Tobramycin-loaded nanoparticles of thiolated chitosan for ocular drug delivery: Preparation, mucoadhesion and pharmacokinetic evaluation

Enhanced ocular retention and intraocular pressure-lowering efficacy of hydrophobic microspheres for glaucoma treatment

Glaucoma eye drops often suffer from low bioavailability due to rapid drug release and poor ocular retention. This study aimed to address these challenges by developing betaxolol hydrochloride-loaded mesoporous silica polyacrylic resin microspheres (BH@MCM-41 MPs) and comparing their safety, ocular retention, and intraocular pressure (IOP)-lowering efficacy with previously reported betaxolol hydrochloride-loaded montmorillonite polyacrylic resin microspheres (BH@MMT MPs), BH solution, and commercially available Betoptic®. Both BH@MCM-41 MPs and BH@MMT MPs demonstrated sustained drug release over 12 h and good biocompatibility. The impact of physicochemical particle characteristics on micro-interactions with tear film mucins and corneal epithelial cells was investigated. BH@MCM-41 MPs exhibited significantly higher mucin-binding capacity compared to BH@MMT MPs, with approximately double the binding at mucin concentrations over 0.4 mg·mL-1. Rose Bengal assays indicated a more hydrophobic surface for BH@MCM-41 MPs, with a binding constant (K) of 88.51, compared to 69.84 for BH@MMT MPs. In addition, these positively charged microspheres demonstrated prolonged precorneal retention, with BH@MCM-41 MPs achieving 58.17 minutes, compared to 44.49 minutes for BH@MMT MPs. Tear pharmacokinetics further confirmed the extended precorneal residence time of these formulations. Ex vivo corneal permeation studies revealed that the hydrophobic surface of BH@MCM-41 MPs enhanced interaction with corneal epithelial cells, promoting drug release and permeation. The area under the IOP reduction curve (AUC0-36h) for BH@MCM-41 MPs was 1.2-fold greater than for BH@MMT MPs, and significantly higher than for the BH solution and Betoptic. These findings suggest that BH@MCM-41 MPs offer enhanced efficacy for sustained glaucoma treatment through improving precorneal retention.

Nanoparticles of quercetin-gellan gum conjugate for the controlled delivery of fluconazole

The aim of the study was to formulate the polymeric nanoparticles for the controlled delivery of fluconazole (FCZ) to enhance its absorption, mucosal adherence, and bioavailability. FCZ-loaded gellan gum-quercetin conjugate (GQC) nanoparticles (FCZ-loaded NGQ) were prepared by ionic gelatin method using GQC, surfactants, co-surfactants, and cross-linker. The nanoparticles were then characterized by various physical and chemical analytical tools such as 1H NMR, FTIR, XRD, DSC, TGA, particle size, zeta potential, and SEM analysis. All the nanoparticles have a nanosized range from 108 nm to 123 nm with a zeta potential of -12 mV to -20 mV which shows their stability. The NGQ3 (optimized formulation) loaded with FCZ have a PDI of 0.20 ± 0.02 and % entrapment efficiency of 32.3 ± 2.8 %. These studies also showed promising results of 85 % drug release, the value for zero order kinetics of R2 was 0.999, mucosal adherence of 24 h, and the highest values of permeation was shown by NGQ3 of 60 %. The improved antifungal activity of prepared NGQ3-DL against Candida albicans was observed compared to the pure drug. The nanoparticles may offer enhanced bioavailability and controlled release of FCZ, making them a potential breakthrough in managing FCZ resistant infections.

Recent progress in chitosan-based nanoparticles for drug delivery: a review on modifications and therapeutic potential

Chitosan, obtained from chitin by deacetylation, is a versatile biopolymer known for its biocompatibility, biodegradability and environmental friendliness. Combined with its chemical and physical modifiability, these properties have made chitosan an important material in biomedical and pharmaceutical fields, especially in drug delivery systems. Chitosan-based nanomaterials exhibit enhanced functions through various chemical modifications such as thiolation, acetylation, carboxylation and phosphorylation, as well as through physical and enzymatic approaches. These modifications address inherent limitations such as poor solubility, limited acid resistance and insufficient mechanical strength, expanding the applications of chitosan in tissue engineering, gene therapy, vaccine delivery, wound healing and bioimaging. This review provides an in-depth analysis of the chemical structure, physicochemical properties and modification strategies of chitosan. It also explores current methodologies for preparing chitosan nanoparticles, along with drug loading and release techniques. Various targeting strategies employed in chitosan-based delivery systems are examined in detail. To illustrate the clinical relevance of these approaches, representative examples from recent therapeutic studies are included. Moreover, it highlights future research directions and the innovation potential of chitosan-based materials.

