Development of a dual delivery of levofloxacin and prednisolone acetate via PLGA nanoparticles/ thermosensitive chitosan-based hydrogel for postoperative management: An in-vitro and ex-vivo study

Absorption enhancement strategies in chitosan-based nanosystems and hydrogels intended for ocular delivery: Latest advances for optimization of drug permeation

Ophthalmic diseases can be presented as acute diseases like allergies, ocular infections, etc., or chronic ones that can be manifested as a result of systemic disorders, like diabetes mellitus, thyroid, rheumatic disorders, and others. Chitosan (CS) and its derivatives have been widely investigated as nanocarriers in the delivery of drugs, genes, and many biological products. The biocompatibility and biodegradability of CS made it a good candidate for ocular delivery of many ingredients, including immunomodulating agents, antibiotics, ocular hypertension medications, etc. CS-based nanosystems have been successfully reported to modulate ocular diseases by penetrating biological ocular barriers and targeting and controlling drug release. This review provides guidance to drug delivery formulators on the most recently published strategies that can enhance drug permeation to the ocular tissues in CS-based nanosystems, thus improving therapeutic effects through enhancing drug bioavailability. This review will highlight the main ocular barriers to drug delivery observed in the nano-delivery system. In addition, the CS physicochemical properties that contribute to formulation aspects are discussed. It also categorized the permeation enhancement strategies that can be optimized in CS-based nanosystems into four aspects: CS-related physicochemical properties, formulation components, fabrication conditions, and adopting a novel delivery system like implants, inserts, etc. as described in the published literature within the last ten years. Finally, challenges encountered in CS-based nanosystems and future perspectives are mentioned.

Trends in sustainable chitosan-based hydrogel technology for circular biomedical engineering: A review

Eco-friendly materials have emerged in biomedical engineering, driving major advances in chitosan-based hydrogels. These hydrogels offer a promising green alternative to conventional polymers due to their non-toxicity, biodegradability, biocompatibility, environmental friendliness, affordability, and easy accessibility. Known for their remarkable properties such as drug encapsulation, delivery capabilities, biosensing, functional scaffolding, and antimicrobial behavior, chitosan hydrogels are at the forefront of biomedical research. This paper explores the fabrication and modification methods of chitosan hydrogels for diverse applications, highlighting their role in advancing climate-neutral healthcare technologies. It reviews significant scientific advancements and trends chitosan hydrogels focusing on cancer diagnosis, drug delivery, and wound care. Additionally, it addresses current challenges and green synthesis practices that support a circular economy, enhancing biomedical sustainability. By providing an in-depth analysis of the latest evidence on climate-neutral management, this review aims to facilitate informed decision-making and foster the development of sustainable strategies leveraging chitosan hydrogel technology. The insights from this comprehensive examination are pivotal for steering future research and applications in sustainable biomedical solutions.

In vitro and ex vivo models of microbial keratitis: Present and future

Microbial keratitis (MK) is an infection of the cornea, caused by bacteria, fungi, parasites, or viruses. MK leads to significant morbidity, being the fifth leading cause of blindness worldwide. There is an urgent requirement to better understand pathogenesis in order to develop novel diagnostic and therapeutic approaches to improve patient outcomes. Many in vitro, ex vivo and in vivo MK models have been developed and implemented to meet this aim. Here, we present current in vitro and ex vivo MK model systems, examining their varied design, outputs, reporting standards, and strengths and limitations. Major limitations include their relative simplicity and the perceived inability to study the immune response in these MK models, an aspect widely accepted to play a significant role in MK pathogenesis. Consequently, there remains a dependence on in vivo models to study this aspect of MK. However, looking to the future, we draw from the broader field of corneal disease modelling, which utilises, for example, three-dimensional co-culture models and dynamic environments observed in bioreactors and organ-on-a-chip scenarios. These remain unexplored in MK research, but incorporation of these approaches will offer further advances in the field of MK corneal modelling, in particular with the focus of incorporation of immune components which we anticipate will better recapitulate pathogenesis and yield novel findings, therefore contributing to the enhancement of MK outcomes.

