Abstract:

The α-amylase & cellulase@ZIF-8 (A&C@ZIF-8) nanoparticles with good catalytic activity and thermal stability are fabricated by in situ growth method in bulk solution to couple with solvent extraction process for effective extraction of anthocyanins from black rice. In these nanoparticles, the encapsulated α-amylase and cellulase allow dissociation of plant cell wall via hydrolysis of the α-1,4 glycosidic bond and β-1,4 glycosidic bond. Meanwhile, due to the spatial confinement of ZIF-8 matrix, both enzymes can exhibit good thermal stability and solvent tolerance. The A&C@ZIF-8 nanoparticles show polygonal-spherical shape with average sizes of 405nm, and loading content of 18% for both enzymes. The immobilized α-amylase and cellulase in the A&C@ZIF-8 nanoparticles show good tolerance in environment with temperature higher than 72℃, with their activities respectively 33.2% and 247.3% higher than that of their free enzyme counterparts. By coupling the A&C@ZIF-8 nanoparticles with ethanol-water system for co-extraction of anthocyanins from black rice, the extracted amount of anthocyanins can reach 200.39mg/100g, showing an 26.3% increase as compared to the extraction only with ethanol-water system. This work provides a new strategy for the innovative design and fabrication of enzyme-immobilized functional materials for extraction of actives in plant cells.

Key words: enzyme immobilization, metal organic framework, anthocyanin, biocatalysis

摘要：

利用体相原位生长法制备了具有优良催化活性和稳定性的α-淀粉酶&纤维素酶@ZIF-8（A&C@ZIF-8）纳米颗粒，结合溶剂萃取过程，可实现黑米中花青素的有效提取。该纳米颗粒中的α-淀粉酶和纤维素酶能分别通过水解多糖链上的α-1,4糖苷键和β-1,4糖苷键来解离植物细胞壁。同时，由于ZIF-8框架良好的空间限域保护作用，这两种酶展现出良好的高温环境耐受性和有机溶剂耐受性。该纳米颗粒的平均粒径为405nm，呈现多角球形颗粒状，其对两种酶的总负载量为18%（质量分数）。A&C@ZIF-8纳米颗粒中的酶可耐受72℃的高温环境，此时α-淀粉酶和纤维素酶的活性分别比其游离酶高出33.2%和247.3%。此外，当利用A&C@ZIF-8纳米颗粒结合溶剂萃取过程进行花青素协同提取时，其每100g提取量达到了200.39mg/g，比仅利用溶剂萃取时的提取效果提升了26.3%。该工作为创新设计和构建用于植物细胞中活性物质提取的固定化酶复合功能材料提供了新策略。

关键词: 酶固定化, 金属有机框架, 花青素, 生物催化