Abstract:

Objective Currently, conventional hemostatic dressings have the problem of low hemostatic efficiency and are prone to adhere to the wound, causing secondary bleeding. Although chitosan exhibits excellent biocompatibility and antibacterial properties, its hemostatic performance still requires improvement. In order to address this issue, the hemostatic properties of chitosan using chemical modification and electrospinning technology is optimized, which holds significant theoretical and practical value for developing high-efficiency hemostatic materials. In this study, alkylated chitosan (N-CS)/polyvinyl alcohol (PVA) nanofiber membranes was prepared via electrospinning technology.
Method N-CS with varying degrees of substitution (6.25%-58.65%) and carbon chain lengths (C12/C18) was synthesized via reductive amination, and N-CS/PVA nanofiber membranes (NCP0-NCP4) was prepared by blending and electrospinning. In order to characterize the materials, FT-IR and elemental analysis were adopted to confirm the chemical modification. SEM was employed to observe the fiber morphology, while mechanical tests evaluated the membrane strength. Contact angle measurements analyzed hydrophilicity/hydrophobicity, and Zeta potential tests detected surface charge. Finally, in vitro blood clotting tests (WBCT) and cytotoxicity assays (MTT and fluorescence double staining) comprehensively assessed the hemostatic performance and biosafety.
Results Alkylation modification significantly enhanced the coagulation properties of chitosan. The degree of substitution of alkyl chitosan showed a dual effect on the coagulation performance. For alkyl chitosan in the same substitution degree range, the longer carbon chain length was beneficial to improve the coagulability of chitosan (C18>C12). With the increase of the substitution degree of alkyl, the coagulability of alkyl chitosan increased first and then decreased. It shows that the high substitution degree leads to excessive hydrophobicity, which is not conducive to the contact between the material and the blood, but prolonging the coagulation time. When the substitution degree of octadecyl chitosan was 19.60%, it showed the best coagulation effect, and the coagulation time was shortened to 68 s. In the performance test of N-CS/PVA nanofibrous membranes, the fiber diameter of nanofibrous membranes gradually decreased from 273.76 nm to 237.83 nm. Low amount of N-CS had good micro-morphology and mechanical properties. However, the excessive amount of N-CS led to the beading problem of the nanofiber membrane, and the mechanical strength decreased to (2.81±0.57) MPa. When the content of N-CS was 20%, it had better overall performance. Among them, the water contact angle was 68.5°, and the dynamic blood contact angle was less than 90°, which was both hemophilic and moderately hydrophobic. At the same time, when pH=7, the membrane shows a positive charge, it can adsorb negatively charged coagulation factors and thus promote coagulation, and the coagulation time is shortened by 39.50% compared with that of medical gauze. And the cytotoxicity test showed that the cell proliferation rate was more than 90%, demonstrating good hemostatic performance and biosafety.
Conclusion A highly efficient hemostatic N-CS/PVA nanofiber membrane was successfully developed by combining the synergistic effects of alkyl chain length and degree of substitution with electrospinning. Octadecyl chitosan with a moderate degree of substitution can significantly shorten the blood clotting time. When the N-CS content is 20%, the fiber morphology and mechanical strength are well balanced. The hemostatic efficiency is significantly better than that of conventional gauze, and the material has high biosafety, thus is suitable for emergency treatment of complex wounds. Future work needs to further verify its clinical applicability and long-term stability, and explore the combination with other bioactive factors to enhance multifunctionality.

Key words: alkylated chitosan, modification, electrospinning, hemostatic property, biosafety, hemostatic dressing, polyvinyl alcohol, reductive amination