Photo-responsive oxidase-like nanozymes are attractive and highly desirable because they can directly activate O₂ instead of using unstable and destructive H₂O₂ as oxidant and their activities are photo-switchable by turning light on or off. However, their practical applications are confronted with challenges such low photocatalytic efficiencies. Regulation of charge-carriers migration and separation efficiency is an efficient strategy to enhance photocatalytic performance. Herein, Au@NH₂-MIL-125(Ti) nanocomposite was constructed by loading Au nanoparticles on the NH₂-MIL-125(Ti) semiconductor for enhanced photocatalytic activity and explored as a photo-responsive oxidase-like mimic. Its oxidase-mimicking activity is about 3 times higher than that of the pristine NH₂-MIL-125(Ti) towards colorimetric substrate 3,3′,5,5′-tetramethylbenzidine (TMB) under light irradiation, probably due to the formation of Schottky barrier at the junction between the NH₂-MIL-125(Ti) and the Au nanoparticles. The enhanced charge transfer and separation in Au@NH₂-MIL-125(Ti) are verified by photoluminescence spectroscopy and photoelectrochemical experiments. Meanwhile, kinetic analysis demonstrates that the photo-responsive oxidase-like mimic exhibits lower K_m value (0.026 mM) and higher V_max (13.56 nM s⁻¹) than the natural horseradish peroxidase (K_m = 0.43 mM, V_max = 10 nM s⁻¹). Radical trapping experiments assured the ·OH and h⁺ were the major reactive species in the photocatalytic oxidations. Based on its photo-responsive oxidase-like activity and inhibition effect of cysteine, a green colorimetric platform with high sensitivity and selectivity was developed for cysteine detection, with a good linear relationship (1–10 μM) and a very low detection limit of 0.15 μM. This work may shed light on the development of MOF-based photo-responsive oxidase-like mimics for environmentally benign colorimetric biosensing.

光响应性氧化酶样纳米酶是有吸引力的并且是高度期望的，因为它们可以直接激活O ₂而不是使用不稳定和破坏性的H ₂ O ₂作为氧化剂，并且它们的活性可以通过打开或关闭光进行光切换。然而，它们的实际应用面临诸如低光催化效率的挑战。调节载流子迁移和分离效率是增强光催化性能的有效策略。这里，金@ NH ₂ -MIL-125（Ti）的纳米复合材料，构建通过加载的Au纳米颗粒上NH ₂-MIL-125（Ti）半导体具有增强的光催化活性，并被研究为一种光响应性氧化酶样模拟物。在光照射下，其对比色底物3,3'，5,5'-四甲基联苯胺（TMB）的模拟氧化酶活性比原始NH ₂ -MIL-125（Ti）高约3倍。NH ₂ -MIL-125（Ti）与Au纳米粒子之间的连接处的肖特基势垒 通过光致发光光谱和光电化学实验证实了Au @ NH ₂ -MIL-125（Ti）中增强的电荷转移和分离。同时，动力学分析表明，类似光反应性氧化酶的模拟物表现出较低的K _m值（0.026 mM）和较高的V_max（13.56 nM s ^-1）比天然辣根过氧化物酶（K _m = 0.43 mM，V _max = 10 nM s ^-1）。自由基捕获实验确保了·OH和h ⁺是光催化氧化中的主要反应物种。基于其类似光反应性氧化酶的活性和半胱氨酸的抑制作用，开发了一种用于半胱氨酸检测的具有高灵敏度和选择性的绿色比色平台，具有良好的线性关系（1-10μM）和非常低的检测限0.15微米 这项工作可能会为基于MOF的光敏性比色生物传感的基于MOF的光响应氧化酶样模拟物的开发提供启示。