Mixtures of aqueous solutions of chitosan hydrochloride (CS·HCl, 1–4 wt.%) and Pluronic F-127 (Pl F-127, 25 wt.%) were studied using vibrational and rotational viscometry; the optimal aminopolysaccharide concentration (3 wt.%) and the CS·HCl:Pl F-127 ratio (30:70) to obtain a thermosensitive hydrogel were found. It was shown that at 4 °C, such mixed compositions were viscous liquids, while at 37 °C for 1–2 min, they undergo a thermally reversible transition to a shape-stable hydrogel with a developed level of structure formation, satisfactory viscosity and high mucoadhesive parameters (maximum pull-off force F_max = 1.5 kN/m²; work of adhesion W = 66.6 × 10⁻³ J). Adding D-ascorbic acid to the hydrogel led to orientational ordering of the supramolecular structure of the mixed system and significantly improved mucoadhesion (F_max = 4.1 kN/m², W = 145.1 × 10⁻³ J). A microbiological study revealed the high antibacterial activity of the hydrogel against Gram-negative and Gram-positive bacterial strains. The treatment of mixed bacterial infection in cows demonstrated the possibility of the in situ formation of a viscoelastic gel and revealed its high therapeutic effect. It has been suggested that our thermosensitive mucoadhesive CS·HCl:Pl F-127 hydrogels could be considered as independent veterinary drugs and pharmaceuticals.

The blood-brain barrier (BBB) is a physiological barrier that actively interacts between the circulatory system and the Central nervous system. Simulating the functioning of the BBB is one of the most important tasks. The result will have significance for not only fundamental science but also for applied science. It is known that the physiological permeability of the BBB is disturbed in various pathologies of the Central nervous system (ischemia, brain hypoxia, injuries and tumors, neurodegenerative diseases). Changes in permeability are selective and often with ineffective pharmacotherapy. Therefore, if scientists can simulate the barrier, they can conduct optimal studies of the efficiency of drugs. The simulated barrier is composed of membranes and three types of basic cells, astrocytes, endothelial cells, and pericytes. Several requirements are imposed on the membrane, such as the passage of water and small molecules, formation of close contact with cells, and control of large molecules passage. In this work, we use gelatin-based film for BBB imitation due to its high biocompatibility. Since gelatin is initially water-soluble, we modified it with methacrylate groups to make it able for cross-linking. Four modified gelatin membranes that differ in the degree of cross-linking were obtained by varying the concentration of photoinitiator methacrylate groups and the time of UV radiation. The obtained membranes were used to study their biological properties, immunohistochemistry, cell proliferation, and morphometry. It was shown, that membrane with an average degree of cross-linking demonstrated the optimal properties for cell adhesion and proliferation.