Biopolymeric Innovations in Ophthalmic Surgery: Enhancing Devices and Drug Delivery Systems

The interface between material science and ophthalmic medicine is witnessing significant advances with the introduction of biopolymers in medical device fabrication. This review discusses the impact of biopolymers on the development of ophthalmic devices, such as intraocular lenses, stents, and various prosthetics. Biopolymers are emerging as superior alternatives due to their biocompatibility, mechanical robustness, and biodegradability, presenting an advance over traditional materials with respect to patient comfort and environmental considerations. We explore the spectrum of biopolymers used in ophthalmic devices and evaluate their physical properties, compatibility with biological tissues, and clinical performances. Specific applications in oculoplastic and orbital surgeries, hydrogel applications in ocular therapeutics, and polymeric drug delivery systems for a range of ophthalmic conditions were reviewed. We also anticipate future directions and identify challenges in the field, advocating for a collaborative approach between material science and ophthalmic practice to foster innovative, patient-focused treatments. This synthesis aims to reinforce the potential of biopolymers to improve ophthalmic device technology and enhance clinical outcomes.

Thermoresponsive in situ forming and self-healing double-network hydrogels as injectable dressings for silymarin/levofloxacin delivery for treatment of third-degree burn wounds

Our study aimed to introduce a novel double-cross-linked and thermoresponsive hydrogel with remarkable potential for accelerating third-degree burn wound healing. Burn injuries are recognized as challenging, critical wounds. Especially in third-degree burns, treatment is demanding due to extended wounds, irregular shapes, significant exudation, and intense pain during dressing changes. In this work, hydrogels made of zwitterionic chitosan and dialdehyde starch (ZCS and ZDAS) were created to deliver silymarine (SM) and levofloxacin (LEV). The hydrogels were effortlessly produced using dynamic Schiff base linkages and ionic interactions between ZCS and ZDAS at appropriate times. The pore uniformity, gel fraction, and commendable swelling properties can imply a suitable degree of Schiff base cross-link. The hydrogel demonstrated outstanding shape retention, and significant self-healing and flexibility abilities, enabling it to uphold its form even during bodily movements. After injecting biocompatible hydrogel on the wound, a notable acceleration in wound closure was observed on day 21 (98.1 ± 1.10 %) compared to the control group (75.1 ± 6.13 %), and histopathological analysis revealed a reduction of inflammation that can be linked to remarkable antioxidant and antibiotic properties. The results demonstrate the hydrogel's efficacy in promoting burn wound healing, making it a promising candidate for medical applications.

Injectable hydrogels embedded with chitosan nanoparticles coated with hyaluronic acid for sequential release of dual drugs

An effective treatment for some disease, such as the model disease acute retinal necrosis (ARN), requires a combination of different drugs which should be administered at a certain interval. The precise sequential and long-term drug release are the critical questions. In this work, the as-prepared chitosan nanoparticles (CS-NPs) coated with hyaluronic acid (HA) were embedded in the aldehyde β-cyclodextrin (ACD)/aminated hyaluronic acid (NHA) hydrogels to synthesize injectable hydrogels loaded with dual drugs named DEX-CS-NPs/GCV-Gel and HA-DEX-CS-NPs/GCV-Gel. In the first 24 h and 48 h, the releases of DEX from DEX-CS-NPs/GCV-Gel were 128.5 % and 82.8 % faster than those from HA-DEX-CS-NPs/GCV-Gel, respectively. There was no DEX released from HA-DEX-CS-NPs/GCV-Gel at the first 7 h, which has never been reported before, although some hydrogel systems loaded with different drugs release different drugs simultaneously at different rate which have been well studied. This is a good start of a precise sequence release. The composite hydrogels possessed appropriate rheology, gel time, degradation performance, and ideal cytocompatibility. The injectable hydrogel loaded with dual drugs presenting a precise sequential and long-term release has great potential in the treatment of diseases requiring combinations of drugs being released sequentially at different treating stages.

Applications and Recent Developments of Hydrogels in Ophthalmology

Hydrogels are a type of functional polymer material with a three-dimensional network structure composed of physically or chemically cross-linked polymers. All hydrogels have two common features: first, their structure contains a large number of hydrophilic groups; therefore, they have a high water content and can swell in water. Second, they have good regulation, and the physical and chemical properties of their cross-linked network can be changed by environmental factors and deliberate modification methods. In recent years, the application of hydrogels in ophthalmology has gradually attracted attention. By selecting an appropriate composition and cross-linking mode, hydrogels can be used in different fields for various applications, such as gel eye drops, in situ gel preparation, intravitreal injection, and corneal contact lenses. This Review provides a detailed introduction to the classification of hydrogels and their applications in glaucoma, vitreous substitutes, fundus diseases, corneal contact lenses, corneal diseases, and cataract surgery.

