Entrapment of halloysite nanotubes (HNTs) loaded with enzyme, into a polymer matrix (PVA/Alg), is a way to produce an environment surrounding the adsorbed enzyme molecules which improves the enzyme properties such as storage and operational stability. Hence, in this study, we optimised the factors affecting lipase adsorption onto halloysite nanotubes including halloysite amounts (5, 42.5 and 80 mg), lipase concentrations (30, 90 and 150 µg/ml), temperatures (5, 20 and 35 °C) and adsorption times (30, 165 and 300 min). The optimal conditions were determined as an halloysite amount of 50 to 80 mg, a lipase concentration of 30 to 57 μg/ml, an adsorption temperature of 20 °C and an adsorption time of 165 min, which resulted in a specific activity and adsorption efficiency of 15,000 (U/g protein) and 70%, respectively. Then, lipase adsorbed under optimal conditions was entrapped in a PVA/Alg hydrogel. The formation mechanism of immobilized lipase was investigated by FESEM and FTIR. Subsequent entrapment of adsorbed lipase improved the lipase storage and operational stability. K m , V max , K cat and K cat / K m values showed an increase in the entrapped HNT-lipase performance in comparison with the free and adsorbed lipase.

中文翻译：

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吸附在埃洛石纳米管上并被包裹在聚乙烯醇/藻酸盐水凝胶中的脂肪酶的生化方面的增强：再利用最稳定的脂肪酶的策略

将加载有酶的埃洛石纳米管 (HNT) 捕获到聚合物基质 (PVA/Alg) 中是一种在吸附的酶分子周围产生环境的方法，从而改善酶的性质，例如储存和操作稳定性。因此，在本研究中，我们优化了影响埃洛石纳米管吸附脂肪酶的因素，包括埃洛石量（5、42.5 和 80 毫克）、脂肪酶浓度（30、90 和 150 µg/ml）、温度（5、20 和 35 °C） ) 和吸附时间 (30、165 和 300 分钟)。最佳条件为埃洛石用量50～80 mg，脂肪酶浓度30～57 μg/ml，吸附温度20℃，吸附时间165 min，得到比活性和吸附效率分别为 15,000（U/g 蛋白质）和 70%。然后，在最佳条件下吸附的脂肪酶被包裹在 PVA/Alg 水凝胶中。通过FESEM和FTIR研究了固定化脂肪酶的形成机制。随后吸附的脂肪酶的截留提高了脂肪酶的储存和操作稳定性。K m 、V max 、K cat 和K cat / K m 值显示与游离和吸附的脂肪酶相比，截留的HNT-脂肪酶性能增加。