Abstract：
Enzymatic biofuel cells have become powerful tools in biosensing, which however generally suffer from the limited loading efficiency as well as low catalytic activity and poor stability of bioenzymes. Herein, the hierarchical porous metal-organic frameworks (MOFs) are synthesized using tannic acid (TA) for structural etching, which realizes co-encapsulation of glucose dehydrogenase (GDH) and nicotinamide adenine dinucleotide (NAD+ ) cofactor in zeolitic imidazolate framework (ZIF-L) and are further used as the biocatalytic microreactors to modify bioanode. In this work, the TA-controlled etching can not only expand the pore size of microreactors, but also achieve the reorientation of enzymes in their lower surface energy form, therefore enhancing the biocatalysis of cofactor-dependent enzyme. Meanwhile, the topological DNA tetrahedron is assembled on the microreactors, which acts as the microRNA-responsive \"lock\" to perform the cascade signal amplification of exonuclease III-assisted target recycling on bioanode and hybridization chain reaction (HCR) on biocathode. The proposed self-powered biosensor has achieved a detection limit as low as 2 aM (6 copies miRNA-21 in a 5 µL of sample), which is further successfully applied to identify cancer cells and clinical serums of breast cancer patients based on the different levels of miRNA-21, holding great potential in accurate disease identification and clinical diagnosis.
摘要：
酶生物燃料电池已经成为生物传感的有力工具,然而,其通常遭受有限的负载效率以及低的催化活性和差的生物酶稳定性。在这里，使用单宁酸（TA）进行结构蚀刻，合成了分层多孔金属有机骨架（MOFs），它实现了葡萄糖脱氢酶（GDH）和烟酰胺腺嘌呤二核苷酸（NAD）辅因子在沸石咪唑酯框架（ZIF-L）中的共封装，并进一步用作生物催化微反应器来修饰生物阳极。在这项工作中,TA控制的刻蚀不仅可以扩大微反应器的孔径，而且还实现了低表面能形式的酶的重新定向，因此增强了辅因子依赖性酶的生物催化。同时,拓扑DNA四面体在微反应器上组装，它充当microRNA响应“锁”，以在生物阳极上执行外切核酸酶III辅助靶标再循环的级联信号扩增和在生物阴极上的杂交链反应（HCR）。拟议的自供电生物传感器已达到低至2aM的检测极限（5µL样品中有6个拷贝的miRNA-21），根据miRNA-21的不同水平，进一步成功地应用于乳腺癌患者的癌细胞和临床血清的鉴定，在准确的疾病鉴定和临床诊断中具有巨大的潜力。
