上转换-二氧化钛红外光催化降解呕吐毒素作用机理及产物安全性评价研究

Deoxynivalenol (DON) is a mycotoxin mainly produced by the fungi Fusarium graminearum. Many food crops are contaminated by DON, which leads to considerable damage to human health. Therefore, it has been an advanced research hotspot to control and degrade DON in food safety and quality control. Photocatalytic degradation is an oxidation technology with high efficiency and safety, and it has significant advantages in the application of DON degradation. TiO2 photocatalyst induced photocatalytic degradation only under UV radiation exposure, and the infrared light has not been used efficiently due to the limitation of band-gaps. Moreover, whether the products of photocatalytic degradation are safe to human and environment are yet unclear. Therefore, upconversion-TiO2 photocatalyst would be synthesized and its photocatalytic degradation behaviors would be studied under infrared light radiation exposure using DON as a model. All levels of degradation products of DON would be analyzed and identified. The process and mechanism of photocatalytic degradation of DON would be studied according to the structure of products. In addition, the cell models and animal models would be established. Whether the products of DON degradation have a harmful effect on intestinal cells and intestinal tissue would be illuminated by using technologies of cytotoxicology, immunohistochemistry, and physiology and pathology. Thus, the safety of the products of photocatalytic degradation can be evaluated. The research would provide theoretical basis and guidance for the application of photocatalysis technique for mycotoxins degradation.

呕吐毒素是小麦赤霉病病原菌禾谷镰刀菌产生的一种真菌毒素，会对粮食作物造成严重污染，并极大的危害人体健康。对呕吐毒素的阻控、降解成为食品质量安全控制研究的热点。光催化降解技术是一种高效、安全的氧化技术，将其应用于呕吐毒素的降解具有显著优势。但现有的二氧化钛光催化剂受到自身禁带宽度限制，仅能在紫外光辐照下进行催化反应，太阳能中红外光未得到有效利用；并且光催化降解呕吐毒素作用机制及产物的安全性尚不明确。本项目拟合成上转换-二氧化钛复合光催化剂，以呕吐毒素为降解模型，研究在红外光辐照下的光催化降解行为；分析鉴定呕吐毒素光催化后的各级降解产物，推导光催化反应历程，阐明降解作用机理；建立细胞模型和动物模型，通过细胞毒理实验、免疫组化法及生理病理学分析等技术，阐明呕吐毒素降解产物对肠道细胞的毒性作用和对肠道组织的损伤情况，评价产物安全性。本研究将为光催化技术在真菌毒素降解中的应用提供理论依据和指导。

真菌毒素会对粮食作物和食品造成严重污染，并极大的危害人体健康。为有效控制脱除真菌毒素，保障粮食食品安全，本课题开展了光催化降解真菌毒素的系统研究。首先成功构筑了一种新型核壳结构的NaYF4:Yb,Tm@TiO2纳米材料并进行表征，阐明了其在红外光辐照下启动光催化效应的机制。以粮食中的呕吐毒素（DON）为目标降解模型，组建光催化反应装置，经60分钟处理后新型光催化材料对DON的降解率达到95%以上，降解速率为常规TiO2的三倍。分析鉴定了呕吐毒素经光催化后的三种降解产物和结构（m/z=329.399、311.243和280.913）。建立了细胞模型和动物模型，通过细胞毒理分析、免疫组化分析及生理病理学分析等，证明了光催化降解产物细胞毒性显著下降为低毒甚至无毒；考察了降解产物对小鼠生长性能，脏器指数，血液学指标、血清生化指标，肠道组织氧化应激水平和紧密连接蛋白表达，肝脏、空肠组织病理情况以及小鼠肠道菌群变化，证明降解产物对小鼠的体内毒性大大降低，达到了预期消减控制目的。研究光催化过程对小麦品质的影响，结果显示光催化组小麦粉的营养品质变化与对照组无显著差异，而小麦粉的加工品质（色度，糊化特性）变化显著。此外，本课题还研究构建了一系列灵敏度高、适用性强、简便快捷的真菌毒素检测技术，包括适配体识别检测试纸条，DNA水凝胶荧光检测传感器，荧光-SERS双模式检测传感器，对于毒素的检测灵敏度达到0.01 ppb。结合生物分子识别和荧光成像手段，研究构建了新型纳米探针标记的细胞毒性评价方法，可更好的评估降解前后真菌毒素的毒性变化，为光催化降解技术的使用安全性提供证明。本课题研究建立了一种高效绿色光催化降解脱除呕吐毒素技术，并证明了其具有高降解效率和较好的使用安全性，进一步将该项技术与粮食储藏、食品加工环节结合，可以为粮食食品中真菌毒素等化学污染物的阻控消除提供新策略新方法。