact on the synthesis process; examine the potential for developing bioactive polysaccharide-based ocular drug nanocarriers; propose four strategies for designing novel drug delivery nanomaterials; and suggest reviewing the behavior of nanomaterials in ocular tissues.

Chitosan and its Derivatives for Ocular Delivery Formulations: Recent Advances and Developments

Chitosan (CS) is a hemi-synthetic cationic linear polysaccharide produced by the deacetylation of chitin. CS is non-toxic, highly biocompatible, and biodegradable, and it has a low immunogenicity. Additionally, CS has inherent antibacterial properties and a mucoadhesive character and can disrupt epithelial tight junctions, thus acting as a permeability enhancer. As such, CS and its derivatives are well-suited for the challenging field of ocular drug delivery. In the present review article, we will discuss the properties of CS that contribute to its successful application in ocular delivery before reviewing the latest advances in the use of CS for the development of novel ophthalmic delivery systems. Colloidal nanocarriers (nanoparticles, micelles, liposomes) will be presented, followed by CS gels and lenses and ocular inserts. Finally, instances of CS coatings, aiming at conferring mucoadhesiveness to other matrixes, will be presented.

Recent Advances in Electrospun Sustainable Composites for Biomedical, Environmental, Energy, and Packaging Applications

Electrospinning has gained constant enthusiasm and wide interest as a novel sustainable material processing technique due to its ease of operation and wide adaptability for fabricating eco-friendly fibers on a nanoscale. In addition, the device working parameters, spinning solution properties, and the environmental factors can have a significant effect on the fibers' morphology during electrospinning. This review summarizes the newly developed principles and influence factors for electrospinning technology in the past five years, including these factors' interactions with the electrospinning mechanism as well as its most recent applications of electrospun natural or sustainable composite materials in biology, environmental protection, energy, and food packaging materials.

Dual drug-loaded coaxial nanofibers for the treatment of corneal abrasion

Corneal abrasion is a scratch wound on the surface of the anterior segment of the eye, which can predispose a patient to corneal infection and scarring, particularly if the cut penetrates to the deep corneal layers. Here we investigate a novel approach to co-administer an anti-scarring agent and an antibiotic, both being incorporated into one dosage form so as to accelerate wound closure and to treat any associated infection. More specifically, we have used electrospun fibers as a means of incorporating the two drugs into distinct compartments via coaxial electrospinning. Samples were characterised using a range of imaging, spectroscopic and thermal methods, while an HPLC assay has been developed to allow measurement of the concentration of both drug components in both the initial fibers and on release. Fibers loaded with pirfenidone in the hydrophobic polymer, PLGA, as the outer layer and moxifloxacin in the hydrophilic polymer PVP as the inner layer were successfully prepared, with smooth and non-porous surfaces and a mean diameter of circa 630 nm. TEM image demonstrated clear distinctive layers (a core and a shell), suggesting the successful preparation of the drug-loaded coaxial fibers, supported by HPLC entrapment studies, while fluorescence microscopy confirmed the presence of the moxifloxacin within the fibers. The fibers were capable of extending the release of both drugs, hence raising the possibility of a single daily dose of the drug-loaded coaxial fibers for the treatment of corneal abrasion.

Crosslinked Hyaluronan Electrospun Nanofibers for Ferulic Acid Ocular Delivery

Electrospun nanofibers are gaining interest as ocular drug delivery platforms that may adapt to the eye surface and provide sustained release. The aim of this work was to design an innovative ophthalmic insert composed of hyaluronan (HA) nanofibers for the dual delivery of an antioxidant (ferulic acid, FA) and an antimicrobial peptide (ε-polylysine, ε-PL). Polyvinylpyrrolidone (PVP) was added to facilitate the electrospinning process. Fibers with diameters of approx. 100 nm were obtained with PVP 5%-HA 0.8% w/v and PVP 10%-HA 0.5% w/v mixtures in ethanol:water 4:6 v/v. An increase in PVP concentration to 20% w/v in both presence and absence of HA rendered fibers of approx. 1 µm. PVP 5%-HA 0.8% w/v fibers were loaded with 83.3 ± 14.0 µg FA per mg. After nanofibers crosslinking with ε-PL, blank and FA-loaded inserts showed a mean thickness of 270 ± 21 µm and 273 ± 41 µm, respectively. Blank and FA-loaded inserts completely released ε-PL within 30 min under sink conditions, whereas FA-loaded inserts released the antioxidant within 20 min. Both blank and FA-loaded inserts were challenged against Pseudomonas aeruginosa and Staphylococcus aureus, demonstrating their efficacy against relevant microbial species.