Thermo-Responsive Sol-Gel-Based Nano-Carriers Containing Terbinafine HCl: Formulation, In Vitro and Ex Vivo Characterization, and Antifungal Activity

The current research aims to create a sol-gel-based nanocarrier containing terbinafine formulated for transdermal delivery of the drug into the skin. Sol-gel-based nanocarriers were prepared via the cold method using poloxamer-188, poloxamer-407, and distilled water. The prepared formulation was examined for pH, gelation temperature, Fourier transform infrared spectrophotometer (FTIR) analysis, thermal stability analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), particle size analysis, zeta potential, and anti-microbial activity. The in-vitro drug release study of F1 was found to be 94%, which showed greater drug release as compared to F2 and F3. The pH of the formulation was found to be within the range applicable to the skin. The gelation temperature was detected at 28 °C. The SEM images of formulations have spotted various particles well-segregated from each other. Analysis of formulations showed a mean globule size diameter of 428 nm, zeta potential values of 0.04 mV, refractive index (1.329), and viscosity (5.94 cP). FTIR analysis confirmed various functional groups' presence in the prepared formulation. Thermal analysis has confirmed the stability of the drug within the prepared formulation. The growth of inhibition was found to be 79.2% in 60 min, which revealed that the prepared formulation has shown good permeation from the membrane. Hence, the sol-gel-based nanocarrier formulation of terbinafine was successfully developed and evaluated.

A New Era in Ocular Therapeutics: Advanced Drug Delivery Systems for Uveitis and Neuro-Ophthalmologic Conditions

The eye's intricate anatomical barriers pose significant challenges to the penetration, residence time, and bioavailability of topically applied medications, particularly in managing uveitis and neuro-ophthalmologic conditions. Addressing this issue, polymeric nano-based drug delivery systems (DDS) have surfaced as a promising solution. These systems enhance drug bioavailability in hard-to-reach target tissues, extend residence time within ocular tissues, and utilize biodegradable and nanosized polymers to reduce undesirable side effects. Thus, they have stimulated substantial interest in crafting innovative treatments for uveitis and neuro-ophthalmologic diseases. This review provides a comprehensive exploration of polymeric nano-based DDS used for managing these conditions. We discuss the present therapeutic hurdles posed by these diseases and explore the potential role of various biopolymers in broadening our treatment repertoire. Our study incorporates a detailed literature review of preclinical and clinical studies from 2017 to 2023. Owing to advancements in polymer science, ocular DDS has made rapid strides, showing tremendous potential to revolutionize the treatment of patients with uveitis and neuro-ophthalmologic disorders.

Weibull β value for the discernment of drug release mechanism of PLGA particles

Mathematical models are used to characterize and optimize drug release in drug delivery systems (DDS). One of the most widely used DDS is the poly(lactic-co-glycolic acid) (PLGA)-based polymeric matrix owing to its biodegradability, biocompatibility, and easy manipulation of its properties through the manipulation of synthesis processes. Over the years, the Korsmeyer-Peppas model has been the most widely used model for characterizing the release profiles of PLGA DDS. However, owing to the limitations of the Korsmeyer-Peppas model, the Weibull model has emerged as an alternative for the characterization of the release profiles of PLGA polymeric matrices. The purpose of this study was to establish a correlation between the n and β parameters of the Korsmeyer-Peppas and Weibull models and to use the Weibull model to discern the drug release mechanism. A total of 451 datasets describing the overtime drug release of PLGA-based formulations from 173 scientific articles were fitted to both models. The Korsmeyer-Peppas model had a mean Akaike Information Criteria (AIC) value of 54.52 and an n value of 0.42, while the Weibull model had a mean AIC of 51.99 and a β value of 0.55, and by using reduced major axis regression values, a high correlation was found between the n and β values. These results demonstrate the ability of the Weibull model to characterize the release profiles of PLGA-based matrices and the usefulness of the β parameter for determining the drug release mechanism.

