A composite System Combining Self-Targeted Carbon Dots and Thermosensitive Hydrogels for Challenging Ocular Drug Delivery

Antioxidant Carbon Dots Nanozyme Loaded in Thermosensitive in situ Hydrogel System for Efficient Dry Eye Disease Treatment

Purpose

Dry eye disease (DED) is a multifactorial ocular surface disease with a rising incidence. Therefore, it is urgent to construct a reliable and efficient drug delivery system for DED treatment.

Methods

In this work, we loaded C-dots nanozyme into a thermosensitive in situ gel to create C-dots@Gel, presenting a promising composite ocular drug delivery system to manage DED.

Results

This composite ocular drug delivery system (C-dots@Gel) demonstrated the ability to enhance adherence to the corneal surface and extend the ocular surface retention time, thereby enhancing bioavailability. Furthermore, no discernible ocular surface irritation or systemic toxicity was observed. In the DED mouse model induced by benzalkonium chloride (BAC), it was verified that C-dots@Gel effectively mitigated DED by stabilizing the tear film, prolonging tear secretion, repairing corneal surface damage, and augmenting the population of conjunctival goblet cells.

Conclusion

Compared to conventional dosage forms (C-dots), the C-dots@Gel could prolong exhibited enhanced retention time on the ocular surface and increased bioavailability, resulting in a satisfactory therapeutic outcome for DED.

Advancing glioblastoma imaging: Exploring the potential of organic fluorophore-based red emissive carbon dots

Over time, the interest in developing stable photosensitizers (PS) which both absorb and emit light in the red region (650 and 950 nm) has gained noticeable interest. Recently, carbon dots (CDs) have become the material of focus to act as a PS due to their high extinction coefficient, low cytotoxicity, and both high photo and thermal stability. In this work, a Federal and Drug Association (FDA) approved Near Infra-Red (NIR) organic fluorophore used for photo-imaging, indocyanine green (ICG), has been explored as a precursor to develop water-soluble red emissive CDs which possess red emission at 697 nm. Furthermore, our material was found to yield favorable red-imaging capabilities of glioblastoma stem-like cells (GSCs) meanwhile boasting low toxicity. Additionally with post modifications, our CDs have been found to have selectivity towards tumors over healthy tissue as well as crossing the blood-brain barrier (BBB) in zebrafish models.

Mitigation of pesticide-mediated ocular toxicity via nanotechnology-based contact lenses: a review

The xenobiotic stress exerted by pesticides leads to the deterioration of human and animal health including ocular health. Acute or prolonged exposure to these agricultural toxicants has been implicated in a number of pathological conditions of the eye such as irritation, epiphora or hyper-lacrimation, abrasions on the ocular surface, and decreased visual acuity. The issue is compounded by the fact that tissues of the eye absorb pesticides faster than other organs of the body and are more susceptible to damage as well. However, there is a lacuna in our knowledge regarding the ways by which pesticide exposure-mediated ocular insult might be counteracted. Topical instillation of drugs known to combat the pesticide induced toxicity has been explored to mitigate the detrimental impact of pesticide exposure. However, topical eye drop solutions exhibit very low bioavailability and limited drug residence duration in the tear film decreasing their efficacy. Contact lenses have been explored in this respect to increase bioavailability of ocular drugs, while nanoparticles have lately been utilized to increase drug bioavailability and increase drug residence duration in different tissues. The current review focuses on drug delivery and futuristic aspects of corneal protection from ocular toxicity using contact lenses.

Progress in drug delivery and diagnostic applications of carbon dots: a systematic review

Carbon dots (CDs), which have particle size of less than 10 nm, are carbon-based nanomaterials that are used in a wide range of applications in the area of novel drug delivery in cancer, ocular diseases, infectious diseases, and brain disorders. CDs are biocompatible, eco-friendly, easy to synthesize, and less toxic with excellent chemical inertness, which makes them very good nanocarrier system to deliver multi-functional drugs effectively. A huge number of researchers worldwide are working on CDs-based drug delivery systems to evaluate their versatility and efficacy in the field of pharmaceuticals. As a result, there is a tremendous increase in our understanding of the physicochemical properties, diagnostic and drug delivery aspects of CDs, which consequently has led us to design and develop CDs-based theranostic system for the treatment of multiple disorders. In this review, we aim to summarize the advances in application of CDs as nanocarrier including gene delivery, vaccine delivery and antiviral delivery, that has been carried out in the last 5 years.

In Vitro and Ex Vivo Models for Assessing Drug Permeation across the Cornea

Drug permeation across the cornea remains a major challenge due to its unique and complex anatomy and physiology. Static barriers such as the different layers of the cornea, as well as dynamic aspects such as the constant renewal of the tear film and the presence of the mucin layer together with efflux pumps, all present unique challenges for effective ophthalmic drug delivery. To overcome some of the current ophthalmic drug limitations, the identification and testing of novel drug formulations such as liposomes, nanoemulsions, and nanoparticles began to be considered and widely explored. In the early stages of corneal drug development reliable in vitro and ex vivo alternatives, are required, to be in line with the principles of the 3Rs (Replacement, Reduction, and Refinement), with such methods being in addition faster and more ethical alternatives to in vivo studies. The ocular field remains limited to a handful of predictive models for ophthalmic drug permeation. In vitro cell culture models are increasingly used when it comes to transcorneal permeation studies. Ex vivo models using excised animal tissue such as porcine eyes are the model of choice to study corneal permeation and promising advancements have been reported over the years. Interspecies characteristics must be considered in detail when using such models. This review updates the current knowledge about in vitro and ex vivo corneal permeability models and evaluates their advantages and limitations.

