Luan Pan-Pan, Jiang Yan-Jun, Zhang Song-Ping, Gao Jing, Su Zhi-Guo, Ma Guang-Hui, Zhang Yu-Fei
National Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Science, Beijing 100190, China; School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, China.
School of Chemical Engineering and Technology, Hebei University of Technology, Tianjin 300130, China.
J Biosci Bioeng. 2014 Nov;118(5):575-82. doi: 10.1016/j.jbiosc.2014.05.003. Epub 2014 Jun 7.
Our work here, for the first time, reported the use of chitosan-mediated biomimetic silica nanoparticles in enzyme immobilization. In order to make clear the relationship among silicification process, silica nanoparticle structure and immobilized enzyme activity, a mechanism of chitosan-mediated silicification using sodium silicate as the silica source was primarily evaluated. Chitosan was demonstrated effectively to promote the silicification not only in accelerating the aggregation rate of sodium silicate, but also in templating the formation of silica nanoparticles. Although the whole biomimetic silicification process contained polycondensation-aggregation-precipitation three stages, the elemental unit in precipitated silica was confirmed to be nanoparticles with 100 nm diameter regardless of the chitosan and silicate concentration used. Furthermore, the effect of enzyme on silicification process was also investigated. The introducing of manganese peroxidase (MnP) to silica precursor solution had no obvious effect on the silicification rate and nanoparticle morphology. The residual activity and embedding rate of immobilized MnP were 64.2% and 36.4% respectively under the optimum conditions. In addition, compared to native MnP, the MnP embedded in chitosan/silica nanoparticles exhibited improved stability against organic solvent and ultrasonic wave. After ultrasonic treatment for 20 min, 77% of the initial activity was remained due to the protective effect of chitosan/silica nanoparticles, while native MnP lost almost all of its original activity.
我们在此的工作首次报道了壳聚糖介导的仿生二氧化硅纳米颗粒在酶固定化中的应用。为了明确硅化过程、二氧化硅纳米颗粒结构与固定化酶活性之间的关系，我们初步评估了以硅酸钠为硅源的壳聚糖介导硅化的机制。结果表明，壳聚糖不仅能有效促进硅化，加速硅酸钠的聚集速率，还能作为模板促进二氧化硅纳米颗粒的形成。尽管整个仿生硅化过程包含缩聚 - 聚集 - 沉淀三个阶段，但无论壳聚糖和硅酸盐的浓度如何，沉淀二氧化硅中的基本单元均被确认为直径为100纳米的纳米颗粒。此外，我们还研究了酶对硅化过程的影响。将锰过氧化物酶（MnP）引入二氧化硅前驱体溶液对硅化速率和纳米颗粒形态没有明显影响。在最佳条件下，固定化MnP的残余活性和包埋率分别为64.2%和36.4%。此外，与天然MnP相比，包埋在壳聚糖/二氧化硅纳米颗粒中的MnP对有机溶剂和超声波的稳定性有所提高。经过20分钟的超声处理后，由于壳聚糖/二氧化硅纳米颗粒的保护作用，仍保留了77%的初始活性，而天然MnP几乎失去了所有原始活性。
