Nanozymes-based optical sensors are widely used in the field of disease diagnosis, but most of the metal-based nanomaterials with peroxidase-like would not only require the addition of unstable and slightly toxic hydrogen peroxide but also often be affected by their own oxidase-like activity leading to the problems such as poor reproducibility and environmental pollution. Moreover, single-mode biosensors are subject to signal instability, which can lead to false-positive or false-negative results. Hence, we synthesized two three-component covalent organic frameworks (COFs) with the oxidase-like and ascorbate oxidase-like activities using benzo[1,2-b:3,4-b':5,6-b'']trithiophene-2,5,8-tricarboxaldehyde (BTT) and 1,3,5-tris(4-formylphenyl)benzene (TFPB) as the nodes, and 1,4-diaminobenzene (PA) and 4,4-diaminodiphenyl (BD) as the linker units. Both three-component COFs had narrow band gaps (2.16 eV and 2.27 eV), excellent electron transport properties, and high enzyme-like specific activities (4.32 U mg⁻¹ and 1.82 U mg⁻¹). Based on these, a colorimetric and ratiometric fluorescence dual-mode cascade catalytic platform was developed to detect the activity of alkaline phosphatase (ALP), a marker for diseases such as liver and bone. The constructed analytical methods had a detection limit as low as 0.10 U L⁻¹ and were successfully used to detect ALP levels in human serum. This work also provides a new idea for developing an efficient multimodal detection and evaluation platform using nanozymes based on novel COFs.

中文翻译：

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基于三组分共价有机框架的光激活双功能纳米酶，用于碱性磷酸酶的比色和比例荧光双模式检测


基于纳米酶的光学传感器在疾病诊断领域得到了广泛的应用，但大多数具有过氧化物酶样的金属基纳米材料不仅需要添加不稳定且略带毒性的过氧化氢，而且经常受到自身氧化酶样活性的影响，导致重现性差、环境污染等问题。此外，单模生物传感器容易受到信号不稳定的影响，这可能导致假阳性或假阴性结果。因此，我们以苯并[1,2-b：3,4-b'：5,6-b'']三噻吩-2,5,8-三甲醛（BTT）和1,3,5-三（4-甲酰基苯基）苯（TFPB）为节点，以1,4-二氨基苯（PA）和4,4-二氨基二苯（BD）为连接单元，合成了两个具有氧化酶样和抗坏血酸氧化酶样活性的三组分共价有机框架（COFs）。两种三组分 COF 均具有窄带隙（2.16 eV 和 2.27 eV）、优异的电子传递特性和高酶样比活性（4.32 U ^mg-1 和 1.82 U ^mg-1）。基于这些，开发了比色和比率荧光双模式级联催化平台来检测碱性磷酸酶 （ALP） 的活性，碱性磷酸酶 （ALP） 是肝脏和骨骼等疾病的标志物。构建的分析方法的检测限低至 0.10 U ^L-1，并成功用于检测人血清中的 ALP 水平。这项工作还为使用基于新型 COF 的纳米酶开发高效的多模式检测和评估平台提供了新思路。