Injectable hydrogels based on biopolymers for the treatment of ocular diseases.

Injectable hydrogels based on biopolymers, fabricated utilizing diverse chemical and physical methodologies, exhibit exceptional physical, chemical, and biological properties. They have multifaceted applications encompassing wound healing, tissue regeneration, and across diverse scientific realms. This review critically evaluates their largely uncharted potential in ophthalmology, elucidating their diverse applications across an array of ocular diseases. These conditions include glaucoma, cataracts, corneal disorders (spanning from age-related degeneration to trauma, infections, and underlying chronic illnesses), retina-associated ailments (such as diabetic retinopathy, retinitis pigmentosa, and age-related macular degeneration (AMD)), eyelid abnormalities, and uveal melanoma (UM). This study provides a thorough analysis of applications of injectable hydrogels based on biopolymers across these ocular disorders. Injectable hydrogels based on biopolymers can be customized to have specific physical, chemical, and biological properties that make them suitable as drug delivery vehicles, tissue scaffolds, and sealants in the eye. For example, they can be engineered to have optimum viscosity to be injected intravitreally and sustain drug release to treat retinal diseases. Their porous structure and biocompatibility promote cellular infiltration to regenerate diseased corneal tissue. By accentuating their indispensable role in ocular disease treatment, this review strives to present innovative and targeted approaches in this domain, thereby advancing ocular therapeutics.

Antiepileptic drug-loaded and multifunctional iron oxide@silica@gelatin nanoparticles for acid-triggered drug delivery.

The current study developed an innovative design for the production of smart multifunctional core-double shell superparamagnetic nanoparticles (NPs) with a focus on the development of a pH-responsive drug delivery system tailored for the controlled release of Phenytoin, accompanied by real-time monitoring capabilities. In this regard, the ultra-small superparamagnetic iron oxide@silica NPs (IO@Si MNPs) were synthesized and then coated with a layer of gelatin containing Phenytoin as an antiepileptic drug. The precise saturation magnetization value for the resultant NPs was established at 26 emu g-1. The polymeric shell showed a pH-sensitive behavior with the capacity to regulate the release of encapsulated drug under neutral pH conditions, simultaneously, releasing more amount of the drug in a simulated tumorous-epileptic acidic condition. The NPs showed an average size of 41.04 nm, which is in the desired size range facilitating entry through the blood-brain barrier. The values of drug loading and encapsulation efficiency were determined to be 2.01 and 10.05%, respectively. Moreover, kinetic studies revealed a Fickian diffusion process of Phenytoin release, and diffusional exponent values based on the Korsmeyer-Peppas equation were achieved at pH 7.4 and pH 6.3. The synthesized NPs did not show any cytotoxicity. Consequently, this new design offers a faster release of PHT at the site of a tumor in response to a change in pH, which is essential to prevent epileptic attacks.

Facile encapsulation of cyanoacrylate-based bioadhesive by electrospray method and investigation of the process parameters.

Polymer microcapsules containing cyanoacrylates have represented a promising option to develop self-healing biomaterials. This study aims to develop an electrospray method for the preparation of capsules using poly(methyl methacrylate) (PMMA) as the encapsulant and ethyl 2-cyanoacrylate (EC) as the encapsulate. It also aims to study the effect of the electrospray process parameters on the size and morphology of the capsules. The capsules were characterized using Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and field-emission scanning electron microscopy (FE-SEM). Moreover, the effects of electrospray process parameters on the size were investigated by Taguchi experimental design. FTIR and TGA approved the presence of both PMMA and EC without further reaction. FE-SEM micrograph demonstrated that an appropriate choice of solvents, utilizing an appropriate PMMA:EC ratio and sufficient PMMA concentration are critical factors to produce capsules dominantly with an intact and spherical morphology. Utilizing various flow rates (0.3-0.5 ml/h) and applied voltage (18-26 kV), capsules were obtained with a 600-1000 nm size range. At constantly applied voltages, the increase in flow rate increased the capsule size up to 40% (ANOVA, p ≤ 0.05), while at constant flow rates, the increase in applied voltage reduced the average capsule size by 3.4-26% (ANOVA, p ≤ 0.05). The results from the Taguchi design represented the significance of solution flow rate, applied voltage, and solution concentration. It was shown that the most effective parameter on the size of capsules is flow rate. This research demonstrated that electrospray can be utilized as a convenient method for the preparation of sub-micron PMMA capsules containing EC. Furthermore, the morphology of the capsules is dominated by solvents, PMMA concentration, and PMMA:EC ratio, while the average size of the capsules can be altered by adjusting the flow rate and applied voltage of the electrospray process.

Chitosan-based nanosystems for cancer diagnosis and therapy: Stimuli-responsive, immune response, and clinical studies.