Overview of Antimicrobial Biodegradable Polyester-Based Formulations

As the clinical complications induced by microbial infections are known to have life-threatening side effects, conventional anti-infective therapy is necessary, but not sufficient to overcome these issues. Some of their limitations are connected to drug-related inefficiency or resistance and pathogen-related adaptive modifications. Therefore, there is an urgent need for advanced antimicrobials and antimicrobial devices. A challenging, yet successful route has been the development of new biostatic or biocide agents and biomaterials by considering the indisputable advantages of biopolymers. Polymers are attractive materials due to their physical and chemical properties, such as compositional and structural versatility, tunable reactivity, solubility and degradability, and mechanical and chemical tunability, together with their intrinsic biocompatibility and bioactivity, thus enabling the fabrication of effective pharmacologically active antimicrobial formulations. Besides representing protective or potentiating carriers for conventional drugs, biopolymers possess an impressive ability for conjugation or functionalization. These aspects are key for avoiding malicious side effects or providing targeted and triggered drug delivery (specific and selective cellular targeting), and generally to define their pharmacological efficacy. Moreover, biopolymers can be processed in different forms (particles, fibers, films, membranes, or scaffolds), which prove excellent candidates for modern anti-infective applications. This review contains an overview of antimicrobial polyester-based formulations, centered around the effect of the dimensionality over the properties of the material and the effect of the production route or post-processing actions.

Research Progress of Bioinspired Nanostructured Systems for the Treatment of Ocular Disorders

How to enhance the bioavailability and prolong the residence time of drugs in the eye present the major barriers to traditional eye delivery. Nanotechnology has been widely used in ocular drug delivery systems because of its advantages of minimizing adverse reactions, decreasing the frequency of administration, prolonging the release time, and improving the bioavailability of the drug in the eye. As natural product-based nanostructured systems, bioinspired nanostructured systems have presented as less toxic, easy to prepare, and cost-effective and have potential application value in the field of nanotechnology. A systematic classification of bioinspired nanostructured systems based on their inspiration source and formulation and their brief applications in disease are presented here. A review of recent research progress of the bioinspired nanostructured systems for the treatment of the anterior and posterior segment of ocular disorders is then presented in detail. Finally, current challenges and future directions with regard to manufacturing bioinspired nanomaterials are provided.

Immune modulating nanoparticles for the treatment of ocular diseases

Ocular diseases are increasingly influencing people’s quality of life. Complicated inflammatory mechanisms involved in the pathogenic process of ocular diseases make inflammation-targeting treatment a potential therapeutic approach. The limited efficacy of conventional anti-inflammatory therapeutic strategies, caused by various objective factors, such as complex ocular biological barriers, and subjective factors, such as poor compliance, are promoting the development of new therapeutic methods. With the advantages of considerable tissue permeability, a controllable drug release rate, and selective tissue targeting ability, nanoparticles have successfully captured researchers’ attention and have become a research hotspot in treating ocular diseases. This review will focus on the advantages of nanosystems over traditional therapy, the anti-inflammation mechanisms of nanoparticles, and the anti-inflammatory applications of nanoparticles in different ocular diseases (ocular surface diseases, vitreoretinopathy, uveal diseases, glaucoma, and visual pathway diseases). Furthermore, by analyzing the current situation of nanotherapy and the challenges encountered, we hope to inspire new ideas and incentives for designing nanoparticles more consistent with human physiological characteristics to make progress based on conventional treatments. Overall, some progress has been made in nanoparticles for the treatment of ocular diseases, and nanoparticles have rather broad future clinical translation prospects.

Optimization and Characterization of Low-Molecular-Weight Chitosan-Coated Baicalin mPEG-PLGA Nanoparticles for the Treatment of Cataract

The present study was to evaluate the potential effectiveness of low-molecular-weight chitosan-coated baicalin methoxy poly(ethylene glycol)-poly(d,l-lactic-co-glycolic acid) (mPEG-PLGA) nanoparticles (BA LCH NPs) for the treatment of cataract. mPEG-PLGA NPs were optimized by the Box-Behnken design and the central composite design based on the encapsulation efficiency and drug loading. Then, the BA LCH NPs were characterized based on morphology, particle size, and zeta potentials. The analytical data of differential scanning calorimetry, X-ray diffraction, and transmission electron microscopy depicted the drug excipient compatibility. In vitro, we evaluated cell viability, cellular uptake, potential ocular irritation, transcorneal permeability, and the precorneal retention of BA LCH NPs. In vivo, the chronic selenium cataract model was selected to assess the therapeutic effect of BA LCH NPs. The size of BA LCH NPs was within the range from 148 to 219 nm and the zeta potential was 19-25 mV. Cellular uptake results showed that the fluorescence intensity of the preparations in each group increased with time, and the fluorescence intensity of the LCH NP group was significantly higher than that of the solution group. The optimized BA LCH NPs improved precorneal residence time without causing eye irritation and also showed a sustained release of BA through the cornea for effective management of cataract. Also, fluorescence tracking on the rabbit cornea showed increased corneal retention of the LCH NPs. In addition, the results of therapeutic efficacy demonstrated that BA LCH NPs can significantly reduce the content of malondialdehyde and enhanced the activities of catalase, superoxide dismutase, and glutathione peroxidase, which was comparable to positive control and better than the BA solution group. Thus, it can be inferred that the BA LCH NPs are a promising drug delivery system for enhancing the ophthalmic administration of BA to the posterior segment of the eye and improving cataract symptoms.

