目的 采用成分"敲出法"结合表面元素分析法探究青黛低润湿性的关键影响因素，为调控改变青黛表面润湿性提供科学依据。方法 以N，N-二甲基甲酰胺为溶媒，采用超声法分别提取0~5次，每次提取30 min，滤过，干燥，制得6种有机物含量差异明显的青黛粉末。采用HPLC法测定6种青黛中靛蓝与靛玉红的含量，测定接触角、表面自由能及其分量、粒度，进行表面形貌及表面元素分析、红外光谱分析等指标，采用相关分析法探讨青黛有机物含量与润湿性的关系。结果 HPLC结果显示，随着提取次数的增加，靛蓝含量从3.320%下降至0.112%，靛玉红含量从0.120%下降至0.006%，在纯水中的接触角从53.56°下降至34.84°，表面自由能的极性分量从24.880 mJ/m²增加至38.701 mJ/m²，非极性分量变化不大，表面自由能总量从46.523 mJ/m²增加至62.240 mJ/m²。扫描电镜显示青黛表面的颗粒物逐步消失，表面变得光滑平整；能谱仪Mapping扫描显示，N元素逐步减少，Ca、Si元素略有增加；粒度分布、红外光谱变化不大；相关性分析显示，靛蓝、靛蓝与靛玉红含量之和与接触角呈显著正相关，含量越高，润湿性越差。结论 青黛有机物被敲出后，接触角、表面自由能极性分量与表面自由能总量显著增大，润湿性增加。附着于青黛表面的有机物是导致其低润湿性的关键影响因素，采用粉体表面改性技术改善其亲水性应针对有机物展开。

Objective To explore the key factors affecting the low wettability of Indigo Naturalis by using "knockout" method combined with surface element analysis, so as to provide scientific basis for regulating and changing the wettability of Indigo Naturalis. Methods Using N,N-dimethylformamide as solvent, six Indigo Naturalis powders were prepared by ultrasonic extraction for 0-5 times, 30 min for each time, filtration and drying process. The contents of indigo and indirubin in six kinds of Indigo Naturalis were determined by HPLC. The contact angle, surface free energy and its components, particle size, surface morphology, surface element analysis and infrared spectroscopy were determined. The relationship between the content of organic matter and wettability of Indigo Naturalis was discussed by correlation analysis. Results With the increase of extraction times, the content of indigo decreased from 3.320% to 0.112%, the content of indirubin decreased from 0.120% to 0.006%, the contact angle in pure water decreased from 53.56 degrees to 34.84 degrees, the polar component of surface free energy increased from 24.880 to 38.701 mJ/m², the non-polar component changed little, and the total surface free energy increased from 46.523 to 62.240 mJ/m². Scanning electron microscopy (SEM) showed that the particulate matter on the surface of Indigo Naturalis was gradually disappeared, and the surface became smooth; Mapping scanning by energy spectrometer showed that N element was gradually decreased, Ca and Si element were increased slightly; Particle size distribution and infrared spectrum changed little; Correlation analysis showed that the content of indigo, indigo and indirubin was positively correlated with the contact angle, and the higher the content, the worse the wettability. Conclusion The contact angle, polar component of surface free energy and total surface free energy of Indigo Natural was significantly increased after knockout, and the wettability was increased. Organic substances adhering to the surface of Indigo Naturalis were the key factors leading to its low wettability. To improve the hydrophilicity of Indigo Naturalis by powder surface modification technology, it is necessary to focus on organic substances.

国家自然科学基金资助项目（81773918）；国家重点研发计划——中医药现代化（2018YFC1707200）；成都中医药大学中药学学科特色创新科研团队（CXTD2018006）