Thermosensitive Chitosan-Containing Hydrogels: Their Formation, Properties, Antibacterial Activity, and Veterinary Usage

Resveratrol-loaded microemulsion based thermosensitive hydrogel for potential topical treatment of the vaginal inflammation

BACKGROUND

Vaginal inflammation is a prevalent gynecological condition. If left untreated, it can potentially spread to the urinary and reproductive systems.

METHODS

In this study, we propose a resveratrol-loaded microemulsion-based thermosensitive hydrogel (Res-Me-Tsgel) and compare it with a chitosan hydrogel-based Res-Me-Cogel. We characterized the different characters of Res-Me-Tsgel. The safety of Res-Me-Tsgel was also evaluated in vitro and in vivo. Finally, we measured the retention of Res in the vagina after drug administration.

RESULTS

The Res-Me-Tsgel we prepared is a transparent liquid solution at room temperature that rapidly forms a gel at 37oC. Compared to Res solution and Res-Me, both Res-Me-Cogel and Res-Me-Tsgel demonstrate superior sustained release properties. Both in vitro and in vivo studies confirm the excellent biosafety profile of Res-Me-Cogel and Res-Me-Tsgel. Vaginal administration of these formulations in rats results in prolonged retention of resveratrol within the vagina. Notably, due to its improved flow into vaginal folds after administration, the retention of Resveratrol was approximately three times higher for the Res-Me-Tsgel group compared to the Res-Me-Cogel group at 24 h post-administration. Overall, these findings highlight the potential application of Res-Me-Tsgel as an effective means for vaginal inflammation.

CONCLUSIONS

We developed a novel micromulsion based thermosensitive hydrogel for the delivery of Res. The sustained release of Res and favorable vaginal retention from Res-Me-Tsgel make them promise as a potential candidate for local intravaginal therapy.

Editorial on the Special Issue "Chitosan Functional Hydrogels: Synthesis and Applications"

Chitin, a polysaccharide composed of β-(1-4)-linked 2-deoxy-2-acetamido-d-glucose units, is found in cell walls of different organisms, including crustaceans, fungi, insects, some algae, microorganisms, and some invertebrate animals, and its deacetylation into chitosan confers it with incredible chemical versatility allowing it to be processed into numerous products [...].

A Comprehensive Review of Cross-Linked Gels as Vehicles for Drug Delivery to Treat Central Nervous System Disorders

Gels are attractive candidates for drug delivery because they are easily producible while offering sustained and/or controlled drug release through various mechanisms by releasing the therapeutic agent at the site of action or absorption. Gels can be classified based on various characteristics including the nature of solvents used during preparation and the method of cross-linking. The development of novel gel systems for local or systemic drug delivery in a sustained, controlled, and targetable manner has been at the epitome of recent advances in drug delivery systems. Cross-linked gels can be modified by altering their polymer composition and content for pharmaceutical and biomedical applications. These modifications have resulted in the development of stimuli-responsive and functionalized dosage forms that offer many advantages for effective dosing of drugs for Central Nervous System (CNS) conditions. In this review, the literature concerning recent advances in cross-linked gels for drug delivery to the CNS are explored. Injectable and non-injectable formulations intended for the treatment of diseases of the CNS together with the impact of recent advances in cross-linked gels on studies involving CNS drug delivery are discussed.

Evaluation of Physically and/or Chemically Modified Chitosan Hydrogels for Proficient Release of Insoluble Nystatin in Simulated Fluids

To avoid fungal spreading in the bloodstream and internal organs, many research efforts concentrate on finding appropriate candidiasis treatment from the initial stage. This paper proposes chitosan-based physically or chemically cross-linked hydrogels aimed to provide sustained release of micronized nystatin (NYSm) antifungal drug, known for its large activity spectrum. Nystatin was demonstrated itself to provide hydrodynamic/mechanic stability to the chitosan hydrogel through hydrophobic interactions and H-bonds. For chemical cross-linking of the succinylated chitosan, a non-toxic diepoxy-functionalized siloxane compound was used. The chemical structure and composition of the hydrogels, also their morphology, were evidenced by infrared spectroscopy (FTIR), by energy dispersive X-ray (EDX) analysis and by scanning electron microscopy (SEM), respectively. The hydrogels presented mechanical properties which mimic those of the soft tissues (elastic moduli < 1 MPa), necessary to ensure matrix accommodation and bioadhesion. Maximum swelling capacities were reached by the hydrogels with higher succinic anhydride content at both pH 7.4 (429%) and pH 4.2 (471%), while higher amounts of nystatin released in the simulative immersion media (57% in acidic pH and 51% in pH 7.4) occurred from the physical cross-linked hydrogel. The release mechanism by non-swellable matrix diffusion and the susceptibility of three Candida strains make all the hydrogel formulations effective for NYSm local delivery and for combating fungal infections.