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Label-free fluorescent and electrochemical biosensors based on defective G-quadruplexes
Biosensors and Bioelectronics ( IF 12.6 ) Pub Date : 2018-07-18 , DOI: 10.1016/j.bios.2018.07.033
Jing Zhang , Liang-Liang Wang , Mei-Feng Hou , Li-Pei Luo , Yi-Juan Liao , Yao-Kun Xia , An Yan , Yun-Ping Weng , Lu-Peng Zeng , Jing-Hua Chen

Abnormal levels of guanine closely associated with plenty of diseases are usually used as a biomarker for clinical diagnosis. In order to detect guanine and its derivatives accurately, in this paper, a defective G-quadruplex (DGQ) containing a G-vacancy at one of its G-quartet layers, and two kinds of G-quadruplex specific indicators including thioflavine T (ThT) and hemin were used for constructing a fluorescent and an electrochemical biosensor, respectively. In brief, a G-rich DNA probe is designed to form either hairpin or DGQ structure. In the absence of guanine, G-rich probes prefer to maintain hairpin structure and nearly have no interaction with ThT or hemin, leading to almost negligible signals. Upon addition of guanine, the G-rich probe fold into DGQ structure and then the G-vacancy in it is filled up immediately by guanine via Hoogsteen hydrogen bonds, resulting canonical G-quadruplex formation. Accordingly, ThT or hemin can selectively combine with G-quadruplex, giving rise to distinct fluorescent or current signal changes for label-free detection of guanine. Benefiting from the perfect discriminative ability of guanine towards DGQ and ThT/hemin against standard G-quadruplex, the fluorescent and electrochemical biosensors present better sensitivity and selectivity for guanine detection with the limit of detection (LOD) as low as 18.26 and 0.36 nM, respectively. Successful attempts were also made in applying the proposed electrochemical biosensor to detect guanine in drugs and urine, obtaining satisfactory recovery rates of 99~104% and 96~106%, respectively.



中文翻译:

基于有缺陷的G-四链体的无标记荧光和电化学生物传感器

与许多疾病密切相关的鸟嘌呤异常水平通常被用作临床诊断的生物标志物。为了准确检测鸟嘌呤及其衍生物,本文提出了一种缺陷的G-四链体(DGQ),该缺陷的G-四链体在其一个G-四链体层上具有一个G-空位,并且有两种G-四链体特异性指示剂,包括硫黄素T(ThT)。 )和血红素分别用于构建荧光和电化学生物传感器。简而言之,将富含G的DNA探针设计为形成发夹或DGQ结构。在缺乏鸟嘌呤的情况下,富含G的探针倾向于保持发夹结构,并且几乎不与ThT或血红素相互作用,从而导致几乎可以忽略的信号。加入鸟嘌呤后,富G的探针折叠成DGQ结构,然后鸟嘌呤通过Hoogsteen氢键立即填充其中的G空位,从而形成规范的G四联体。因此,ThT或血红素可以选择性地与G-四链体结合,从而产生明显的荧光或电流信号变化,从而实现鸟嘌呤的无标记检测。得益于鸟嘌呤对DGQ和ThT / hemin对标准G四联体的完美区分能力,荧光和电化学生物传感器对鸟嘌呤的检测具有更好的灵敏度和选择性,检出限(LOD)分别低至18.26和0.36 nM。 。在将拟议的电化学生物传感器应用于药物和尿液中鸟嘌呤的检测中,也取得了成功的尝试,分别获得了令人满意的99-104%和96〜106%的回收率。

更新日期:2018-07-18
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