We report a novel facile upconversion fluorescent and colorimetric dual-readout assay for H₂O₂ as well as H₂O₂-related analytes via enzyme-controlled cyclic signal amplification strategy. As a proof of application demonstration, the highly sensitive detection of choline and acetylcholine chloride (ACh) was performed. This sensing strategy involves the reaction of ACh with acetylcholinesterase (AChE) to generate choline which is followed catalytically oxidized by choline oxidase (ChOx) to produce H₂O₂. The generated H₂O₂ can transform Fe²⁺ to Fe³⁺ and free hydroxyl radical (OH). The as-produced Fe³⁺ and OH can simultaneously oxidize o-phenylenediamine (OPD) to 2,3-diaminophennazine (OPDox) and the Fe³⁺ was reduced to Fe²⁺. The Fe²⁺ produced from the redox processes between Fe³⁺ and OPD could be cycle used to generate OPDox that can significantly quench upconversion nanoparticles (UCNPs) fluorescence based on inner filter effects (IFE) and cause a visible change from colorless to yellow color. The phenomenon is further designed as a colorimetric logic gate. Moreover, we also detected H₂O₂, glucose, lactate and uric acid (UA) with the higher sensitivity by utilizing the assay strategy, which revealed the extensive applications of the proposed sensing strategy in biomedical analysis.

我们报告了通过酶控制的循环信号放大策略对H ₂ O ₂以及H ₂ O ₂相关分析物的新型简便上转换荧光和比色法双读数测定。作为应用演示的证据，对胆碱和乙酰胆碱氯化物（ACh）进行了高灵敏度检测。这种传感策略涉及ACh与乙酰胆碱酯酶（AChE）的反应生成胆碱，然后胆碱氧化酶（ChOx）催化氧化胆碱以生成H ₂ O ₂。产生的H ₂ O ₂可以将Fe ²⁺转变为Fe ³⁺和游离羟基（哦）。生成的Fe ³⁺和OH可同时将邻苯二胺（OPD）氧化为2,3-二氨基苯那嗪（OPDox），并将Fe ³⁺还原为Fe ²⁺。由Fe ³⁺和OPD之间的氧化还原过程产生的Fe ²⁺可以循环用于产生OPDox，该OPDox可以基于内部滤镜效应（IFE）显着淬灭上转换纳米粒子（UCNPs）荧光，并导致从无色到黄色的可见变化。 。该现象被进一步设计为比色逻辑门。此外，我们还检测到H ₂ O ₂，葡萄糖，乳酸盐和尿酸（UA）具有更高的灵敏度，这是通过利用该测定策略来进行的，从而揭示了所提出的传感策略在生物医学分析中的广泛应用。