A new way to detect GAA trinucleotide repeats (TNRs) based on a solution-gated graphene transistor (SGGT) with high performance was developed. Friedreich's ataxia (FRDA) is a neurodegenerative disease where the first intron of the frataxin (FXN) gene exhibits an extended GAA repeat region. Herein, a SGGT biosensor was constructed based on G-quadruplex DNAzymes and graphene channels. The DNAzymes quantify the captured target DNA by producing a strong catalytic current signal depending on the peroxidase-like activity. The higher the target DNA quantity captured on the gate electrode is, the higher is the concentration of DNAzymes on the surface of the gate electrode, which generates a high catalytic current. Due to the excellent self-amplifying performance of the transistor, the current signal of the SGGT is several hundreds of times larger than in conventional electrochemistry under identical detection conditions. Moreover, a large current signal can be obtained in the case of a low concentration of H₂O₂ when compared to the case of an enzyme-catalyzed transistor. The SGGT biosensor also exhibits an ultra-low detection limit (32.25 fM), a wide linear range (100 fM–100 nM), and excellent selectivity. The results show that the SGGT biosensor has great potential in the early diagnosis of neurodegenerative diseases.

中文翻译：

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一种新型溶液门控石墨烯晶体管生物传感器，用于超灵敏地检测三核苷酸重复序列。

开发了一种新的基于溶液门控石墨烯晶体管（SGGT）的GAA三核苷酸重复序列（TNR）检测方法。Friedreich共济失调（FRDA）是一种神经退行性疾病，其中frataxin（FXN）基因的第一个内含子表现出扩展的GAA重复区域。在此，基于G-四链体DNA酶和石墨烯通道构建了SGGT生物传感器。DNAzyme通过产生强催化电流信号（取决于过氧化物酶样活性）来量化捕获的目标DNA。栅电极上捕获的目标DNA量越高，栅电极表面上DNA酶的浓度就越高，从而产生高催化电流。由于晶体管出色的自放大性能，在相同的检测条件下，SGGT的电流信号比常规电化学方法大数百倍。而且，在低浓度的H的情况下可以获得大电流信号与酶催化晶体管的情况相比为₂ O ₂。SGGT生物传感器还具有超低检测限（32.25 fM），宽线性范围（100 fM–100 nM）和出色的选择性。结果表明，SGGT生物传感器在神经退行性疾病的早期诊断中具有巨大的潜力。