Cancer, a global health challenge of utmost severity, necessitates innovative approaches beyond conventional treatments (e.g., surgery, chemotherapy, and radiation therapy). Unfortunately, these approaches frequently fail to achieve comprehensive cancer control, characterized by inefficacy, non-specific drug distribution, and the emergence of adverse side effects. Nanoscale systems based on natural polymers like chitosan have garnered significant attention as promising platforms for cancer diagnosis and therapy owing to chitosan's inherent biocompatibility, biodegradability, nontoxicity, and ease of functionalization. Herein, recent advancements pertaining to the applications of chitosan nanoparticles in cancer imaging and drug/gene delivery are deliberated. The readers are introduced to conventional non-stimuli-responsive and stimuli-responsive chitosan-based nanoplatforms. External triggers like light, heat, and ultrasound and internal stimuli such as pH and redox gradients are highlighted. The utilization of chitosan nanomaterials as contrast agents or scaffolds for multimodal imaging techniques e.g., magnetic resonance, fluorescence, and nuclear imaging is represented. Key applications in targeted chemotherapy, combination therapy, photothermal therapy, and nucleic acid delivery using chitosan nanoformulations are explored for cancer treatment. The immunomodulatory effects of chitosan and its role in impacting the tumor microenvironment are analyzed. Finally, challenges, prospects, and future outlooks regarding the use of chitosan-based nanosystems are discussed.

Encapsulation of Cerium Nitrate within Poly(urea-formaldehyde) Microcapsules for the Development of Self-Healing Epoxy-Based Coating.

In order to study the release of cerium nitrate in a self-healing epoxy-based coating, poly (urea-formaldehyde) (PUF) microcapsules containing cerium nitrate were synthesized. The effects of healing agent concentration and weight percent of microcapsules in the epoxy resin were studied through the incorporation of microcapsules within an epoxy-based coating. The prepared microcapsules were characterized using thermogravimetric analysis and Fourier transform infrared spectroscopy and confirmed the successful encapsulation of cerium nitrate within PUF capsules. The self-healing performance of the prepared epoxy coating was investigated in 0.6 M NaCl solution using electrochemical impedance spectroscopy (EIS) tests. The EIS results indicated the successful release of encapsulated cerium nitrate from PUF microcapsules once the damage occurred in the epoxy coating, which led to effective self-healing of the epoxy-based coating. The presence of chlorine and cerium ions in the solution led to the precipitation of cerium hydroxides and oxides in the scratched area as a passive layer which hindered the corrosion in the damaged area. In addition, the EIS results showed that the healing performance of the coatings depends on the weight percent of microcapsules and the concentration of the self-healing agent. The highest self-healing performance was achieved for the maximum amount of microcapsule incorporation (10 wt %), while the increase in the microcapsule percent led to a decrease in the adhesion of the coating to the substrate.

Effects of water absorption on the mechanical properties of hybrid natural fibre/phenol formaldehyde composites.

This investigation is carried out to understand the effects of water absorption on the mechanical properties of hybrid phenol formaldehyde (PF) composite fabricated with Areca Fine Fibres (AFFs) and Calotropis Gigantea Fibre (CGF). Hybrid CGF/AFF/PF composites were manufactured using the hand layup technique at varying weight percentages of fibre reinforcement (25, 35 and 45%). Hybrid composite having 35 wt.% showed better mechanical properties (tensile strength ca. 59 MPa, flexural strength ca. 73 MPa and impact strength 1.43 kJ/m2) under wet and dry conditions as compared to the other hybrid composites. In general, the inclusion of the fibres enhanced the mechanical properties of neat PF. Increase in the fibre content increased the water absorption, however, after 120 h of immersion, all the composites attained an equilibrium state.

The Effect of Carbon Black on the Properties of Plasticised Wheat Gluten Biopolymer.

Wheat gluten biopolymers generally become excessively rigid when processed without plasticisers, while the use of plasticisers, on the other hand, can deteriorate their mechanical properties. As such, this study investigated the effect of carbon black (CB) as a filler into glycerol-plasticised gluten to prepare gluten/CB biocomposites in order to eliminate the aforementioned drawback. Thus, biocomposites were manufactured using compression moulding followed by the determination of their mechanical, morphological, and chemical properties. The filler content of 4 wt% was found to be optimal for achieving increased tensile strength by 24%, and tensile modulus by 268% along with the toughness retention based on energy at break when compared with those of glycerol-plasticised gluten. When reaching the filler content up to 6 wt%, the tensile properties were found to be worsened, which can be ascribed to excessive agglomeration of carbon black at the high content levels within gluten matrices. Based on infrared spectroscopy, the results demonstrate an increased amount of ß-sheets, suggesting the formation of more aggregated protein networks induced by increasing the filler contents. However, the addition of fillers did not improve fire and water resistance in such bionanocomposites owing to the high blend ratio of plasticiser to gluten.