The high catalytic efficiency of enzyme cascade reaction mainly depends on optimal interenzyme distance regulated by the special scaffolds. In this work, the rigid PtNPs with different sizes were employed as scaffolds to regulate interenzyme distance for efficient enzyme cascade amplification to construct electrochemical biosensor for sensitive detection of matrix metalloproteinases-2 (MMP-2), which overcame the drawbacks of instable construction and sophisticated preparation induced by conventional scaffolds such as metal–organic frameworks (MOFs), DNA nanostructures. Here, cucurbit[7]uril functionalized PtNPs (CB[7]@PtNPs) was utilized to load ferrocene (Fc)-labeled horseradish peroxidase (HRP) and glucose oxidase (GOx) via host–guest interaction between Fc and CB[7], respectively, resulting in the formation of a stable three-dimensional netlike structure containing amounts of enzymes. Interestingly, the enzyme cascade reaction regulated by 10 nm PtNPs as scaffold showed highly catalytic efficiency. Meanwhile, the PtNPs could also serve as catalyst to accelerate the enzyme cascade reaction with further enhanced catalytic efficiency. As a result, the proposed biosensor exhibited excellent sensitivity with a wide linear range of 0.1 pg·mL^–1 to 20 ng·mL^–1 and a detection limit of 0.03 pg·mL^–1 for MMP-2. Such a strategy opened a new avenue for adopting metal nanoparticles to regulate interenzyme distance for efficient enzyme cascade amplification, thus providing a universal and easy operating method for sensitively detecting various targets such as DNA, metal ion, and protein.

中文翻译：

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PtNPs作为支架调节酶间距离，以构建高效的酶级联扩增，用于MMP-2的超灵敏电化学检测。

酶级联反应的高催化效率主要取决于特殊支架调节的最佳酶间距离。在这项工作中，使用不同大小的刚性PtNPs作为支架来调节酶间距离，以有效地进行酶级联扩增，从而构建了用于敏感检测基质金属蛋白酶2（MMP-2）的电化学生物传感器，克服了结构不稳定和复杂的缺点。由常规支架（如金属有机框架（MOF），DNA纳米结构）诱导的制备。在这里，葫芦[7]尿嘧啶功能化的PtNP（CB [7] @PtNPs）被用来通过Fc和CB之间的客体相互作用来装载二茂铁（Fc）标记的辣根过氧化物酶（HRP）和葡萄糖氧化酶（GOx）。 ， 分别，导致形成稳定的三维网状结构，其中包含一定数量的酶。有趣的是，由10 nm PtNPs作为支架调节的酶级联反应显示出很高的催化效率。同时，PtNPs还可以作为促进酶级联反应的催化剂，进一步提高催化效率。结果，所提出的生物传感器在0.1 pg·mL的宽线性范围内表现出优异的灵敏度。MMP-2的检测限为^–1至20 ng·mL ^–1，检测限为0.03 pg·mL ^–1。这种策略为采用金属纳米颗粒调节酶间距离以有效地进行酶级联扩增开辟了一条新途径，从而为灵敏地检测各种靶标（例如DNA，金属离子和蛋白质）提供了一种通用且简便的操作方法。