Nanozymes become currently a frontier of chemical research. However, exploiting a novel nanozyme with high activity, good stability and reproducibility is challenging. Here, size-controllable Fe-N/C nanozymes containing exclusive single Fe atoms coordinated Fe-N_x sites were succesfully prepared through a facile pyrolysis of size controllable Fe-Zn ZIFs precursors. The Fe-N/C nanozymes exhibit exceptional high oxidase-mimicking activity able to catalyze oxidation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) by dissolved oxygen to generate blue product. Their catalytic activities can be regulated by modulating the molar ratios of methanol to metal salts (e.g., Fe and Zn) through which the size controllable Fe-Zn ZIFs precursors are obtained. Upon introduction of ascorbic acid (AA) into Fe-N/C/TMB system, complete inhibition of TMB oxidation was observed, resulting in significant decline in absorbance with a clear color change. In the presence of alkaline phosphatase (ALP), ascorbic acid 2-phosphate (AAP) is hydrolyzed to produce ascorbic acid (AA). When coupled with AAP, a novel colorimetric biosensor platform was fabricated for ALP activity screening in the range of 0.05 U/L-100 U/L (four orders of magnitude) with an ultra-low limit of detection of 0.02 U/L. The work provides a promising strategy to rationally design the transition metal-N/C single-atom nanozyme with high oxidase-like activity.

纳米酶目前成为化学研究的前沿。然而，开发具有高活性，良好稳定性和可再现性的新型纳米酶是具有挑战性的。在此，含有排他的单个Fe原子的尺寸可控的Fe-N / C纳米酶与Fe-N _x配位通过大小可控的Fe-Zn ZIFs前体的轻松热解成功地制备了这些位点。Fe-N / C纳米酶表现出卓越的高氧化酶模拟活性，能够催化无色的3,3'，5,5'-四甲基联苯胺（TMB）被溶解的氧氧化，生成蓝色产物。可以通过调节甲醇与金属盐（例如，Fe和Zn）的摩尔比来调节其催化活性，通过该摩尔比可获得尺寸可控的Fe-Zn ZIFs前体。将抗坏血酸（AA）引入Fe-N / C / TMB系统后，观察到TMB氧化被完全抑制，导致吸光度显着下降，并具有明显的颜色变化。在碱性磷酸酶（ALP）的存在下，抗坏血酸2-磷酸（AAP）水解生成抗坏血酸（AA）。当与AAP结合使用时，制造了一种新型比色生物传感器平台，用于ALP活性筛查，范围为0.05 U / L-100 U / L（四个数量级），检测极限为超低0.02 U / L。这项工作为合理设计具有高氧化酶样活性的过渡金属-N / C单原子纳米酶提供了一个有前途的策略。