Paper-based microfluidic analytical devices (μPADs) have become promising alternatives to clinical laboratory-based methods for point-of-care testing (POCT) of biomarkers in family care and resource-limited communities. Here, Co-doped carbon dots (Co-CDs) nanozyme with outstanding oxidase-mimicking catalytic activity and red fluorescent emission were prepared, and combined adhered-3D μPAD (A-3D μPAD) to monitor facilely alkaline phosphatase (ALP) level in whole blood samples. Co-CDs catalyzed the oxidization of nonfluorescent o-phenylenediamine (OPD) into 2,3-diaminophenazine (oxOPD) with yellow fluorescent emission due to the generation of tremendous O2•- species. With addition of ALP, ALP hydrolyzed l-ascorbic acid 2-phosphate into ascorbic acid, and the latter was oxidized by Co-CDs, then reacted with OPD to form blue fluorescent emission 3-(dihydroxyethyl)furo [3,4-b]quinoxaline-1-one (DFQ). Both DFQ and oxOPD quenched the fluorescence intensity of Co-CDs via inner-filter effect. The cascade reaction of ALP/Co-CDs was incorporated into A-3D μPAD based on above sensing principles. A-3D μPAD enabled sample pretreatment, cascade reaction and signal output, and integrated portable minimized device and smartphone for visual ALP detection. The linear range and limit of detection for ALP were 0.5–150 U L−1 and 0.1 U L−1, respectively, and the color varied from red, yellow to blue. The detection results for whole blood samples were consistent with biochemical detector. The efficiency, disposability, practicality and low-cost of A-3D μPAD can be extended to determine various biomarkers, and provided technical support for nanozyme applications in POCT environments.

中文翻译：

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基于钴掺杂碳点纳米酶氧化酶模拟活性的粘附-3D 纸微流控分析装置，用于碱性磷酸酶的即时检测


在家庭护理和资源有限社区中，基于纸张的微流控分析设备 （μPAD） 已成为基于临床实验室的生物标志物即时检测 （POCT） 方法的有前途的替代方案。在这里，制备了具有出色氧化酶模拟催化活性和红色荧光发射的共掺杂碳点 （Co-CDs） 纳米酶，并结合粘附的 3D μPAD （A-3D μPAD） 来监测全血样品中的简单碱性磷酸酶 （ALP） 水平。Co-CDs 催化非荧光邻苯二胺 （OPD） 氧化成 2,3-二氨基吩嗪 （oxOPD），由于产生大量 O2•- 物质，具有黄色荧光发射。加入ALP，ALP将l-抗坏血酸2-磷酸水解成抗坏血酸，后者被Co-CDs氧化，然后与OPD反应生成蓝色荧光发射3-（二羟乙基）呋喃[3,4-b]喹喔啉-1-酮（DFQ）。DFQ 和 oxOPD 都通过内滤光片效应淬灭了 Co-CDs 的荧光强度。基于上述传感原理，将 ALP/Co-CDs 的级联反应掺入 A-3D μPAD 中。A-3D μPAD 支持样品预处理、级联反应和信号输出，并集成了便携式最小化设备和智能手机，用于视觉 ALP 检测。ALP 的线性范围和检测限分别为 0.5-150 U L-1 和 0.1 U L-1，颜色从红色、黄色到蓝色不等。全血标本检测结果与生化检测仪一致。A-3D μPAD 的效率、可处置性、实用性和低成本可以扩展到确定各种生物标志物，并为 POCT 环境中的纳米酶应用提供技术支持。