The development of wearable detection devices that can achieve noninvasive, on-site and real-time monitoring of sweat metabolites is of great demand and practical significance for point-of-care testing and healthcare monitoring. Monitoring uric acid (UA) content in sweat provides a simple and promising way to reduce the risk of gout and hyperuricemia. Traditional bioenzyme based UA assays suffer from high cost, poor stability, inconvenience for storage and easy deactivation of bioenzymes. Wearable microfluidic colorimetric detection device for sweat UA detection has not been reported. The development of novel wearable microfluidic colorimetric detection chip with no requirement of bioenzymes for sweat UA detection is of great importance for health care monitoring. Firstly, Co@MnO nanozyme with high oxidase-like activity was synthesized and characterized. Co@MnO can catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) directly to generate blue-green colored ox-TMB. Green colored 2,2′-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) radical (ABTS) was produced by the oxidation of ABTS by potassium persulfate. UA exhibits distinct quenching effect on Co@MnO catalyzed TMB colorimetric reaction system and ABTS based colorimetric system, leading to obvious color fading of the two colorimetric systems. Then, a flexible microfluidic colorimetric detection chip for UA detection was fabricated by assembling Co@MnO/TMB modified paper chips and ABTS modified paper chips into a polydimethylsiloxane (PDMS) microfluidic chip. The fabricated microfluidic colorimetric detection chip exhibits good linear relationship for sweat UA detection. The linear range is from 20 to 200 μmol/L with detection limit as low as 6.6 μmol/L. Good results were obtained for the detection of UA in actual sweat from three volunteers. This work provides two bio-enzyme free colorimetric detection systems for UA detection. Furthermore, a simple, low-cost and selective flexible wearable microfluidic colorimetric detection chip was fabricated for noninvasive and on-site detection of sweat UA, which holds great application potential for personal health monitoring and point-of-care testing.

中文翻译：

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柔性微流控比色检测芯片集成ABTS·+和Co@MnO2纳米酶催化TMB反应体系，用于无生物酶检测汗液尿酸

开发可实现汗液代谢物无创、现场实时监测的可穿戴检测设备对于床旁检测和医疗保健监测具有巨大的需求和实际意义。监测汗液中的尿酸（UA）含量为降低痛风和高尿酸血症的风险提供了一种简单而有前景的方法。传统的基于生物酶的UA检测方法存在成本高、稳定性差、储存不便、生物酶易失活等问题。用于汗液UA检测的可穿戴微流控比色检测装置尚未见报道。开发无需生物酶的新型可穿戴微流控比色检测芯片进行汗液UA检测对于医疗保健监测具有重要意义。首先，合成并表征了具有高氧化酶活性的Co@MnO纳米酶。 Co@MnO可以直接催化3,3′,5,5′-四甲基联苯胺(TMB)的氧化生成蓝绿色的ox-TMB。绿色 2,2'-偶氮双-(3-乙基苯并噻唑啉-6-磺酸)自由基 (ABTS) 是通过过硫酸钾氧化 ABTS 产生的。 UA对Co@MnO催化的TMB比色反应体系和基于ABTS的比色体系表现出明显的猝灭作用，导致两个比色体系均出现明显的褪色。然后，通过将Co@MnO/TMB修饰纸芯片和ABTS修饰纸芯片组装到聚二甲基硅氧烷（PDMS）微流控芯片中，制备了用于UA检测的柔性微流控比色检测芯片。所制作的微流控比色检测芯片对于汗液UA检测表现出良好的线性关系。线性范围为 20 至 200 μmol/L，检测限低至 6.6 μmol/L。对三名志愿者实际汗液中UA的检测取得了良好的结果。本工作提供了两种用于UA检测的无生物酶比色检测系统。此外，还制作了一种简单、低成本、选择性柔性可穿戴微流控比色检测芯片，用于无创、现场检测汗液UA，在个人健康监测和即时检测方面具有巨大的应用潜力。