Construction of a CaHPO4-PGUS1 hybrid nanoflower through protein-inorganic self-assembly,and its application in glycyrrhetinic acid 3-O-mono-β-D-glucuronide preparation

Glycyrrhetinic acid 3-O-mono-b-D-glucuronide (GAMG), an important pharmaceutical intermediate and functional sweetener, has broad applications in the food and medical industries. A green and cost-effective method for its preparation is highly desired. Using site-directed mutagenesis, we previously obtained a variant of β-glucuronidase from Aspergillus oryzae Li-3 (PGUS1), which can specifically transform glycyrrhizin (GL) into GAMG. In this study, a facile method was established to prepare a CaHPO₄-PGUS1 hybrid nanoflower for enzyme immobilization, based on protein-inorganic hybrid self-assembly. Under optimal conditions, 1.2 mg of a CaHPO₄-PGUS1 hybrid nanoflower precipitate with 71.2% immobilization efficiency, 35.60 mg·g⁻¹ loading capacity, and 118% relative activity was obtained. Confocal laser scanning microscope and scanning electron microscope results showed that the enzyme was encapsulated in the CaHPO₄-PGUS1 hybrid nanoflower. Moreover, the thermostability of the CaHPO₄-PGUS1 hybrid nanoflower at 55°C was improved, and its half-life increased by 1.3 folds. Additionally, the CaHPO₄-PGUS1 hybrid nanoflower was used for the preparation of GAMG through GL hydrolysis, with the conversion rate of 92% in 8 h, and after eight consecutive runs, it had 60% of its original activity.     

基于SnO_2纳米花气体传感器快速检测牛奶中的单增李斯特菌

以单增李斯特菌特征性代谢物3-羟基-2-丁酮为检测靶点,水热法合成与之匹配的敏感材料,制备出单增李斯特菌特异检测半导体气体传感器。采用X射线衍射和透射电子显微镜手段对材料的结构和形貌进行表征。并分析传感器对3-羟基-2-丁酮标准气体的气敏性能及其在牛奶中单增李斯特菌的检测效果。结果表明,本研究合成的SnO_2材料为纳米花结构。制备出的单增李斯特菌特异检测半导体气体传感器对3-羟基-2-丁酮灵敏度高、响应恢复时间短、选择性和稳定性好。用于检测单增李斯特菌时,传感器的灵敏度与细菌浓度呈现出良好的线性关系,线性方程为lg(S-1)=0.198 3lg C-0.472 5(R~2=0.990 1)。本方法快速灵敏、操作简便,可用于食品中单增李斯特菌的快速检测。     

SnO2纳米花的水热合成及其光催化性能研究

采用简单水热法合成出了成分纯净、形貌良好、光催化性能优良的SnO2纳米花,并对合成产物进行物相分析、形貌观察、微观结构分析、比表面积测试及光催化性能测试.结果表明:该SnO2纳米材料形貌均一,呈花形,花片厚度为5 nm左右.合成产物为四方金红石相结构,成分纯净、结晶性好,比表面积大,对亚甲基蓝、甲基橙、罗丹明B、刚果红四种有机染料具有良好的光催化活性,降解时间短,降解率高.该合成产物作为光催化剂具有可重用性.