Harnessing the immunomodulatory potential of chitosan and its derivatives for advanced biomedical applications

The success of biomaterial applications in medicine, particularly in tissue engineering, relies on achieving a balance between promoting tissue regeneration and controlling the immune response. Due to its natural origin, high biocompatibility, and versatility, chitosan has emerged as a promising biomaterial especially for immunomodulation purposes. Immunomodulation, refers to the deliberate alteration of the immune system's activity to achieve a desired therapeutic effect either by enhancing or suppressing the function of specific immune cells, signaling pathways, or cytokine production. This modulation opens up the unlimited possibilities for the use of biomaterials, especially about the use of natural polymers such as chitosan. Although numerous chitosan-based immunoregulatory strategies have been demonstrated over the past two decades, the lack of in-depth exploration hinders the full potential of strategies that include chitosan and its derivatives in biomedical applications. Thus, in this review, the possible immunomodulatory effects of chitosan, chitosan derivatives and their potential combined with various agents and therapies are investigated in detail. Moreover, this report includes agents for localized immune response control, chitosan-based strategies with complementary immunomodulatory properties to create synergistic effects that will influence the success of cell therapies for enhanced tissue acceptance and regeneration. Finally, the challenges and outlook of chitosan-based therapies as a powerful tool for improving immunomodulatory applications are discussed for paving the way for further studies.

Nanotechnology-based non-invasive strategies in ocular therapeutics: Approaches, limitations to clinical translation, and safety concerns

The eye is a highly sensitive and vital component that significantly affects human quality of life. Diseases that affect the eye are major contributors to visual impairment and blindness and can have a profound effect on an individual's well-being. Ocular drug delivery is challenging because of physiological and anatomical barriers. Invasive Intravitreal administration is primarily used for the treatment and management of posterior segmental disease. However, frequent intravitreal administration is associated with adverse effects. Furthermore, topical administration results in less than 5% ocular bioavailability, leading to a void in the safe and efficacious management of posterior segment diseases. Nanocarrier-based systems have been well explored as ocular therapeutics to overcome the sub-therapeutic management attributed to conventional eye drops and physiological and anatomical barriers. Since the first report of nanoparticles to date, the nanocarrier system has come a long way with the simplicity and versatility offered by the system. Significant progress has been made in the development of noninvasive nanocarrier systems and their interactions with the ocular surface. The nanocarrier system enhances precorneal retention, limits nontherapeutic absorption, and offers controlled drug release. This review aims to provide an overview of the recent advancements in noninvasive nanocarrier-based topical ocular drug delivery systems, including their interaction with the ocular surface, the barriers to their translation to clinical settings, and the associated scale-up challenges.

Topical Ocular Drug Delivery: The Impact of Permeation Enhancers

Topical ophthalmic drug delivery targeting the posterior segment of the eye has become a key area of interest due to its non-invasive nature, safety, ease of application, patient compliance, and cost-effectiveness. However, achievement of effective drug bioavailability in the posterior ocular segment is a significant challenge due to unique ocular barriers, including precorneal factors and anatomical barriers, like the cornea, the conjunctiva, and the sclera. Successful ocular drug delivery systems require increased precorneal residence time and improved corneal penetration to enhance intraocular bioavailability. A promising strategy to overcome these barriers is incorporating drug penetration enhancers (DPEs) into formulations. These compounds facilitate drug delivery by improving permeability across otherwise impermeable or poorly permeable membranes. At the ocular level, they act through three primary mechanisms: breaking tear film stability by interfering with the mucous layer; disrupting membrane components such as phospholipids and proteins; and loosening epithelial cellular junctions. DPEs offer significant potential to improve bioavailability and therapeutic outcomes, particularly for drugs targeting the posterior segment of the eye. This review is focused on analyzing the current literature regarding the use of penetration enhancers in topical ocular drug delivery, highlighting their mechanisms of action and potential to revolutionize ophthalmic treatments.

