目的 筛选多种常用的微针基质辅料，制备具有合适机械强度和柔韧性的载中华眼镜蛇神经毒素（neurotoxin，NT）可溶性微针（dissolvable microneedles，DMN）（DMN-NT），并对其进行体内外评价。方法 采用两步真空模板填充法制备不同材料构成的DMN，并对其进行力学特性分析，通过重量法对其吸湿性进行考察，利用正置显微镜对其形态特征进行考察，筛选最佳基质材料后制备DMN-NT，并对微针的载药量、机械性能、在体溶解、在体恢复、体外释放度、离体皮肤渗透与稳定性等进行评价。结果 针尖最佳基质材料为20%聚乙烯吡咯烷酮K90（PVP K90）和20%透明质酸（相对分子质量为10 000），背衬层最佳基质材料为7.5%羟丙基甲基纤维素（HPMC，E5LV型）和15%聚乙烯醇（PVA-0588）。正置显微镜和体式显微镜下观察发现DMN-NT针体垂直，排列整齐；每片DMN-NT的载药量为（172.22±1.30）μg或（17.38±0.57）μg；力学性能测试结果显示，DMN-NT针尖受力可达（39.88±3.09）N，大于微针穿刺皮肤所需的破坏力0.05 N，表明DMN-NT有较好的机械强度，亚甲基蓝染色实验结果表明微针具有较好的穿刺性；在体溶解实验结果显示，在10 min内DMN-NT大部分溶解；在体恢复实验结果为给药30 min后针孔痕迹几乎不见，表明DMN-NT的生物相容性好，安全性高；体外释放结果表明DMN-NT在pH值为7.4的PBS中8 min的累积释放率达（93.65±4.29）%；离体皮肤渗透结果显示，10 h后微针的累积药物渗透百分率达到（97.99±2.80）%，而药物水溶液中药物几乎没有透过皮肤；DMN-NT稳定性初步评价结果良好。结论 制备的DMN可以穿刺皮肤角质层，具有较好的溶解性和生物相容性，可以高效经皮递送大分子药物。

Objective To screen various commonly used microneedle matrix excipients and prepare dissolvable microneedles (DMN) with suitable mechanical strength and flexibility for delivering Chinese cobra (Naja atra Laurenti)-derived neurotoxin (NT). Methods The DMNs were prepared by using a two-step vacuum mold-filling method. Their morphological, mechanical and hygroscopic properties were characterized by upright microscope, texture analyzer and gravimetric method respectively to select the optimal matrix material. Then the DMN loaded with neurotoxin (DMN-NT) was prepared with the optimal matrix material, and the drug loading, mechanical properties, in vivo dissolving behavior, in vivo skin recovery, in vitro drug release, ex vivo transdermal permeation and stability of the DMN-NT were evaluated. Results The optimal matrix materials for the needle body were 20% of polyvinylpyrrolidone K90 (PVP K90) and 20% of hyaluronic acid (M_W 10 000), while the backing layer was composed of 7.5% of hydroxypropyl methyl cellulose (HPMC, E5LV) and 15% of polyvinyl alcohol (PVA-0588). Under the upright microscope and the stereomicroscope, the DMN-NT needles were arranged neatly and vertically. Each DMN-NT patch had a drug loading of (172.22 ±1.30) μg or (17.38 ±0.57) μg. The mechanical properties evaluation results showed that the pressure applied to the DMN-NT needle tip could reach (39.88 ±3.09) N, exceeding the force required (0.05 N) for microneedle to penetrate the skin, indicating good mechanical strength. The results of methylene blue staining experiments showed that the DMN-NT had desirable penetration property. In the in vivo dissolving experiment, most of the DMN-NT dissolved within 10 min. The in vivo recovery experiment showed that the trace in skin induced by DMN-NT were almost invisible 30 min after administration, indicating good biocompatibility and high safety. The in vitro release test results showed that the cumulative released percent of DMN-NT in PBS with pH 7.4 reached (93.65 ±4.29)% in 8 min. The results of the ex vivo skin permeation test showed that the transdermal permeated percent of neurotoxin from the DMNs reached (97.99 ±2.80)% after 10 h, while almost no drug permeated across the skin from the drug aqueous solution. The preliminary evaluation results of stability of the DMN-NT were acceptable. Conclusion The DMNs prepared in this study can penetrate the skin stratum corneum, have good dissolvability and biocompatibility, and can efficiently deliver macromolecular drugs transdermally.

R283.6

国家自然科学基金项目（82174096）；浙江省大学生创新训练项目（202310344055）