Polymeric Nanoparticles-Loaded Hydrogels for Biomedical Applications: A Systematic Review on In Vivo Findings

Clinically available medications face several hurdles that limit their therapeutic activity, including restricted access to the target tissues due to biological barriers, low bioavailability, and poor pharmacokinetic properties. Drug delivery systems (DDS), such as nanoparticles (NPs) and hydrogels, have been widely employed to address these issues. Furthermore, the DDS improves drugs’ therapeutic efficacy while reducing undesired side effects caused by the unspecific distribution over the different tissues. The integration of NPs into hydrogels has emerged to improve their performance when compared with each DDS individually. The combination of both DDS enhances the ability to deliver drugs in a localized and targeted manner, paired with a controlled and sustained drug release, resulting in increased drug therapeutic effectiveness. With the incorporation of the NPs into hydrogels, it is possible to apply the DDS locally and then provide a sustained release of the NPs in the site of action, allowing the drug uptake in the required location. Additionally, most of the materials used to produce the hydrogels and NPs present low toxicity. This article provides a systematic review of the polymeric NPs-loaded hydrogels developed for various biomedical applications, focusing on studies that present in vivo data.

Poly(lactic-co-glycolic) acid nanoparticles as a delivery system for fish oil in wound healing

The objective of the study was to design, synthetize and characterize poly(lactic-co-glycolic) acid (PLGA) nanoparticles (NPs) with entrapped fish oil (FO) for possible application in a cutaneous wound healing. Morphology of NPs was evaluated by transmission electron microscopy. Antimicrobial characteristics were tested using the disk diffusion method and plate count method, and cytotoxicity was evaluated by the MTT assay. Fish oil (y) was released from PLGA NPs within the time interval (x) of 96 h according to equation y = 6.2 + 0.914x. PLGA-FO NPs did not affect growth of Staphylococcus aureus or methicillin-resistant S. aureus (MRSA) strains. No cytotoxic effect of the tested NPs on the keratinocyte cell line was observed for concentration of 1 µg/ml. PLGA-FO NPs represent an interesting alternative for wound healing due to an excellent biocompatibility and unique release profile of FO, despite their lack of antimicrobial efficiency.

Chitosan-anthracene hydrogels as controlled stiffening networks

In this study, we report the synthesis of single and dual-crosslinked anthracene-functional chitosan-based hydrogels in the absence of toxic initiators. Single crosslinking was achieved through dimerization of anthracene, whereas dual-crosslinked hydrogel was formed through dimerization of anthracene and free radical photopolymerization of methacrylated-chitosan in the presence of non-toxic initiator riboflavin, a well-known vitamin B2. Both single and dual-crosslinked hydrogels were found to be elastic, as was determined through rheological analysis. We observed that the dual-crosslinked hydrogels exhibited higher Young's modulus than the single-crosslinked hydrogels, where the modulus for single and dual-crosslinked hydrogels were measured as 9.2 ± 1.0 kPa and 26 ± 2.8 kPa, respectively resulting in significantly high volume of cells in dual-crosslinked hydrogel (2.2 × 10⁷ μm³) compared to single-crosslinked (4.9 × 10⁶ μm³). Furthermore, we investigated the cytotoxicity of both hydrogels towards 3T3-J2 fibroblast cells through CellTiter-Glo assay. Finally, immunofluorescence staining was carried out to evaluate the impact of hydrogel modulus on cell morphology. This study comprehensively presents functionalization of chitosan with anthracene, uses nontoxic initiator riboflavin, modulates the degree of crosslinking through dimerization of anthracene and free radical photopolymerization, and further modulates cell behavior through the alterations of hydrogel properties.