Antibacterial Lecithin/Chitosan Nanoparticles for the Sustained Release of Ciprofloxacin to Treat Ocular Bacterial Infections

Ocular drug-delivery is one of the most challenging areas owing to nature of ocular tissues. Various nanoformulations have been designed and investigated for drug-delivery to achieve high drug bioavailability. The major focus of these preparations available in market is to utilize nanomaterial as drug-carrier only, with less focus on developing functional-nanomaterials, which is a key knowledge gap in the field. To address this, we developed a nanoparticulate system from bioactive-polymers, having intrinsic antimicrobial and mucoadhesiveness, loaded with ciprofloxacin (cipro) to treat ocular bacterial infections. Cipro-loaded lecithin/chitosan nanoparticles were prepared and characterized for their physiochemical properties. They exhibited good drug loading efficiency and showed sustained drug-release for 72 h, with slow release for first 4 h followed by a burst release in phosphate buffered saline and simulated tear fluid. Cipro-loaded nanoparticles were assessed for their antibacterial potential against Staphylococcus aureus (96 %) and Pseudomonas aeruginosa (72 %) using optical density, disc-diffusion method, live-dead assay, and demonstrated promising antibacterial properties. The drug-loaded nanoparticles showed good cytocompatibility (~90 %) towards murine fibroblasts and rabbit corneal cells. Being amphiphilic in nature, the nanoparticles exhibited mucoadhesiveness, hemocompatibility (<4 %) and, thus, proving to be a promising candidate for treating ocular infections. This approach ensures efficient drug delivery and synergic/additive therapeutic effects.

Chitosan-based nanoarchitectures for siRNA delivery in cancer therapy: A review of pre-clinical and clinical importance

The gene therapy has been developed into a new cancer treatment option. Now that we know which molecular components contribute to carcinogenesis, we may use gene therapy to target particular signalling pathways in cancer treatment. Problems with gene therapy include genetic tool degradation in blood, off-targeting features, and inadequate tumor site accumulation; new delivery mechanisms are needed to address these issues. A polysaccharide made from chitin, chitosan has found extensive use in the creation of nanoparticles. The delivery of genes in the treatment of illnesses, particularly cancer, has made use of nanostructures modified with chitosan. Topics covered in this review center on cancer treatment using chitosan-based polymers for siRNA delivery. This study aims to assess the potential of chitosan nanoparticles for the simultaneous administration of siRNA and anti-cancer medications. In cancer treatment, these nanoparticles can transport phytochemicals or chemotherapeutics together with siRNA. In addition, chitosan nanoparticles loaded with siRNA can inhibit the growth and spread of human malignancies by delivering siRNA that targets particular genes. Chitosan nanoparticles loaded with siRNA can heighten the responsiveness of cancer cells. Future therapeutic applications of chitosan nanoparticles may open the path for cancer treatment, thanks to their biocompatibility and biosafety.

From Preformulative Design to In Vivo Tests: A Complex Path of Requisites and Studies for Nanoparticle Ocular Application. Part 1: Design, Characterization, and Preliminary In Vitro Studies

Ocular pathologies are widely diffused worldwide, and their effective treatment, combined with a high patient compliance, is sometimes challenging to achieve due to the barriers of the eye; in this context, the use of nanoparticles for topical ophthalmic application could represent a successful strategy. Aiming to develop nanoplatforms with potential clinical applications, great attention has to be paid to their features, in relation to the route of administration and to the pharmacopoeial requirements. This review (part 1) thus embraces the preliminary steps of nanoparticle development and characterization. At the beginning, the main barriers of the eye and the different administration routes are resumed, followed by a general description of the advantages of the employment of nanoparticles for ocular topical administration. Subsequently, the preformulative steps are discussed, deepening the choice of raw materials and determining the quantitative composition. Then, a detailed report of the physicochemical and technological characterization of nanoparticles is presented, analyzing the most relevant tests that should be performed on nanoparticles to verify their properties and the requisites (both mandatory and suggested) demanded by regulatory agencies. In conclusion, some preliminary noncellular in vitro evaluation methods are described. Studies from in vitro cellular assays to in vivo tests will be discussed in a separate (part 2) review paper. Hence, this overview aims to offer a comprehensive tool to guide researchers in the choice of the most relevant studies to develop a nanoplatform for ophthalmic drug administration.