Preparation and Evaluation of Eudragit® L100 Nanoparticles Loaded Impregnated with KT Tromethamine Loaded PVA -HEC Insertions for Ophthalmic Drug Delivery

Purpose: The purpose of the present study was to improve the ocular delivery for ketorolac tromethamine (KT) used to treat inflammation of the eye.

Methods: Eudragit nanoparticles loaded with KT were prepared and incorporated in polyvinyl alcohol (PVA) and hydroxyethyl cellulose (HEC) films. Nanoparticles were characterized by Fourier transform-infrared (FT-IR), scanning electron microscopy (SEM). Physicochemical properties and encapsulation effciency were investigated for nanoparticles. Also, the inserts were evaluated for their physiochemical parameters like percentage moisture absorption, percentage moisture loss, thickness and folding endurance.

Results: Mean particle size and zeta potential were in range of 153.8-217 nm and (-10.8) - (-40.7) mV, respectively. The results show that the use of a surfactant has not led to any major change on drug loading. The loading increases with the amount of polymer. The insert had a thickness varying from 0.072 ± 0.0098 to 0.0865 ± 0.0035 mm. The thicknesses of the inserts and the folding endurance increased with the total polymer concentration. The physicochemical properties showed that the Eudragit® L-100 nanoparticles loaded PVA-HEC films could be an effective carrier for KT.

Conclusion: For the first time, inserts of Eudragit nanoparticles were successfully prepared for ophthalmic drug delivery system to prevent frequent drug administration and enhance patient compliance.

Regenerative medicine and drug delivery: Progress via electrospun biomaterials

Worldwide research on electrospinning enabled it as a versatile technique for producing nanofibers with specified physio-chemical characteristics suitable for diverse biomedical applications. In the case of tissue engineering and regenerative medicine, the nanofiber scaffolds' characteristics are custom designed based on the cells and tissues specific needs. This fabrication technique is also innovated for the production of nanofibers with special micro-structure and secondary structure characteristics such as porous fibers, hollow structure, and core- sheath structure. This review attempts to critically and succinctly capture the vast number of developments reported in the literature over the past two decades. We then discuss their applications as scaffolds for induction of cells growth and differentiation or as architecture for being used as graft for tissue engineering. The special nanofibers designed for improving regeneration of several tissues including heart, bone, central nerve system, spinal cord, skin and ocular tissue are introduced. We also discuss the potential of the electrospinning in drug delivery applications, which is a critical factor for cell culture, tissue formation and wound healing applications.

Novel drug delivery methods for the treatment of keratitis: moving away from surgical intervention

Introduction: Corneal ulceration is one of the leading causes of blindness especially in low- and mid-income countries (LMICs). Surgical treatment of microbial keratitis is associated with multiple challenges that include non-availability of donor corneal tissues, lack of trained corneal surgeons, and poor compliance to follow up care. As a result, the surgery fails in 70-90% cases. Therefore, improving outcome of medical treatment and thereby avoiding the need for the surgery is an unmet need in the care of corneal ulcer cases.Areas covered: In this review article, the authors have tried to compile information on the novel drug-delivery systems that have potential to enhance success of medical management. We have discussed the following systems: cyclodextrins, gel formulations, colloidal system, nanoformulations, drug-eluting contact lens, microneedle patch, and ocular inserts.Expert opinion: The goals of corneal ulcer treatment are as follows: rapid eradication of causative microorganisms, control of damage from induced inflammation and microbial toxins, and facilitation of repair. The ocular surface anatomy poses several challenges for drug delivery using standard topical therapy. The novel drug-delivery systems mentioned above aim to enhanced tear solubility; superior stability; improved bio-availability; reduced toxicity; besides facilitating targeted drug delivery and convenience of administration.