Abstract: Objective　To investigate the feasibility of silk nanofiber hydrogel (SNF) as drug carrier and the efficacy of silk nanofiber hydrogel-loaded asiaticoside(SNF-AC) combined with CO2 fractional laser in the treatment of hypertrophic scar. Methods　SNF-AC was prepared and characterized. Then, the rabbit ear hypertrophic scar model was constructed in vivo, and intervention was performed as follows: ①CO2 fractional laser combined with SNF-AC (L+SNF-AC group); ②CO2 fractional laser(L group) ③SNF-AC (SNF-AC group); ④blank control group(Control group). On day 7 and 14 after intervention, the thickness of hypertrophic scar was measured, the vascularity was evaluated, the histological morphology was observed by HE staining, and the arrangement of collagen fibers was observed by Masson staining. Results　The surface morphology and rheological behavior of SNF-AC were similar to that of silk nanofiber hydrogel, and the characteristic peak of Raman spectrum showed that asiaticoside could be successfully loaded into SNF. The relative thickness change value was L+SNF-AC group > L group > SNF-AC group > Control group on the 7th day after treatment. The difference between the L+SNF-AC group and the Control group was statistically significant, as well as the difference between the L group and the Control group. On the 14th day after treatment, the relative thickness change of L+SNF-AC group was higher than that of the other three groups, but there was no statistical difference among the groups. No matter on day 7 or day 14 after treatment, the vascularity change in L+SNF-AC group was significantly better than that in the other three groups, with statistical differences. HE staining of hypertrophic scar showed that on the 14th day after treatment, the surface of hypertrophic scar tended to be flat in the L+SNF-AC group, while the surface of hypertrophic scar in the other three groups were raised to varying degrees. Masson staining results showed that on the 14th day after treatment, collagen fibers in L+SNF-AC group and L group were flat and tended to normal tissue, while collagen fibers in SNF-AC group and Control group were disordered. Conclusion　SNF is suitable as a drug carrier for hypertrophic scar. And CO2 fractional laser combined with SNF-AC can reduce the thickness of hypertrophic scar and improve the vascular distribution of hypertrophic scar, which is an effective scar treatment method.

Key words: Silk nanofiber hydrogels, 　Laser-assisted transdermal drug delivery, 　CO2 fractional laser, 　Hypertrophic scar