From Preformulative Design to in Vivo Tests: A Complex Path of Requisites and Studies for Nanoparticle Ocular Application. Part 2: In Vitro, Ex Vivo, and In Vivo Studies

The incidence of ocular pathologies is constantly increasing, as is the interest of the researchers in developing new strategies to ameliorate the treatment of these conditions. Nowadays, drug delivery systems are considered among the most relevant approaches due to their applicability in the treatment of a great variety of inner and outer eye pathologies through painless topical administrations. The design of such nanocarriers requires a deep study of many aspects related to the administration route but also a consideration of the authorities and pharmacopeial requirements, in order to achieve a clinical outcome. On such bases, the scope of this review is to describe the path of the analyses that could be performed on nanoparticles, along with the assessment of their applicability for ophthalmic treatments. Preformulation studies, physicochemical and technological characterization, and preliminary noncellular in vitro studies have been described in part 1 of this review. Herein, first the in vitro cellular assays are described; subsequently, nonocular organotypic tests and ex vivo studies are reported, as to present the various analyses to which the formulations can be subjected before in vivo studies, described in the last part. In each step, the models that could be used are presented and compared, highlighting the pros and cons. Moreover, their reliability and eventual acceptance by regulatory agencies are discussed. Hence, this review provides an overview of the most relevant assays applicable for nanocarriers intended for ophthalmic administration to guide researchers in the experimental decision process.

Comment on Ma et al.'s "The Preventive Effect of Gentamicin in the Irrigating Solution on Endophthalmitis Caused by Methicillin-Resistant Staphylococcus epidermidis After Phacoemulsification with Intraocular Lens Implantation in Rabbits"

In their recent publication, the authors explored the preventive effect of gentamicin in the irrigating solution on endophthalmitis caused by methicillin-resistant Staphylococcus epidermidis (MRSE) after phacoemulsification with intraocular lens (IOL) implantation in rabbits. This letter commends the authors for their innovative approach and discusses the potential of chitosan-based intraocular lenses as a future solution for reducing the incidence of endophthalmitis. Chitosan's natural antibacterial properties, coupled with its capacity for sustained drug release and surface modification, make it a promising material for IOLs. This letter highlights recent advancements and suggests areas for further research to fully realize the potential of chitosan-based IOLs in ocular surgery.

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.

Impacts of designed vanillic acid-polymer-magnetic iron oxide nanocomposite on breast cancer cells

The engineered nano-vehicle was constructed using magnetic iron oxide nanoparticles (MIONs) and chitosan (CTS) to stabilize anticancer agent vanillic acid (VNA) which was loaded on CTS-coated MIONs nanocarrier, and more importantly, to achieve sustained VNA release and subsequent proper anticancer activity. The new thermally stable VNA-CTS- MIONs nanocomposite was spherical with a middle diameter of 6 nm and had a high drug loading of about 11.8 %. The MIONs and resulting nanocomposite were composed of pure magnetite and therefore, were superparamagnetic with saturation magnetizations of 53.3 and 45.7 emu.g-1, respectively. The release profiles of VNA from VNA-CTS-MIONs nanocomposite in different pH values were sustained and showed controlled pH-responsive delivery of the loaded VNA with 89 % and 74 % percentage release within 2354 and 4046 min at pH 5 and 7.4, respectively, as well as were in accordance with the pseudo-second-order model. The VNA-CTS-MIONs nanocomposite treatment at diverse concentrations remarkably decreased the viability and promoted ROS accumulation and apoptosis in the MDA-MB-231 breast cancer cells. Hence, it can be a propitious candidate for the management of breast cancer in the future.

Weaponizing chitosan and its derivatives in the battle against lung cancer

Lung cancer (LC) is a crisis of catastrophic proportions. It is a global problem and urgently requires a solution. The classic chemo drugs are lagging behind as they lack selectivity, where their side effects are spilled all over the body, and these adverse effects would be terribly tragic for LC patients. Therefore, they could make a bad situation worse, inflict damage on normal cells, and inflict pain on patients. Since our confidence in classic drugs is eroding, chitosan can offer a major leap forward in LC therapy. It can provide the backbone and the vehicle that enable chemo drugs to penetrate the hard shell of LC. It could be functionalized in a variety of ways to deliver a deadly payload of toxins to kill the bad guys. It is implemented in formulation of polymeric NPs, lipidic NPs, nanocomposites, multiwalled carbon nanotubes, and phototherapeutic agents. This review is a pretty clear proof of chitosan's utility as a weapon in battling LC. Chitosan-based formulations could work effectively to kill LC cells. If a researcher is looking for a vehicle for medication for LC therapy, chitosan can be an appropriate choice.

