Microparticles based on natural and synthetic polymers for ophthalmic applications

Polymers and their engineered analogues for ocular drug delivery: Enhancing therapeutic precision

Ocular drug delivery is constrained by anatomical and physiological barriers, necessitating innovative solutions for effective therapy. Natural polymers like hyaluronic acid, chitosan, and gelatin, alongside synthetic counterparts such as PLGA and PEG, have gained prominence for their biocompatibility and controlled release profiles. Recent strides in polymer conjugation strategies have enabled targeted delivery through ligand integration, facilitating tissue specificity and cellular uptake. This versatility accommodates combined drug delivery, addressing diverse anterior (e.g., glaucoma, dry eye) and posterior segment (e.g., macular degeneration, diabetic retinopathy) afflictions. The review encompasses an in-depth exploration of each natural and synthetic polymer, detailing their individual advantages and disadvantages for ocular drug delivery. By transcending ocular barriers and refining therapeutic precision, these innovations promise to reshape the management of anterior and posterior segment eye diseases.

Applications of Natural, Semi-Synthetic, and Synthetic Polymers in Cosmetic Formulations

Cosmetics composed of synthetic and/or semi-synthetic polymers, associated or not with natural polymers, exhibit a dashing design, with thermal and chemo-sensitive properties. Cosmetic polymers are also used for the preparation of nanoparticles for the delivery of, e.g., fragrances, with the purpose to modify their release profile and also reducing the risk of evaporation. Besides, other cosmetically active nutrients, dermal permeation enhancers, have also been loaded into nanoparticles to improve their bioactivities on the skin. The use of natural polymers in cosmetic formulations is of particular relevance because of their biocompatible, safe, and eco-friendly character. These formulations are highly attractive and marketable to consumers, and are suitable for a plethora of applications, including make-up, skin, and hair care, and as modifiers and stabilizers. In this review, natural synthetic, semi-synthetic, and synthetic polymers are discussed considering their properties for cosmetic applications. Their uses in conventional and novel formulations are also presented.

Fractionation of direct dyes using modified vapor grown carbon nanofibers and zirconia in cellulose acetate blend membranes

In the textile industry, membrane technology has been widely employed for the exclusion of direct dyes. In this research paper, firstly vapor grown carbon nanofibers (VGCNFs) were functionalized with carboxylates group via piranha oxidation, and then series of CA/PEO-PPO-PEO triblock copolymers were prepared by blending with varying weight percentages of modified VGCNFs and Zirconia (ZrO₂). The structural morphologies of membranes were visualized by scanning electron microscope (SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM), which exhibits the dispersity of dual fillers in polymer matrix thus improving the microstructure of resultant membranes. The experimental data indicates that the modified VGCNF and ZrO₂ nanoparticles were shown increase hydrophilic character. The direct dyes rejection were successfully after filler addition, which were 96% (for Direct Red), 99% (for Direct Blue) and 93% (for Direct Orange). The membranes showed a better antifouling property even after several washing cycles along with improved biofouling property, both of these properties showed a better membrane life. As an outcome, this research could have been a great potential to be used to treat dyes in textile industry.

Metal-organic frameworks, NH2-MIL-88(Fe), as carriers for ophthalmic delivery of brimonidine

We have proposed a metal-organic framework (MOF), NH₂-MIL-88(Fe), as a novel carrier for topical drug delivery to the eye. The NH₂-MIL-88(Fe) particles were prepared via a solvothermal synthesis method and their structure was confirmed by powder X-ray diffraction, Fourier transform infrared analysis, thermogravimetric analysis, electron microscopy, and N₂ adsorption-desorption measurements. When brimonidine, an anti-glaucoma medicine, was encapsulated into NH₂-MIL(Fe)-88 (i.e., NH₂-MIL-88(Fe)/Br), the drug was loaded at 121.3 µg/mg and released in a sustained manner for up to 12 h. The NH₂-MIL-88(Fe)/Br exhibited mucoadhesive properties and remained on rabbit eyes for a period of up to 4 h. Consequently, a high concentration of brimonidine was found in tears for a prolonged period after the administration of NH₂-MIL-88(Fe)/Br, which resulted in a greater than two-fold increase in drug bioavailability and activity period compared with those of Alphagan P, which are brimonidine eye drops already approved for clinical use. Hence, NH₂-MIL-88(Fe) is suggested to be a promising carrier for topical delivery to the eye that provides enhanced bioavailability of ocular drugs.

STATEMENT OF SIGNIFICANCE

We suggest NH₂-MIL(Fe)-88, a type of metal-organic frameworks (MOFs), as delivery carriers of an ophthalmic drug, brimonidine. The NH₂-MIL(Fe)-88 particles possess a mucoadhesive property, hence prolonged retention in the preocular space when topically administered to the eye. The particles can also encapsulate the drug in their micro-pores, through which the drug can be released in a sustained manner. Therefore, when tested to rabbit eyes in vivo, the drug-loaded NH₂-MIL(Fe)-88 particles were shown to enhance the ocular drug bioavailability, as compared with Alphagan P, the marketed eye drops of brimonidine.

5-Fluorouracil nanoparticles inhibit hepatocellular carcinoma via activation of the p53 pathway in the orthotopic transplant mouse model

Biodegradable polymer nanoparticle drug delivery systems provide targeted drug delivery, improved pharmacokinetic and biodistribution, enhanced drug stability and fewer side effects. These drug delivery systems are widely used for delivering cytotoxic agents. In the present study, we synthesized GC/5-FU nanoparticles by combining galactosylated chitosan (GC) material with 5-FU, and tested its effect on liver cancer in vitro and in vivo. The in vitro anti-cancer effects of this sustained release system were both dose- and time-dependent, and demonstrated higher cytotoxicity against hepatic cancer cells than against other cell types. The distribution of GC/5-FU in vivo revealed the greatest accumulation in hepatic cancer tissues. GC/5-FU significantly inhibited tumor growth in an orthotropic liver cancer mouse model, resulting in a significant reduction in tumor weight and increased survival time in comparison to 5-FU alone. Flow cytometry and TUNEL assays in hepatic cancer cells showed that GC/5-FU was associated with higher rates of G0-G1 arrest and apoptosis than 5-FU. Analysis of apoptosis pathways indicated that GC/5-FU upregulates p53 expression at both protein and mRNA levels. This in turn lowers Bcl-2/Bax expression resulting in mitochondrial release of cytochrome C into the cytosol with subsequent caspase-3 activation. Upregulation of caspase-3 expression decreased poly ADP-ribose polymerase 1 (PARP-1) at mRNA and protein levels, further promoting apoptosis. These findings indicate that sustained release of GC/5-FU nanoparticles are more effective at targeting hepatic cancer cells than 5-FU monotherapy in the mouse orthotropic liver cancer mouse model.