Macromol

The bulk radical copolymerization of N-vinylcaprolactam (VCL) and N-vinylimidazole (VI) initiated by 2,2′-azobisisobutyronitrile (AIBN) was investigated. The composition of the resulting amphiphilic copolymers is always enriched in VI units and is independent of the initiator concentration in the range from 0.001 to 0.1 mol L⁻¹. The reactivity ratios calculated at an AIBN concentration of 0.005 mol L⁻¹ (r_VI = 5.33 ± 0.58 and r_VCL = 0.21 ± 0.01) are practically identical to those previously obtained at 0.01 mol L⁻¹. The independence of the copolymer composition from the initiator concentration is due to the self-assembly of amphiphilic macromolecules formed during copolymerization.

This study investigates composition-microstructure-rheology-performance relationships in Carbopol-based emulgels and bigels containing different oils. Optical microscopy revealed polydisperse droplets in liquid paraffin, isopropyl myristate, and almond oil formulations, whereas cetyl alcohol systems exhibited larger, irregular birefringent particles with Maltese cross-like patterns. All formulations showed shear-thinning behavior and predominantly elastic responses (G′ > G″). Cetyl alcohol-based emulgels exhibited higher elastic moduli and viscosity than those containing other oils. Increasing Carbopol concentration from 0.5% to 1% enhanced elasticity and viscosity, while reducing viscosity losses during heating from 10 to 40 °C from 35 to 40% to 11–26%. Bigels containing 20% and 30% oleogel exhibited elastic moduli approximately 20% and 80% higher than the hydrogel, respectively, suggesting possible synergistic mechanical reinforcement. Correlation analysis revealed relationships between rheological parameters, drug release, and spreadability. Viscosities above approximately 150 Pa·s were associated with reduced drug release, while moderate viscosity favored a balance between structural integrity, spreadability, and release performance. The absence of visible changes after 12 months of storage was consistent with temperature-ramp rheology results, suggesting potential use as a preliminary screening tool for formulation stability. Overall, oil phase selection, phase structuring, and Carbopol concentration enable tailoring stable and functional emulgel and bigel formulations for pharmaceutical and cosmetic applications.

Bleeding remains a leading cause of death in trauma and surgery, which drives the search for effective local hemostatic materials. Chitosan is a promising candidate because of its biocompatibility, biodegradability, and intrinsic hemostatic activity, yet chitosan hydrogels remain poorly characterized in terms of hemocompatibility. This study assessed the hemocompatibility and hemostatic activity of chitosan hydrogels with varying degrees of crosslinking and their complexes with ficin. Hydrogels were synthesized using 1,4-butanediol diglycidyl ether and characterized by ζ-potential measurements. Hemocompatibility was evaluated through hemolysis, hemoglobin spectroscopy, erythrocyte cytoarchitecture, and lymphocyte viability assays. Ficin was immobilized by adsorption and covalent binding, and hemostatic properties were assessed via swelling and kinetic blood coagulation. The hydrogels showed a statistically significant inverse dose-dependent hemolytic effect, attributed to their low colloidal stability. In contrast, hemoglobin spectra, erythrocyte cytoarchitecture, and lymphocyte viability showed no statistically significant changes. Adsorption immobilization provided higher protein loading and proteolytic activity than covalent binding. Ficin-containing compositions significantly accelerated blood coagulation compared with pristine hydrogels. These findings confirm the potential of the developed hydrogels and their ficin complexes as hemocompatible hemostatic materials.