Moxifloxacin-loaded nanoparticles of thiolated xyloglucan for ocular drug delivery: Permeation, mucoadhesion and pharmacokinetic evaluation

The current study goal was to improve mucoadhesive potential and ocular pharmacokinetics of nanoparticles of thiolated xyloglucan (TXGN) containing moxifloxacin (MXF). Thiolation of xyloglucan (XGN) was achieved with esterification with 3-mercaptopropionic acid. TXGN was characterized by NMR and FTIR analysis. The nanoparticles of TXGN were prepared using ionic-gelation method and evaluate the antibacterial properties. TXGN and nanoparticles were determined to possess 0.06 and 0.08 mmol of thiol groups/mg of polymer by Ellman's method. The ex-vivo bioadhesion time of TXGN and nanoparticles was higher than XGN in a comparative assessment of their mucoadhesive properties. The creation of a disulfide link between mucus and TXGN is responsible for the enhanced mucoadhesive properties of TXGN (1-fold) and nanoparticles (2-fold) over XGN. Improved MXF penetration in nanoparticulate formulation (80 %) based on TXGN was demonstrated in an ex-vivo permeation research utilizing rabbit cornea. Dissolution study showed 95 % release of MXF from nanoparticles. SEM images of nanoparticles showed spherical shape and cell viability assay showed nontoxic behavior when tested on RPE cell line. Antibacterial analysis revealed a zone of inhibition of 31.5 ± 0.5 mm for MXF, while NXM3 exhibited an expanded zone of 35.5 ± 0.4 mm (p < 0.001). In conclusion, thiolation of XGN improves its bioadhesion, permeation, ocular-retention and pharmacokinetics of MXF.

Efficient drug delivery potential and antimicrobial activity of biocompatible hydrogels of dextrin/Na-alginate/PVA

Ceftriaxone sodium belongs to the third-generation cephalosporin group and is used intramuscular and intravenous route as a broad-spectrum antibiotic. This research aims to prepare biocompatible hydrogels for targeted delivery of ceftriaxone sodium by parental route. Different proportions of polymers (natural and synthetic) in the presence of cross-linker were synthesized by solvent casting method. Ceftriaxone sodium was loaded in hydrogels in different concentrations and its drug release behavior was evaluated along with swelling and biodegradation analysis. The characterization of hydrogel was done by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) to analyze surface morphology and functional groups involved in the formation of dextrin/Na-alginate/PVA hydrogels loaded with the drug. Thermogravimetric analysis (TGA) was confirmed by thermal stability and degradation pattern of loaded and unloaded hydrogels. The drug-loaded samples presented promising antimicrobial activity against S. aureus and P. multocida and their cytotoxic nature was also studied. Drug release analysis using simulated intestinal fluid (SIF) and phosphate buffer saline(PBS) for the circulatory system shows the consistent release of the drug. The findings unveiled the development of a biocompatible and innovative hydrogel, which has potential advantages for biomedical application, particularly in enhancing the therapeutic efficacy of ceftriaxone sodium drug.

Nanoparticles of Thiolated Xanthan Gum for the Oral Delivery of Miconazole Nitrate: In Vitro and In Vivo Evaluation

The objective of this research was to develop a mucoadhesive delivery system that improves permeation for the administration of poorly absorbed oral medications. Thiolation of xanthan gum (XGM) was carried out by esterification with mercaptobutyric acid. Fourier-transformed infrared spectroscopy was used to confirm thiol-derivatization. Using Ellman's technique, it was revealed that the xanthan-mercaptobutyric acid conjugate had 4.7 mM of thiol groups in 2 mg/mL of polymeric solution. Using mucosa of sheep intestine, the mucoadhesive properties of XGM and thiolated xanthan gum (TXGM) nanoparticles were investigated and we found that TXGM had a longer bioadhesion time than XGM. The disulfide link that forms between mucus and thiolated XGM explains why it has better mucoadhesive properties than XGM. A study on in vitro miconazole (MCZ) release using phosphate buffer (pH 6.8) found that TXGM nanoparticles released MCZ more steadily than MCZ dispersion did. A 1-fold increase in the permeation of MCZ was observed from nanoparticles using albino rat intestine compared to MCZ. Albino rats were used to test the pharmacokinetics of MCZ, and the results showed a 4.5-fold increase in bioavailability. In conclusion, the thiolation of XGM enhances its bioavailability, controlled release of MCZ for a long period of time, and mucoadhesive activity.