Timely monitoring of circulating tumor DNA (ctDNA) in serum is meaningful for personalized diagnosis and treatment for lung cancer. Cheap and efficient point-of-care testing (POCT) has emerged as a promising method, especially in a low-resource setting. Herein, (i) a 3D pop-up paper-based POCT device was designed and manufactured via a cheap method; it was used for saving time and efficiently building a biosensor; (ii) a novel cobalt boride nanosheet (CoB NS) nanozyme with abundant groups was used for POCT dual-mode signal transduction and then a portable smartphone/pressure meter to readout; (iii) a user-friendly smartphone app was fabricated for achieving more convenient POCT. Detailly, the dual-mode signal generated was based on the CoB NS with peroxidase activity to catalyze a chromogenic agent to develop color and with catalase activity to catalyze decomposition of H₂O₂ to O₂. Density functional theory (DFT) and experimental results showed a good catalysis performance of the CoB NS via studying its five possible catalytic pathways, in which the metal Co is the catalytic active site center that acts as the electron donor and promotes electron transfer between the CoB NS and the adsorbed substrates. Benefiting from that, the proposed method showed good analytical ability in detecting ctDNA. Besides, its accuracy was valued by comparing it with the standard qPCR method to detect real samples from tumor cells and tumor-bearing mice, which showed a consistent result and potential practical applicability of the proposed method for POCT ctDNA. In general, this work not only provided a dual-mode POCT platform that could also be applied for other analytes but also first revealed the nanozyme properties of the CoB NS and inspired its new application from electrocatalysis, energy, etc. to biomedicine.

中文翻译：

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弹出式纸质生物传感器，用于基于具有双酶活性的新型 CoB 纳米片的双模式肺癌 ctDNA 测定和用于读数的便携式智能手机/气压计


及时监测血清中的循环肿瘤 DNA （ctDNA） 对肺癌的个体化诊断和治疗具有重要意义。廉价高效的即时检测 （POCT） 已成为一种很有前途的方法，尤其是在资源匮乏的环境中。在此，（i） 通过一种廉价的方法设计和制造了一种 3D 弹出式纸质 POCT 设备;它用于节省时间和有效地构建生物传感器;（ii） 使用具有丰富基团的新型硼化钴纳米片 （CoB NS） 纳米酶进行 POCT 双模式信号转导，然后使用便携式智能手机/压力计进行读数;（iii） 制造了一个用户友好的智能手机应用程序，以实现更方便的 POCT。详细地，产生的双模式信号基于 CoB NS，具有过氧化物酶活性，可催化显色剂显色，具有过氧化氢酶活性，可催化 H₂O₂ 分解为 O₂。密度泛函理论 （DFT） 和实验结果表明，通过研究 CoB NS 的 5 种可能的催化途径，其中金属 Co 是催化活性位点中心，充当电子供体，促进 CoB NS 与吸附底物之间的电子转移。得益于此，所提出的方法在检测 ctDNA 方面表现出良好的分析能力。此外，通过与标准 qPCR 方法进行比较来检测来自肿瘤细胞和荷瘤小鼠的真实样本，其准确性受到重视，这表明所提出的方法对 POCT ctDNA 具有一致的结果和潜在的实际适用性。 总的来说，这项工作不仅提供了一个双模式 POCT 平台，也可以应用于其他分析物，而且首次揭示了 CoB NS 的纳米酶特性，并激发了其从电催化、能源等到生物医学的新应用。