Anti-Bacterial Activity of Chitosan-Alginate-Poly (Vinyl Alcohol) Hydrogel Containing Entrapped Peppermint Essential Oil

Cryostructuring of Polymeric Systems: 67 Properties and Microstructure of Poly(Vinyl Alcohol) Cryogels Formed in the Presence of Phenol or Bis-Phenols Introduced into the Aqueous Polymeric Solutions Prior to Their Freeze-Thaw Processing

Poly(vinyl alcohol) (PVA) physical cryogels that contained the additives of o-, m-, and p-bis-phenols or phenol were prepared, and their physico-chemical characteristics and macroporous morphology and the solute release dynamics were evaluated. These phenolic additives caused changes in the viscosity of initial PVA solutions before their freeze-thaw processing and facilitated the growth in the rigidity of the resultant cryogels, while their heat endurance decreased. The magnitude of the effects depended on the interposition of phenolic hydroxyls in the molecules of the used additives and was stipulated by their H-bonding with PVA OH-groups. Subsequent rinsing of such "primary" cryogels with pure water led to the lowering of their rigidity. The average size of macropores inside these heterophase gels also depended on the additive type. It was found also that the release of phenolic substances from the additive-containing cryogels occurred via virtually a free diffusion mechanism; therefore, drug delivery systems such as PVA cryogels loaded with either pyrocatechol, resorcinol, hydroquinone, or phenol, upon the in vitro agar diffusion tests, exhibited antibacterial activity typical of these phenols. The promising biomedical potential of the studied nanocomposite gel materials is supposed.

Recent Development of Functional Chitosan-Based Hydrogels for Pharmaceutical and Biomedical Applications

Chitosan is a promising naturally derived polysaccharide to be used in hydrogel forms for pharmaceutical and biomedical applications. The multifunctional chitosan-based hydrogels have attractive properties such as the ability to encapsulate, carry, and release the drug, biocompatibility, biodegradability, and non-immunogenicity. In this review, the advanced functions of the chitosan-based hydrogels are summarized, with emphasis on fabrications and resultant properties reported in literature from the recent decade. The recent progress in the applications of drug delivery, tissue engineering, disease treatments, and biosensors are reviewed. Current challenges and future development direction of the chitosan-based hydrogels for pharmaceutical and biomedical applications are prospected.

Incorporation of Saqez essential oil into polyvinyl alcohol/chitosan bilayer hydrogel as a potent wound dressing material

Nowadays, many studies are conducted on multilayer hydrogels for wound dressing. On the other hand, considering the emergence of bacterial resistance to common antibiotics, studies on the use of natural essential oils and their derivatives that have antibacterial and antioxidant activity can be useful. Herein, a novel bilayer hydrogel developed from polyvinyl alcohol and chitosan with the incorporation of Saqez essential oil (SEO) was synthesized. The results showed a gel-type structure with specific compression and flexibility, while the microscopic images confirmed the formation of a bilayer hydrogel. Further, the data showed that increasing the concentration of SEO reduces the swelling and water vapor permeability and increases the water retention and hydrophobicity of the hydrogel surface. The effects of the combination of SEO in the bilayer hydrogel led to a strong antioxidant property and increased antimicrobial activity. Also, the in vitro results demonstrated that the bilayer hydrogels are biocompatible, non-toxic, and blood compatible. Finally, the results of the in vivo tests showed that these bilayer hydrogels had good homeostatic efficiency. Overall, the obtained results indicate that these bilayer hydrogels are promising candidates for wound dressing.