关键词: 罗布麻, 纳米纤维素, 抗菌率, 体外凝血指数

Abstract: This study utilized natural Apocynum fiber from Xinjiang as the raw material to prepare Apocynum cellulose nanofibrils via an efficient and green 2,2,6,6, tetramethyl-1-piperidinyloxy(TEMPO)-mediated oxidation method. The key advantage of this method lies in its selective oxidation of the C6 primary hydroxyl groups of cellulose, converting them into negatively charged carboxyl groups. This transformation offers significant benefits. Furthermore, a composite cellulose nanofibrils (denoted as BC) was fabricated by impregnating the Apocynum cellulose nanofibrils with Bletilla striata polysaccharide solution. A comprehensive characterization was conducted to investigate the microstructure and functional properties of the Apocynum cellulose nanofibrils. Analyses using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) confirmed that the prepared Apocynum cellulose nanofibrils exhibited a fibrillated morphology with a small diameter, primarily distributed between 20–40 nm. The smallest average diameter of (22.74 ± 0.86) nm was achieved at a preparation temperature of 50 ℃. XRD patterns confirmed that the Apocynum cellulose nanofibrils maintained the cellulose I crystalline structure with a high crystallinity index after TEMPO oxidation, ensuring good mechanical strength. The FTIR spectrum showed a distinct absorption peak at approximately 1,600 cm⁻¹, corresponding to the asymmetric stretching vibration of -COO- groups, providing direct chemical evidence for the successful conversion of C6 hydroxyls to carboxylates. Antibacterial tests demonstrated that the Apocynum cellulose nanofibrils possessed significant antibacterial activity, which was concentration-dependent. The inhibition rates against Staphylococcus aureus and Escherichia coli exceeded 90% at Apocynum cellulose nanofibril concentrations of 80 mg/mL and 100 mg/mL, respectively. These tests comprehensively revealed the microstructure, antibacterial properties, and application potential of Apocynum cellulose nanofibrils. To explore practical applications, the Apocynum cellulose nanofibril was impregnated into Bletilla striata solutions of different mass concentrations to create composite materials with hemostatic potential. The composite prepared with a 10% Bletilla striata solution (BC 10) exhibited optimal hemostatic performance, showing a coagulation time of 161.3 s, an in vitro blood clotting index of 57.2%, and a hemolysis rate below 5%. Further increases in the Bletilla striata concentration beyond 10% did not significantly enhance the coagulation performance. These results indicate that the Bletilla striata-modified Apocynum cellulose nanofibril possesses effective in vitro coagulation properties and excellent blood compatibility. The developed composite material demonstrates promising potential for application in wound dressing and hemostatic fields.

Key words: apocynum, cellulose nanofibrils, antibacterial activity, in vitro coagulation index