Nanomaterials Laboratory, Catalysis & Fine Chemicals, CSIR-Indian Institute of Chemical Technology, Hyderabad 500 007, India.
ACS Appl Mater Interfaces. 2020 Oct 7;12(40):45476-45484. doi: 10.1021/acsami.0c11195. Epub 2020 Sep 22.
Designing a strategy for encasing enzymes and nanozymes in microreactors with spatial confinement in a way to improve the selectivity and activity of nanozymes is an exciting goal. In the present work, we report a facile route to encapsulate glucose oxidase (GOx) and poly(ethylenimine) (PEI)-conjugated magnetite nanoparticles (FeO-PEI) in the hollow interior of hybrid microreactors. The microreactors are prepared by polyallylamine hydrochloride (PAH)-mediated silica (SiO) nanoparticle assembly on calcium carbonate (CaCO) particles as a removable core. By tuning both shape and phase (vaterite/calcite and pure calcite) of CaCO, it allows generation of GOx and FeO-PEI-encapsulated silica hollow microspheres (GOx-FeO@SHS) and microcubes (GOx-FeO@SHC). As observed, in a biomimetic cascade catalysis, the confined GOx in the microreactors is able to catalyze oxidation of glucose to gluconic acid and hydrogen peroxide (HO), followed by the activation of HO by FeO-PEI for the oxidation of the chromogenic substrate -phenylenediamine (oPD) to 2,3-diaminophenazine. Comparison of the peroxidase-like activity of the encapsulated FeO-PEI shows that the hollow microspheres (GOx-FeO@SHS) result in activity 14 times higher than that of the hollow microcubes (GOx-FeO@SHC), which in turn is corroborated to the differential loading capacity of GOx in microspheres and microcubes. The evaluation of kinetic parameters indicates a fivefold increase in the catalytic constant () of FeO-PEI confined in hollow microspheres (GOx-FeO@SHS) compared to the mixture comprising free GOx and FeO-PEI in solution. It suggests that the confined space in the microreactors allows the tandem reactions of GOx and FeO-PEI to take place in close proximity, leading to an improved overall activity. This indeed is seen in the obtained for FeO@SHS (GOx added externally during the assay), which is 14 times lower than that of GOx-FeO@SHS.
设计一种策略，通过空间限制将酶和纳米酶封装在微反应器中，以提高纳米酶的选择性和活性，这是一个令人兴奋的目标。在本工作中，我们报告了一种简便的方法，将葡萄糖氧化酶（GOx）和聚（乙二胺）（PEI）修饰的磁铁矿纳米颗粒（FeO-PEI）封装在中空混合微反应器中。微反应器是通过聚烯丙基氯化铵（PAH）介导的二氧化硅（SiO）纳米颗粒在作为可去除核的碳酸钙（CaCO）颗粒上组装制备的。通过调节 CaCO 的形状和相（球霰石/方解石和纯方解石），可以生成 GOx 和 FeO-PEI 封装的二氧化硅中空微球（GOx-FeO@SHS）和微立方体（GOx-FeO@SHC）。如观察到的，在仿生级联催化中，微反应器中受限的 GOx 能够催化葡萄糖氧化为葡萄糖酸和过氧化氢（HO），然后由 FeO-PEI 激活 HO 以氧化显色底物 -苯二胺（oPD）为 2,3-二氨基吩嗪。比较封装的 FeO-PEI 的过氧化物酶样活性表明，中空微球（GOx-FeO@SHS）的活性比中空微立方体（GOx-FeO@SHC）高 14 倍，这反过来又与微球和微立方体中 GOx 的不同负载能力相符。动力学参数的评估表明，与游离 GOx 和 FeO-PEI 在溶液中的混合物相比，受限在中空微球中的 FeO-PEI 的催化常数（kcat）增加了 5 倍（GOx-FeO@SHS）。这表明微反应器中的受限空间允许 GOx 和 FeO-PEI 的串联反应在近距离发生，从而提高整体活性。在添加到测定中的外部 GOx 的 FeO@SHS（GOx@SHS）获得的 中确实可以看到这一点，其值比 GOx-FeO@SHS 低 14 倍。