Functional Carbon Quantum Dots for Ocular Imaging and Therapeutic Applications

Carbon quantum dots (CDs) are a class of emerging carbonaceous nanomaterials that have received considerable attention due to their excellent fluorescent properties, extremely small size, ability to penetrate cells and tissues, ease of synthesis, surface modification, low cytotoxicity, and superior water dispersion. In light of these properties, CDs are extensively investigated as candidates for bioimaging probes, efficient drug carriers, and disease diagnostics. Functionalized CDs represent a promising therapeutic candidate for ocular diseases. Here, this work reviews the potential use of functionalized CDs in the diagnosis and treatment of eye-related diseases, including the treatment of macular and anterior segment diseases, as well as targeting Aβ amyloids in the retina.

L-Arginine-Functionalized Carbon Dots with Enhanced Red Emission and Upregulated Intracellular L-Arginine Intake for Obesity Inhibition

Obesity is a major global health problem that significantly increases the risk of many other diseases. Herein, a facile method of suppressing lipogenesis and obesity using L-arginine-functionalized carbon dots (L-Arg@CDots) is reported. The prepared CDots with a negative surface charge form stronger bonds than D-arginine and lysine with L-Arg in water. The L-Arg@CDots in the aqueous solution offer a high photoluminescence quantum yield of 23.6% in the red wavelength region. The proposed L-Arg functionalization strategy not only protects the red emission of the CDots from quenching by water molecules but also enhances the intracellular uptake of L-Arg to reduce lipogenesis. Injection of L-Arg@CDots can reduce the body weight increase in ob/ob mice by suppressing their food intake and shrinking the white adipose tissue cells, thereby significantly inhibiting obesity.

Design and Optimization of In Situ Gelling Mucoadhesive Eye Drops Containing Dexamethasone

Poor bioavailability of eye drops is a well-known issue, which can be improved by increasing the residence time on the eye surface and the penetration of the active pharmaceutical ingredient (API). This study aims to formulate in situ gelling mucoadhesive ophthalmic preparations. To increase the residence time, the formulations were based on a thermosensitive polymer (Poloxamer 407 (P407)) and were combined with two types of mucoadhesive polymers. Dexamethasone (DXM) was solubilized by complexation with cyclodextrins (CD). The effect of the composition on the gel structure, mucoadhesion, dissolution, and permeability was investigated with 3³ full factorial design. These parameters of the gels were measured by rheological studies, tensile test, dialysis membrane diffusion, and in vitro permeability assay. The dissolution and permeability of the gels were also compared with DXM suspension and CD-DXM solution. The gelation is strongly determined by P407; however, the mucoadhesive polymers also influenced it. Mucoadhesion increased with the polymer concentration. The first phase of drug release was similar to that of the CD-DXM solution, then it became prolonged. The permeability of DXM was significantly improved. The factorial design helped to identify the most important factors, thereby facilitating the formulation of a suitable carrier for the CD-DXM complex.

Bibliometric analysis of articles on nanoemulsion and/or in-situ gel for ocular drug delivery system published during the 2011–2021 period

The bibliometric data were extracted from the Scopus database to investigate the conceptual framework of ocular nanoemulsion and/or in-situ gel drug delivery system using “ocular” AND “nanoemulsion” OR “in-situ gel” keywords. The data were evaluated with RStudio and VOSviewer program.

The results reveal that the publication trends tend to increase continually. India is the most impactful country, and the most constructive institution is Department of Pharmaceutics and Industrial Pharmacy, Faculty of Pharmacy, Cairo University. International Journal of Pharmaceutics is the top influential source. Ali A is the most prolific author. The title of the most impactful article was In-situ gelling systems based on Pluronic F127/Pluronic F68 formulations for ocular drug delivery”. “Controlled release” is the most popular keyword.

These results provide insights for stimulating research collaborations and revealing open issues of controlled-release ocular preparation to overcome an ocular barrier and enhance patient compliance.

Novel Gels: An Emerging Approach for Delivering of Therapeutic Molecules and Recent Trends

Gels are semisolid, homogeneous systems with continuous or discrete therapeutic molecules in a suitable lipophilic or hydrophilic three-dimensional network base. Innovative gel systems possess multipurpose applications in cosmetics, food, pharmaceuticals, biotechnology, and so forth. Formulating a gel-based delivery system is simple and the delivery system enables the release of loaded therapeutic molecules. Furthermore, it facilitates the delivery of molecules via various routes as these gel-based systems offer proximal surface contact between a loaded therapeutic molecule and an absorption site. In the past decade, researchers have potentially explored and established a significant understanding of gel-based delivery systems for drug delivery. Subsequently, they have enabled the prospects of developing novel gel-based systems that illicit drug release by specific biological or external stimuli, such as temperature, pH, enzymes, ultrasound, antigens, etc. These systems are considered smart gels for their broad applications. This review reflects the significant role of advanced gel-based delivery systems for various therapeutic benefits. This detailed discussion is focused on strategies for the formulation of different novel gel-based systems, as well as it highlights the current research trends of these systems and patented technologies.